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Tesi sul tema "Sperrm competition"

Autore: Grafiati

Pubblicato: 5 ottobre 2024

Ultima modifica: 31 luglio 2025

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1

Meunier, Léna. "Reproductive biology and senescence impact on postcopulatory sexual selection in a wild polyandrous bird, the North African Houbara Bustard (Chlamydotis undulata undulata)." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCK028.

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Abstract (sommario):

Résumé La polyandrie, lorsque les femelles s'accouplent avec plusieurs mâles, augmente les possibilités de sélection sexuelle, car outre la compétition entre les mâles pour l'accès à la femelle (sélection sexuelle pré-copulatoire), les spermatozoïdes des différents mâles sont également en compétition pour la fécondation (sélection sexuelle post-copulatoire). En conséquence, la plupart des descendants sont engendrés par le dernier mâle qui s’est accouplé avec la femelle, un phénomène appelé "last male precedence" (LMP). En plus de l'ordre d'accouplement, la quantité et la qualité des spermatozo

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2

Siva-Jothy, M. T. "Sperm competition in the odonata." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370301.

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3

Eady, Paul E. "Sperm competition in Callosobruchus maculatus." Thesis, University of Sheffield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263760.

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4

Fryer, Timothy James Osborne. "ESS models of sperm competition." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266803.

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5

Gilbert, Lucy. "Sperm competition in the western gull." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389759.

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6

Cook, Penelope Anne. "Sperm competition in butterflies and moths." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307641.

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7

Lovell-Mansbridge, Claire. "Sperm competition in the feral pigeon Columba livia." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364193.

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8

Hunter, Fiona M. "Sperm competition in the Northern fulmar (Fulmaris glacialis)." Thesis, University of Sheffield, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304668.

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9

Ramm, Steven Andrew. "Sperm competition and its evolutionary consequences in rodents." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436259.

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10

Preston, Brian T. "Sexual selection and sperm competition in Soay sheep." Thesis, University of Stirling, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391526.

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11

Bayram, Helen. "A proteomic study of sperm competition in mammals." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2008418/.

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Abstract (sommario):

Sperm competition, when sperm from more than one male compete to fertilise the same ova, has driven a diversity of adaptations. Increasingly, molecular techniques have been used to study the effect of post-copulatory sexual selection, including sperm competition, on proteins that are essential to reproduction. Genomic studies have revealed the rapid evolution of ejaculate proteins in polyandrous species. Additionally, there is evidence that gene expression can be altered plastically, in response to cues of sperm competition. Such studies are limited however, as the transcriptome does not alway

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12

Morrow, Edward Hugh. "The evolution of sperm length." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367026.

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13

Siegmund, Barbara W. "Sperm competition in the scorpionfly Panorpa communis (Mecoptera, Insecta)." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=983080682.

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14

Fu, Peng. "Sperm competition and alternative mating tactics in bluegill sunfish." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0015/MQ54204.pdf.

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15

Ransford, Mark Oliver. "Sperm competition in the 2-spot ladybird, Adalia bipunctata." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444755.

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16

Cooper, Gillian. "Analysis of genetic variation and sperm competition in dragonflies." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259897.

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17

Cunningham, Emma Jane Ann. "Forced copulation and sperm competition in the mallard Anas platyrhynchos." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262851.

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18

Pateman-Jones, Christopher. "Sperm competition and male mating tactics in the bitterling fishes." Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/29741.

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Abstract (sommario):

Bitterling are a group of freshwater fishes that lay their eggs on the gills of living freshwater mussels, using the mussel as a protective environment for embryo development and utilising the mussels own respiration to ensure fertilisation. This unusual spawning mechanism, using a spawning site that can be easily manipulated, makes bitterling ideal of reinvestigating sperm competition and making system evolution. Here, using a range of bitterling species, a series of aquarium experiments were conducted, as well as morphological and histological studies of the sperm and testes. It was shown th

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19

Rouse, James Luke. "Cognitive mechanisms underlying responses to sperm competition in Drosophila melanogaster." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/17072/.

