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Articoli di riviste sul tema "Sperrm competition"

Autore: Grafiati

Pubblicato: 5 ottobre 2024

Ultima modifica: 31 luglio 2025

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1

André, Gonçalo I., Renée C. Firman, and Leigh W. Simmons. "Phenotypic plasticity in genitalia: baculum shape responds to sperm competition risk in house mice." Proceedings of the Royal Society B: Biological Sciences 285, no. 1882 (2018): 20181086. http://dx.doi.org/10.1098/rspb.2018.1086.

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Abstract (sommario):

Males are known to adjust their expenditure on testes growth and sperm production in response to sperm competition risk. Genital morphology can also contribute to competitive fertilization success but whether male genital morphology can respond plastically to the sperm competition environment has received little attention. Here, we exposed male house mice to two different sperm competition environments during their sexual development and quantified phenotypic plasticity in baculum morphology. The sperm competition environment generated plasticity in body growth. Males maturing under sperm comp

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Lüke, Lena, Polly Campbell, María Varea Sánchez, Michael W. Nachman, and Eduardo R. S. Roldan. "Sexual selection on protamine and transition nuclear protein expression in mouse species." Proceedings of the Royal Society B: Biological Sciences 281, no. 1783 (2014): 20133359. http://dx.doi.org/10.1098/rspb.2013.3359.

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Post-copulatory sexual selection in the form of sperm competition is known to influence the evolution of male reproductive proteins in mammals. The relationship between sperm competition and regulatory evolution, however, remains to be explored. Protamines and transition nuclear proteins are involved in the condensation of sperm chromatin and are expected to affect the shape of the sperm head. A hydrodynamically efficient head allows for fast swimming velocity and, therefore, more competitive sperm. Previous comparative studies in rodents have documented a significant association between the l

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Champion de Crespigny, Fleur E., and Nina Wedell. "Wolbachia infection reduces sperm competitive ability in an insect." Proceedings of the Royal Society B: Biological Sciences 273, no. 1593 (2006): 1455–58. http://dx.doi.org/10.1098/rspb.2006.3478.

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The maternally inherited bacterium Wolbachia pipientis imposes significant fitness costs on its hosts. One such cost is decreased sperm production resulting in reduced fertility of male Drosophila simulans infected with cytoplasmic incompatibility (CI) inducing Wolbachia . We tested the hypothesis that Wolbachia infection affects sperm competitive ability and found that Wolbachia infection is indeed associated with reduced success in sperm competition in non-virgin males. In the second male role, infected males sired 71% of the offspring whereas uninfected males sired 82% of offspring. This is

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4

Hoysak, Drew J., N. Robin Liley, and Eric B. Taylor. "Raffles, roles, and the outcome of sperm competition in sockeye salmon." Canadian Journal of Zoology 82, no. 7 (2004): 1017–26. http://dx.doi.org/10.1139/z04-073.

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In species with male alternative reproductive phenotypes, one phenotype is usually disadvantaged in mating competition. In salmonid fishes, large late-maturing males pair with nesting females and maintain close contact before and during spawning. Small early-maturing males have little contact with nesting females and, during spawning, begin to release sperm after the paired male. The effects of male phenotype and timing of ejaculation on success in sperm competition are not known. In this study, we determined paternity of offspring resulting from in vitro competitive fertilizations to examine

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5

Engqvist, Leif, and Klaus Reinhold. "Sperm competition games: optimal sperm allocation in response to the size of competing ejaculates." Proceedings of the Royal Society B: Biological Sciences 274, no. 1607 (2006): 209–17. http://dx.doi.org/10.1098/rspb.2006.3722.

