Dissertations / Theses on the topic 'Grime life history strategies'
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Ross, Caroline Ann. "Life-history strategies of primates." Thesis, University College London (University of London), 1989. http://discovery.ucl.ac.uk/1349897/.
Full textWatson, A. P. "Life history strategies in fungal breeding Drosophila." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382839.
Full textManyanga, Phelex. "Evolution of life history strategies in Lophoziaceae." Doctoral thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/6130.
Full textIncludes bibliographical references (leaves 117-135).
This study used data from literature and data from the field to analyse the patterns of variation in life history characters among members of the liverwort family Lophoziaceae. A combination of Principal Component and Cluster analyses was used to analyse data from literature in testing for recurrent suites of life history variation among species of the family. Data from literature were also used to examine the relationship between mode of reproduction and reproductive system (sexuality) and between diaspore (spore or gemma) frequency and sexuality. Data from the field were used to establish diaspore (spore and gemma) sizes and their production per capsule or shoot and to test for relationships between diaspore size and production per shoot/capsule and also between diaspore sizes and proportion of germination.
Niva, Mikael. "Life History Strategies in Linnaea borealis." Doctoral thesis, Uppsala : University Library : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3604.
Full textCaradine, Emma L. "The life-history strategies of riparian spiders (Araneae)." Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/29774.
Full textWeisser, W. W. "Foraging and life history strategies in multi-trophic communities." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240464.
Full textNakano, Mariko. "Life history strategies of an amphidiploid species, Drosera tokaiensis." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147869.
Full textIchie, Tomoaki. "Resource allocation strategies along life history of dipterocarp trees." 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150870.
Full textShipway, John Reuben. "Aspects of the life history strategies of the Teredinidae." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/aspects-of-the-life-history-strategies-of-the-teredinidae(46eb09dc-f79c-4fa8-88aa-3c3ac172b121).html.
Full textJohannsson, V. "Life history strategies of blackflies (Simulidae) in Icelandic lake-outlets." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372319.
Full textShizuka, Daizaburo. "Parental strategies and family life of American Coots: brood parasitism, sibling rivalry, and life history /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
Full textPratt, Thomas C. "The impact of predation of pumpkinseed, Lepomis gibbosus, life history strategies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0002/MQ30228.pdf.
Full textMar, Khyne U. "The demography and life history strategies of timber elephants in Myanmar." Thesis, University College London (University of London), 2002. http://discovery.ucl.ac.uk/1446021/.
Full textThomaz, Diogo Miguel Pereira Fernandes. "Alternative life-history strategies in male Atlantic salmon (Salmo salar L.)." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/34249.
Full textKobayashi, Keito. "Life-history strategies of the invasive naturalized tall bamboos in Japan." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263716.
Full textGarcia-Pena, Gabriel Ernesto. "Phylogenetic comparative analyses of breeding systems and life-history strategies in shorebirds." Thesis, University of Bath, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527144.
Full textOrton, R. A. "The life-history strategies of two species of stream-dwelling freshwater snails." Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379698.
Full textJacobs, Jerry Dale. "Regulation of life history strategies with individuals in predictable and unpredictable environments /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5169.
Full textBirget, Philip Laurent Guillaume. "Evolutionary ecology of parasites : life-history traits, phenotypic plasticity, and reproductive strategies." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/28805.
Full textLöbel, Swantje. "Metapopulation and metacommunity processes, dispersal strategies and life-history trade-offs in epiphytes." Doctoral thesis, Uppsala universitet, Ekologisk botanik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-106847.
Full textSenarelagd disputation från: 2009-09-26, Lindahlsalen, EBC, Villavägen 9, 75236 Uppsala, Uppsala, 10:00
Cutts, Christopher John. "Metabolic rate, territoriality and life-history strategies of juvenile Atlantic salmon (Salmo salar L.)." Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360178.
Full textOkuda, Noboru. "Life history and sexual strategies of the cardinal fish (Pisces:Apogonidae) in the temperate sea." 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/86473.
Full textPollitt, Laura C. "Evolutionary ecology of transmission strategies in protozoan parasites." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5771.
Full textLord, Joshua Pratt 1986. "Modeling of Life History Strategies in Organisms with Indeterminate Growth, with a Focus on the Distribution and Life History of the Gumboot Chiton Cryptochiton stelleri." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10827.
