scholarly journals Long sperm fertilize more eggs in a bird

2015 ◽  
Vol 282 (1799) ◽  
pp. 20141897 ◽  
Author(s):  
Clair Bennison ◽  
Nicola Hemmings ◽  
Jon Slate ◽  
Tim Birkhead
Keyword(s):  
Sperm Competition ◽  
Reproductive Traits ◽  
Fertilization Success ◽  
Swimming Velocity ◽  
Sperm Length ◽  
Complex Interactions ◽  
Female Reproductive Traits ◽  
Sperm Size ◽  
The Relationship ◽  
Main Factor

Sperm competition, in which the ejaculates of multiple males compete to fertilize a female's ova, results in strong selection on sperm traits. Although sperm size and swimming velocity are known to independently affect fertilization success in certain species, exploring the relationship between sperm length, swimming velocity and fertilization success still remains a challenge. Here, we use the zebra finch ( Taeniopygia guttata ), where sperm size influences sperm swimming velocity, to determine the effect of sperm total length on fertilization success. Sperm competition experiments, in which pairs of males whose sperm differed only in length and swimming speed, revealed that males producing long sperm were more successful in terms of (i) the number of sperm reaching the ova and (ii) fertilizing those ova. Our results reveal that although sperm length is the main factor determining the outcome of sperm competition, complex interactions between male and female reproductive traits may also be important. The mechanisms underlying these interactions are poorly understood, but we suggest that differences in sperm storage and utilization by females may contribute to the outcome of sperm competition.

scholarly journals Sperm midpiece length predicts sperm swimming velocity in house mice

2010 ◽  
Vol 6 (4) ◽  
pp. 513-516 ◽  
Author(s):  
Renée C. Firman ◽  
Leigh W. Simmons
Keyword(s):  
Sperm Competition ◽  
Sperm Morphology ◽  
House Mice ◽  
Swimming Velocity ◽  
Sperm Velocity ◽  
Sperm Midpiece ◽  
Sperm Competition Risk ◽  
Sperm Size ◽  
The Relationship

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 competitiveness. Few investigations have attempted to address this problem. Here, we investigated the relationship between sperm morphology and sperm velocity in house mice ( Mus domesticus ). We conducted in vitro sperm velocity assays on males from established selection lines, and found that sperm midpiece size was the only phenotypic predictor of sperm swimming velocity.

Effects of alternative male mating strategies on characteristics of sperm production in the Atlantic salmon ( Salmo salar ): theoretical and empirical investigations

1995 ◽  
Vol 350 (1334) ◽  
pp. 391-399 ◽  
Keyword(s):  
Atlantic Salmon ◽  
Sperm Competition ◽  
Salmo Salar ◽  
Reproductive Traits ◽  
Fertilization Success ◽  
Mating Strategies ◽  
Male Mating ◽  
Sperm Length ◽  
Male Mating Strategies ◽  
Natural Variance

Atlantic salmon ( Salmo salar ) males mature as either tiny precocious parr before seaward migration, or as older and larger anadromous males. Anadromous males dominate the spawning redds and aggressively defend females against parr intrusions. Parr gain fertilizations by sneaking in to ejaculate while anadromous males and females spawn. Such differences in mating advantage generate asymmetries in risk of sperm competition between the male strategies. Theoretical sperm competition models predict that males typically mating in disfavoured roles (here, the parr strategy) should be selected to offset this disadvantage by investing more into spermatogenesis to achieve fertilization success. First, we present a theoretical model which analyses gametic expenditure for salmon parr and anadromous male reproductive strategies. We then use the natural variance in mating pattern within this species to compare empirically how males invest in spermatogenesis. A range of reproductive traits were measured for both male strategies. Absolutely, anadromous males have larger testes and produce greater numbers of sperm than parr males. However, results show that parr invest relatively more heavily into total spermatogenesis, and have a larger gonosomatic index than anadromous males. Relative to body size, parr produced greater numbers of sperm and volumes of stripped ejaculate. There was no difference in sperm length between the two male strategies. However, more sperm were motile in parr ejaculates, and these sperm lived longer than anadromous male sperm. Our findings may explain how male parr, under elevated risks of sperm competition and occupying a disfavoured mating role (parr weigh only 0.15% of the average body mass of anadromous males) achieve disproportionately high fertilization success.

scholarly journals Delineating the roles of males and females in sperm competition

2013 ◽  
Vol 280 (1772) ◽  
pp. 20132047 ◽  
Author(s):  
Jonathan P. Evans ◽  
Patrice Rosengrave ◽  
Clelia Gasparini ◽  
Neil J. Gemmell
Keyword(s):  
Sperm Competition ◽  
Chinook Salmon ◽  
Competitive Ability ◽  
Oncorhynchus Tshawytscha ◽  
Fertilization Success ◽  
Interactive Effects ◽  
Swimming Velocity ◽  
Ovarian Fluid ◽  
Males And Females ◽  
Paternity Success

