scholarly journals Selection on Sperm Count, but Not on Sperm Morphology or Velocity, in a Wild Population of Anolis Lizards

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2369
Author(s):  
Ariel F. Kahrl ◽  
Matthew C. Kustra ◽  
Aaron M. Reedy ◽  
Rachana S. Bhave ◽  
Heidi A. Seears ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Sperm Morphology ◽  
Wild Population ◽  
Sperm Count ◽  
Experimental Studies ◽  
Male Reproductive Success ◽  
Brown Anole ◽  
Postcopulatory Selection ◽  
Highly Correlated ◽  
Sperm Traits

Sperm competition is a widespread phenomenon that shapes male reproductive success. Ejaculates present many potential targets for postcopulatory selection (e.g., sperm morphology, count, and velocity), which are often highly correlated and potentially subject to complex multivariate selection. Although multivariate selection on ejaculate traits has been observed in laboratory experiments, it is unclear whether selection is similarly complex in wild populations, where individuals mate frequently over longer periods of time. We measured univariate and multivariate selection on sperm morphology, sperm count, and sperm velocity in a wild population of brown anole lizards (Anolis sagrei). We conducted a mark-recapture study with genetic parentage assignment to estimate individual reproductive success. We found significant negative directional selection and negative quadratic selection on sperm count, but we did not detect directional or quadratic selection on any other sperm traits, nor did we detect correlational selection on any trait combinations. Our results may reflect pressure on males to produce many small ejaculates and mate frequently over a six-month reproductive season. This study is the first to measure multivariate selection on sperm traits in a wild population and provides an interesting contrast to experimental studies of external fertilizers, which have found complex multivariate selection on sperm phenotypes.

scholarly journals Sperm morphology and count vary with fine-scale changes in local density in a wild lizard population

Oecologia ◽  
2019 ◽  
Vol 191 (3) ◽  
pp. 555-564 ◽  
Author(s):  
Matthew C. Kustra ◽  
Ariel F. Kahrl ◽  
Aaron M. Reedy ◽  
Daniel A. Warner ◽  
Robert M. Cox
Keyword(s):  
Sperm Competition ◽  
Social Environment ◽  
Natural Variation ◽  
Sperm Morphology ◽  
Local Density ◽  
Sperm Count ◽  
Operational Sex Ratio ◽  
Island Population ◽  
Fine Scale ◽  
Sperm Traits

Abstract Given that sperm production can be costly, theory predicts that males should optimally adjust the quantity and/or quality of their sperm in response to their social environment to maximize their paternity success. Although experiments demonstrate that males can alter their ejaculates in response to manipulations of the social environment and studies show that ejaculate traits covary with social environment across populations, it is unknown whether individual variation in sperm traits corresponds to natural variation found within wild populations. Using an island population of brown anole lizards (Anolis sagrei), we tested the prediction that sperm traits (sperm count, sperm morphology, sperm velocity) respond to natural variation in the risk of sperm competition, as inferred from the local density and operational sex ratio (OSR) of conspecifics. We found that males living in high-density areas of the island produced relatively larger sperm midpieces, smaller sperm heads, and lower sperm counts. Sperm traits were unrelated to OSR after accounting for the covariance between OSR and density. Our findings broaden the implications of sperm competition theory to intrapopulation social environment variation by showing that sperm count and sperm morphology vary with fine-scale differences in density within a single wild population.

VARIATION IN MALE REPRODUCTIVE SUCCESS IN A WILD POPULATION OF REINDEER

2005 ◽  
Vol 69 (3) ◽  
pp. 1163-1170 ◽  
Author(s):  
KNUT H. RØED ◽  
ØYSTEIN HOLAND ◽  
HALLVARD GJØSTEIN ◽  
HELGE HANSEN
Keyword(s):  
Reproductive Success ◽  
Wild Population ◽  
Male Reproductive Success

scholarly journals Sperm Numbers as a Paternity Guard in a Wild Bird

Cells ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 231
Author(s):  
Melissah Rowe ◽  
Annabel van Oort ◽  
Lyanne Brouwer ◽  
Jan T. Lifjeld ◽  
Michael S. Webster ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Sperm Competition ◽  
Ecological Factors ◽  
Fertilization Success ◽  
Male Reproductive Success ◽  
Male Mating ◽  
Sexually Selected Traits ◽  
Paternity Success ◽  
Mating Conditions ◽  
Sperm Traits

