Dissertations / Theses on the topic 'Queer ecology'

This thesis seeks to bridge feminist and environmental justice movements through the literature of black women writers. These writers create an archive that contribute towards the liberation of queer, black, and transgender peoples. In the novel Parable of the Talents, Octavia Butler constructs a world that highlights the pervasive effects of climate change. As climate change expedites poverty, Americans begin to blame others, such as queer people, for the destruction of their country. Butler depicts the dangers of fundamentalism as a response to climate change, highlighting an imperative for a movement that does not romanticize the environment as heteronormative, but a space where queers can flourish. Just as queer and environmental justice movements are codependent on one another, feminist movements cannot be separate from black and transgender liberation. This thesis will demonstrate how writers, such as Audre Lorde, Toni Morrison, Angela Davis, and Janet Mock, help establish a feminism that resists the erasure of black and transgender people.

This thesis is a botanical reading of Chaucer’s Merchant’s Tale. Focusing on the climactic scene in which May, the young bride of January, declares her “sore” desire for “smale peres green” before engaging in adulterous sex with her husband’s servant, Damian, I intersect object-oriented ontological theory with aspects of medieval botany to garner an understanding of Chaucer’s ecological thought. Through this approach, I find that Chaucer demonstrates sensitivity to what Timothy Morton and Mel Chen describe as “queer ecology”: an emerging branch of eco-theory which explores queer challenges to heteronormativity in non-human ecologies and objects. In this way, Chaucer presents an important challenge to the church definitions of “Nature”—particularly as it was defined in Thomas Aquinas’s Summa Theologicae—that emerged during the thirteenth century. Thus, this thesis contributes to ongoing studies of animacy and non-human ecologies in medieval literature and complicates Timothy Morton’s exclusion of non-moderns from contemporary ecological theory.
Arts, Faculty of
English, Department of
Graduate

Potential alliances between queers and animals populate queer scholarship, while dominant culture has relegated both groups to similar sites of subjugation and abjection. My work presents utopic visions crafted from these shared sites of marginalization and asks how they can enable new biopolitical communities. I ask: can we co-habitate, with non-human animals, these particular sites of marginalization in a manner that enables cross-species, affective solidarity? And can this co-habitation also encourage ruptures within heteronormative and human-centric paradigms? Rescuing the subjectivity and cultures of animals from extent subjugations can build new multispecies communities that are essential in an era of environmental devastation and climate change. Through printmaking, installation and time-based media, I explore real, psychological and metaphorical environments of cross-species encounters.

Resumen Natural Hysteria... es una investigacio'n basada en una pra'ctica transdisciplinaria que documenta el proceso de produccio'n de un ciclo de performances basadas en el texto: rituales, presentaciones teatrales, acciones callejeras y presentaciones de video, canciones y talleres. Es una respuesta arti'stica al deterioro de nuestro medio ambiente y los ataques contra la diversidad cultural y biolo'gica que esta'n llevando a cabo un sistema capitalista basado en la acumulacio'n de riqueza a toda costa que nos esta' llevando al borde de un colapso ecolo'gico. Se procede a trave's de un ana'lisis de otras pra'cticas arti'sticas disidentes que comparten una perspectiva queer, feminista, postcolonial o ecolo'gica que las vincula a los conceptos explorados en mi trabajo para contextualizarlo en el campo expandido de las artes contempora'neas. La "histeria" alternativa que forma la base conceptual de este proyecto tiene sus inicios en los albores de la edad moderna y traza una historia de dominacio'n de los "otros": se centra principalmente en las mujeres, en el ge'nero y en los disidentes sexuales, las personas de color y los animales. La explotacio'n de los recursos naturales y humanos es una consecuencia de una cosmovisio'n basada en el establecimiento de oposiciones binarias que permiten que el "otro" sea clasificado y dominado. Por ejemplo: hombre / mujer, blanco / negro, hetero / homosexual, cultura / naturaleza. La construccio'n de estos "otros" - "femenino", "nativo", "queer", "naturaleza" - excluye a estos sujetos de la construccio'n de una identidad dominante que, sin embargo, depende de estas categori'as para su existencia. En el Renacimiento, los campos de las ciencias y las humanidades no estaban separados. La visio'n mecanicista del mundo no habi'a superado por completo las creencias paganas en la magia y en una fuerza espiritual que reside en todos los seres. Esta visio'n era una reliquia de la era precristiana y finalmente seri'a erradicada por las fuerzas unidas del Estado y la Iglesia a trave's de los procesos de la Inquisicio'n, la caza de brujas, la colonizacio'n y la nueva religio'n de la "Ciencia". Todos estos procesos han producido un gran cambio en nuestra relacio'n con la naturaleza, que en la actualidad se considera una entidad totalmente inerte. La naturaleza ya no forma parte de nuestro ser y se ha convertido simplemente en materia prima. La colonizacio'n continu'a hoy bajo una poli'tica neoliberal que utiliza el concepto de desarrollo para requisar territorio de los pueblos indi'genas a fin de explotar sus recursos naturales. Esto se justifica clasificando estas personas como primitivas porque su modo de vida se basa en vivir en equilibrio con la naturaleza. La funcio'n de una pra'ctica arti'stica poli'ticamente comprometida es desafiar la nocio'n de que no existe una alternativa al sistema actual. El marco teo'rico y arti'stico de esta investigacio'n ha conducido al desarrollo de un alter ego performativo, el chama'n transge'nero Geyserbird, y a la configuracio'n de una serie de performances que incluye rituales participativos, instalaciones con presencia y la reapropiacio'n queer de espacios industriales abandonados. El chama'n transge'nero es un ser espiritual que va ma's alla' de las limitaciones del sistema de ge'nero binario y se conecta con las culturas indi'genas. El despliegue de esta figura en un contexto contempora'neo invita al pu'blico a imaginar otras posibilidades para si' mismos y para nuestra sociedad.
Abstract Natural Hysteria... is a trans-disciplinary practice led investigation which documents the process of production of a cycle of text based performances -rituals, street actions, theatrical presentations, and video presentations, songs and workshops. It is an artistic response to the deterioration of our environment and the attacks on cultural and biological diversity being carried out by a capitalist system based on the accumulation of wealth at all costs which is leading us to the border of an ecological collapse. It proceeds through an analyses of other dissident artistic practices which share a queer, feminist postcolonial or ecological perspective linking them to the concepts explored in my work in order to contextualise it in the expanded field of the contemporary arts. The alternative "hysteria" that forms the conceptual basis of this project has its beginnings in the dawn of the modern age and traces a history of domination of those "others": focusing mainly on women, gender and sexual dissidents, people of colour and animals. The exploitation of natural and human resources is a consequence of a worldview based on the establishment of binary oppositions that allow the "other" to be classified and dominated. For example: man / woman, white / black, hetero / homosexual, culture / nature. The construction of these "others" - the "feminine", the "native", the "queer", "nature" - excludes these subjects from the construction of a master identity that, nevertheless, depends on these categories for its existence. In the Renaissance the fields of the sciences and the humanities were not separated. The mechanistic view of the world had not completely overcome pagan beliefs in magic and in a spiritual force which resides in all beings. This vision was a relic of the pre-Christian era and would finally be eradicated by the united forces of State and Church through the processes of the Inquisition, the witch hunts, colonization and the new religion of "Science". All of these processes have produced a huge change in our relationship with nature, currently seen as a totally inert entity. Nature is no longer part of our being and has became nothing more than raw material. Colonisation continues today under a neoliberal politics which uses the concept of development to requisition territory from indigenous people in order to exploit its natural resources. This is justified by qualifying these people as primitive because their way of life is based on living in equilibrium with nature. The function of a politically engaged artistic practise is to challenge the notion that no alternative exists to the current system. The theoretical and artistic framework of this investigation has led to the development of a performative alter ego, the transgender shaman Geyserbird, and to the configuration of a series of performances which included participatory rituals, installations with presence and the queer appropriation of abandoned industrial spaces. The transgender shaman is a spiritual being who goes beyond the limitations of the binary gender system and connects to indigenous cultures. The deployment of this figure in a contemporary context, invites the public to imagine other possibilities for themselves and for our society
Resum Natural Hysteria... e's una investigacio' basada en una pra¿ctica transdisciplina¿ria que documenta el proce's de produccio' d'un cicle de performances basades en el text: rituals, presentacions teatrals, acciones al carrers i presentacions de vi'deo, canc¿ons i tallers. E's una resposta arti'stica a la deteriorament del nostre medi ambient i els atacs contra la diversitat cultural i biolo¿gica que esta¿ duent a terme un sistema capitalista basat en l'acumulacio' de riquesa costi el que costi que ens esta¿ portant a la vora d'un col·lapse ecolo¿gic. Es procedeix a trave's d'una ana¿lisi d'altres pra¿ctiques arti'stiques dissidents que comparteixen una perspectiva queer, feminista, postcolonial o ecolo¿gica que les vincula amb els conceptes explorats en el meu treball per contextualitzar-ho en el camp expandit de les arts contempora¿nies. La "histe¿ria" alternativa que forma la base conceptual d'aquest projecte te' els seus inicis en les albors de l'edat moderna i trac¿a una histo¿ria de dominacio' dels "altres": se centra principalment en les dones, en el ge¿nere i en els dissidents sexuals, les persones de color i els animals. L'explotacio' dels recursos naturals i humans e's una consequ¿e¿ncia d'una cosmovisio' basada en l'establiment d'oposicions bina¿ries que permeten que l'"altre" sigui classificat i dominat. Per exemple: home / dona, blanc / negre, hetero / homosexual, cultura / naturalesa. La construccio' d'aquests "altres" - "femeni'", "natiu", "queer", "naturalesa" - exclou aquests subjectes de la construccio' d'una identitat dominant que, no obstant aixo¿, depe'n d'aquestes categories per a la seua existe¿ncia. En el Renaixement, els camps de les cie¿ncies i les humanitats no estaven separats. La visio' mecanicista del mo'n no havia superat per complet les creences paganes en la ma¿gia i en una forc¿a espiritual que resideix en tots els e'ssers. Aquesta visio' era una reli'quia de l'era precristiana i finalment seria eradicada per les forces unides de l'Estat i l'Esgle'sia a trave's dels processos de la Inquisicio', la cac¿a de bruixes, la colonitzacio' i la nova religio' de la "Cie¿ncia". Tots aquests processos han produi¿t un gran canvi en la nostra relacio' amb la naturalesa, que en l'actualitat es considera una entitat totalment inerta. La naturalesa ja no forma part del nostre e'sser i s'ha convertit simplement en mate¿ria preval. La colonitzacio' continua avui sota una poli'tica neoliberal que utilitza el concepte de desenvolupament per a requisar territori dels pobles indi'genes a fi d'explotar els seus recursos naturals. Aixo¿ es justifica classificant aquestes persones com a primitives perque¿ la seua manera de vida es basa en viure en equilibri amb la naturalesa. La funcio' d'una pra¿ctica arti'stica poli'ticament compromesa e's desafiar la nocio' que no existeix una alternativa al sistema actual. El marc teo¿ric i arti'stic d'aquesta investigacio' ha condui¿t al desenvolupament d'un alter ego performatiu, el xaman transge¿nere Geyserbird, i a la configuracio' d'una se¿rie de performances que inclou rituals participatius, instal·lacions amb prese¿ncia i la reapropiacio' queer d'espais industrials abandonats. El xaman transge¿nere e's un ser espiritual que va me's enlla¿ de les limitacions del sistema de ge¿nere binari i es connecta amb les cultures indi'genes. El desplegament d'aquesta figura en un context contemporani convida al pu'blic a imaginar altres possibilitats per a ells mateixos i per a la nostra societat.
Bell, G. (2018). NATURAL HYSTERIA (a queer response to ecocide): An exercise in Living Art, Participatory Rituals and Queer Ecology -or- How I discovered Geyserbird, the Transgender Shaman within [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/111925
TESIS