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Sperm competition theory predicts that when males are certain of sperm competition, they should decrease sperm investment in matings with an increasing number of competing ejaculates. How males should allocate sperm when competing with differently sized ejaculates, however, has not yet been examined. Here, we report the outcomes of two models assuming variation in males' sperm reserves and males being faced with different amounts of competing sperm. In the first ‘spawning model’, two males compete instantaneously and both are able to assess the sperm competitive ability of each other. In the s

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6

Vuarin, Pauline, Yves Hingrat, Loïc Lesobre, Michel Saint Jalme, Frédéric Lacroix, and Gabriele Sorci. "Sperm competition accentuates selection on ejaculate attributes." Biology Letters 15, no. 3 (2019): 20180889. http://dx.doi.org/10.1098/rsbl.2018.0889.

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Ejaculate attributes are important factors driving the probability of fertilizing eggs. When females mate with several males, competition between sperm to fertilize eggs should accentuate selection on ejaculate attributes. We tested this hypothesis in the North African houbara bustard ( Chlamydotis undulata undulata ) by comparing the strength of selection acting on two ejaculate attributes when sperm from single males or sperm from different males were used for insemination. In agreement with the prediction, we found that selection on ejaculate attributes was stronger when sperm of different

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7

Singson, Andrew, Katherine L. Hill, and Steven W. L’Hernault. "Sperm Competition in the Absence of Fertilization in Caenorhabditis elegans." Genetics 152, no. 1 (1999): 201–8. http://dx.doi.org/10.1093/genetics/152.1.201.

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Abstract Hermaphrodite self-fertilization is the primary mode of reproduction in the nematode Caenorhabditis elegans. However, when a hermaphrodite is crossed with a male, nearly all of the oocytes are fertilized by male-derived sperm. This sperm precedence during reproduction is due to the competitive superiority of male-derived sperm and results in a functional suppression of hermaphrodite self-fertility. In this study, mutant males that inseminate fertilization-defective sperm were used to reveal that sperm competition within a hermaphrodite does not require successful fertilization. Howeve

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8

Sloan, Nadia S., Maxine Lovegrove, and Leigh W. Simmons. "Social manipulation of sperm competition intensity reduces seminal fluid gene expression." Biology Letters 14, no. 1 (2018): 20170659. http://dx.doi.org/10.1098/rsbl.2017.0659.

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A considerable body of evidence supports the prediction that males should increase their expenditure on the ejaculate in response to sperm competition risk. The prediction that they should reduce their expenditure with increasing sperm competition intensity is less well supported. Moreover, most studies have documented plasticity in sperm numbers. Here we show that male crickets Teleogryllus oceanicus exhibit reduced seminal fluid gene expression and accessory gland mass in response to elevated sperm competition intensity. Together with previous research, our findings suggest that strategic ad

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9

Firman, Renée C., and Leigh W. Simmons. "Sperm midpiece length predicts sperm swimming velocity in house mice." Biology Letters 6, no. 4 (2010): 513–16. http://dx.doi.org/10.1098/rsbl.2009.1027.

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Evolutionary biologists have argued that there should be a positive relationship between sperm size and sperm velocity, and that these traits influence a male's sperm competitiveness. However, comparative analyses investigating the evolutionary associations between sperm competition risk and sperm morphology have reported inconsistent patterns of association, and in vitro sperm competition experiments have further confused the issue; in some species, males with longer sperm achieve more competitive fertilization, while in other species males with shorter sperm have greater sperm competitivenes

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10

Calhim, Sara, Stephen Pruett-Jones, Michael S. Webster, and Melissah Rowe. "Asymmetries in reproductive anatomy: insights from promiscuous songbirds." Biological Journal of the Linnean Society 128, no. 3 (2019): 569–82. http://dx.doi.org/10.1093/biolinnean/blz100.

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Abstract Directional asymmetry in gonad size is commonly observed in vertebrates and is particularly pronounced in birds, where the left testis is frequently larger than the right. The adaptive significance of directional asymmetry in testis size is poorly understood, and whether it extends beyond the testes (i.e. side-correspondent asymmetry along the reproductive tract) has rarely been considered. Using the Maluridae, a songbird family exhibiting variation in levels of sperm competition and directional testis asymmetry, yet similar in ecology and life history, we investigated the relative ro

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11

Firman, Renée C. "Of mice and women: advances in mammalian sperm competition with a focus on the female perspective." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200082. http://dx.doi.org/10.1098/rstb.2020.0082.