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 of social and ecological factors that determine the opportunity for mating events both within and outside of the social pair-bond. Here, we test for an effect of sperm quantity and sperm size on male reproductive success in the red-back fairy-wren (Malurus melanocephalus) while simultaneously accounting for pre-copulatory sexual selection and potential socio-ecological correlates of male mating success. We found that sperm number (i.e., cloacal protuberance volume), but not sperm morphology, was associated with reproductive success in male red-backed fairy-wrens. Most notably, males with large numbers of sperm available for copulation achieved greater within-pair paternity success. Our results suggest that males use large sperm numbers as a defensive strategy to guard within-pair paternity success in a system where there is a high risk of sperm competition and female control of copulation. Finally, our work highlights the importance of accounting for socio-ecological factors that may influence male mating opportunities when examining the role of sperm traits in determining male reproductive success.

047. SPERM COMPETITION, INBREEDING AND THE EVOLUTION OF SUPERIOR EJACULATES

2009 ◽  
Vol 21 (9) ◽  
pp. 12 ◽  
Author(s):  
J. Fitzpatrick
Keyword(s):  
Reproductive Success ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Sperm Quality ◽  
Male Reproductive Success ◽  
High Quality ◽  
Genetic Quality ◽  
Viable Sperm ◽  
And Performance ◽  
Reproductive Consequences

The production of viable sperm is essential for male reproductive success. However, because females in many species mate with several males during a single reproductive episode, leading to sperm competition, a male's reproductive success also depends critically on the ability of his sperm to compete efficiently with those from rival males for fertilizations. Therefore, males who regularly encounter sperm competition are expected to produce high quality ejaculates. Here, I will provide an overview of how sperm morphology and performance are influenced by sperm competition, both within and between species, using recent empirical examples. Having established the importance of producing high quality ejaculates in males experiencing sperm competition, I will then examine the reproductive consequences of producing sub-optimal sperm. Given the well known role that inbreeding plays in reducing genetic quality and reproductive success, I will focus in particular on how inbreeding acts to reduce sperm quality. Finally, I will examine the consequences of inbreeding for male reproductive success in species where sperm competition is rampant. Together, these results highlight the evolutionary importance of sperm competition and inbreeding in shaping ejaculate traits.

scholarly journals Linking sperm length and velocity: the importance of intramale variation

2010 ◽  
Vol 6 (6) ◽  
pp. 797-799 ◽  
Author(s):  
John L. Fitzpatrick ◽  
Francisco Garcia-Gonzalez ◽  
Jonathan P. Evans
Keyword(s):  
Sperm Morphology ◽  
Current Evidence ◽  
Swimming Velocity ◽  
Sperm Length ◽  
Functional Link ◽  
Form And Function ◽  
Selection For ◽  
Highly Correlated ◽  
And Function ◽  
Sperm Traits

Selection imposed through sperm competition is commonly thought to promote the evolution of longer sperm, since sperm length is assumed to be positively associated with sperm swimming velocity. Yet, the basis for this assumption remains controversial, and there is surprisingly little intraspecific evidence demonstrating such a link between sperm form and function. Here, we show that sperm length and velocity are highly correlated in the sea urchin Heliocidaris erythrogramma , but importantly we report that failure to account for within-male variation in these sperm traits can obscure this relationship. These findings, in conjunction with the mounting evidence for extremely high levels of intra-specific variance in sperm traits, suggest that a functional link between sperm morphology and velocity may be more prevalent than what current evidence suggests. Our findings also suggest that selection for faster swimming sperm may promote the evolution of longer sperm, thereby supporting recent findings from macroevolutionary studies.

