scholarly journals Sperm competition when transfer is dangerous

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200073
Author(s):  
Cristina Tuni ◽  
Jutta Schneider ◽  
Gabriele Uhl ◽  
Marie E. Herberstein
Keyword(s):  
Sperm Competition ◽  
Female Choice ◽  
Male Mating ◽  
Theme Issue ◽  
Sperm Activation ◽  
Proximate Mechanisms ◽  
Mating Order ◽  
Seminal Fluids ◽  
Sperm Depletion

Aggressive and cannibalistic female spiders can impose strong selection on male mating and fertilization strategies. Furthermore, the distinctive reproductive morphology of spiders is predicted to influence the outcome of sperm competition. Polyandry is common in spiders, leading to defensive male strategies that include guarding, plugging and self-sacrifice. Paternity patterns are highly variable and unlikely to be determined solely by mating order, but rather by relative copulation duration, deployment of plugs and cryptic female choice. The ability to strategically allocate sperm is limited, either by the need to refill pedipalps periodically or owing to permanent sperm depletion after mating. Further insights now rely on unravelling several proximate mechanisms such as the process of sperm activation and the role of seminal fluids. This article is part of the theme issue ‘Fifty years of sperm competition’.

Fertilization dynamics of sperm from different male mating tactics in bluegill (Lepomis macrochirus)

2005 ◽  
Vol 83 (12) ◽  
pp. 1638-1642 ◽  
Author(s):  
Albrecht I Schulte-Hostedde ◽  
Gary Burness
Keyword(s):  
Sperm Competition ◽  
Lepomis Macrochirus ◽  
Fertilization Success ◽  
Male Mating ◽  
Motile Sperm ◽  
Mating Tactics ◽  
Sperm Activation ◽  
Competition Theory ◽  
Sperm Density ◽  
Over Time

Sperm competition results in the evolution of ejaculate characteristics such as high sperm density, high motility, and fast sperm swimming speed. A fundamental assumption of sperm competition theory is that ejaculates with high motility and fast-swimming sperm have an advantage with respect to fertilization success. We tested this assumption by studying the fertilization dynamics of alternative mating tactics (cuckolders and parentals) of male bluegill (Lepomis macrochirus Rafinesque, 1819). Sneakers (cuckolders) have faster swimming sperm and a higher proportion of motile sperm immediately following sperm activation than do parentals; however, these variables decline more quickly over time in sneaker sperm than in the sperm of parental males. We used a controlled fertilization experiment to test the prediction that parental males will have higher fertilization success than sneakers late in the sperm activation cycle because of the reduced rate of decline in ejaculate quality over time. We found that as the time from sperm activation increases parental sperm fertilizes more eggs than the sperm of sneakers. Our results support the idea that fertilization success is higher when ejaculates contain a higher proportion of either motile sperm or faster swimming sperm, all else being equal. In addition, after controlling for time from sperm activation, we found a significant bias in fertilization success toward parental males, suggesting that cryptic female choice might play a role in fertilization dynamics.

scholarly journals The baculum affects paternity success of first but not second males in house mouse sperm competition

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lennart Winkler ◽  
Anna K. Lindholm ◽  
Steven A. Ramm ◽  
Andreas Sutter
Keyword(s):  
Sperm Competition ◽  
Mating Behavior ◽  
Sperm Motility ◽  
Fertilization Success ◽  
Male Mating ◽  
Geometric Morphometric ◽  
Selfish Genetic Element ◽  
Mating Order ◽  
Male Mating Behavior ◽  
Paternity Success

AbstractThe vast variation observed in genital morphology is a longstanding puzzle in evolutionary biology. Studies showing that the morphology of the mammalian baculum (penis bone) can covary with a male’s paternity success indicate a potential impact of baculum morphology on male fitness, likely through influencing sperm competition outcomes. We therefore measured the size (measurements of length and width) and shape (geometric morphometric measurements) of the bacula of male house mice used in previously published sperm competition experiments, in which two males mated successively with the same female in staged matings. This enabled us to correlate baculum morphology with sperm competition success, incorporating potential explanatory variables related to copulatory plugs, male mating behavior and a selfish genetic element that influences sperm motility. We found that a wider baculum shaft increased a male’s paternity share when mating first, but not when mating second with a multiply-mating female. Geometric morphometric shape measurements were not clearly associated with fertilization success for either male. We found limited evidence that the effect of baculum morphology on male fertilization success was altered by experimental removal of the copulatory plug. Furthermore, neither genetic differences in sperm motility, nor covariation with male mating behavior mediated the effect of baculum morphology on male fertilization success. Taken together with previous findings, the mating-order effects we found here suggest that baculum-mediated stimulation by the first male might be particularly important for fertilization.

