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 Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination

2016 ◽  
Vol 283 (1843) ◽  
pp. 20161883 ◽  
Author(s):  
Viola Pavlova ◽  
Jacob Nabe-Nielsen ◽  
Rune Dietz ◽  
Christian Sonne ◽  
Volker Grimm
Keyword(s):  
Reproductive Success ◽  
Population Growth ◽  
Polar Bear ◽  
Allee Effect ◽  
Polychlorinated Biphenyl ◽  
Sperm Quality ◽  
Male Competition ◽  
Male Reproductive Success ◽  
Male Mating ◽  
Polar Bears

Polar bears ( Ursus maritimus ) from East Greenland and Svalbard exhibited very high concentrations of polychlorinated biphenyls (PCBs) in the 1980s and 1990s. In Svalbard, slow population growth during that period was suspected to be linked to PCB contamination. In this case study, we explored how PCBs could have impacted polar bear population growth and/or male reproductive success in Svalbard during the mid-1990s by reducing the fertility of contaminated males. A dose–response relationship linking the effects of PCBs to male polar bear fertility was extrapolated from studies of the effects of PCBs on sperm quality in rodents. Based on this relationship, an individual-based model of bear interactions during the breeding season predicted fertilization success under alternative assumptions regarding male–male competition for females. Contamination reduced pregnancy rates by decreasing the availability of fertile males, thus triggering a mate-finding Allee effect, particularly when male–male competition for females was limited or when infertile males were able to compete with fertile males for females. Comparisons of our model predictions on age-dependent reproductive success of males with published empirical observations revealed that the low representation of 10–14-year-old males among breeding males documented in Svalbard in mid-1990s could have resulted from PCB contamination. We conclude that contamination-related male infertility may lead to a reduction in population growth via an Allee effect. The magnitude of the effect is largely dependent on the population-specific mating system. In eco-toxicological risk assessments, appropriate consideration should therefore be given to negative effects of contaminants on male fertility and male mating behaviour.

scholarly journals Sperm Bauplan and Function and Underlying Processes of Sperm Formation and Selection

2021 ◽  
Author(s):  
Maria Eugenia Teves ◽  
Eduardo R.S. Roldán
Keyword(s):  
Reproductive Success ◽  
Molecular Mechanisms ◽  
Sperm Cells ◽  
Male Reproductive Success ◽  
Haploid Nucleus ◽  
Selective Forces ◽  
And Performance ◽  
And Function ◽  
Underlying Processes ◽  
Mammalian Spermatozoa

The spermatozoon is a highly differentiated and polarized cell, with two main structures: the head, containing a haploid nucleus and the acrosomal exocytotic granule, and the flagellum, which generates energy and propels the cell; both structures are connected by the neck. The sperm's main aim is to participate in fertilization, thus activating development. Despite this common bauplan and function there is an enormous diversity in structure and performance of sperm cells. For example, mammalian spermatozoa may exhibit several head patterns and overall sperm lengths ranging from ~30 to 350 µm. Mechanisms of transport in the female tract, preparation for fertilization, and recognition and interaction with the oocyte also show considerable variation. There has been much interest in understanding the origin of this diversity, both in evolutionary terms and in relation to mechanisms underlying sperm differentiation in the testis. Here, relationships between sperm bauplan and function are examined at two levels. First, analyzing the selective forces that drive changes in sperm structure and physiology to understand the adaptive values of this variation and impact on male reproductive success. Second, examining cellular and molecular mechanisms of sperm formation in the testis that may explain how differentiation can give rise to such a wide array of sperm forms and functions.