Full textThe gumboot chiton Cryptochiton stelleri is the largest intertidal invertebrate herbivore on rocky shores in the Pacific Northwest. This study documented the larval development, metamorphosis, distribution and life history of this species. Growth rings in valves of Cryptochiton stelleri and Katharina tunicata were used to determine age and showed life spans of at least 40 years for C. stelleri and 17 years for K. tunicata. Field surveys in southern Oregon showed that C. stelleri populations are densest in small coves as a result of mortality, food availability, or larval retention. Growth curves based on length, weight and volume were created for several intertidal invertebrates. When incorporated into energy allocation models, length-based curves can underestimate growth and exaggerate an energetic shift from growth to reproduction. Estimates of food intake and reproductive output showed that continuous growth leads to higher food intake and increased fecundity in several organisms with indeterminate growth.
Committee in Charge: Dr. Alan L. Shanks, Chair; Dr. Cynthia D. Trowbridge; Dr. Richard B. Emlet
Bongard, Terje. "Life history strategies, mate choice, and parental investment among Norwegians over a 300-year period." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-802.
Full textIn this thesis, seven papers concerning life history, mate choice and parental investment strategies are presented. Data was compiled from old church books from two parishes in Central Norway from 1700-1900, Soknedal and Smøla (Paper I-IV). Also the results of three questionnaires are presented (Paper V-VII). Results show that access to stable resources was the main predictor of number of children born and number of grandchildren produced within and between two human populations (Paper I). The two studied villages (Soknedal and Smøla) were at the same latitude, but had different resource foundation in that the coastal parish (Smøla) had access to year round fishing. This extra resource affected most life history traits of particularly low class women, who produced significantly more grandchildren than their sisters without this stable resource. Birth rank and family size also affected the life history of children (Paper II). Here we considered the survival rate, the probabilities of becoming married and migration rate from the home parish in relation to status of mother, family size, sex of the children, birth rank, sex ratio of siblings, year of birth and age of the mother. We found that the future reproductive value of boys was greatly affected by both family size and birth rank, in that boys from larger families and boys late in birth rank had a lower probability of getting married and a higher probability of migrating from the parish. No such relations were found for girls. We conclude that a difference in the access to parental resources during childhood affected the life history of boys, but not that of girls.
There was no support for longer birth intervals between the births of two boys compared to other sex combinations of children (Paper III). Short birth intervals (less than two years) between two children led to higher mortality among both the first-born and second-born in such combinations There were significant differences in birth interval between high and low status women in both parishes. Also the poorer parish of Soknedal had longer birth intervals than Smøla for both status groups. The survival rate increased significantly when birth intervals exceeded 2 years, both for a child and its next sibling. The optimal birth rate in Soknedal seems to be slightly over three years. In a multilinear regression analysis, the number of children of mother was, not surprisingly, the most important variable in explaining the variation in birth interval. Laterborn children had longer birth intervals (Paper III).
In Paper IV we tested the inbreeding avoidance between related individuals in Soknedal parish, and found this to be significant. We found, however, no statistically significant differences in fertility between the three groups called non-locally, consanguineous and locally married couples.
Physical variables in human mate choice were tested on a sample of students (Paper V). There was a significant correlation between the age of a man and a woman and the height of the two individuals in a pair. However, none of the correlations or cross-correlations between height, weight, hair colour or eye colour were statistically significant. Within a pair there was a highly significant positive correlation between the attractiveness of a man and a woman. We also tested if strangers could pick out mates by facial looks. 101 test persons were presented a series of four photos, two males and two females and asked to pick out the pair. The pair was correctly picked out in about 40 % of the cases, which was higher than random. Altogether almost 90 percent of the test persons were able to pick out the pair more frequently than random. There was no significant difference between the sexes in their ability to pick out the right pair from photos. Paper VI presents results concerning female view of the male commitment into a relationship, his economic status variables and his ambition levels. We tested predictions derived from evolutionary biology concerning female mate choice through a questionnaire presented to female subscribers of a Norwegian magazine. The expectations of a stable economic wealth prior to engagement affected positively the length of relationships. The partner's economic stability, the respondent's perceived economic satisfaction and the partner’s investment in children from previous relationships were significantly higher in an ongoing than in a broken relationship. These factors are predicted to be crucial to mate choice and ultimately fitness-enhancing. Finally, in Paper VII phenotypic levels of daily-life parental-offspring conflicts in two different social contexts were studied; 1) between biological parents and their offspring at home, and 2) between the adults and the same children in the nursery school. Parents and nursery school teachers were asked how the children acted in conflicting situations that frequently occur during a day. Parents reported a higher level of conflict with their children than did teachers from nursery schools. Parents did not experience differences in conflict level between boys and girls, while nursery school teachers did experience such differences. The results give support for the hypothesis that children have an innate and selected mechanism that guides them in different social contexts, and that they easily assess differences important for the level of care and attention they can expect to get. Children expect a higher investment from their parents than from their teachers, and therefore solicit more in the parent-offspring context. Such context-related behaviour among children will optimise their own social status and benefits in the form of resources and attention, and is the conceptual background for parent-offspring conflict.