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 competitive fertilization trials. Our design involved a series of 10 factorial crosses, each involving two ‘focal’ rival males whose sperm competed against those from a single ‘standardized’ (non-focal) rival for a genetically uniform set of eggs in the presence of OF from two focal females. This design enabled us to attribute variation in competitive fertilization success among focal males, females (OF) and their interacting effects, while controlling for variation attributable to differences in the sperm competitive ability of rival males, and male-by-female genotypic interactions. Using this experimental framework, we found that variation in sperm competitiveness could be attributed exclusively to differences in the sperm competitive ability of focal males, a conclusion supported by subsequent analyses revealing that variation in sperm swimming velocity predicts paternity success. Together, these findings provide evidence that variation in paternity success can be attributed to intrinsic differences in the sperm competitive ability of rival males, and reveal that sperm swimming velocity is a key target of sexual selection.

scholarly journals Inbreeding depresses sperm competitiveness, but not fertilization or mating success in male Tribolium castaneum

2010 ◽  
Vol 277 (1699) ◽  
pp. 3483-3491 ◽  
Author(s):  
Łukasz Michalczyk ◽  
Oliver Y. Martin ◽  
Anna L. Millard ◽  
Brent C. Emerson ◽  
Matthew J. G. Gage
Keyword(s):  
Sperm Competition ◽  
Inbreeding Depression ◽  
Tribolium Castaneum ◽  
Mating Behaviour ◽  
Fertilization Success ◽  
Heterozygote Advantage ◽  
Length Variation ◽  
Sperm Length ◽  
Mating Pattern ◽  
Normal Fertilization

As populations decline to levels where reproduction among close genetic relatives becomes more probable, subsequent increases in homozygous recessive deleterious expression and/or loss of heterozygote advantage can lead to inbreeding depression. Here, we measure how inbreeding across replicate lines of the flour beetle Tribolium castaneum impacts on male reproductive fitness in the absence or presence of male–male competition. Effects on male evolution from mating pattern were removed by enforcing monogamous mating throughout. After inbreeding across eight generations, we found that male fertility in the absence of competition was unaffected. However, we found significant inbreeding depression of sperm competitiveness: non-inbred males won 57 per cent of fertilizations in competition, while inbred equivalents only sired 42 per cent. We also found that the P 2 ‘offence’ role in sperm competition was significantly more depressed under inbreeding than sperm ‘defence’ (P 1 ). Mating behaviour did not explain these differences, and there was no difference in the viability of offspring sired by inbred or non-inbred males. Sperm length variation was significantly greater in the ejaculates of inbred males. Our results show that male ability to achieve normal fertilization success was not depressed under strong inbreeding, but that inbreeding depression in these traits occurred when conditions of sperm competition were generated.

scholarly journals Sperm morphology, adenosine triphosphate (ATP) concentration and swimming velocity: unexpected relationships in a passerine bird

2016 ◽  
Vol 283 (1837) ◽  
pp. 20161558 ◽  
Author(s):  
Clair Bennison ◽  
Nicola Hemmings ◽  
Lola Brookes ◽  
Jon Slate ◽  
Tim Birkhead
Keyword(s):  
Sperm Morphology ◽  
Passerine Bird ◽  
Negative Association ◽  
Swimming Velocity ◽  
Sperm Function ◽  
Sperm Length ◽  
Atp Content ◽  
Number Of Individuals ◽  
The Relationship ◽  
Sperm Traits

The relationship between sperm energetics and sperm function is poorly known, but is central to our understanding of the evolution of sperm traits. The aim of this study was to examine how sperm morphology and ATP content affect sperm swimming velocity in the zebra finch Taeniopygia guttata . We exploited the high inter-male variation in this species and created extra experimental power by increasing the number of individuals with very long or short sperm through artificial selection. We found a pronounced quadratic relationship between total sperm length and swimming velocity, with velocity increasing with length up to a point, but declining in the very longest sperm. We also found an unexpected negative association between midpiece length and ATP content: sperm with a short midpiece generally contained the highest concentration of ATP. Low intracellular ATP is therefore unlikely to explain reduced swimming velocity among the very longest sperm (which tend to have a shorter midpiece).