The reproductive status of both sexes affects the frequency of mating and the reproductive success of males in the ball roller beetle Canthon cyanellus cyanellus (Coleoptera: Scarabaeidae)

Behaviour ◽  
2009 ◽  
Vol 146 (11) ◽  
pp. 1499-1512 ◽  
Author(s):  
Mario Favila ◽  
Ivette Chamorro-Florescano
Keyword(s):  
Reproductive Success ◽  
Sperm Competition ◽  
Reproductive Status ◽  
Female Pair ◽  
Female Reproductive Status ◽  
Viable Sperm ◽  
Males And Females

AbstractSeveral studies have shown that males assess female reproductive status and use different mechanisms to increase their reproductive success. However, a male's reproductive status can also affect its own reproductive success. In Canthon cyanellus cyanellus, a male–female pair makes several brood balls during nesting and both care for the brood balls. However, in females that are transported to the nest by males, the spermatheca is often already filled with viable sperm from other males, such that sperm competition is strong. We analyze the effect of the reproductive status of males and females on the frequency of mating during brood ball construction, as well as the reproductive success of males that nest with previously mated females. Virgin and previously mated males copulated with the same frequency before the construction of each brood ball when they nested with virgin females. However, when both types of males nested with previously mated females, the frequency of mating increased before the construction of the first brood ball. The paternity of previously mated males was significantly higher (82%) than that of virgin males (62%). Therefore, the reproductive status of both sexes of C. c. cyanellus affects the frequency of mating and the reproductive success of males.

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.

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.

Detection of multiple paternity and sperm storage in a captive colony of the central Asian tortoise, Testudo horsfieldii

2006 ◽  
Vol 84 (4) ◽  
pp. 520-526 ◽  
Author(s):  
Emily E. Johnston ◽  
Matthew S. Rand ◽  
Stephan G. Zweifel
Keyword(s):  
Reproductive Success ◽  
Microsatellite Markers ◽  
Sperm Competition ◽  
Genomic Library ◽  
Multiple Paternity ◽  
Female Mate Choice ◽  
Sperm Storage ◽  
Male Reproductive Success ◽  
Critical Measure ◽  
Central Asian

Reproductive success is a critical measure of an organism’s fitness. Determining reproductive success in vertebrates is confounded by the concealed mechanism and timing of fertilization (e.g., sperm competition and storage). To assess the relationship between observed mating behavior and reproductive success in the central Asian tortoise, Testudo horsfieldii Gray, 1844, we determined individual genotypes from a captive colony of adults and their offspring. We constructed a size-selected genomic library from T. horsfieldii and screened for polymorphic microsatellite markers. The screen resulted in identification of two novel microsatellite regions. Cross-species amplification of microsatellite markers using primers developed for the bog turtle, Glyptemys muhlenbergii (Schoepff, 1801), resulted in isolation of three additional polymorphic microsatellites for T. horsfieldii. The five loci, which have between 5 and 17 alleles and observed heterozygosities between 0.44 and 0.90, were used to determine the frequency of multiple paternity in the captive colony. We found evidence for multiple paternity in 27% of the clutches examined, as well as evidence for overwinter sperm storage and variance in adult male reproductive success. These data indicate that ample opportunity exists for sperm competition and female mate choice in T. horsfieldii.

scholarly journals Genetic coordination of sperm morphology and seminal fluid proteins promotes male reproductive success in Drosophila melanogaster

2021 ◽  
Author(s):  
Jake Galvin ◽  
Erica Larson ◽  
Sevan Yedigarian ◽  
Mohammad Rahman ◽  
Kirill Borziak ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Reproductive Success ◽  
Sperm Competition ◽  
Seminal Fluid ◽  
Fertilization Success ◽  
Male Reproductive Success ◽  
Sperm Length ◽  
Seminal Fluid Proteins ◽  
Female Remating ◽  
Paternity Success