scholarly journals Temporal dynamics of competitive fertilization in social groups of red junglefowl ( Gallus gallus ) shed new light on avian sperm competition

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200081 ◽  
Author(s):  
Rômulo Carleial ◽  
Grant C. McDonald ◽  
Lewis G. Spurgin ◽  
Eleanor A. Fairfield ◽  
Yunke Wang ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Temporal Dynamics ◽  
Gallus Gallus ◽  
Fertilization Success ◽  
Relative Importance ◽  
Theme Issue ◽  
Natural Conditions ◽  
Red Junglefowl ◽  
Older Males

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 last increased a male's probability of fertilization, but only for eggs ovulated in the last days of a trial. Conversely, older males, and those mating with more polyandrous females, had consistently lower fertilization success. Similarly, resistance to a male's mating attempts, particularly by younger females, reduced fertilization probability. After considering these factors, male social status, partner relatedness and the estimated state of male extragonadal sperm reserves did not predict sperm competition outcomes. These results shed new light on sperm competition dynamics in taxa such as birds, with prolonged female sperm storage and staggered fertilizations. This article is part of the theme issue ‘Fifty years of sperm competition’.

scholarly journals Ageing and sociality: why, when and how does sociality change ageing patterns?

2021 ◽  
Vol 376 (1823) ◽  
pp. 20190727
Author(s):  
Judith Korb ◽  
Jürgen Heinze
Keyword(s):  
Social Insects ◽  
Social Insect ◽  
Reproductive Potential ◽  
Group Living ◽  
Nutrient Sensing ◽  
Theme Issue ◽  
Proximate Mechanisms ◽  
Social Animals ◽  
Downstream Processes

Individual lifespans vary tremendously between and also within species, but the proximate and ultimate causes of different ageing speeds are still not well understood. Sociality appears to be associated with the evolution of greater longevity and probably also with a larger plasticity of the shape and pace of ageing. For example, reproductives of several termites and ants reach lifespans that surpass those of their non-reproductive nestmates by one or two decades. In this issue, 15 papers explore the interrelations between sociality and individual longevity in both, group-living vertebrates and social insects. Here, we briefly give an overview of the contents of the various contributions, including theoretical and comparative studies, and we explore the similarities and dissimilarities in proximate mechanisms underlying ageing among taxa, with particular emphasis on nutrient-sensing pathways and, in insects, juvenile hormone. These studies point to an underestimated role of more downstream processes. We highlight the need for reliable transcriptomic markers of ageing and a comprehensive ageing theory of social animals, which includes the reproductive potential of workers, and considers the fact that social insect queens reach maturity only after a prolonged period of producing non-reproductive workers. This article is part of the theme issue ‘Ageing and sociality: why, when and how does sociality change ageing patterns?’

scholarly journals The role of female reproductive fluid in sperm competition

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200077 ◽  
Author(s):  
Clelia Gasparini ◽  
Andrea Pilastro ◽  
Jonathan P. Evans
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
Fertilization Success ◽  
Sperm Velocity ◽  
Theme Issue ◽  
Diverse Range ◽  
Diverse Species ◽  
Selected Functions ◽  
Sperm Traits

The role of non-gametic components of the ejaculate (seminal fluid) in fertility and sperm competitiveness is now well established. Surprisingly, however, we know far less about female reproductive fluid (FRF) in the context of sexual selection, and insights into male–FRF interactions in the context of sperm competition have only recently emerged. Despite this limited knowledge, evidence from taxonomically diverse species has revealed insights into the effects of FRF on sperm traits that have previously been implicated in studies of sperm competition. Specifically, through the differential effects of FRF on a range of sperm traits, including chemoattraction and alterations in sperm velocity, FRF has been shown to exert positive phenotypic effects on the sperm of males that are preferred as mating partners, or those from the most compatible or genetically diverse males. Despite these tantalizing insights into the putative sexually selected functions of FRF, we largely lack a mechanistic understanding of these processes. Taken together, the evidence presented here highlights the likely ubiquity of FRF-regulated biases in fertilization success across a diverse range of taxa, thus potentially elevating the importance of FRF to other non-gametic components that have so far been studied largely in males. This article is part of the theme issue ‘Fifty years of sperm competition'.

