scholarly journals Tactic-specific differences in seminal fluid influence sperm performance

2013 ◽  
Vol 280 (1755) ◽  
pp. 20122891 ◽  
Author(s):  
Lisa Locatello ◽  
Federica Poli ◽  
Maria B. Rasotto
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
Fertilization Rate ◽  
Fertilization Success ◽  
Mating Tactics ◽  
Recognition Mechanism ◽  
Self Recognition ◽  
Sperm Competition Risk ◽  
Grass Goby ◽  
Zosterisessor Ophiocephalus

Seminal fluid often makes up a large part of an ejaculate, yet most empirical and theoretical studies on sperm competition have focused on how sperm characteristics (number and quality) affect fertilization success. However, seminal fluid influences own sperm performance and may potentially influence the outcome of sperm competition, by also affecting that of rivals. As a consequence males may be expected to allocate their investment in both sperm and seminal fluid in relation to the potential level of competition. Grass goby ( Zosterisessor ophiocephalus ) is an external fertilizer with guard-sneaker mating tactics, where sperm competition risk varies according to the tactic adopted. Here, we experimentally manipulated grass goby ejaculates by separately combining sperm and seminal fluid from territorial and sneaker males. While sperm of sneaker and territorial males did not differ in their performance when they interacted with their own seminal fluid only, sperm of sneakers increased their velocity and fertilization rate in the presence of territorial males' seminal fluid. By contrast, sneaker males' seminal fluid had a detrimental effect on the performance of territorial males' sperm. Sperm velocity was unaffected by the seminal fluid of males employing the same tactic, suggesting that seminal fluid's effect on rival-tactic sperm is not based on a self/non-self recognition mechanism. Our findings show that cross interactions of sperm and seminal fluid may influence the fertilization success of competing ejaculates with males investing in both sperm and seminal fluid in response to sperm competition risk.

scholarly journals Social manipulation of sperm competition intensity reduces seminal fluid gene expression

2018 ◽  
Vol 14 (1) ◽  
pp. 20170659 ◽  
Author(s):  
Nadia S. Sloan ◽  
Maxine Lovegrove ◽  
Leigh W. Simmons
Keyword(s):  
Gene Expression ◽  
Sperm Competition ◽  
Seminal Fluid ◽  
Fertilization Success ◽  
Accessory Gland ◽  
Fluid Composition ◽  
Competition Intensity ◽  
Teleogryllus Oceanicus ◽  
Sperm Competition Risk ◽  
Considerable Body

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 adjustments in seminal fluid composition contribute to competitive fertilization success in this species.

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.

Post-Copulatory Sexual Selection

2021 ◽  
Author(s):  
Patricia L.R. Brennan ◽  
Dara N. Orbach
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Female Choice ◽  
Reproductive Tract ◽  
Seminal Fluid ◽  
Fertilization Success ◽  
Female Reproductive Tract ◽  
Cryptic Female Choice ◽  
Trade Offs ◽  
Morphological Criteria

The field of post-copulatory sexual selection investigates how female and male adaptations have evolved to influence the fertilization of eggs while optimizing fitness during and after copulation, when females mate with multiple males. When females are polyandrous (one female mates with multiple males), they may optimize their mating rate and control the outcome of mating interactions to acquire direct and indirect benefits. Polyandry may also favor the evolution of male traits that offer an advantage in post-copulatory male-male sperm competition. Sperm competition occurs when the sperm, seminal fluid, and/or genitalia of one male directly impacts the outcome of fertilization success of a rival male. When a female mates with multiple males, she may use information from a number of traits to choose who will sire her offspring. This cryptic female choice (CFC) to bias paternity can be based on behavioral, physiological, and morphological criteria (e.g., copulatory courtship, volume and/or composition of seminal fluid, shape of grasping appendages). Because male fitness interests are rarely perfectly aligned with female fitness interests, sexual conflict over mating and fertilization commonly occur during copulatory and post-copulatory interactions. Post-copulatory interactions inherently involve close associations between female and male reproductive characteristics, which in many species potentially include sperm storage and sperm movement inside the female reproductive tract, and highlight the intricate coevolution between the sexes. This coevolution is also common in genital morphology. The great diversity of genitalia among species is attributed to sexual selection. The evolution of genital attributes that allow females to maintain reproductive autonomy over paternity via cryptic female choice or that prevent male manipulation and sexual control via sexually antagonistic coevolution have been well documented. Additionally, cases where genitalia evolve through intrasexual competition are well known. Another important area of study in post-copulatory sexual selection is the examination of trade-offs between investments in pre-copulatory and post-copulatory traits, since organisms have limited energetic resources to allocate to reproduction, and securing both mating and fertilization is essential for reproductive success.

scholarly journals Sperm competition risk drives plasticity in seminal fluid composition

BMC Biology ◽  
2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Steven A. Ramm ◽  
Dominic A. Edward ◽  
Amy J. Claydon ◽  
Dean E. Hammond ◽  
Philip Brownridge ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
Fluid Composition ◽  
Sperm Competition Risk

scholarly journals Exposure to sperm competition risk improves survival of virgin males

2013 ◽  
Vol 9 (2) ◽  
pp. 20121188 ◽  
Author(s):  
Joshua P. Moatt ◽  
Calvin Dytham ◽  
Michael D. F. Thom
Keyword(s):  
Sperm Competition ◽  
Life History Traits ◽  
Seminal Fluid ◽  
Fluid Composition ◽  
Short Term ◽  
Investment In Reproduction ◽  
Sperm Competition Risk ◽  
Total Investment ◽  
Improvement In Survival ◽  
Striking Effect