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Although initially lagging behind discoveries being made in other taxa, mammalian sperm competition is now a productive and advancing field of research. Sperm competition in mammals is not merely a ‘sprint-race’ between the gametes of rival males, but rather a race over hurdles; those hurdles being the anatomical and physiological barriers provided by the female reproductive tract, as well as the egg and its vestments. With this in mind, in this review, I discuss progress in the field while focusing on the female perspective. I highlight ways by which sperm competition can have positive effect

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12

RADWAN, JACEK, and WOJCIECH WITALIŃSKI. "Sperm competition." Nature 352, no. 6337 (1991): 671–72. http://dx.doi.org/10.1038/352671b0.

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13

Wigby, Stuart, and Tracey Chapman. "Sperm competition." Current Biology 14, no. 3 (2004): R100—R103. http://dx.doi.org/10.1016/j.cub.2004.01.013.

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14

Hughes, A. L. "Sperm Competition." Bulletin of the Entomological Society of America 33, no. 3 (1987): 202–3. http://dx.doi.org/10.1093/besa/33.3.202a.

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15

Castillo, Dean M., and Leonie C. Moyle. "Intraspecific sperm competition genes enforce post-mating species barriers in Drosophila." Proceedings of the Royal Society B: Biological Sciences 281, no. 1797 (2014): 20142050. http://dx.doi.org/10.1098/rspb.2014.2050.

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Sexual selection and sexual conflict are considered important drivers of speciation, based on both theoretical models and empirical correlations between sexually selected traits and diversification. However, whether reproductive isolation between species evolves directly as a consequence of intrapopulation sexual dynamics remains empirically unresolved, in part because knowledge of the genetic mechanisms (if any) connecting these processes is limited. Here, we provide evidence of a direct mechanistic link between intraspecies sexual selection and reproductive isolation. We examined genes with

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16

Carleial, Rômulo, Grant C. McDonald, Lewis G. Spurgin, et al. "Temporal dynamics of competitive fertilization in social groups of red junglefowl ( Gallus gallus ) shed new light on avian sperm competition." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200081. http://dx.doi.org/10.1098/rstb.2020.0081.

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Studies of birds have made a fundamental contribution to elucidating sperm competition processes, experimentally demonstrating the role of individual mechanisms in competitive fertilization. However, the relative importance of these mechanisms and the way in which they interact under natural conditions remain largely unexplored. Here, we conduct a detailed behavioural study of freely mating replicate groups of red junglefowl, Gallus gallus , to predict the probability that competing males fertilize individual eggs over the course of 10-day trials. Remating frequently with a female and mating l

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LAWNICZAK, MARA K. N., and DAVID J. BEGUN. "A QTL analysis of female variation contributing to refractoriness and sperm competition in Drosophila melanogaster." Genetical Research 86, no. 2 (2005): 107–14. http://dx.doi.org/10.1017/s0016672305007755.

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Sperm competition is an important fitness component in many animal groups. Drosophila melanogaster males exhibit substantial genetic variation for sperm competitive ability and females show considerable genetic variation for first versus second male sperm use. Currently, the forces responsible for maintaining genetic variation in sperm competition related phenotypes are receiving much attention. While several candidate genes contributing to the variation seen in male competitive ability are known, genes involved in female sperm use remain largely undiscovered. Without knowledge of the underlyi

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18

Fisher, Heidi S., Luca Giomi, Hopi E. Hoekstra, and L. Mahadevan. "The dynamics of sperm cooperation in a competitive environment." Proceedings of the Royal Society B: Biological Sciences 281, no. 1790 (2014): 20140296. http://dx.doi.org/10.1098/rspb.2014.0296.