scholarly journals Gamete-mediated mate choice: towards a more inclusive view of sexual selection

2018 ◽  
Vol 285 (1883) ◽  
pp. 20180836 ◽  
Author(s):  
Jukka Kekäläinen ◽  
Jonathan P. Evans
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sperm Competition ◽  
Female Choice ◽  
Mating Systems ◽  
Molecular Level ◽  
Evolutionary Significance ◽  
Random Interactions ◽  
Physiological Processes ◽  
The Everyday

‘Sperm competition’—where ejaculates from two or more males compete for fertilization—and ‘cryptic female choice’—where females bias this contest to suit their reproductive interests—are now part of the everyday lexicon of sexual selection. Yet the physiological processes that underlie these post-ejaculatory episodes of sexual selection remain largely enigmatic. In this review, we focus on a range of post-ejaculatory cellular- and molecular-level processes, known to be fundamental for fertilization across most (if not all) sexually reproducing species, and point to their putative role in facilitating sexual selection at the level of the cells and gametes, called ‘gamete-mediated mate choice’ (GMMC). In this way, we collate accumulated evidence for GMMC across different mating systems, and emphasize the evolutionary significance of such non-random interactions among gametes. Our overall aim in this review is to build a more inclusive view of sexual selection by showing that mate choice often acts in more nuanced ways than has traditionally been assumed. We also aim to bridge the conceptual divide between proximal mechanisms of reproduction, and adaptive explanations for patterns of non-random sperm–egg interactions that are emerging across an increasingly diverse array of taxa.

Sperm Competition and the Dynamics of X Chromosome Drive: Stability and Extinction

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1721-1731 ◽  
Author(s):  
Jesse E Taylor ◽  
John Jaenike
Keyword(s):  
Sex Ratio ◽  
Sperm Competition ◽  
X Chromosome ◽  
Sex Chromosome ◽  
Basin Of Attraction ◽  
Male Mating ◽  
Male And Female ◽  
Mating Rate ◽  
Female Mating ◽  
Balanced Polymorphism

AbstractSeveral empirical studies of sperm competition in populations polymorphic for a driving X chromosome have revealed that Sex-ratio males (those carrying a driving X) are at a disadvantage relative to Standard males. Because the frequency of the driving X chromosome determines the population-level sex ratio and thus alters male and female mating rates, the evolutionary consequences of sperm competition for sex chromosome meiotic drive are subtle. As the SR allele increases in frequency, the ratio of females to males also increases, causing an increase in the male mating rate and a decrease in the female mating rate. While the former change may exacerbate the disadvantage of Sex-ratio males during sperm competition, the latter change decreases the incidence of sperm competition within the population. We analyze a model of the effects of sperm competition on a driving X chromosome and show that these opposing trends in male and female mating rates can result in two coexisting locally stable equilibria, one corresponding to a balanced polymorphism of the SR and ST alleles and the second to fixation of the ST allele. Stochastic fluctuations of either the population sex ratio or the SR frequency can then drive the population away from the balanced polymorphism and into the basin of attraction for the second equilibrium, resulting in fixation of the SR allele and extinction of the population.

Relative testis size and mating systems in anurans: large testis in multiple-male mating in foam-nesting frogs

2011 ◽  
Vol 61 (2) ◽  
pp. 225-238 ◽  
Author(s):  
Wen Bo Liao ◽  
Zhi Ping Mi ◽  
Cai Quan Zhou ◽  
Ling Jin ◽  
Xian Han ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Published Data ◽  
Male Mating ◽  
Data Sets ◽  
Testis Size ◽  
Data Set ◽  
Monogamous Species ◽  
Large Testis ◽  
Testes Size ◽  
Testis Mass

AbstractComparative studies of the relative testes size in animals show that promiscuous species have relatively larger testes than monogamous species. Sperm competition favours the evolution of larger ejaculates in many animals – they give bigger testes. In the view, we presented data on relative testis mass for 17 Chinese species including 3 polyandrous species. We analyzed relative testis mass within the Chinese data set and combining those data with published data sets on Japanese and African frogs. We found that polyandrous foam nesting species have relatively large testes, suggesting that sperm competition was an important factor affecting the evolution of relative testes size. For 4 polyandrous species testes mass is positively correlated with intensity (males/mating) but not with risk (frequency of polyandrous matings) of sperm competition.

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