Denne doktoravhandlingen består av syv arbeider innenfor feltet human atferdsøkologi. I motsetning til sosiologisk tilnærming forsøker humanbiologien å finne universelle trekk som er like for alle. Medfødte trekk trenger ofte en utløsende miljøfaktor. Poenget er imidlertid at på et evolusjonært grunnlag følger det logisk å tro at alle individer vil respondere mer eller mindre likt. I forhold til noen atferdstrekk er dette lett å vise, som for eksempel smerte, latter, sjalusi eller sinne. Andre trekk kan bare testes statistisk, som for eksempel at barn maser mer på foreldrene sine enn på andre voksne, eller at trangen til å emigrere er større når en gutt fødes sent i fødselsrekka, slik jeg har vist her.
De fire første arbeidene er analyser av data fra kirkebøker fra Soknedal og Smøla mellom 1700-1900. De tre siste er resultater fra tre spørreundersøkelser foretatt i årene 1993- 2002. Soknedal og Smøla har en biologisk relevant ulikhet i at Smølaboerne hadde tilgang på fiske året rundt, noe som stabiliserte mattilgangen. Denne ulikheten ga seg utslag i at lavstatuskvinner fra Smøla fikk flere barnebarn enn lavstatuskvinner fra Soknedal (Paper I). Blant høystatuskvinner var det ingen forskjell. Størrelsen på søskenflokken og nummer i fødselsrekkefølgen bestemte viktige livshistorieparametre (Paper II). Kjønnsforskjellene var store og ga seg utslag i at en senerefødt gutt hadde lavere sjanse for å overleve, lavere sjanse for å bli gift, men høyere sannsynlighet for å emigrere. Slik var det ikke for jentene. Dette er i tråd med seleksjonsprinsippene for arter med høy foreldreinvestering ved at tidligfødte menn som arvet mest ressurser ble attraktive og fikk livsløp med større sjanser for etterkommere. Også fødselsintervallene betyr mye for livsløpet (Paper III). For korte mellomrom mellom fødslene gir lavere ressurstilgang til barna (både det som er født før og etter) og dermed lavere fitness, men samtidig bør total reproduktiv periode utnyttes. Dermed kan det beregnes et optimalt fødselsintervall som gir flest overlevende og attraktive etterkommere. Det finnes noe data på at det å få gutter er mer ressurskrevende, og vil øke det optimale intervallet, men materialet fra Midt-Norge viste ikke dette. I Paper IV så jeg på om beslektede individer unngikk å gifte seg med hverandre, hvilket de gjorde. Sannsynligheten for å gifte seg med en slektning var ganske stor på den tiden (24 %), men bare 9 % av høystatus- og 6 % av lavstatuskvinnene giftet seg med slektninger. Partnervalg er et område det er gjort ganske mye forskning på, og vi gjentok en del av de undersøkelsene som viser at vi ofte velger partnere som matcher oss i fysiske variabler (Paper V). Vi fant bare korrelasjon mellom alder og høyde, og ikke mellom høyde, vekt, hårfarge eller øyefarge. Vi fant en god korrelasjon i skjønnhetsscore. Vi la ut foto av to menn og to kvinner og lot ti personer velge ut hvem som var sammen av disse. Tilfeldig ville 25 % velge riktig, men forsøkspersonene klarte nesten 40 % rett. Dette støtter hypotesen om at vi ser etter tegn og trekk som er relevante for hvor attraktive vi er, og at dette er en universell egenskap hos mennesker. Disse egenskapene trenger ikke være fysisk utseende, men kan være atferdstrekk forbundet med omsorgsevne og økonomi. Bladet ”KK” betalte for en spørreundersøkelse blant sine abonnenter hvor vi blant annet spurte om økonomi, ambisjoner og innsats hos tidligere og nåværende mannlige partnere (Paper VI). Det var god korrelasjon mellom utilfredsstillende økonomi, manglende innsats og omsorg, lavt ambisjonsnivå og graden av skilsmisse og brudd i forholdene. Menn som