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In this thesis I use Drosophila melanogaster as a model organism to study the possible cognitive mechanisms controlling plastic behavioural responses to sperm competition. This plastic behaviour involves a male D. melanogaster responding to the presence of a rival male by increasing mating duration when housed with a female. I provide a general context to the work (Chapter 1) before examining my model in more temporal detail by investigating how the length of time males were exposed to a high sperm competition environment affected maintenance time of the plastic behaviour. I show that for male

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20

Todd, Amanda Claire. "Mating strategies and sperm competition in New Zealand geckos (Family Gekkonidae)." Thesis, University of Canterbury. Zoology, 2003. http://hdl.handle.net/10092/1421.

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Most species of reptile studied to date have polygynandrous mating systems and possess specialised sperm storage regions. Consequently, there is a high potential for sperm competition in this group. Using comparative analyses, I examined the level of sperm competition in New Zealand geckos and how this has influenced the evolution of their reproductive morphology. Across lizards and snakes, there was more than a 40-fold variation in relative testis size. New Zealand geckos fell in the middle of this range and lacked sexual dimorphism in head size, suggesting that most species have polyg

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21

Nicholls, E. Henry. "Male adaptations to sperm competition in the sand martin Riparia riparia." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322914.

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22

Lane, Meg. "Sperm competition and sexual selection in western grey kangaroos Macropus fuliginosus." Thesis, Lane, Meg (2014) Sperm competition and sexual selection in western grey kangaroos Macropus fuliginosus. Honours thesis, Murdoch University, 2014. https://researchrepository.murdoch.edu.au/id/eprint/25342/.

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Abstract (sommario):

Macropods exhibit the second largest sexual dimorphism in body size for any vertebrate, suggesting there is a major role of sexual selection, with the potential for different mating tactics amongst male kangaroos. It is suggested that dominant males invest heavily in large forelimb muscles, which aids in male-male competition, female coercion and increased attractiveness to females, gaining them the majority of matings. A subdominant male may not invest in muscle mass development, but rather rely on other reproductive tactics such as sneaky matings and investment in competitive spermatozoa cha

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23

Poli, Federica. "Ejaculates in competition: a sperm race influenced by the seminal fluid?" Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424137.

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Abstract (sommario):

ABSTRACT In the last forty years, the historical notion of monogamous females has been gradually eroded away, and female multiple mating is now look as a common and ubiquitous phenomenon in nature, triggering theoretical and experimental attention to its biological implications and evolutionary consequences. Sexual selection is the evolutionary process that favours the increase in frequency of the genes that confer a reproductive advantage to the individuals carrying them. Polyandry implies that sexual selection may persist even after the copulation up to the point of fertilization, and in

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24

Rodrigues, Marcos. "Breeding strategies of the chiffchaff." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318813.

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25

Thomsen, Ruth. "Sperm competition and the function of masturbation in Japanese macaques (Macaca fuscata)." Connect to this title online, 2000. http://edoc.ub.uni-muenchen.de/archive/00000105/.

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26

Thomsen, Ruth. "Sperm Competition and the Function of Masturbation in Japanese Macaques (Macaca fuscata)." Diss., lmu, 2001. http://nbn-resolving.de/urn:nbn:de:bvb:19-1059.

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27

Leach, Brenda J. "Competition and the evolution of sperm characteristics in Pacific salmon, Oncorhynchus spp." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22341.pdf.

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28

Svensson, Ola. "Sexual selection in Pomatoschistus – nests, sperm competition, and paternal care." Doctoral thesis, Stockholm : Zoologiska institutionen, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-298.

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29

Lemaître, Jean-François. "Sperm competition and male social dominance in the bank vole (Myodes glareolus)." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533995.

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30

Staples, Alison. "Anatomical aspects of sperm competition in the male zebra finch Taeniopygia guttata." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364383.

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31

Fletcher, Fiona Jane Campbell. "Male and female aspects of sperm competition in the zebra finch, Taeniopygia guttata." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387766.

