scholarly journals Decision letter: Sperm competition risk drives rapid ejaculate adjustments mediated by seminal fluid

2017 ◽  
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
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.

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 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.

scholarly journals Sperm competition risk drives rapid ejaculate adjustments mediated by seminal fluid

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Michael J Bartlett ◽  
Tammy E Steeves ◽  
Neil J Gemmell ◽  
Patrice C Rosengrave
Keyword(s):  
Sperm Competition ◽  
Oncorhynchus Tshawytscha ◽  
Seminal Fluid ◽  
Sperm Velocity ◽  
Competition Theory ◽  
Increased Risk ◽  
Rapid Changes ◽  
Sperm Competition Risk ◽  
Rapid Adjustment

In many species, males can make rapid adjustments to ejaculate performance in response to sperm competition risk; however, the mechanisms behind these changes are not understood. Here, we manipulate male social status in an externally fertilising fish, chinook salmon (Oncorhynchus tshawytscha), and find that in less than 48 hr, males can upregulate sperm velocity when faced with an increased risk of sperm competition. Using a series of in vitro sperm manipulation and competition experiments, we show that rapid changes in sperm velocity are mediated by seminal fluid and the effect of seminal fluid on sperm velocity directly impacts paternity share and therefore reproductive success. These combined findings, completely consistent with sperm competition theory, provide unequivocal evidence that sperm competition risk drives plastic adjustment of ejaculate quality, that seminal fluid harbours the mechanism for the rapid adjustment of sperm velocity and that fitness benefits accrue to males from such adjustment.

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 Author response: Sperm competition risk drives rapid ejaculate adjustments mediated by seminal fluid

2017 ◽  
Author(s):  
Michael J Bartlett ◽  
Tammy E Steeves ◽  
Neil J Gemmell ◽  
Patrice C Rosengrave
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
Author Response ◽  
Sperm Competition Risk

Effects of condition and sperm competition risk on sperm allocation and storage in neriid flies

2019 ◽  
Author(s):  
Zachariah Wylde ◽  
Angela Crean ◽  
Russell Bonduriansky
Keyword(s):  
Sperm Competition ◽  
Perceived Risk ◽  
Reproductive Tract ◽  
Female Reproductive Tract ◽  
The Body ◽  
Condition Dependence ◽  
Ejaculate Size ◽  
Sperm Competition Risk ◽  
High Condition ◽  
Allocation Strategies

Abstract Ejaculate traits can be sexually selected and often exhibit heightened condition-dependence. However, the influence of sperm competition risk in tandem with condition-dependent ejaculate allocation strategies is relatively unstudied. Because ejaculates are costly to produce, high-condition males may be expected to invest more in ejaculates when sperm competition risk is greater. We examined the condition-dependence of ejaculate size by manipulating nutrient concentration in the juvenile (larval) diet of the neriid fly Telostylinus angusticollis. Using a fully factorial design we also examined the effects of perceived sperm competition risk (manipulated by allowing males to mate first or second) on the quantity of ejaculate transferred and stored in the three spermathecae of the female reproductive tract. To differentiate male ejaculates, we fed males nontoxic rhodamine fluorophores (which bind to proteins in the body) prior to mating, labeling their sperm red or green. We found that high-condition males initiated mating more quickly and, when mating second, transferred more ejaculate to both of the female’s posterior spermathecae. This suggests that males allocate ejaculates strategically, with high-condition males elevating their ejaculate investment only when facing sperm competition. More broadly, our findings suggest that ejaculate allocation strategies can incorporate variation in both condition and perceived risk of sperm competition.

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.

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