Sperm competition between the ejaculates of multiple males for the fertilization of a given set of ova is taxonomically widespread. Males have evolved remarkable adaptations to increase their reproductive success under postcopulatory sexual selection, which in many species includes the ability to modify behaviour and ejaculate characteristics plastically to match the perceived level of sperm competition. Males of the model species Drosophila melanogaster increase mating duration and modify seminal fluid composition in response to short-term changes in sperm competition risk. If these responses increase a male's total investment in reproduction, he must either trade-off this cost against other life-history traits or suffer reduced survival. We tested whether mounting a plastic sperm competition response bears an instantaneous survival cost, and instead found that male D. melanogaster exposed to a high risk of sperm competition survive 12 per cent longer than those at low risk, equating to a 49 per cent reduction in the hourly hazard of death. This striking effect was found only among virgins: the high cost of mating in this species eliminates any such benefit among non-virgin males. Our results suggest that the improvement in survival found among virgins may be a product of males’ tactical responses to sperm competition.

scholarly journals Phenotypic plasticity in genitalia: baculum shape responds to sperm competition risk in house mice

2018 ◽  
Vol 285 (1882) ◽  
pp. 20181086 ◽  
Author(s):  
Gonçalo I. André ◽  
Renée C. Firman ◽  
Leigh W. Simmons
Keyword(s):  
Phenotypic Plasticity ◽  
Sperm Competition ◽  
Fertilization Success ◽  
House Mice ◽  
Genital Morphology ◽  
Geometric Morphometric ◽  
Sperm Competition Risk ◽  
Male House ◽  
Male Genital Morphology ◽  
Competition Environment

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 competition risk were larger and heavier than males maturing under no sperm competition risk. We used a landmark-based geometric morphometric approach to measure baculum size and shape. Independent of variation in body size, males maintained under risk of sperm competition had a relatively thicker and more distally extended baculum bulb compared with males maintained under no sperm competition risk. Plasticity in baculum shape paralleled evolutionary responses to selection from sperm competition reported in previous studies of house mice. Our findings provide experimental evidence of socially mediated phenotypic plasticity in male genitalia.

scholarly journals Sperm competition, alternative mating tactics and context-dependent fertilization success in the burying beetle, Nicrophorus vespilloides

2007 ◽  
Vol 274 (1615) ◽  
pp. 1309-1315 ◽  
Author(s):  
Clarissa M House ◽  
John Hunt ◽  
Allen J Moore
Keyword(s):  
Sperm Competition ◽  
Fertilization Success ◽  
Mating Strategies ◽  
Alternative Mating Tactics ◽  
Sterile Male ◽  
Burying Beetle ◽  
Mating Tactics ◽  
Competition Theory ◽  
Nicrophorus Vespilloides ◽  
Biological Context

Fertilization success in sperm competition is often determined by laboratory estimates of the proportion of offspring sired by the first ( P 1 ) or second ( P 2 ) male that mates. However, inferences from such data about how sexual selection acts on male traits in nature may be misleading if fertilization success depends on the biological context in which it is measured. We used the sterile male technique to examine the paternity of the same male in two mating contexts in the burying beetle, Nicrophorus vespilloides , a species where males have alternative mating strategies based on the presence or absence of resources. We found no congruence in the paternity achieved by a given male when mating under different social conditions. P 2 estimates were extremely variable under both conditions. Body size was unrelated to success in sperm competition away from a carcass but, most probably through pre-copulatory male–male competition, influenced fertilization success on a carcass. The contribution of sperm competition is therefore dependent on the conditions under which it is measured. We discuss our findings in relation to sperm competition theory and highlight the need to consider biological context in order to link copulation and fertilization success for competing males.

Mating system and alternative male mating tactics in the grass goby Zosterisessor ophiocephalus (Teleostei: Gobiidae)

2000 ◽  
Vol 137 (5-6) ◽  
pp. 1041-1048 ◽  
Author(s):  
C. Mazzoldi ◽  
M. Scaggiante ◽  
E. Ambrosin ◽  
M. B. Rasotto
Keyword(s):  
Mating System ◽  
Male Mating ◽  
Mating Tactics ◽  
Grass Goby ◽  
Zosterisessor Ophiocephalus

scholarly journals Socially cued seminal fluid gene expression mediates responses in ejaculate quality to sperm competition risk

2017 ◽  
Vol 284 (1861) ◽  
pp. 20171486 ◽  
Author(s):  
Leigh W. Simmons ◽  
Maxine Lovegrove
Keyword(s):  
Gene Expression ◽  
Sperm Competition ◽  
Seminal Fluid ◽  
Protein Composition ◽  
Theoretical Models ◽  
Fluid Composition ◽  
Sperm Viability ◽  
Considerable Evidence ◽  
Sperm Competition Risk ◽  
Seminal Fluid Protein

There is considerable evidence that males will increase the number of sperm ejaculated in response to sperm competition risk. However, whether they have the capacity to adjust seminal fluid components of the ejaculate has received less attention. Male crickets ( Teleogryllus oceanicus ) have been shown to adjust the viability of sperm in their ejaculate in response to sperm competition risk. Here we show that socially mediated plasticity in sperm viability is probably due, at least in part, to male adjustments in the protein composition of the seminal fluid. Seven seminal fluid protein genes were found to have an increased expression in males exposed to rival calls. Increased expression of these genes was correlated with increased sperm viability in whole ejaculates, and gene knockdown confirmed that at least one of these proteins promotes sperm viability. Our results lend support for recent theoretical models that predict complex responses in male allocation to seminal fluid composition in response to sperm competition risk.

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