The following essay and digital projects each engage both with a unique aspect of contemporary queer Appalachian art and culture as well as the ways in which oral history and digital humanities methodologies can be used to generate collaborative research possibilities. The first essay is an exploration of two LGBTQ+ Appalachian artists, Dustin Hall and Charles Williams, and the ways in which their work uses Donna Haraway’s “naturecultures” and Jose Muñoz’ understanding of queer futurity to rethink human relationships with non-human nature. The first digital project is an online exhibition of queer Appalachian artists and their work, bolstered by oral history interviews, that provides a platform for these artists to connect with one another and reach a wider audience. The second digital project is a digital archive of the Queer Appalachia Project’s Instagram account, serving as a means to hold the Project accountable for their numerous scandals and provide a resource for Appalachian Studies researchers to access the account in a way which is more easily navigable than the social media site. Together, these three projects embody an interdisciplinary intervention into the fields of Appalachian Studies, rural queer studies, oral history, and the digital humanities.

GHOST TREE SOCIAL tells a coming out story of sorts. In terms of style, many of the poems are short, imagistic lyrics, though some are extended catalogues. Specific natural images—lakes, rivers, and snow—are often contrasted with cultural markers. The imagistic poems are thinking through the work of Sylvia Plath. The catalogue poems shift between diaristic, narrative, and critical modes, responding to the poetry of Elizabeth Bishop and the essays of Edouard Glissant. Voice-driven fragments disrupt the more traditional lyric poems. The fragments fall between formal lyrics like confetti from a gay club’s rafters; or the fragments hold the lyric poems in bondage. The lyric poem then re-signifies as form through resonances with the other discursive and poetic form of the fragment. Following critical writers such as Adrienne Rich and Audre Lorde, the re-signification of lyric form reflects the need for new signs for self and community organized queerly as opposed to more typical binary categories—man or woman, living or dead, rich or poor, white or black—where the first term is privileged and the second term often denigrated.

The study of aposematic coloration and mimicry has a long and distinguished history, and has stimulated scientific inquiry in areas as diverse as chemistry, evolution, ecology, and behavior. Yet, many questions regarding signal function and ecological dynamics remain unknown. This dissertation attempts to address some of these questions about how a visual warning signal functions and how the environment changes its efficacy. First, I evaluated the role of luminance contrast in aposematic signaling using milkweed bugs as model prey and Chinese mantids as model predators. Predators learned to avoid unpalatable prey sooner and remembered to avoid unpalatable prey for longer when the prey had higher luminance contrast with the background. These results help define what makes a visual signal conspicuous and designate the importance of high luminance contrast in the efficacy of a warning color signal. Another important characteristic of warning coloration is the reason for the advertisement. I was able to identify and quantify the toxic compounds in both the host plant and the viceroy butterfly, a putative aposematic insect. These results provide a chemical mechanism for previous research that demonstrated that the viceroy was unpalatable to avian predators. Next, I was able to test the role of geographic variation in host plant and viceroy chemical defense and how that variation compared with the local abundance of a mimicry co-model of the viceroy, the queen butterfly. The results indicated the viceroy was more chemically defended and more unpalatable in locations where the queen was at low abundances. This result suggests that mimicry evolves in a geographic mosaic of co-evolution. Finally, I used molecular phylogenetic approaches to reconstruct and test the evolution of mimicry in the North American admiral butterflies (Limenitis: Nymphalidae). One species, L. arthemis, evolved the black, pipevine swallowtail mimetic form but later reverted to the white-banded ancestral form. This character reversion is strongly correlated with the geographic absence of the model species and its host plant, not the mimics host plant distribution. These results support the idea that loss of model in a geographic area is not an evolutionary stopping point for a Batesian mimic.