Spermatozoal morphology is highly variable both among and within species and in ways that can significantly impact fertilization success. In Drosophila melanogaster, paternity success depends on sperm length of both competing males and length of the female's primary sperm storage organ. We found that genes upregulated in long sperm testes are enriched for lncRNAs and seminal fluid proteins (Sfps). Transferred in seminal fluid to the female during mating, Sfps are secreted by the male accessory glands (AG) and affect female remating rate, physiology, and behavior with concomitant advantages for male reproductive success. Despite being upregulated in long sperm testes, they have no known function in testis tissue. We found that Sex Peptide and ovulin (Acp26Aa) knockouts resulted in shorter sperm, suggesting that Sfps may regulate sperm length during spermatogenesis. However, knockout of AG function did not affect sperm length, suggesting that AG expression has no influence on spermatogenic processes. We also found that long sperm males are better able to delay female remating, suggesting higher Sfp expression in AG. These results might suggest that long sperm males have a double advantage in sperm competition by both delaying female remating, likely through transfer of more Sfps, and by resisting sperm displacement. However, we also found that this extra advantage does not necessarily translate to more progeny or higher paternity success. Thus, we found that multiple components of the ejaculate coordinate to promote male reproductive success at different stages of reproduction, but the realized fitness advantages in sperm competition are uncertain.

scholarly journals Reproductive consequences of an extra long-term sperm storage organ

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Akashdeep Dhillon ◽  
Tabashir Chowdhury ◽  
Yolanda E. Morbey ◽  
Amanda J. Moehring
Keyword(s):  
Reproductive Success ◽  
Candidate Gene ◽  
Sperm Competition ◽  
Sperm Storage ◽  
Female Fitness ◽  
Storage Organ ◽  
Empirical Tests ◽  
Reproductive Consequences

Abstract Background Sperm storage plays a key role in the reproductive success of many sexually-reproducing organisms, and the capacity of long-term sperm storage varies across species. While there are theoretical explanations for why such variation exists, to date there are no controlled empirical tests of the reproductive consequences of additional long-term sperm storage. While Dipterans ancestrally have three long-term sperm organs, known as the spermathecae, Drosophila contain only two. Results We identified a candidate gene, which we call spermathreecae (sp3), in which a disruption cause the development of three functional spermathecae rather than the usual two in Drosophila. We used this disruption to test the reproductive consequences of having an additional long-term sperm storage organ. Compared to females with two spermathecae, females with three spermathecae store a greater total number of sperm and can produce offspring a greater length of time. However, they did not produce a greater total number of offspring. Conclusions Thus, additional long-term sperm storage in insects may increase female fitness through extending the range of conditions where she produces offspring, or through increasing the quality of offspring via enhanced local sperm competition at fertilization.

Male lake sturgeon (Acipenser fulvescens) migratory and spawning behaviors are associated with sperm quality and reproductive success

2020 ◽  
Vol 77 (12) ◽  
pp. 1943-1959
Author(s):  
Douglas L. Larson ◽  
Jacob G. Kimmel ◽  
Joseph J. Riedy ◽  
Jonathan Hegna ◽  
Edward A. Baker ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Sperm Quality ◽  
Lake Sturgeon ◽  
Operational Sex Ratio ◽  
Computer Assisted ◽  
Acipenser Fulvescens ◽  
Male Reproductive Success ◽  
Upstream Migration ◽  
Sperm Depletion

Intra-annual reproductive investments may not be predictive of male reproductive success because of the effects of intra- and intersexual interactions on sperm depletion. For long-lived iteroparous fish species such as lake sturgeon (Acipenser fulvescens), reproductive effort may affect lifetime reproductive success. Radio frequency identification antennas were placed at the mouth of the Upper Black River, Michigan, and downstream of spawning locations to quantify male migratory and mating behaviors, including upstream migration time (UT), river residence time (RT), number of intra-annual spawning migrations (IM), interannual spawning interval, and operational sex ratio during 2017–2018. Computer assisted sperm analysis was used to quantify sperm quality. RT had a strong negative influence on sperm concentration and with measures of sperm quality. RT and the number of females encountered were positively associated with male reproductive success (number of offspring sired) across years. RT, IM, and UT were negatively associated with sperm quality, indicating sperm depletion is a reliable measure of sexual activity. Results demonstrate trade-offs between benefits and costs associated with current reproductive effort on future reproduction.

Sign in / Sign up

Export Citation Format

Share Document