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Sperm cooperation has evolved in a variety of taxa and is often considered a response to sperm competition, yet the benefit of this form of collective movement remains unclear. Here, we use fine-scale imaging and a minimal mathematical model to study sperm aggregation in the rodent genus Peromyscus . We demonstrate that as the number of sperm cells in an aggregate increase, the group moves with more persistent linearity but without increasing speed. This benefit, however, is offset in larger aggregates as the geometry of the group forces sperm to swim against one another. The result is a non-m

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19

Alonzo, Suzanne H., and Tommaso Pizzari. "Selection on female remating interval is influenced by male sperm competition strategies and ejaculate characteristics." Philosophical Transactions of the Royal Society B: Biological Sciences 368, no. 1613 (2013): 20120044. http://dx.doi.org/10.1098/rstb.2012.0044.

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Female remating rate dictates the level of sperm competition in a population, and extensive research has focused on how sperm competition generates selection on male ejaculate allocation. Yet the way ejaculate allocation strategies in turn generate selection on female remating rates, which ultimately influence levels of sperm competition, has received much less consideration despite increasing evidence that both mating itself and ejaculate traits affect multiple components of female fitness. Here, we develop theory to examine how the effects of mating on female fertility, fecundity and mortali

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20

Firman, Renée C., Jamie N. Tedeschi, and Francisco Garcia-Gonzalez. "Sperm sex ratio adjustment in a mammal: perceived male competition leads to elevated proportions of female-producing sperm." Biology Letters 16, no. 6 (2020): 20190929. http://dx.doi.org/10.1098/rsbl.2019.0929.

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Mammal sex allocation research has focused almost exclusively on maternal traits, but it is now apparent that fathers can also influence offspring sex ratios. Parents that produce female offspring under conditions of intense male–male competition can benefit with greater assurance of maximized grand-parentage. Adaptive adjustment in the sperm sex ratio, for example with an increase in the production of X-chromosome bearing sperm (CBS), is one potential paternal mechanism for achieving female-biased sex ratios. Here, we tested this mechanistic hypothesis by varying the risk of male–male competi

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Rowe, Melissah, Annabel van Oort, Lyanne Brouwer, et al. "Sperm Numbers as a Paternity Guard in a Wild Bird." Cells 11, no. 2 (2022): 231. http://dx.doi.org/10.3390/cells11020231.

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Sperm competition is thought to impose strong selection on males to produce competitive ejaculates to outcompete rival males under competitive mating conditions. Our understanding of how different sperm traits influence fertilization success, however, remains limited, especially in wild populations. Recent literature highlights the importance of incorporating multiple ejaculate traits and pre-copulatory sexually selected traits in analyses aimed at understanding how selection acts on sperm traits. However, variation in a male’s ability to gain fertilization success may also depend upon a range

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22

Yeates, Sarah E., Sigurd Einum, Ian A. Fleming, et al. "Atlantic salmon eggs favour sperm in competition that have similar major histocompatibility alleles." Proceedings of the Royal Society B: Biological Sciences 276, no. 1656 (2008): 559–66. http://dx.doi.org/10.1098/rspb.2008.1257.

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Polyandry and post-copulatory sexual selection provide opportunities for the evolution of female differential sperm selection. Here, we examined the influence of variation in major histocompatibility (MH) class I allelic composition upon sperm competition dynamics in Atlantic salmon. We ran in vitro fertilization competitions that mimicked the gametic microenvironment, and replicated a paired-male experimental design that allowed us to compare differences in sperm competition success among males when their sperm compete for eggs from females that were genetically either similar or dissimilar a

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Gasparini, Clelia, Elizabeth M. Speechley, and Giovanni Polverino. "The bold and the sperm: positive association between boldness and sperm number in the guppy." Royal Society Open Science 6, no. 7 (2019): 190474. http://dx.doi.org/10.1098/rsos.190474.