Sperm length influences fertilization success during sperm competition in the snail Viviparus ater

2003 ◽  
Vol 12 (2) ◽  
pp. 485-492 ◽  
Author(s):  
A. Oppliger ◽  
Y. Naciri-Graven ◽  
G. Ribi ◽  
D. J. Hosken
Keyword(s):  
Sperm Competition ◽  
Fertilization Success ◽  
Sperm Length

scholarly journals Selection on sperm morphology under relaxed sperm competition in a wild passerine bird

2008 ◽  
Vol 5 (1) ◽  
pp. 58-61 ◽  
Author(s):  
Sara Calhim ◽  
Helene M Lampe ◽  
Tore Slagsvold ◽  
Tim R Birkhead
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Reproductive Traits ◽  
Female Preference ◽  
Passerine Bird ◽  
High Heritability ◽  
Individual Consistency ◽  
Sperm Size

Theories regarding the role of sexual selection on the evolution of sperm traits are based on an association between pre-copulatory (e.g. female preference) and post-copulatory (e.g. ejaculate quality) male reproductive traits. In tests of these hypotheses, sperm morphology has rarely been used, despite its high heritability and intra-individual consistency. We found evidence of selection for longer sperm through positive phenotypic associations between sperm size and the two major female preference traits in the pied flycatcher, Ficedula hypoleuca . Our results support the sexually selected sperm hypothesis in a species under low sperm competition and demonstrate that natural and pre-copulatory sexual selection forces should not be overlooked in studies of intraspecific sperm morphology evolution.

scholarly journals Sperm competition in squamate reptiles

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200079
Author(s):  
Christopher R. Friesen ◽  
Ariel F. Kahrl ◽  
Mats Olsson
Keyword(s):  
Sperm Competition ◽  
Reproductive Tract ◽  
Multiple Paternity ◽  
Fertilization Success ◽  
Sperm Storage ◽  
Female Reproductive Tract ◽  
Life History Strategies ◽  
The Face ◽  
And Function ◽  
Sperm Size

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 aid in long-term sperm storage. In doing so, we present a new analysis of the relationship between sperm size, the strength of sperm competition and the duration of female sperm storage. Lizards and snakes are a diverse group that has provided many excellent models for the study of an array of life-history strategies. However, when it comes to postcopulatory sexual selection, there is much left to discover. This article is part of the theme issue ‘Fifty years of sperm competition'.

scholarly journals Sperm competition differentially affects swimming velocity and size of spermatozoa from closely related muroid rodents: head first

Reproduction ◽  
2011 ◽  
Vol 142 (6) ◽  
pp. 819-830 ◽  
Author(s):  
Laura Gómez Montoto ◽  
María Varea Sánchez ◽  
Maximiliano Tourmente ◽  
Juan Martín-Coello ◽  
Juan José Luque-Larena ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Swimming Speed ◽  
Comparative Studies ◽  
Sperm Head ◽  
Swimming Velocity ◽  
Evolutionary Changes ◽  
Muroid Rodents ◽  
Sperm Swimming Speed ◽  
Sperm Size ◽  
Head Area

Sperm competition favours an increase in sperm swimming velocity that maximises the chances that sperm will reach the ova before rival sperm and fertilise. Comparative studies have shown that the increase in sperm swimming speed is associated with an increase in total sperm size. However, it is not known which are the first evolutionary steps that lead to increases in sperm swimming velocity. Using a group of closely related muroid rodents that differ in levels of sperm competition, we here test the hypothesis that subtle changes in sperm design may represent early evolutionary changes that could make sperm swim faster. Our findings show that as sperm competition increases so does sperm swimming speed. Sperm swimming velocity is associated with the size of all sperm components. However, levels of sperm competition are only related to an increase in sperm head area. Such increase is a consequence of an increase in the length of the sperm head, and also of the presence of an apical hook in some of the species studied. These findings suggest that the presence of a hook may modify the sperm head in such a way that would help sperm swim faster and may also be advantageous if sperm with larger heads are better able to attach to the epithelial cells lining the lower isthmus of the oviduct where sperm remain quiescent before the final race to reach the site of fertilisation.

scholarly journals How sperm competition shapes the evolution of testes and sperm: a meta-analysis

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200064
Author(s):  
Stefan Lüpold ◽  
Raïssa A. de Boer ◽  
Jonathan P. Evans ◽  
Joseph L. Tomkins ◽  
John L. Fitzpatrick
Keyword(s):  
Sperm Competition ◽  
Meta Analysis ◽  
Empirical Studies ◽  
Reproductive Behaviour ◽  
Analytical Framework ◽  
Sperm Length ◽  
Other Information ◽  
Theoretical Predictions ◽  
Testes Size ◽  
Sperm Size

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 empirical studies demonstrating every possible response. Here, we synthesize nearly 40 years of sperm competition research in a meta-analytical framework to determine how the evolution of sperm number (i.e. testes size) and sperm size (i.e. sperm head, midpiece, flagellum and total length) is influenced by varying levels of sperm competition across species. Our findings support the long-held assumption that higher levels of sperm competition are associated with relatively larger testes. We also find clear evidence that sperm competition is associated with increases in all components of sperm length. We discuss these results in the context of different theoretical predictions and general patterns in the breeding biology and selective environment of sperm. This article is part of the theme issue ‘Fifty years of sperm competition’.

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