viste ambisjoner, hadde felles økonomi, investerte i kvinnens tidligere barn og hadde økning i inntekt, ble sjeldnere skilt. Et interessant resultat var at menn som ble karakterisert som svært ambisiøse hadde økt sjanse for brudd med partneren. Dette kan ha flere grunner, hvorav to er nærliggende: 1) En overinvestering i karriere må nødvendigvis ta tid og krefter, og det vil gå utover investeringen i hjemmet. Her er det viktig å huske at det er den følelsesmessige reaksjonen hos partner som er viktig, og ikke nødvendigvis antall kroner som teller. 2) Menn med karriere er attraktive, og vil få flere tilbud og muligheter for andre partnere. I den siste undersøkelsen kartla vi ulikheter i hvordan biologiske foreldre og barnehageansatte oppfatter konflikter med barn (Paper VII). Ut fra evolusjonær biologi kan en predisere at barn vil være tilpasset å kreve mer av sine foreldre enn av andre voksne, og at dette vil gi seg utslag i et høyere konfliktnivå med det samme barnet, avhengig av hvem som i øyeblikket har omsorgen. Vi fant støtte for prediksjonen ved at i alle de undersøkte situasjonene med det samme barnet oppfattet den biologiske forelderen et høyere konfliktnivå enn den barnehageansatte.
Det er utgitt en svært omfattende bok på norsk som oppsummerer hva som er oppnådd hittil innen fagretningene sprunget ut av evolusjonær biologi (Mysterud, 2003). Boken anbefales til alle som arbeider med mennesker på alle plan. Evolusjonsbiologi er en del av naturvitenskapen, og er dermed logisk sammenhengende på en annen måte enn samfunnsvitenskapene. Evolusjonsbiologi er grunnleggende konsistent og sammenhengende med hele den menneskelige vitenskap, og det er derfor ikke logisk eller rasjonelt å velge å se bort fra de problematiske sidene av denne forskningen.
Evanson, Melissa. "Chinook salmon population dynamics and life history strategies in the Squamish River Watershed, BC, Canada." Diss., Restricted to subscribing institutions, 2009. http://proquest.umi.com/pqdweb?did=1722403321&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
Full textWalker, Alan Melville. "Life history strategies in anadromous trout, Salmo trutta L., with special reference to osmoregulatory physiology." Thesis, University of St Andrews, 1998. http://hdl.handle.net/10023/15003.
Full textStanton, Samuel Andrew. "Structure and function of the external ciliation of larval bivalves with different life history strategies." Thesis, University of Portsmouth, 2012. https://researchportal.port.ac.uk/portal/en/theses/structure-and-function-of-the-external-ciliation-of-larval-bivalves-with-different-life-history-strategies(7cd70842-de3a-4e51-93a1-b3578c45861b).html.
Full textJackson, Jenee James. "Sociosexual Development: Infusing the Belsky, Steinberg, and Draper Model with Sexual Selection." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/196156.
Full textEaston, Lyndlee Carol, and lyndlee easton@flinders edu au. "LIFE HISTORY STRATEGIES OF AUSTRALIAN SPECIES OF THE HALOPHYTE AND ARID ZONE GENUS FRANKENIA L. (FRANKENIACEAE)." Flinders University. Biological Sciences, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20081124.105244.
Full textPullin, A. S. "Life history strategies of the butterflies, Inachis io and Aglais urticae, feeding on nettle, Urtica dioica." Thesis, Oxford Brookes University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370503.
Full textSuwandy, Jason. "Temporal Currency: Life-history strategies of a native marine invertebrate increasingly exposed to urbanisation and invasion." Thesis, University of Canterbury. School of Biological Sciences, 2012. http://hdl.handle.net/10092/7322.