In this dissertation, I experimentally examine predation-induced mortality upon juvenile queen conch, Strombus gigas, and assess the importance of select habitat predator and conch characteristics affecting predation intensity. Experiments were conducted during the summer and early fall of 1987, 1988, 1990 and 1991 in seagrass beds and adjacent sand flats near Lee Stocking Island, Exuma Cays, Bahamas. These experiments indicate that various factors act interactively to produce habitat-specific mortality rates in queen conch due to predation. These include (1) habitat type, whereby seagrass beds offer some protection; (2) local population dynamics, such that populated seagrass beds appear to enhance conch survival; (3) population density in some seagrass beds, such that mortality is inversely density-dependent; (4) conch size, such that larger conch have higher survival rates, depending on the specific type of habitat; and (5) predation intensity and predator guilds, which likely differ across habitats, producing habitat-specific mortality rates. When integrated with complementary studies of queen conch trophodynamics, these results provide critical information regarding key ecological factors affecting conch survival. In particular, results from the hatchery-reared experiments demonstrate the potential use of hatchery-reared stocks in natural habitats, and hence a valuable option for enhancement of fishery stocks throughout the Caribbean. In general, the integration of results obtained in this dissertation, with complementary studies of queen conch trophodynamics, should provide valuable suggestions of queen conch habitats, densities and scales of patchiness producing highest survivorship and growth rates in nature.

The traditional view of a lifelong monogamy between a king and a queen has recently been challenged in termites. In several species, multiple parthenogenetically-produced secondary queens replace the primary queen and mate with the primary king; this strategy is referred to as “Asexual Queen Succession” (AQS). The aim of my thesis was to investigate the modalities of reproduction and the ecology of neotropical soil-feeding termites from the Termitinae, with a focus on the inquiline termite Cavitermes tuberosus in the Termes group.In the first axis, we investigated the modalities of reproduction of C. tuberosus. (i) AQS is the main reproductive strategy of this species. (ii) The evolution of AQS requires the propensity of parthenogens to develop into neotenic queens. In C. tuberosus, secondary queens develop from a developmental stage of “aspirants” which participate to the social tasks usually undertaken by workers, as long as the primary queen is alive. (iii) In AQS species, a female-biased sex ratio is expected in the dispersing reproductives. In C. tuberosus, sex ratio varies among years and according to the type of reproductives, and the population sex ratio is balanced. These results raise hints on queen-king conflict over the sex ratio.In the second axis, we described the ecology and symbioses of C. tuberosus. (iv) Wolbachia, an endosymbiotic bacterium mainly known for manipulating the reproduction of arthropods in order to enhance its own transmission, infects all individuals in societies. This bacterium, particularly abundant in a gut-associated bacteriome, may play a role in the nutrition of C. tuberosus; both partners would have evolved a mutualistic symbiosis. (v) Inquiline termites live in a nest built by other termite species and do not forage outside. Physico-chemical measures and microbiota sequencing revealed that C. tuberosus is a generalist nest-feeder.Finally, we expanded our study of the breeding systems in the phylogenetic proximity of C. tuberosus. (vi) We described Palmitermes impostor, a new genus and species as a sister-group to the genus Cavitermes. (vii) AQS is the main reproductive strategy in P. impostor, and queens of Spinitermes trispinosus and Inquilinitermes inquilinus are able to reproduce parthenogenetically. Therefore, it appears likely that the conditional use of sexual and asexual reproductions is a preadaptation common to the whole Termes group, and that it evolved into a stable element of their breeding system at least in some species.Overall, our results open new perspectives in the understanding of reproductive strategies in termites and their relationships with their bacterial symbionts.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Little is known about the behavioral patterns of honey bee queens. To determine if mated honey bee queens possess diel rhythmicity in behavior, we observed them in glass-sided observation hives using three types of observation regimes: focal studies consisting of 2-hour and 24-hour continuous observations as well as scan-sampling of multiple queens. All behaviors (active: walking, inspecting, egg-laying, begging for food, feeding, and grooming self; inactive: standing) occurred at all times of day and night, but no queen showed consistent diel rhythmicity in any of the individual behaviors. There were no consistent diel differences in active versus inactive behaviors or the number of bees in the queen's retinue. This arrhythmicity was unchanged despite daily changes in both light and temperature levels. The arrhythmic behavior observed by most of the honey bee queens inside the colony appears to be similar to that exhibited by worker bees before they initiate foraging behavior.