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Assessing the consequences of personality traits on reproductive success is one of the most important challenges in personality studies and critical to understand the evolutionary implications of behavioural variability among animals. Personality traits are typically associated with mating acquisition in males, and, hence, linked to variation in their reproductive success. However, in most species, sexual selection continues after mating, and sperm traits (such as sperm number and quality) become very important in determining post-mating competitive success. Here, we investigate whether variat

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Moschilla, Joe A., Joseph L. Tomkins, and Leigh W. Simmons. "Males adjust their manipulation of female remating in response to sperm competition risk." Proceedings of the Royal Society B: Biological Sciences 287, no. 1934 (2020): 20201238. http://dx.doi.org/10.1098/rspb.2020.1238.

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To reduce the potential for sperm competition, male insects are thought to inhibit the post-mating reproductive behaviour of females through receptivity-inhibiting compounds transferred in the ejaculate. Selection is expected to favour phenotypic plasticity in male post-copulatory expenditure, with males investing strategically in response to their perceived risk of sperm competition. However, the impact that socially cued strategic allocation might have on female post-mating behaviour has rarely been assessed. Here, we varied male perception of sperm competition risk, both prior to and during

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Evans, Jonathan P., Patrice Rosengrave, Clelia Gasparini, and Neil J. Gemmell. "Delineating the roles of males and females in sperm competition." Proceedings of the Royal Society B: Biological Sciences 280, no. 1772 (2013): 20132047. http://dx.doi.org/10.1098/rspb.2013.2047.

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Disentangling the relative roles of males, females and their interactive effects on competitive fertilization success remains a challenge in sperm competition. In this study, we apply a novel experimental framework to an ideally suited externally fertilizing model system in order to delineate these roles. We focus on the chinook salmon, Oncorhynchus tshawytscha , a species in which ovarian fluid (OF) has been implicated as a potential arbiter of cryptic female choice for genetically compatible mates. We evaluated this predicted sexually selected function of OF using a series of factorial compe

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Birkhead, T. R. "Enduring Sperm Competition." Journal of Avian Biology 25, no. 3 (1994): 167. http://dx.doi.org/10.2307/3677071.

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Zheng, W., C. Strobeck, and N. Stacey. "The steroid pheromone 4-pregnen-17,20ss-diol-3-one increases fertility and paternity in goldfish." Journal of Experimental Biology 200, no. 22 (1997): 2833–40. http://dx.doi.org/10.1242/jeb.200.22.2833.

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Previous studies in goldfish (Carassius auratus) showed that the oocyte maturation-inducing steroid 4-pregnen-17,20ss-diol-3-one (17,20ssP) functions after release as a pheromone that increases male serum gonadotropin II (GtH II) concentration, milt (sperm and seminal fluid) volume and sexual activity, effects hypothesized to increase male reproductive success in the sperm competition of multi-male spawnings. The present study tested this hypothesis by determining whether overnight exposure to 17,20ssP increases fertility. In pair spawnings, 17,20ssP-exposed males fertilized a greater percenta

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Sutter, Andreas, and Simone Immler. "Within-ejaculate sperm competition." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200066. http://dx.doi.org/10.1098/rstb.2020.0066.

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Sperm competition was defined by Geoff Parker 50 years ago as the competition between sperm from two or more males over the fertilization of a set of eggs. Since the publication of his seminal paper, sperm competition has developed into a large field of research, and many aspects are still being discovered. One of the relatively poorly understood aspects is the importance of selection and competition among sperm within the ejaculate of a male. The sheer number of sperm present in a male's ejaculate suggests that the competition among sibling sperm produced by the same male may be intense. In t

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Kustra, Matthew C., and Suzanne H. Alonzo. "Sperm and alternative reproductive tactics: a review of existing theory and empirical data." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200075. http://dx.doi.org/10.1098/rstb.2020.0075.