Full textHughes, Martin Robert. "What makes a ferox? : the drivers & consequences of alternative life history strategies in S. trutta." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8280/.
Full textStarling, Amanda. "Behavioural plasticity of life history traits in the New Zealand avifauna." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1327.
Full textBradford, Michael J. "The role of environmental heterogeneity in the evolution of life history strategies of the striped ground cricket /." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70319.
Full textClauss, Maria Johanna. "Life history strategies in variable environments: Demography, delayed germination and bet-hedging in a desert annual Plantago." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/282885.
Full textVolpe, Lane Elizabeth. "Using life-history theory to evaluate the nighttime parenting strategies of first-time adolescent and adult mothers." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/287/.
Full textDe, Waal Caroli. "Dispersal, dormancy, life history and breeding systems of southern African Asteraceae : risk-reducing strategies in unpredictable environments." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96736.
Full textENGLISH ABSTRACT: How organisms respond to unpredictable environments is a fundamental question in evolutionary ecology. For example, plants may reduce the risk of reproductive failure by spreading their reproductive effort in space (dispersal) or in time (dormancy, iteroparity). Similarly, different plant breeding systems, (for example the ability to autonomously self-fertilise) may reduce the risk of reproductive failure in environments where pollination in particular is unreliable. Each of these strategies may be affected by selective pressures exerted by heterogeneous abiotic and biotic environments (e.g. unreliable rainfall patterns or range edge habitats). However, there is little theoretical or empirical consensus on how these strategies are related. In Chapter 2, I explore the association between dispersal and breeding system traits and range edge proximity. I show that annual daisies from Namaqualand, South Africa, are characterised by two discreet syndromes: high selfing ability associated with good dispersal and obligate outcrossing associated with lower dispersal, regardless of range position. This chapter illustrates that selection on both breeding system and dispersal traits may act consistently across distribution ranges. Because co-flowering plants often share pollinators, their fecundity is likely affected by changes in pollinator visitation rates or the transfer of conspecific relative to heterospecific pollen. In Chapter 3 I experimentally investigate the effects of con- and heterospecific density and spatial distribution pattern on pollination and fecundity in annual Namaqualand daisies. I show that increasing conspecific density and aggregation enhanced fecundity through increased mate availability and reduced heterospecific interference, independent of pollinator visitation rates. Moreover, I demonstrate the benefits of autonomous selfing when mates are limited and the potential for interspecific pollen transfer is high. In Chapter 4, I examine relative investment in dispersal vs. dormancy in seed heteromorphic Dimorphotheca (Asteraceae) species in relation to life history, rainfall unpredictability and range edge proximity. I show annuals and perennials differ significantly in the relative investment in different dispersal strategies. However, my findings provide little support for theoretical predictions of bet-hedging strategies in unpredictable or range edge habitats. This chapter emphasises the role of local environmental factors on fruit set that may obscure expected patterns across broad climatic gradients. Because of different costs and benefits of dispersal in space and time, we may expect negative patterns of covariation among dispersal and dormancy as alternative risk-reducing strategies. In Chapter 5, I provide evidence for a trade-off between these traits across 27 wind- dispersed daisy species from South Africa. This trade-off did not depend on life history effects, but was inconsistent at different levels of biological organisation. I also show that the effects of life history on spatial and temporal dispersal were inconsistent. Taken together, my research illustrates the importance of simultaneously investigating different risk-reducing strategies, because associations among them are clearly complex and often contradict theoretical expectations. Moreover I show that the effects of life history and phylogenetic relatedness cannot be disregarded. My findings underscore the importance of dispersal in space and time as well as autonomous selfing as risk-reducing responses to unreliable environments.
Hülsmann, Stephan. "Population dynamics of Daphnia galeatat in the biomanipulated Bautzen Reservoir: life history strategies against food deficiency and predation." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2003. http://nbn-resolving.de/urn:nbn:de:swb:14-1060170274484-94614.
Full textBoyette, Adam Howell. "Parental investment and men's sexual behavior : life history theory and reproductive strategies in a sample of American men." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/Fall2006/a_boyette_121106.pdf.
Full textLagrue, Clement, and n/a. "Alternative life-history strategies in the trematode Coitocaecum parvum (Opecoelidae) : effects of environmental factors and within-host competition." University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080905.111744.