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A vespa social basal Mischocyttarus nomurae Richards tem ocorrência exclusiva no Brasil e foi registrada nos estados do Ceará, Bahia e Minas Gerais. Na Bahia, ocorre em três municípios da Chapada Diamantina: Lençóis, Mucugê e Rio de Contas. Nesta última, foram estudadas populações com relação à sua biologia básica, buscando responder perguntas relacionadas aos seguintes aspectos: morfologia externa dos imaturos, perfis comportamental, morfofisiológico e químico, substituição de rainhas, arquitetura de ninhos e hábitos de nidificação. Com relação à morfologia dos imaturos, a taxa média de crescimento da larva foi de 1,48. Com exceção da larva de 1o ínstar, que revelou-se menor do que o ovo, a espécie apresentou o padrão do grupo: presença de lobos, estes em número de dois e projetados para a frente, só totalmente desenvolvidos quando a larva atinge o 5o instar; as mandíbulas das larvas de 5o instar apresentam um único dente alongado e o primeiro espiráculo é mais do que duas (3,1) vezes maior em diâmetro que os demais. As cápsulas cefálicas da larva de 5º ínstar e da pré-pupa não diferiram significativamente. Após os estudos dos perfis morfofisiológico, químico e comportamental, foi verificado que as fêmeas de M. nomurae não apresentam distinção em sua morfologia externa, mas cinco tipos de desenvolvimento ovariano foram observados, três menos desenvolvidos (A1, A2 e B) e dois mais desenvolvidos (C e D). Foram detectados 34 compostos na sua cutícula, cujas cadeias variaram de 18 a 33 átomos de carbono. Os compostos consistiram em alcanos lineares (9%), alcanos ramificados (89%) e alcenos (2%). Foram identificados três grupos de fêmeas: Operária 1, Operária 2 e Rainha e a análise discriminante do perfil dos hidrocarbonetos cuticulares relacionada a esses grupos de fêmeas apresentou um p-valor significativo (Wilks' lambda= 0,135, F= 1.665, p = 0,0227). Após oito dias da remoção da fêmea dominante do ninho, em todas as colônias, exceto uma, a fêmea era anteriormente a fêmea β. Fêmeas com ovários não desenvolvidos podem realizar comportamentos de fêmea dominante, assim como uma fêmea com ovário desenvolvido comportouse como forrageadora típica. Houve diferença entre algumas atividades exercidas pelas fêmeas posicionadas em 2º lugar no ranking (fêmea β) e as demais fêmeas do ninho (3ª posição em diante), antes e após a remoção experimental da rainha. M. nomurae apresenta um sistema de gerontocracia flexível na sua substituição de rainhas e suas fêmeas sucessoras tornam-se mais agressivas que as rainhas originais, assumindo tarefas de dominantes, mesmo sem estarem inseminadas. Como algumas espécies do gênero, a maioria das colônias apresentou hábitos de nidificação relacionados a ambientes antrópicos. Destes, 61,2% das colônias utilizaram material de origem vegetal (madeira e palha). A altura média de construção do ninho com relação ao solo foi elevada, semelhante as das demais espécies do gênero (2,20 ± 0,83, 0,45 – 5,00m). A maioria dos ninhos foi construída com o favo voltado para baixo (70,15%) e em substrato horizontal (53,73%). O único favo do ninho pode ser arredondado ou elíptico, raramente retangular. O número de camadas de mecônio variou de zero a cinco e a espécie M. nomurae apresenta ninhos pequenos, com suas colônias apresentando um baixo número de adultos produzidos, embora haja uma alta taxa de reutilização de células.
The basal social wasp Mischocyttarus nomurae Richards occurs exclusively in Brazil, having been recorded there in the states of Ceará, Bahia, and Minas Gerais. It is known to occur in three municipalities in the Chapada Diamantina mountains of Bahia State: Lençóis, Mucugê, and Rio de Contas. Population studies were undertaken in the latter municipality to address questions related to the basic biology of M. nomurae: the external morphologies of the immatures; their behavior; their morpho-physiological and chemical profiles; queen substitutions; nest architecture, and nidification habits. In terms of the morphologies of the immatures, the mean larval growth rate was 1.48. With the exception of the 1st instar larvae, which are smaller than the eggs, the species demonstrated the standard developmental pattern for the group: the presence of lobes (two) projected forward, those only becoming fully developed in the 5th instar stage; mandibles in the 5th instar stage with a single elongated tooth, and the first spiracle with a diameter more than two (3.1) times greater than the others. The cephalic capsules of the 5th instar larvae and pre-pupae do not significantly differ. Studies of the morpho-physiological, chemical, and behavioral profiles of those wasps indicated that the females of M. nomurae do not have distinct external morphologies, although five different types of ovarian development were observed: three less-developed types (A1, A2 and B); and two more developed types (C and D). Thirty-four distinct chemical compounds were detected in the cuticle, with carbon chains varying from 18 to 33 atoms. Those carbon compounds consisted of linear alkanes (9%), branched alkanes (89%), and alkenes (2%). Three groups of females were identified: Workers 1, Workers 2, and Queens. Discriminant analyses of the cuticular hydrocarbons of those female groups demonstrated a significant p-value (Wilks' lambda= 0.135, F= 1.665, p = 0.0227). Eight days after the removal of the dominant female from the nest, female substitutions were observed all of the colonies (except one) assuming the condition of a new queen (from the ranks of the β females). Females with undeveloped ovaries do not perform behaviors associated with dominant females, nor do females with developed ovaries behave as typical foragers. There were differences between some of the activities performed by second-rank females (β females) and other females in the same nest (from the 3rd position down), both before and after experimentally removing the queen. M. nomurae demonstrates a flexible gerontocratic system in terms of queen substitutions, and the new queens become more aggressive than the original queens, assuming dominant roles even without being inseminated. As with many species of the same genus, most of the colonies nidify in anthropically modified environments. Of those colonies, 61.2% built nests using plant material (wood and leaves). The nests were constructed at reasonably high mean heights above ground level (2.20 ± 0.83 m; from 0.45 – 5.00 m), similar to other species of the genus. Most of the nests were affixed to horizontal substrates (53.73%) and constructed with the comb facing downward (70.15%). A nest comb can be rounded or elliptic, rarely rectangular. The numbers of meconium layers varied from zero to five. The nests of M. nomurae are generally small, with their colonies producing only small numbers of adults - although with high rates of comb cell reutilization.

Ants and other social Hymenoptera (social bees and wasps) have a remarkable mating strategy. Social Hymenoptera live in societies where reproduction is monopolized by a fertile caste consisting of males and queens. On the other hand, the logistical tasks of the colony are carried out by a sterile female caste known as workers. Reproductive individuals mate during a single bout early in their life and will never engage in additional reproductive events later on. Males die soon after mating while queens store millions of sperm cells in a specialized organ, the spermatheca. Queens will use this sperm stock to fertilize eggs during the rest of their life that can last up to several decades. With a record of 28.5 years in the black garden ant, ant queens have the longest lifespan recorded to date among the social Hymenoptera. In my thesis, I addressed three aspects of ant queen reproduction. First, I tested the effect of mating on the expression of several genes involved namely in fecundity, longevity and immunity. I found that mating induces an up-regulation of the yolk precursor vitellogenin and of the antimicrobial peptide defensin. Second, I measured the intensity of different immune responses in male and queen genital organs in order to determine which immune pathways are activated to protect sperm. Antimicrobial peptide genes are expressed in the genital tract of both sexes and the queen spermatheca is capable of strongly inhibiting bacterial growth. The immune melanization response is, however, overall inactive in the organs tested probably because its unspecific mode of action and cytotoxic by-products are likely to damage sperm cells. Immunity thus seems to be closely regulated in organs that are in contact with sperm. Third, I determined if activation of the queen immune system had an impact on the survival of sperm stored in the spermatheca. There is no detectable effect in young newly mated queens whereas, in one year old queens, immune activation induces a significant reduction in sperm viability. Life stage thus seems to influence queen ability to preserve sperm viability in the event of an immune challenge. In addition, one year old queens have higher sperm viability than newly mated queens suggesting queens are able to displace dead sperm cells from their spermatheca. Finally, I relied on the well-established sequence of behaviors inherent to the early life of ant queens to try to uncover the largely unknown roles of inotocin, the insect ortholog of the vertebrate hormones oxytocin and vasopressin, in regulating insect behavior. I measured gene expression of the inotocin receptor and found that it is highly expressed during social and reproductive behaviors, which is consistent with previous results in vertebrates. Inotocin might thus also be involved in modulating these behaviors in insects, but further studies are needed to be able to fully understand this complex signaling system. Overall, I show that reproduction and immunity are closely linked in ant queens and that the latter provide promising models for investigating the roles of hormones in insects.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

Many bacteria, viruses and other parasites cause severe morbidity or mortality in their host populations, creating strong selection for physiological or behavioural mechanisms to avoid disease. Likewise, changes in host susceptibility and contact patterns can dramatically influence the spread of infectious diseases, and hence selection for traits such as virulence and infectivity range in parasites. Understanding how ecological and evolutionary changes in one population affect selection in another represents a key challenge for theoreticians and empiricists alike, and is essential for gaining further insights into host-parasite relationships. This thesis contains theoretical models that explore how genetic and environmental factors shape the evolutionary and coevolutionary dynamics of hosts and parasites. In particular, the roles of genetic specificity (i.e. genotype-by-genotype interactions) and population mixing patterns are investigated, using both mathematical models and computer simulations. A broad range of scenarios are covered, including the coevolution of broad resistance and infectivity ranges (generalism), the persistence of coevolutionary cycling and the maintenance of sex, the effects of mating behaviour on disease prevalence and evolution, and the evolution of sexual and social behaviour. The models presented herein develop our understanding of host-parasite relationships and highlight the importance of genetic interactions and ecological feedbacks.