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Males that exhibit alternative reproductive tactics (ARTs) often differ in the risk of sperm competition and the energetic trade-offs they experience. The resulting patterns of selection could lead to between-tactic differences in ejaculate traits. Despite extensive research on male ARTs, there is no comprehensive review of whether and what differences in sperm traits exist between male ARTs. We review existing theory on ejaculate evolution relevant to ARTs and then conduct a comprehensive vote-counting review of the empirical data comparing sperm traits between males adopting ARTs. Despite th

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Linhart, O., M. Rodina, D. Gela, M. Kocour, and M. Vandeputte. "Spermatozoal competition in common carp (Cyprinus carpio): what is the primary determinant of competition success?" Reproduction 130, no. 5 (2005): 705–11. http://dx.doi.org/10.1530/rep.1.00541.

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The percentage of sperm motility (92–100%), spermatozoan velocity (112–163 μm·s−1) and control hatching rates (83–96%) were evaluated for each of six gold and five green male common carp (Cyprinus carpio). In all 30 possible paired combinations of sperm-competition tests, hatching rates of 90–97% were achieved. The mean percentage of offspring sired was strongly influenced by the male used (P < 0.001, R 2 = 0.91). The best male sired an average of 88% of the offspring in its competition tests, and the worst male sired only 5%. Spermatozoan-quality parameters could explain only part of the v

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Civetta, Alberto, Kim R. Rosing, and Jolene H. Fisher. "Differences in sperm competition and sperm competition avoidance in Drosophila melanogaster." Animal Behaviour 75, no. 5 (2008): 1739–46. http://dx.doi.org/10.1016/j.anbehav.2007.10.031.

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Friesen, Christopher R., Ariel F. Kahrl, and Mats Olsson. "Sperm competition in squamate reptiles." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200079. http://dx.doi.org/10.1098/rstb.2020.0079.

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Multiple paternity is ubiquitous within the polyphyletic group called ‘reptiles', especially within the lizards and snakes. Therefore, the probability of sperm competition occurring, and being intense, is high. Squamates exhibit a diversity of tactics to ensure fertilization success in the face of sperm competition. The duration of female sperm storage, which can be many months and even years in some species, remains an enigma. Here, we emphasize some mechanisms that might affect patterns of paternity, the source and function of ejaculates and features of the female reproductive tract that may

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Hosken, D. J. "Sperm competition in bats." Proceedings of the Royal Society of London. Series B: Biological Sciences 264, no. 1380 (1997): 385–92. https://doi.org/10.5281/zenodo.13447455.

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Abstract (sommario):

(Uploaded by Plazi for the Bat Literature Project) Sperm competition is a widespread phenomenon influencing the evolution of male anatomy, physiology and behaviour. Bats are an ideal group for studying sperm competition. Females store fertile sperm for up to 200 days and the size of social groups varies from single animals to groups of hundreds of thousands. This study examines the relationship between social group size and investment in spermatogenesis across 31 species of microchiropteran bat using new and published data on testis mass and sperm length. In addition to male competition, I exa

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Hosken, D. J. "Sperm competition in bats." Proceedings of the Royal Society of London. Series B: Biological Sciences 264, no. 1380 (1997): 385–92. https://doi.org/10.5281/zenodo.13447455.

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Abstract (sommario):

(Uploaded by Plazi for the Bat Literature Project) Sperm competition is a widespread phenomenon influencing the evolution of male anatomy, physiology and behaviour. Bats are an ideal group for studying sperm competition. Females store fertile sperm for up to 200 days and the size of social groups varies from single animals to groups of hundreds of thousands. This study examines the relationship between social group size and investment in spermatogenesis across 31 species of microchiropteran bat using new and published data on testis mass and sperm length. In addition to male competition, I exa

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Hosken, D. J. "Sperm competition in bats." Proceedings of the Royal Society of London. Series B: Biological Sciences 264, no. 1380 (1997): 385–92. https://doi.org/10.5281/zenodo.13447455.