Full textHotchkiss, Sarah L. "Life history strategies of three species of Cystophora (Phaeophyta, Fucales) from a shallow subtidal community in South Australia /." Title page, contents and summary only, 1999. http://web4.library.adelaide.edu.au/theses/09PH/09phh832.pdf.
Full textBeesley, Leah. "Environmental stability : its role in structuring fish communities and life history strategies in the Fortescue River, Western Australia /." Connect to this title, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0129.
Full textHülsmann, Stephan. "Population dynamics of Daphnia galeatat in the biomanipulated Bautzen Reservoir: life history strategies against food deficiency and predation." Doctoral thesis, Technische Universität Dresden, 2000. https://tud.qucosa.de/id/qucosa%3A24248.
Full textJanse, van Rensburg Susan. "Ecological significance of variation in Themeda triandra Forsk : a case of intra-specific divergence in life history strategies?" Master's thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/6275.
Full textRangelands are a important resource for commercial, subsistence and game enterprises. However, their variabiligy poses a challenge for their effective management. This thesis was motivated by the need to contribute to a functional classification system for rangelands to guide managers in a way that adequately, yet simply, addresses ecological variation in South African rangelands. The approach was to investigate life history characteristics of rangelands at four sites representing climate extremes. These differed in the amount, and predictability, of rainfall and the incidence of frost. The approach was novel in that a single species, Themeda triandra, was used in an attempt to test predictions on sets of key traits associated with the different rainfall regimes. The underlying hypothesis was that density-dependent processes would be most important in mesic grasslands, requiring frequent defoliation by fire or grazing to maintain a productive Themeda sward. Climate variabiligy would be the most important determinant of grass growth in semi-arid grasslands. Vegetive and reproductive traits of Themeda would be expected to have diverged in response to these different selection pressures in the different populations. Observations were made on reproductive and vegetative traits in field populations in the four study areas and on plants grown from clonal material and seeds in a glasshouse to determine key axes of variation. Population responses to varying light and moisture levels were compared in a glasshouse experiment simulating the effects of different moisture regimes and competitive environments of source populations. Fecundity, seedbank characteristics, seedling numbers and population size structure were compared in field and glasshouse experiments. Production characteristics were compared in a clipping experiment conducted in the field. Results showed that different populations of Themeda exhibit divergent life history characteristics associated with different rainfall and temperature regimes. These differences are evident in the morphology, allocation patterns, leaf traits, germination biology and phenology of populations. The ecological significance and implications of trait divergence were clearly evident in demographic characteristics of the populations, in experimental responses to watering and shading, and in divergent growth responses to clipping experiments. The results were consistent with classic life history theory. In low, unpredictable rainfall regions, populations have evolved r-selected strategies whereas populations from high and predictable rainfall are characterized by K-selected traits. However the incidence of frost is also a factor influencing growth form divergence.
Mell, Hugo. "Fast-slow strategies in human populations : applying insights from life history theory to explain patterns of interindividual variation." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE074.
Full textSocial gradients in behavior have been documented across various domains of people’s lives. In western countries, low SES individuals tend for instance to invest less in their education, to smoke more, are more subject to overweight and are more willing to take risks in financial settings. Being exposed to deprivation therefore seems to elicit a constellation of behaviors that appear to covary in a systematic fashion. This behavioral constellation of deprivation has been mostly interpreted as the product of poor decision making abilities, of a general failure of willpower. In this dissertation we explore a different interpretation that is rooted in adaptive explanations of human behavior. Instead of viewing the behaviors of low SES individuals as suboptimal deviations from a global optimum, they are seen as adjustments of people’s overall life strategies that are, from an evolutionary point of view, adaptive in the particular context of a deprived ecology. Indeed, we will explore the idea that deprived environments select for strategies that put more weight on present outcomes over uncertain future outcomes, and that this present orientation in low SES individuals propagates across a range of decision domains, giving rise to the constellation. To this aim, we first use structural equation models on observational data from a diversity of samples, to analyze the covariation between peoples’ behaviors in several relevant domains (health, reproduction, social trust) and their exposure to deprivation during childhood and/or adulthood. Overall, we find that a lower somatic effort tends to covary with a more short-term reproductive strategy, as well as lower social trust. This pattern is associated with a higher exposure to deprivation, with unique effects of early life conditions. In addition to this empirical work, we further investigate the theoretical underpinnings of our working hypotheses, from an adaptationist perspective. Specifically, we build a formal life history model to predict optimal changes in discounting within and between individuals. This allows us to highlight that the extent to which individuals prefer short-term rewards, should vary depending on two main parameters: 1) the uncertainty around their ability to actually collect delayed rewards, and 2) the opportunity costs of not having the reward during the delay. Finally, we conclude by discussing the promising perspective of further integrating the approach adopted in the present thesis, with more traditional social and behavioural sciences
Miller, David Charles Moorcroft. "An individual-based modelling approach to examine life history strategies of sardine Sardinops sagax in the southern Benguela ecosystem." Doctoral thesis, University of Cape Town, 2006. http://hdl.handle.net/11427/8917.