O presente trabalho teve como objetivo comparar o estabelecimento de sauveiros iniciais em duas áreas de cultivo de cana-de-açúcar com solos de diferentes texturas (médio-argilosa e argilosa) e verificar a influência dos fatores químicos e microbiológicos desses solos no estabelecimento de formigueiros iniciais de A. sexdens rubropilosa. Os sauveiros iniciais foram demarcados após a penetração das içás no solo a partir da revoada. As avaliações foram conduzidas após 40 dias da revoada e foram mantidas semanalmente, por um período de 120 dias ou até a reabertura do canal inicial dos ninhos para forrageamento. No experimento de laboratório, as rainhas foram acondicionadas em potes com solo das duas áreas em 25 ± 2ºC e UR 70%. As avaliações de laboratório foram feitas seguindo-se a mesma metodologia de campo, verificando a atividade dos sauveiros. Os sauveiros mortos foram descartados e as rainhas, foram utilizadas para isolamento de microrganismos para associá-los à causa da morte. As análises dos fatores químicos e microbiológicos do solo incluíram macro e micronutrientes, carbono da biomassa microbiana, contagem do número mais provável de fungos, bactérias e contagem de unidades formadoras de colônias de actinomicetos. Houve uma maior sobrevivência dos sauveiros iniciais de A. sexdens rubropilosa em solos contendo textura argilosa do que médio-argilosa em laboratório. Nas áreas com solo de textura argilosa e médio-argilosa, a sobrevivência dos ninhos foi de 47,8 e 26,7%, respectivamente. No campo, por sua vez, não foram observadas diferenças no estabelecimento dos sauveiros iniciais para as duas áreas de cana-de-açúcar. O carbono da biomassa microbiana bem como o número mais provável de bactérias foi superior no solo de textura médio-argilosa comparativamente ao de textura argilosa. Diferentemente dos resultados de laboratório, os estudos de campo indicaram que à ação dos microrganismos do solo no estabelecimento de sauveiros novos de A. sexdens rubropilosa não foi tão expressiva.
The objective of the present study was to compare the establishment of new ant nests in two sugarcane growing areas with different soil types (sandy clay and clay) and to verify the influence of chemical and microbiological soil factors on nest establishment. In order to determine nest establishment, initial ant nests were marked and accompanied with other activities immediately after nuptial flight. Evaluations for verification of nest establishment were made weekly after 40 days for the period of 120 days. In laboratory experiment, mated queens collected from the two areas with different soils were maintained in plastic pots containing soil from respective areas at 25 ± 2ºC and 70% RH. To verify activities of the ants, a method similar to the one used to the field study was adopted. Dead ants were discarded while dead queens were used for isolation of associated microorganisms to determine the cause of mortality. The analysis of chemical and microbiological factors of the soil determined macro and micro-nutrients including carbon biomass, the most probable number of fungi, bacteria and counting of the colony forming units of the actinomycetes. The establishment of new ant nests occurred significantly more in the sandy clay soil than clay soil in laboratory. In the areas of sandy clay and clay soil the establishments were 47.8 and 26.7%, respectively. In the field was not observed difference in the establishment of new ant nest in both areas. The carbon biomass and most probable number of bacteria were significantly higher in the sandy clay soil when compared with clay soil area. Differently from laboratory results, the field studies indicated that the establishment of new ant nests of A. sexdens rubropilosa was not only based on the soil microrganism.

A National Marine Conservation Area (NMCA) has been proposed for the waters around Gwaii Haanas National Park Reserve/Haida Heritage Site and Parks Canada is interested in obtaining information on the marine resources in the surrounding waters in order to monitor and manage this marine area. Samples were taken from the waters of the fjords and island passages of the proposed NMCA in order to study the relationships between physical and chemical parameters and abundance and diversity of the phytoplankton in these nearshore areas of Gwaii Haanas. This thesis reports nutrient concentrations, phytoplankton biomass (chlorophyll), and physical parameters during the summers (July and August) of 2001 and 2002 for these waters. Samples were collected using the PV Gwaii Haanas II as a ship-of-opportunity. A total often cruises were conducted and samples were taken for salinity, temperature, density, total suspended solids, Secchi disk depth, nitrate, phosphate, and silicic acid concentrations, chlorophyll a concentrations in two size fractions, and samples for phytoplankton identification. These data were compared for spatial and interannual differences by comparing coasts (east vs. west) and by comparing years (2001 vs. 2002). Variability was very high and few comparisons were significant. Mixed layers were shallow or non-existent on both coasts and in both years. Nutrient concentrations were significantly higher in 2002 than in 2001 as there was a greater intensity of upwelling in 2002 as compared with 2001. Nitrate was observed to be a factor limiting phytoplankton growth in a large proportion of stations, and consequently N:P and N:Si ratios were lower than that required for phytoplankton growth. Surface chlorophyll a concentrations showed no differences, but integrated chlorophyll a concentrations showed significantly higher concentrations in 2002 than in 2001. There was more sunlight and less precipitation in 2002 compared to 2001 and there was more phytoplankton at depth as the light penetrated deeper. The most abundant phytoplankton species were Leptocylindrus danicus, Chaetoceros spp., Thalassiosira spp., Skeletonema costatum, and a group of Pseudonitzschia species referred to as "A". Canonical correspondence analysis (CCA) was performed on these data to determine the relationships between environmental variables and phytoplankton community composition. Most of the phytoplankton species and groups were observed where nutrient concentrations were high and the depth of light penetration was greater than average. Dinoflagellates were more often found in warmer water while diatoms were more often found where the water was colder. The depth of the mixed layer had the least influence on phytoplankton distribution while the silicic acid concentration had the greatest influence. This contradicts the real data which found silicic acid to be not a limiting factor at any of the stations. There was little spatial variability found in nutrient and chlorophyll a concentrations, only silicic acid had a significant difference between coasts with higher concentrations on the west coast than the east and the large size fraction (> 5 μm) of chlorophyll a was higher on the east coast than the west coast. Temporal variability was observed with higher nutrient and integrated chlorophyll a concentrations in 2002 compared to 2001. This study has provided the first extensive near-shore physical, chemical, and biological data in the waters surrounding Gwaii Haanas National Park Reserve/Haida Heritage Site, documenting nutrient and chlorophyll concentrations as well as providing a phytoplankton species list. These data will be useful as a baseline for continuing studies throughout Gwaii Haanas as it becomes an NMCA.
Science, Faculty of
Botany, Department of
Graduate