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Abstract (sommario):

(Uploaded by Plazi for the Bat Literature Project) Sperm competition is a widespread phenomenon influencing the evolution of male anatomy, physiology and behaviour. Bats are an ideal group for studying sperm competition. Females store fertile sperm for up to 200 days and the size of social groups varies from single animals to groups of hundreds of thousands. This study examines the relationship between social group size and investment in spermatogenesis across 31 species of microchiropteran bat using new and published data on testis mass and sperm length. In addition to male competition, I exa

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Hosken, D. J. "Sperm competition in bats." Proceedings of the Royal Society of London. Series B: Biological Sciences 264, no. 1380 (1997): 385–92. https://doi.org/10.5281/zenodo.13447455.

Testo completo

Abstract (sommario):

(Uploaded by Plazi for the Bat Literature Project) Sperm competition is a widespread phenomenon influencing the evolution of male anatomy, physiology and behaviour. Bats are an ideal group for studying sperm competition. Females store fertile sperm for up to 200 days and the size of social groups varies from single animals to groups of hundreds of thousands. This study examines the relationship between social group size and investment in spermatogenesis across 31 species of microchiropteran bat using new and published data on testis mass and sperm length. In addition to male competition, I exa

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Hosken, D. J. "Sperm competition in bats." Proceedings of the Royal Society of London. Series B: Biological Sciences 264, no. 1380 (1997): 385–92. https://doi.org/10.5281/zenodo.13447455.

Testo completo

Abstract (sommario):

(Uploaded by Plazi for the Bat Literature Project) Sperm competition is a widespread phenomenon influencing the evolution of male anatomy, physiology and behaviour. Bats are an ideal group for studying sperm competition. Females store fertile sperm for up to 200 days and the size of social groups varies from single animals to groups of hundreds of thousands. This study examines the relationship between social group size and investment in spermatogenesis across 31 species of microchiropteran bat using new and published data on testis mass and sperm length. In addition to male competition, I exa

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Hirohashi, Noritaka, Noriyosi Sato, Yoko Iwata, et al. "Context-dependent behavioural plasticity compromises disruptive selection of sperm traits in squid." PLOS ONE 16, no. 8 (2021): e0256745. http://dx.doi.org/10.1371/journal.pone.0256745.

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Abstract (sommario):

Sperm morphology is generally uniform within a species due to selective pressures that act to achieve better fertilization outcomes under postcopulatory competitive circumstances. Therefore, polyandry that intensifies post-mating sperm competition should constrain intraspecific sperm polymorphism. Contrary to this paradigm, we previously found that a polyandrous squid, Heterololigo bleekeri, produces dimorphic eusperm (flagellum length dimorphism; FLD), which is closely associated with alternative reproductive tactics (ARTs); large males (consorts) transfer their spermatophores inside the fema

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39

Verspoor, Rudi L., Tom A. R. Price, and Nina Wedell. "Selfish genetic elements and male fertility." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200067. http://dx.doi.org/10.1098/rstb.2020.0067.

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Abstract (sommario):

Selfish genetic elements (SGEs) are diverse and near ubiquitous in Eukaryotes and can be potent drivers of evolution. Here, we discuss SGEs that specifically act on sperm to gain a transmission advantage to the next generation. The diverse SGEs that affect sperm often impose costs on carrier males, including damaging ejaculates, skewing offspring sex ratios and in particular reducing sperm-competitive success of SGE-carrying males. How males and females tolerate and mitigate against these costs is a dynamic and expanding area of research. The intense intra-genomic conflict that these selfish e

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40

Birkhead, TR. "Sperm competition: evolutionary causes and consequences." Reproduction, Fertility and Development 7, no. 4 (1995): 755. http://dx.doi.org/10.1071/rd9950755.