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32

Ball, Alexander. "Sexual conflict in the penduline tits (Remizidae) : implications for sperm competition and speciation." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675694.

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Abstract (sommario):

This thesis explores the far-reaching impacts of sexual conflict over care on a suite of traits in the penduline tit family (Remizidae), further confirming the intricate relationships between parental care, mating systems and sexual selection. The results reveal the first genetic phylogeny of this family and suggest that uniparental care evolved once in this group. The transition to uniparental care is associated with rapid evolution of male plumage ornaments most likely driven by increased sexual selection. The results also suggest a relationship between male care and the likelihood of patern

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33

Bellamy, L. A. R. "Sexual selection in stalk-eyed flies : inbreeding depression, sperm competition and larval development." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1347916/.

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Abstract (sommario):

Stalk-eyed flies (Diptera: Diopsidae) have emerged as an important model organism in the study of sexual selection. They are characterised by their eyes being located on elongated stalks that protrude from their heads. In many species, males have larger eyespans than females as a result of female mate preference and malemale competition. In this thesis, I investigated several different aspects of stalk-eyed fly biology. First, I provide a comprehensive review that asks whether the literature supports the hypothesis that male sexual traits suffer from heightend inbreeding depression relative to

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34

Danielson-Francois, Anne. "Variation in Tetragnathid spermathecal structures and sperm competition with descriptions of natural history." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/279954.

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The study of variation in arachnid genitalic structures has contributed to the fields of systematics and sexual selection. Simon (1892--1903) in his Histoire Naturelle des Araignees first divided the ecribellate higher spiders into two groups, the Haplogynae and Entelegynae, using reproductive morphology. Spider genitalia have been used as a taxonomic tool for distinguishing between taxa because of their species-specific morphological variation. Variation in spider genitalic morphology has inspired evolutionary biologists to test mechanisms of sexual selection by which the variation could evol

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35

Manriquez, Patricio H. "Mate choice and reproductive investment in the cheilostome bryozoan Celleporella hyalina (L.)." Thesis, Bangor University, 1999. https://research.bangor.ac.uk/portal/en/theses/mate-choice-and-reproductive-investment-in-the-cheilostome-bryozoan-celleporella-hyalina-l(213eab65-9c53-4769-869d-8fe403021006).html.

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In the present research several aspects of the reproductive biology of the marine hermaphroditic bryozoan, Celleporell hyalin (Linnaeus, 1767) were investigated. First (see Chapter 2), aliquots, of different ages from a stock of allosperm suspension were used to fertilize a series of virgin ramets, so characterizing the decay in fertility of released sperm and any effects of sperm ageing on subsequent embryogenesis and larval metamorphosis. The effect of temperature on the above variables was also investigated. The fertile half-life of C. hvalina sperm was about 1-2 h, although significant dec

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36

Brown, Gordon S. "Sperm competition and male forceps dimorphism in the European earwig Forficula auricularia (Dermaptera: Forficulina)." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/409.

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37

Barnett, Mandy. "Sex in southern african spirostreptida millipedes : mechanisms of sperm competition and cryptic female choice." Doctoral thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/17557.

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Abstract (sommario):

Bibliography: pages 163-179.<br>Spirostreptida millipedes comprise three families, the Harpagophoridae, Spirostreptidae and Odontopygidae. They are polygynandrous. Males transfer sperm via species-specific accessory genitalia called gonopods, that comprise three components, two of which, the emote and telopodite, are involved in processes of sperm transfer. The emotes function to translocate ejaculates from the penes to the vulvae, where they are stored. A delay between insemination and fertilisation provides an arena for syn- and postcopulatory sexual competition. These operate at the gametic

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38

Lethbridge, Fiona Margaret Douglas. "Causes and consequences of ejaculate size in Callosobruchus maculatus beetles." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/8731.