Altruism is defined as a trait in an individual that increases some other individual’s fitness at the expense of her own. Therefore, existence of such traits in a population is an evolutionary paradox, as natural selection should eliminate such a trait. Extreme altruism in the form of eusociality where individuals relinquish their own reproduction to help raise other’s offspring has been an enigma in evolutionary biology since Darwin. Primitively eusocial organisms provide one with a unique system to study the evolution and maintenance of altruism as in these kind of species most of the individuals are capable of developing their reproductive organs, although at a certain point in time, only one or a few individuals actually reproduce. Ropalidia marginata is a primitively eusocial wasp belonging to the insect order Hymenoptera, Family Vespidae. R. marginata colonies are monogynous, although serial polygyny is observed in a colony’s lifetime. Colony initiation happens either by single founding or multiple founding. Newly founded colonies may accept individuals from other colonies, but mature colonies seldom do. Production of males is irregular, and once eclosed, they generally leave their natal nest within a week. The haplodiploidy of Hymenopteran species, i.e. the males being haploid and the females diploid, make them uniquely genetically predisposed for eusociality to evolve as was shown by William Donald Hamilton in his kin selection theory. Primitvely eusocial Hymenopteran species, being susceptible to experimental manipulation, allows one to test the predictions of this theory. In this thesis I have addressed three aspects of the biology of R. marginata using microsatellite markers, which are the following: 1) Distribution of nestmate genetic relatedness in early founding (pre‐emergence) and mature ( post‐emergence colonies) and their comparison (Chapter 3) 2) Role of relatedness and fertility in predicting the queen’s successor (Chapter 4) 3) Genetic structure of populations (Chapter 5) CHAPTER 1. INTRODUCTION: This chapter gives a brief outline of the field of molecular ecology putting its techniques to the context of insect sociobiology. CHAPTER 2. METHODS: This chapter gives a general outline of the molecular genetic methods involved. In addition, the issue of the mutation process in R. marginata microsatellites has also been addressed. There are two main models of mutation for microsatellite evolution i.e. infinite alleles model (IAM) and the step‐wise mutation model (SMM). To understand the actual process of mutation in R. marginata, sets of alleles with continuous sizes were sequenced and aligned. This was repeated for several of the loci. Seven out of the nine loci genotyped revealed clear step‐like mutation pattern and was binned accordingly. Two loci were dropped as the actual nature of step‐sizes in these two loci was unclear. Therefore, the final dataset consisted of genotype for 7 loci. This chapter also discusses the initial steps in data formatting and analysis. CHAPTER 3. GENETIC RELATEDNESS IN DIFFERENT STAGES OF COLONY DEVELOPMENT: In this chapter I have estimated nestmate genetic relatedness using seven polymorphic microsatellite loci in two different stages of colony development of the primitively eusocial wasp Ropalidiamarginata and compared them. In both kinds of nests the average colony relatedness was observed to be less than 0.75, i.e., what is expected for full sib females in Hymenoptera. Moreover, it was observed that the nestmates at the initial colony founding stage are on average less related to each other than in mature colonies. From this, one may postulate that the indirect component of inclusive fitness plays a relatively minor role than its direct component as individuals chose to leave a higher relatedness background in favour of a lower relatedness background. As newly founded colonies are relatively smaller in size than mature colonies, the probability of an individual wasp becoming the queen in this kind of colony is higher than in mature colonies. CHAPTER 4. TESTING THE ROLE OF RELATEDNESS AND FERTILITY IN PREDICTING THE QUEEN’S SUCCESSORS: R. marginata colonies are headed by docile queens. When this queen dies or is removed, one of the workers becomes extremely aggressive. She is known as the potential queen because within a few days she becomes the new queen of the colony and her aggression comes down. Predicting the successor in the presence of the queen has eluded most of the approaches attempted so far. The probability of an individual becoming the queen has been found to be uncorrelated with her body size, aggression, ovarian status or mating status. The only trend that has been observed till date, is a positive correlation with age, but the pattern is not perfect. However, the workers themselves seem to be perfectly aware of who their immediate successor going to be. In this chapter, I have tested several models of queen succession constructed in an inclusive fitness framework. These models have been tested both using relatedness alone as well as using fertility along with relatedness. Predictions of none of the models actually matched the observed sequence of successors. The wasps do not seem to be choosing their successor to maximize their inclusive fitness. CHAPTER 5. GENETIC STRUCTURE OF NATURAL POPULATIONS: I have also looked at the genetic structure of R. marginata populations in a large part of its natural distribution. I have used both F and R statistics to estimate the level of structuring and compared them. Both Fat as well Rst were found to be significantly larger than 0. Also Fis and Ris both were small and not significant suggesting lack of inbreeding. Rst was observed to be higher than Fst. Permutation test revealed a higher contribution of mutation in this structuring than migration, suggesting Rst to be a better measure of genetic structuring in this case. Similar pattern was observed with Anlysis of MOlecular VAriance. Pairwise Fst/(1‐Fst) values were found to be uncorrelated with distance, whereas barely significant trend was observed with Rst/(1‐Rst). The scatter across the trend line in both the cases suggested lack of migration drift equilibrium, with drift being more relative to migration. Higher level of structuring was observed at the level of the colony. However, colonies were rather outbred as was suggested by high and negative values of Fia and Ria values. This is not at all surprising as nestmates are related to each other. The pattern of isolation by distance at the colony level was similar to that observed in case of the populations. However, there was even higher degree of scattering of the individual points in this case. CHAPTER 6. CONCLUSIONS: Hamilton’s inclusive fitness theory has received a wide attention from and acceptance by sociobiologists, and relatedness have been measured in a wide variety of social insects. In this thesis relatedness in the context of colony founding was measured and compared with mature colonies. Also, several models constructed in an inclusive theory framework were experimentally tested. In both, support for indirect fitness was found wanting. The population genetic structure of R. marginata revealed that the sub populations are small in size and migration among them low. It also suggested significant contribution of colony level structuring on the population genetic structuring. Using more modern molecular genetic and statistical techniques, these and similar other questions can be addressed with higher precision and rigour, and such studies are expected to greatly advance our understanding of the basic premise of this thesis, i.e., how can eusociality evolve and be maintained? We hope that the current work will encourage others to ask such questions in other species.

abstract: An important component of insect social structure is the number of queens that cohabitate in a colony. Queen number is highly variable between and within species. It can begin at colony initiation when often unrelated queens form cooperative social groups, a strategy known as primary polygyny. The non-kin cooperative groups formed by primary polygyny have profound effects on the social dynamics and inclusive fitness benefits within a colony. Despite this, the evolution of non-kin queen cooperation has been relatively overlooked in considerations of the evolution of cooperative sociality. To date, studies examining the costs and benefits of primary polygyny have focused primarily on the advantages of multiple queens during colony founding and early growth, but the impact of their presence extends to colony maturity and reproduction. In this dissertation, I evaluate the ecological drivers and fitness consequences of non-kin queen cooperation, by comparing the reproduction of mature single-queen versus polygynous harvester ant (Pogonomyrmex californicus) colonies in the field. I captured and quantified the total number and biomass of reproductives across multiple mating seasons, comparing between populations that vary in the proportion of single queen versus polygynous colonies, to assess the fitness outcomes of queen cooperation. Colonies in a mainly polygynous site had lower reproductive investment than those in sites with predominantly single-queen colonies. The site dominated by polygyny had higher colony density and displayed evidence of resource limitation, pressures that may drive the evolution of queen cooperation. I also used microsatellite markers to examine how polygynous queens share worker and reproductive production with nest-mate queens. The majority of queens fairly contribute to worker production and equally share reproductive output. However, there is a low frequency of queens that under-produce workers and over-produce reproductive offspring. This suggests that cheating by reproducing queens is possible, but uncommon. Competitive pressure from neighboring colonies could reduce the success of colonies that contain cheaters and maintain a low frequency of this phenotype in the population.
Dissertation/Thesis
Doctoral Dissertation Biology 2017