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Abstract (sommario):

The interaction between functional and mechanistic approaches to sperm competition and between male and female perspectives are described and illustrated by a study of the zebra finch, Taeniopygia guttata. Sperm competition experiments in the laboratory show that last male sperm precedence occurs (as it does in many other taxa) although the mechanism is unknown (as in most other taxa). Empirically-derived values were used to construct a mathematical model of sperm competition in the zebra finch. The model indicates that precedence occurs as a consequence of: (i) the temporal pattern of pair co

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41

Lüpold, Stefan, Raïssa A. de Boer, Jonathan P. Evans, Joseph L. Tomkins, and John L. Fitzpatrick. "How sperm competition shapes the evolution of testes and sperm: a meta-analysis." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1813 (2020): 20200064. http://dx.doi.org/10.1098/rstb.2020.0064.

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Abstract (sommario):

Females of many species mate with multiple males, thereby inciting competition among ejaculates from rival males for fertilization. In response to increasing sperm competition, males are predicted to enhance their investment in sperm production. This prediction is so widespread that testes size (correcting for body size) is commonly used as a proxy of sperm competition, even in the absence of any other information about a species' reproductive behaviour. By contrast, a debate about whether sperm competition selects for smaller or larger sperm has persisted for nearly three decades, with empiri

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42

Demont, Marco, Paul I. Ward, Wolf U. Blanckenhorn, Stefan Lüpold, Oliver Y. Martin, and Luc F. Bussière. "How biases in sperm storage relate to sperm use during oviposition in female yellow dung flies." Behavioral Ecology 32, no. 4 (2021): 756–68. http://dx.doi.org/10.1093/beheco/arab026.

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Abstract (sommario):

Abstract Precise mechanisms underlying sperm storage and utilization are largely unknown, and data directly linking stored sperm to paternity remain scarce. We used competitive microsatellite PCR to study the effects of female morphology, copula duration and oviposition on the proportion of stored sperm provided by the second of two copulating males (S2) in Scathophaga stercoraria (Diptera: Scathophagidae), the classic model for sperm competition studies. We genotyped all offspring from potentially mixed-paternity clutches to establish the relationship between a second male’s stored sperm (S2)

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43

Jones, Beatrix, and Andrew G. Clark. "Bayesian Sperm Competition Estimates." Genetics 163, no. 3 (2003): 1193–99. http://dx.doi.org/10.1093/genetics/163.3.1193.

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Abstract (sommario):

Abstract We introduce a Bayesian method for estimating parameters for a model of multiple mating and sperm displacement from genotype counts of brood-structured data. The model is initially targeted for Drosophila melanogaster, but is easily adapted to other organisms. The method is appropriate for use with field studies where the number of mates and the genotypes of the mates cannot be controlled, but where unlinked markers have been collected for a set of females and a sample of their offspring. Advantages over previous approaches include full use of multilocus information and the ability to

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44

Birkhead, T. "Sperm competition in birds." Reviews of Reproduction 3, no. 2 (1998): 123–29. http://dx.doi.org/10.1530/revreprod/3.2.123.

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45

Birkhead, T. "Sperm competition in birds." Reviews of Reproduction 3, no. 2 (1998): 123–29. http://dx.doi.org/10.1530/ror.0.0030123.

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46

Birkhead, Tim. "Distinguished sperm in competition." Nature 400, no. 6743 (1999): 406–7. http://dx.doi.org/10.1038/22650.

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47

Harcourt, A. H. "Sperm Competition in Primates." American Naturalist 149, no. 1 (1997): 189–94. http://dx.doi.org/10.1086/285986.

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48

Hosken, D. J. "Sperm competition in bats." Proceedings of the Royal Society of London. Series B: Biological Sciences 264, no. 1380 (1997): 385–92. http://dx.doi.org/10.1098/rspb.1997.0055.

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49

Stockley, P. "Sperm competition in mammals." Human Fertility 7, no. 2 (2004): 91–97. http://dx.doi.org/10.1080/14647270410001699054.

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50

Birkhead, Tim. "Sperm competition in birds." Trends in Ecology & Evolution 2, no. 9 (1987): 268–72. http://dx.doi.org/10.1016/0169-5347(87)90033-4.

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