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Abstract (sommario):

Post-copulatory sexual selection is a strong evolutionary force, affecting morphological and behavioural traits in males and females in species with polyandrous mating systems. Many insects are subject to sperm competition; sperm from rival males compete to fertilise ova. Since sperm are finite, males should allocate them economically, tailoring ejaculate allocation to suit the reproductive potential of individual matings. Theory suggests when sperm competition risk is high, males should increase sperm numbers to achieve greater reproductive success than their rivals, but evidence of this expe

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39

Yoward, Paul James. "Spider sperm competition : the conduit/cul-de-sac hypothesis : a route to understanding or a dead end?" Thesis, University of York, 1996. http://etheses.whiterose.ac.uk/14176/.

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This thesis is an evaluation of the hypothesis that the spennathecae of spiders affects the sperm precedence patterns in a predictable way (Austad 1984). Spermathecae come in two varieties: cul-de-sac and conduit. Cul-de-sac spennathecae, according to the hypothesis, are supposed to lead to second male sperm priority and conduit to first male sperm priority . The hypothesis was evaluated both directly and indirectly. Direct measurements were made of paternity in two species, Pholcus phalangioides and Tetragnatha montana, both of which are cul-de-sac species. It was found that P. phalangioides

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40

Taylor, Michelle Louise. "Sexual selection and the benefits of mating with attractive males in Drosophila simulans." Thesis, University of Exeter, 2008. http://hdl.handle.net/10036/40883.

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Abstract (sommario):

Over the last century, sexual selection has grown from a controversial theory into a vast field of theoretical and empirical research. Although Darwin outlined two major mechanisms within his theory, male-male competition and female mate choice, the latter has promoted a wealth of research by virtue of its complexity. Despite decades of research into how female preferences and sexually selected traits have evolved, there is still little consensus as to why females prefer the males they do. Preferences are thought to evolve from either direct selection on the preference, as females themselves b

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41

Ziege, Madlen, Kristin Mahlow, Carmen Hennige-Sulz, et al. "Audience effects in the Atlantic molly (Poecilia mexicana) : prudent male mate choice in response to perceived sperm competition risk?" Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4517/.

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Background: Multidirectional interactions in social networks can have a profound effect on mate choice behavior; e.g., Poecilia mexicana males show weaker expression of mating preferences when being observed by a rival. This may be an adaptation to reduce sperm competition risk, which arises because commonly preferred female phenotypes will receive attention also from surrounding males, and/or because other males can copy the focal male's mate choice. Do P. mexicana males indeed respond to perceived sperm competition risk? We gave males a choice between two females and repeated the tests unde

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42

Di, Nisio Andrea. "Evolutionary consequences of producing competitive ejaculates: insights from an artificial selection study for sperm production on Poecilia reticulata." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3424544.

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The aim of my study was to investigate the maintenance of variability for sperm production in the guppy, P. reticulata. Sperm number, which is the main determinant of SC outcome in the Trinidadian guppy population studied in my lab, shows high additive genetic variance despite strong directional selection and very high sire heritability and stronger condition dependence than other ejaculate traits; furthermore, multiply mated females produce higher quality offspring, suggesting that sperm c ompetition, and hence sperm number, may mediate genetic benefits to the female. To clarify the evolution

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43

Rosengrave, Patrice Christina. "Ejaculate traits and ovarian fluid as a potential mechanism for cryptic female choice in chinook salmon (Oncorhynchus tshawytscha)." Thesis, University of Canterbury. School of Biological Sciences, 2010. http://hdl.handle.net/10092/3984.

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Marine and freshwater environments support numerous species of teleost fish with a wide and diverse range of reproductive strategies. Despite the considerable interest in fish reproduction, our knowledge regarding ejaculate traits and factors affecting them is limited. Using computer-assisted sperm analysis (CASA) I measured ejaculate traits (sperm swimming speed, motility, path trajectory, longevity and concentration) from sexually mature chinook salmon (Oncorhynchus tshawytscha) activated in freshwater and ovarian fluid. I also looked at these ejaculate traits in relation to measures of male

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44

Johnson, Jeffery Allan. "A histological comparative study on sperm competition inside the spermathecae in the grasshopper species, Dichromorphaviridis and Chortophaga viridifasciata (Orthoptera: Acrididae)." Raleigh, NC : North Carolina State University, 1998. http://www.lib.ncsu.edu/etd/public/etd-115412312982890/etd.pdf.