Experimental Studies of Sedimentation Basin Dynamics

1977 ◽  
Vol 12 (1) ◽  
pp. 77-90
Author(s):  
J.F. Cordoba-Molina ◽  
P.L. Silveston ◽  
R. R. Hudgins
Keyword(s):  
Dynamic Response ◽  
Froude Number ◽  
Flow Model ◽  
Experimental Studies ◽  
Densimetric Froude Number ◽  
Number Range ◽  
The Real ◽  
Highly Correlated ◽  
Sedimentation Basins ◽  
Simple Flow

Abstract A simple Flow Model is proposed to describe the dynamic response of sedimentation basins. The response predicted by this model is linear as opposed to the real response of the basin which is nonlinear. However, the real response of the basin is highly correlated with its densimetric Froude number, and as a consequence our linear model effectively predicts the response of the basin in a restricted densimetric Froude Number range. Our experiments show that the response of the basin becomes more sluggish and erratic as the densimetric Froude number decreases.

scholarly journals Postweaning maternal care increases male chimpanzee reproductive success

2020 ◽  
Vol 6 (38) ◽  
pp. eaaz5746
Author(s):  
Catherine Crockford ◽  
Liran Samuni ◽  
Linda Vigilant ◽  
Roman M. Wittig
Keyword(s):  
Reproductive Success ◽  
Parental Investment ◽  
Maternal Care ◽  
Parental Loss ◽  
Male Reproductive Success ◽  
Complex Societies ◽  
Successful Reproduction ◽  
Using Data

Humans are unusual among animals for continuing to provision and care for their offspring until adulthood. This “prolonged dependency” is considered key for the evolution of other notable human traits, such as large brains, complex societies, and extended postreproductive lifespans. Prolonged dependency must therefore have evolved under conditions in which reproductive success is gained with parental investment and diminished with early parental loss. We tested this idea using data from wild chimpanzees, which have similarly extended immature years as humans and prolonged mother-offspring associations. Males who lost their mothers after weaning but before maturity began reproducing later and had lower average reproductive success. Thus, persistent mother-immature son associations seem vital for enhancing male reproductive success, although mothers barely provision sons after weaning. We posit that these associations lead to social gains, crucial for successful reproduction in complex social societies, and offer insights into the evolution of prolonged dependency.

POLYGYNY, REPRODUCTIVE SUCCESS AND CHILD HEALTH IN RURAL ETHIOPIA: WHY MARRY A MARRIED MAN?

2006 ◽  
Vol 39 (2) ◽  
pp. 287-300 ◽  
Author(s):  
MHAIRI A. GIBSON ◽  
RUTH MACE
Keyword(s):  
Reproductive Success ◽  
Male Reproductive Success ◽  
Family Status ◽  
Rural Ethiopia ◽  
Younger Age ◽  
Married Individuals ◽  
Males And Females ◽  
Child Nutritional Status ◽  
And Child Health ◽  
Better Than

Summary.This study examines the reproductive success of men and women in rural Ethiopia as a function of their marital status, specifically by comparing polygamously and monogamously married individuals. In line with predictions from evolutionary theory, polygamy is beneficial to male reproductive success (i.e. producing larger numbers of surviving offspring). The success of polygamously married females depends on wife rank: the first wives of polygamous husbands do better than monogamously married women and much better than second or third wives. These effects are mirrored in child nutritional status: the children of second and third wives have lower weight for height. Due to potential, largely unmeasurable differences in marriageability (quality) between individuals, it was not possible to support a model of either resource-holding polygyny combined with female choice or female coercion into unwanted marriages. First wives of polygamously married men marry at a younger age and attract a higher brideprice, suggesting that both the males and females in the marriage are likely to be of higher quality (due to wealth, family status or some other factor such as beauty). Unions that end up monogamous are likely to be between slightly lower quality individuals; and second and third wives, who marry at the oldest ages and attract the lowest brideprice, may be ‘making the best of a bad job’. The relatively long gap between first and second marriages may mean that first wives of highly marriageable males can enjoy considerable reproductive success before their husbands marry again.

Sign in / Sign up

Export Citation Format

Share Document