Full textHypotheses regarding the spawning strategy and recruitment of sardine (Sardinops sagax) in the southern Benguela ecosystem are tested using an individual-based Lagrangian particle tracking model linked with a 3-D hydrodynamic model of the region. Experiments focus on the dispersion of eggs and larvae among possible spawning and nursery areas. The two main areas of interest were the west coast upwelling region and the south coast shelf region (Agulhas Bank). A stage-based temperature-dependent development model is incorporated and vertical positioning schemes are tested. The spatial distribution and size structure of the sardine spawning stock for the period 1991-1999 are presented and a simple size-based fecundity model, combined with modelled recruitment, is used to determine the relative importance of each spawning and nursery area. The area of spawning plays a fundamental role in determining the destination of spawned eggs, and recruitment of sardine in the southern Benguela ecosystem appears to be divided into three recruitment systems by the circulation of the region: eggs spawned west of Cape Agulhas recruiting on the west coast (the WAB/WC-WC system), eggs spawned east of Cape Agulhas recruiting on the west coast (the CAB-WC system), and eggs spawned east of Cape Agulhas recruiting to the south coast (the SC-SC system). There is a slight increase in retention in the two nursery areas during winter, but the transport of eggs and larvae from the Agulhas Bank to the west coast is optimal during spring to early summer. Slow development arising from cold temperatures on the west coast could negatively impact recruitment by increasing offshore loss of individuals before they develop to a stage when they are able to actively avoid offshore currents and through its effect on mortality rate. This could explain the spatial separation of spawning and nursery areas in this system. The vertical position of individuals has an effect on the level of modelled recruitment and mortality rate, but observed vertical distributions of sardine egg and larvae do not significantly increase the level of modelled recruitment to optimal nursery areas. This suggests that efficient transport and retention are traded-off against other factors such as predator avoidance or prey abundance. Observed size structure and spatial distribution of the sardine spawning stock for 1991-1999 fluctuated greatly with most spawning centred on the western Agulhas Bank. When spawning was centred east of Cape Agulhas, recruitment was poor. No significant relationship could be established between potential reproductive output reaching the west coast and estimated recruitment, but positive recruitment anomalies required good transport to, and retention on, the west coast. A conceptual model of the early life history of sardine is proposed in light of limitations imposed by transport and retention of individuals. Lower primary production and the possibility of higher predation on the Agulhas Bank suggest that the south coast supports less recruitment than the west coast. The hypotheses tested using available data and model results could improve the understanding of recruitment of sardine in this complex ecosystem. These need to be validated by field observations. Additionally, further avenues for research that could help in developing a better understanding of the sardine life history in the southern Benguela ecosystem are suggested.
Linhares, Jussiara Candeira SpÃndola. "Reproductive strategies of the crab Ucides cordatus (Crustacea, Brachyura; Ucididae)." Universidade Federal do CearÃ, 2010. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6143.