Ropalidia marginata is characterized as a primitively eusocial wasp due to the absence of morphological differentiation between the queen and worker castes. Unlike other primitively eusocial wasps, however, the queen in this species is a docile individual, who does not use aggression to regulate worker reproduction, and does not act as the central pacemaker of her colony. However, if the queen dies or is experimentally removed, one of the workers steps up her aggression immensely within minutes, and if the queen is not replaced, she develops her ovaries, reduces aggression and takes over as the new queen of the colony. We call her the potential queen (PQ). When I started my work on R. marginata, two very intriguing questions were demanding to be answered, which had developed from work done by my immediate seniors in the lab. I decided to pursue both of these for my thesis. My work has been enriched by inputs from several collaborators and colleagues - I couldn’t have done all of it by myself. So, henceforth, I will be using the word “we”, instead of the first person singular to describe the work that has gone into this thesis. Question 1: Is there a designated successor to the queen in R. marginata? My senior Sujata P. Kardile has shown in her thesis, that in R. cyathiformis, a primitively eusocial wasp very closely related to R. marginata, the queen is always succeeded by the next most aggressive individual in the colony, and so the PQ is easily predictable in the presence of the queen. However, in R. marginata, the PQ appears to be an unspecialized individual, who cannot be predicted in the presence of the queen by using age, ovarian profile or behaviour as the yardsticks. However, the PQ becomes evident within minutes after queen removal. The swiftness with which the PQ is established led us to believe that perhaps the successor to the queen in R. marginata is known to the wasps, though we cannot identify her in the presence of the queen. We designed an experiment to check for the presence of such a ”cryptic successor” in R. marginata. Our experiments involved splitting a normal, queen-right nest into two halves separated by a wire mesh partition, so that the wasps could not move across the mesh. Earlier we had used this set-up to demonstrate that a PQ always establishes herself on the queen-less fragment of the nest. So, to test if there is a cryptic successor, we allowed a PQ to establish herself on the queen-less fragment, and then exchanged the queen and the PQ (designated as PQ1) between the two sides. There is a 50% probability that the cryptic successor, if present, would be on the queen-less side in the beginning. Then, upon exchange, she should be able to hold her position on the other side easily. On the other hand, if the cryptic successor is first on the queen-right side, then, upon exchange, she should take over as the PQ (PQ2), and PQ1 should not be able to hold her status. The cryptic successor hypothesis had two predictions: (i) the PQ1 would lose to a PQ2 in about half the cases, and (ii) there would never be a PQ3. We obtained a PQ2 in 5 out of 8 cases, and we never had a PQ3. So we could conclude that there is indeed one individual who is the designated successor to the queen in R. marginata. Since we could not identify her in the presence of the queen, we call her the cryptic successor. The cryptic successor did not receive even a single act of aggression from the PQ1, or from any other individual in the colony. Thus we conclude that she is acceptable to all the wasps in the colony. We next used the more sophisticated and rigorous method of network analysis to check if the PQ could be predicted due to some unique position she might be holding in the social network on her colony. Since this was a first study in a primitively eusocial insect using network tools, we began by characterizing the social networks of queen-right and queen-less colonies of R. marginata, and compared them with the R. cyathiformis networks to see how different the R. marginata society is from a typical primitively eusocial one. The R. marginata social networks based on dominant-subordinate interactions were low in their centrality measure as compared to the R. cyathiformis networks. However, in both the species, the queen-less networks were highly centralized, star-shaped networks with the PQs at the centre. Neither the queens, nor the PQs were key individuals in the queen-right colonies, but it is interesting to note that the removal of an insignificant node, the queen, resulted in a major change in the network architecture, converting the de-centralized queen-right network into a highly centralized one. Such centralized star-shaped networks are unique, and to our knowledge, the first ever described, in any social system. When we removed the queen from the data set (in silico removal), the resulting network was similar in centrality to the queen-right networks. We then did a comparative analysis of the positional importance of the PQs of the two species, and tried to see if we could use this as a tool to predict the PQ in the queen-right network. In R. cyathiformis, the PQs had consistently high ranks (mostly rank 2) in the network based on the degree index, while the PQs in R. marginata had random ranks in the hierarchy. However, since the PQs are known not to have unique ranks in the dominance hierarchies, we repeated the analysis using data on all interactions from the Q-PQ exchange experiments described above. Neither the cryptic successors nor the losers occupied any unique ranks in the all interactions networks. Thus the successors in R. marginata are truly cryptic, even in their social networks. Since R. marginata is known to be more evolved than typical primitively eusocial species, it is likely that the queen’s successor is identified by the wasps through some subtle cue like smell, and so we cannot identify her using the methods that are adequate for the identification of the PQ in a typical primitively eusocial species like R. cyathiformis. Question 2: How does the queen signal her presence and reproductive status to her workers or, how do the workers perceive the presence of their queen? The fact that in spite of her docility, the queen in R. marginata manages to maintain complete reproductive monopoly in her colony, gives rise to the obvious question of how she suppresses worker reproduction. The most attractive hypothesis is that she uses a pheromone like queens of highly eusocial species. My senior A. Sumana had shown that the queen pheromone, if present, is not a volatile substance. She also showed that the queen interacts at a very low rate with her workers, and so they cannot possibly perceive her by means of direct interactions. Since the PQ steps up her aggression within minutes of queen removal, we used her as a proxy to know how soon the queen’s absence is felt in the colony. We built a model to delineate the relationship between the decay time of the pheromone (td), the average age of the queen’s signal present with the PQ (ta), and the average realization time (tr); where tr = td − ta. Using Dijkstra’s algorithm, we showed that the queen could interact faster with the PQ by using relay interactions. Then using experimental data from 50 colonies, we obtained a ta of 102.9 minutes. The td was 340 minutes, and so we obtained a tr of 237.1 minutes; which meant that the PQ should not perceive the queen’s absence within 237 minutes of queen removal, if the queen pheromone is transmitted by a relay mechanism. However, from our experimental data, we had obtained a tr of 30 minutes. So we concluded that physical interactions, both direct and indirect were inadequate for the workers to perceive their queen. As we had ruled out physical interactions, we then wanted to check if it is possible that the queen applies her pheromone to the nest material, from where it is perceived by the workers when they walk or sit on the nest, or antennate the nest surface. The “rub abdomen behaviour (RA)” has been observed to be quite typical of R. marginata queens, and is not very common in the workers of the species. RA involves rubbing the ventral side of the tip of the abdomen or dragging it on the nest surface while walking. We thought that the queen might be using this behaviour to apply her pheromone on the nest material. So we characterized this behaviour using focal behaviour sampling, and found that the queen rubs her abdomen on the nest once in every 23 minutes. Since the observed tr is 30 minutes, it is quite likely that the queen uses the rub abdomen behaviour to apply her pheromone on the nest. The next step was to check for the source of the queen pheromone. We looked for glands that open near the base of the sting, and the Dufour’s gland was a good choice, as it is known to be involved in the recognition of egg-laying workers in the honeybees. We performed a bioassay in the blind using the crude extract of the Dufour’s gland (prepared in Ringer’s solution) from the queen. The Dufour’s gland extract of a randomly chosen worker and the solvent were used as controls. We found that the PQ responds to the queen’s Dufour’s gland extract by lowering her aggression to 65% of what she was showing on queen removal and before the application of the extract. However, the PQ did not change her behaviour significantly when the worker’s extract or Ringer’s solution was applied. The PQ’s reduction of aggression on application of the queen’s extract mimicked the reaction of PQ’s when the queen is re-introduced on the nest some time after removal. So we hypothesize that the Dufour’s gland is the source of the queen pheromone (signal) in R. marginata. This thesis has opened up newer questions pertaining to the power of the queen and the intricacies of the succession to power in R. marginata. For example, we need to pursue chemical analyses of the Dufour’s gland extract of R. marginata to have conclusive proof of it’s being the source of the queen pheromone. But that is perhaps suitable topic for my juniors in the lab, who can continue the tradition of beginning with questions opened up by their seniors!