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45

au, k. bryant@murdoch edu, and Kate Alexandra Bryant. "The mating system and reproduction in the honey possum, Tarsipes rostratus: a life-history and genetical perspective." Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050505.140613.

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Abstract (sommario):

The honey possum Tarsipes rostratus, a marsupial endemic to South-Western Australia, feeds exclusively upon nectar and pollen. It is one of the smallest marsupials, with adult females (8-12g) significantly larger than adult males (6-9g). Honey possum males have the longest sperm (356µm) recorded for any mammaland the testes represent 4.2% body weight, amongst the largest recorded formammal species. These features suggest that sperm competition is an importantpart of the mating system. This study used a combination of field based studies,DNA analysis and histological examination of the female r

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46

Thompson, Glen Andrew. "Mating behaviour and the reproductive ecology of the big-handed crab, Heterozius rotundifrons A. Milne Edwards, 1867." Thesis, University of Canterbury. Zoology, 1999. http://hdl.handle.net/10092/1515.

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The mating behaviour and reproductive ecology of the big-handed crab Heterozius rotundifrons was studied at Kaikoura between November 1997 and December 1998. H. rotundifrons was found at mean densities of 7.6 per m² (± 1.4) within the middle and low shore levels and varied little between seasons. The variance! mean ratio indicated that males and females aggregated within these shore levels. The sex ratio was significantly female biased during the majority of the year. Allometric growth rates indicated that males and females reached sexual maturity at 11 mm carapace width (CW). In males, sperma

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47

Magris, Martina. "Phenotypic plasticity in male sexually selected traits in response to social cues." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3425756.

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Abstract (sommario):

Reproductive success of males is strongly influenced by their investment in costly sexually selected traits. Fitness returns, however, are often context-dependent and vary with demographic parameters such as sex ratio and population density. Under conditions of environmental variability, the ability to modulate reproductive decisions on the social context is highly beneficial. As a result, phenotypic plasticity of sexually selected traits is widespread. The aim of my study was threefold. Firstly, I worked to expand our current knowledge on phenotypic plasticity in sexually selected traits both

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48

Johnson, Jeffery Allan. "A histological comparative study on sperm competition inside the spermathecae in the grasshopper species, Dichromorpha viridis and Chortophaga viridifasciata (Orthoptera: Acrididae)." NCSU, 1998. http://www.lib.ncsu.edu/theses/available/etd-19980330-170712.

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Abstract (sommario):

<p>The mechanism of sperm transfer and sperm organization inside the spermatheca was investigated in two grasshoppers, (Scudder) and (DeGeer). The spermathecae were examined histologically from females whose copulations were interrupted at various prescribed intervals, either during their first or subsequent mating. Sperm organization inside the spermatheca from 24 to 120 hours after copulation had terminated was also investigated in . Scanning and transmission electron microscopy were used to investigate the distribution and morphology of small hair-like structures inside the spermathecae.<p>

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49

Larsdotter, Mellström Helena. "Life history evolution in a bivoltine butterfly." Doctoral thesis, Stockholms universitet, Zoologiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-81399.

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Abstract (sommario):

Evolution is not always straight-forward, as selection pressures may differ between different generations of the same species. This thesis focuses on the evolution of life history of the model species, the Green-veined White butterfly Pieris napi. In central Sweden P. napi has two generations per year. The directly developing summer generation is short-lived and time stressed, compared to the diapausing generation. In paper I polyandry, defined as female mating rate, was shown to differ between generations but was unaffected by environmental factors. In paper II both males and females of the d

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50

Costello, Aron K. "Female Characteristics that Influence Male Mate Preference in House Mice (Mus Musculus)." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1280754434.

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