Full textCoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
A reproduÃÃo à um dos principais eventos na vida de um indivÃduo, sendo relatados para Brachyura diferentes estratÃgias de reproduÃÃo. Este trabalho tem como objetivo descrever estratÃgias reprodutivas do caranguejo-uÃÃ, Ucides cordatus, no manguezal do Rio IgaraÃà â PI, observando a relaÃÃo das fases do ciclo reprodutivo com fatores ambientais. As coletas foram realizadas durante o perÃodo de 24 meses, nos quais os valores mensais de temperatura e pluviosidade foram registrados. ExcursÃes ao manguezal para a observaÃÃo do comportamento dos caranguejos foram realizadas no perÃodo de reproduÃÃo da espÃcie, denominado âandadaâ. Os ovÃrios e vasos deferentes dos animais foram analisados e classificados quanto ao estÃgio de maturaÃÃo. Os ovos de fÃmeas ovÃgeras foram contados para estimar a fecundidade. Um total de 720 indivÃduos foram analisados. Com base na anÃlise microscÃpica das gÃnadas foi observado que o perÃodo reprodutivo da espÃcie à sazonal e està inserido na estaÃÃo chuvosa. Este perÃodo à determinado por fÃmeas jà que machos estÃo aptos à reproduÃÃo todo o ano. Baseado na anÃlise gonadal, foi observado que o tamanho da largura da carapaÃa no qual 50% das fÃmeas e machos estÃo maturos foi 35,13 mm e 32,71 mm, respectivamente. Para maturaÃÃo morfolÃgica estes valores foram para fÃmeas 46 mm com base no crescimento da largura do abdÃmen e para machos 39,9 e 36,4 mm com base no crescimento dos quelÃpodos e comprimento do gonopÃdio respectivamente. Estes valores sÃo inferiores aos observados para outras regiÃes. A fecundidade observada para populaÃÃo tambÃm se mostrou inferior a de outra regiÃo, quando comparadas Ãs equaÃÃes de fecundidade. Foi verificado que o acasalamento da espÃcie ocorre durante a intermuda. Durante os fenÃmenos de âandadaâ o comportamento visualizado com maior intensidade foi a liberaÃÃo de ovos para o abdÃmen da fÃmea. Um pequeno nÃmero de cÃpulas foi observado, assim como disputas entre machos. Todos estes comportamentos ocorreram durante o perÃodo noturno, o que indica que para esta populaÃÃo o fenÃmeno da âandadaâ ocorre com maior intensidade à noite. Com base nos resultados, foi sugerida a hipÃtese que a alta intensidade de pesca do crustÃceo na regiÃo pode ter desencadeado as mudanÃas observadas na estratÃgia reprodutiva da populaÃÃo quando comparada a de outras regiÃes
The reproduction is one of the main events in an individual's life, being reported for Brachyura different reproduction strategies. This project has aimed to describe reproductive strategies of the caranguejo-uÃÃ, Ucides cordatus, in mangrove of IgaraÃÃ river - PI, observing the relationship of the reproductive cycle phases with environmental factors. The samples were obtained during one period of 24 months. During this period the values of temperature and pluviosity were monthly registered. Excursion to the mangroves for crabs behavior observation were accomplished in the mating period of, called âandadaâ. The ovaries and vas deferens of the animals were analyzed and classified regarding the maturation stage. The eggs of ovigerous females were counted to esteem the fecundity. A total of 720 individuals were analyzed. Based on gonad microscopic analysis it was observed that the reproductive period of the species is seasonal and occurs during at the rainy season. This period is determined by females since males are capable to the reproduction throughout year. Based in the gonadal analysis, it was observed the size of the carapace width where 50% of the females and males were mature, was 35.13 mm and 32.71 mm, respectively. For morphologic maturation these values were 46 mm to females with base in the growth of the width of the abdomen and 39.9 and 36.4 mm for males with base in the growth of the length of the chelipeds and length of the gonopod. These values are smaller when compared to the observed for other areas. The fecundity observed for the population studied was also inferior to the one of another area, when compared the fecundity equations. It was verified that the mating of the species occurs during the intermoult. During the "andada" phenomena, the behavior visualized with larger intensity was the liberation of eggs for the abdomen of the female. A small number of mating were observed, as well as fights among males. All these behaviors occurred during the night period, indicating that, for this population, the phenomenon of the "andada" occur with larger intensity at night. Based on results, it was suggested the hypothesis that the high intensity of fishing of the crustacean in the area might have unchained the changes observed in the reproductive strategy of the population when compared the one of other areas.
Wilson, Scott Darren. "Influence of environmental variation on habitat selection, life history strategies and population dynamics of sympatric ptarmigan in the southern Yukon Territory." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1225.
Full textClay, Thomas Anthony. "Drivers of variation in the migration and foraging strategies of pelagic seabirds." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267809.
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