Division of labour is a hallmark of eusocial insects and is believed to be a major factor in their evolutionary success and ecological dominance. Division of labour can be of two kinds – reproductive division of labour where a minority of individuals are egg-layers or reproductives (kings and queens) and the majority are workers or non-reproductives involved mostly in non-reproductive tasks of the colony (workers). Kings/queens and workers are often referred to as separate castes within a social insect colony. There may be further non-reproductive division of labour within the worker caste, based on their morphology or age. In primitively eusocial organisms there is no morphological caste differentiation between the egg-layers and non-egg-layers resulting in greater flexibility in the social roles of individuals within a colony. This creates a very interesting scenario to study the mechanism of division of labour. Moreover our knowledge regarding division of labour especially non-reproductive division of labour is very limited for primitively eusocial organisms. In this thesis I have studied division of labour in a primitively eusocial wasp species, Ropalidia cyathiformis. R. cyathiformis is a tropical primitively eusocial wasp with a perennial nesting cycle. This species usually has a single dominant queen and several workers. I studied reproductive and non-reproductive division of labour, as well as the role of dominance behaviour in the regulation of both reproductive and non-reproductive activities. In addition to this I have also compared my findings with what is already known in the well-studied congeneric species, Ropalidia marginata. Reproductive division of labour To understand reproductive division of labour in R. cyathiformis, I studied queen succession, by experimentally removing the queen. When the queen was removed, one and only one individual increased her aggression and became the new queen of the colony, unchallenged by any other worker. Such a successor was referred to as a potential queen (PQ) until she lays her first egg. By removing the queen and successive PQs, I showed that there is not just one successor but a strict reproductive hierarchy of up to 3 PQs, who succeed the queen one after the other. Of many variables tested, I found that only the frequency of dominance behaviour was a significant predictor of whether or not an individual is part of the reproductive hierarchy and also of her position in the hierarchy. Dominance behaviour however does not perfectly predict the position of an individual in the reproductive hierarchy because I showed that an average of three more dominant individuals, are bypassed when an individual becomes the next queen or PQ. This was in contrast to the reproductive hierarchy in the congeneric Ropalidia marginata, where age rather than dominance behaviour was a predictor (though imperfect once again) of an individual’s position in the queue. Taken together, my results suggest that (a) these two sister species have evolved two rather different mechanisms of reproductive caste differentiation, (b) that neither of them strictly conform either to the so called “temperate” or “tropical” patterns of queen succession seen in most other species studied so far. Non-reproductive division of labour As mentioned above, non-reproductive division of labour in eusocial insects is based on either the morphology or the age of the individuals within the colony. Since there is no morphological castes present in primitively eusocial species, I focussed on the effect of age on division of labour in R. cyathiformis. I analysed the frequency as well as the probability of performance of four functionally significant tasks namely, two intranidal tasks – feed larva and build as well as two extranidal tasks – bring food and bring building material. I measured absolute as well as relative ages of the wasps. I found that there is an effect of age on division of labour. Age of first performance of the tasks indicated a clear sequence for the initiation of the tasks with intranidal tasks initiated before extranidal tasks. The frequency of task performance (FTP) and absolute age better explained the variation in the data as compared to probability of task performance (PTP) and relative age. This was in contrast to the pattern of age polyethism found in the congeneric species, Ropalidia marginata, where PTP and relative age better explains the variation in the data. This suggests a more flexible age-dependant division of labour in R. marginata and a rigid age polyethism in R cyathiformis. In addition I found that there was no clear-cut partitioning of the intranidal and extranidal tasks in R. cyathiformis, whereas in R. marginata, it has been shown that the frequency of the intranidal tasks decline with age while that of extranidal tasks increase with age. When taken together, I could say that R. marginata has a more strongly developed age polyethism as compared to R. cyathiformis. This study also shows an evolution of age polyethism with R. cyathiformis behaving more like a typical primitively eusocial species while R. marginata more like a highly eusocial species. Role of dominance behaviour in reproductive and non-reproductive division of labour When reproductive regulation in R. cyathiformis was studied, I found that queens of this species target the potential queen (PQ) by showing the maximum frequency per hour of dominance behaviour to the PQ. The PQs on the other hand seem to show the maximum amount of dominance behaviour towards newborns (wasps of age class 0-5 days). Queens seem to regulate only reproductive activities and not the non-reproductive activities as there was no difference in the frequency of both feed larva and bring food behaviour in the colony even after removing the queen. It also appears that dominance behaviour is not used to signal hunger or regulate foraging as there was no significant correlation between the frequency per hour of bring food behaviour and dominance behaviour received. Moreover the foragers do not receive more aggression than other wasps in the colony from either the queen, PQ or intranidal workers. I also found a significant positive correlation between the frequency per hour of bring food behaviour and feed larva behaviour implying that foraging might be a self-regulated process in this species. Hence in R. cyathiformis it appears that dominance behaviour is used only for regulation of reproductive division of labour and not for regulation of non-reproductive division of labour. This was in contrast to the congeneric species, R. marginata where the opposite has been shown to be true; the reproductive regulation is achieved by means of pheromones produced by the queen and work organisation follows a decentralised self-organised manner with intranidal workers signalling or regulating foragers using dominance behaviour. Comparison with Ropalidia marginata Ropalidia cyathiformis and Ropalidia marginata, although congeneric species co-existing in the same habitat, have evolved very different mechanisms for division of labour. R. marginata exhibiting features such as 1) presence of a docile queen 2) reproductive regulation by means of pheromones 3) strongly developed and flexible age polyethism 4) decentralised work organisation seem to be more similar to a highly eusocial organism than to a primitively eusocial species. R. cyathiformis on the other hand seems to exhibit several features typical to a primitively eusocial species, such as 1) presence of a dominant queen 2) reproductive regulation by physical means 3) relatively weak and rigid age polyethism 4) self-regulatory method of work organisation. Hence the two species seem to be at two different stages of evolution with R. marginata appearing to be intermediate between primitively and highly eusocial species.

Yes
A central challenge in microbial community ecology is the delineation of appropriate units of biodiversity, which can be taxonomic, phylogenetic, or functional in nature. The term ‘community’ is applied ambiguously; in some cases, the term refers simply to a set of observed entities, while in other cases, it requires that these entities interact with one another. Microorganisms can rapidly gain and lose genes, potentially decoupling community roles from taxonomic and phylogenetic groupings. Trait-based approaches offer a useful alternative, but many traits can be defined based on gene functions, metabolic modules, and genomic properties, and the optimal set of traits to choose is often not obvious. An analysis that considers taxon assignment and traits in concert may be ideal, with the strengths of each approach offsetting the weaknesses of the other. Individual genes also merit consideration as entities in an ecological analysis, with characteristics such as diversity, turnover, and interactions modeled using genes rather than organisms as entities. We identify some promising avenues of research that are likely to yield a deeper understanding of microbial communities that shift from observation-based questions of ‘Who is there?’ and ‘What are they doing?’ to the mechanistically driven question of ‘How will they respond?’

This thesis has looked at the proximate mechanisms by which eusociality is maintained in colonies of the primitively eusocial wasp Ropalidia marginata. Unlike other typical primitively eusocial species, the R, marginata queen is remarkably docile and non-interactive and hence cannot possibly use aggression to maintain her status. Recent evidence hints at pheromonal queen signalling through the Dufour’s gland. Hence, queen-worker difference in Dufour’s gland composition has been studied in details. Queens and workers differ with respect to overall composition of Dufour’s glands, categories of compounds, and individual compounds as well. The Dufour’s gland compounds may be having a bouquet effect in queen signalling, with individual compounds being less important than the overall composition. The queen pheromone also appears to be an honest signal of fertility, as compounds that differ consistently between queens and workers are correlated with ovarian development of queens, and solitary foundresses and potential queens, who are intermediate between queens and workers in ovarian development, are intermediate in their Dufour’s gland profile as well. When the queen is removed from a colony, one of the workers (potential queen, PQ) shows high aggression, and if the queen is not returned, goes on to become the next queen of the colony. The aggression of PQ comes down as a function of time since queen removal, and correlated with this, the ovaries of PQ increase. Dufour’s gland profile of PQ is similar to workers immediately after queen removal, but comes closer to queens with passage of time. This hints at an interesting transition in maintenance of eusociality from “queen control” by aggression to “queen signal” by pheromone during the queen establishment phase. It has generally been assumed that one set of chemicals can carry multiple information, namely queen signal and colony signal. Initial statistical analysis of chemical composition data showed that perhaps both caste and colony signals can be conveyed by the Dufour’s gland compounds, but detailed analysis cast some doubt on this, as the Dufour’s gland compounds could not be separated into non-overlapping subsets with respect to importance in caste and colony discrimination. A bioassay showed that the wasps do not make colony discrimination from Dufour’s gland compounds. This suggests that the ability to statistically differentiate groups of organisms from their chemical profiles does not guarantee similar discrimination by the organisms themselves, emphasising the need for bioassays to resolve such issues.