scholarly journals Adaptive modulation of sperm production rate in Drosophila bifurca , a species with giant sperm

2007 ◽  
Vol 3 (5) ◽  
pp. 517-519 ◽  
Author(s):  
Adam Bjork ◽  
Romano Dallai ◽  
Scott Pitnick
Keyword(s):  
Sperm Competition ◽  
Production Rate ◽  
Adaptive Modulation ◽  
Sperm Production ◽  
Mating Opportunities ◽  
Sperm Competition Risk ◽  
Solitary Males ◽  
Gamete Production

Sperm have traditionally been regarded as energetically cheap and effectively limitless in supply, although evidence conflicting with this view has become increasingly abundant. For instance, males from a variety of taxa have been shown to strategically partition sperm across ejaculates in response to perceived sperm competition risk. It follows that males might also be predicted to adaptively modulate the rate at which sperm are produced. Here we show that, in the giant sperm producing fruitfly Drosophila bifurca , solitary males with infrequent access to females produce sperm at a much lower rate than males raised in association with females and other males. Our results support the prediction that males with little risk of sperm competition risk or few mating opportunities should divert resources away from gamete production.

scholarly journals Predicting variation in sperm precedence

1997 ◽  
Vol 352 (1355) ◽  
pp. 771-780 ◽  
Author(s):  
Penny A. Cook ◽  
Ian F. Harvey ◽  
Geoffrey A. Parker
Keyword(s):  
Sperm Competition ◽  
Mean Value ◽  
Sperm Production ◽  
Additional Information ◽  
Competition Theory ◽  
Risk Increase ◽  
Large Numbers ◽  
Theoretical Predictions ◽  
Sperm Competition Risk ◽  
Lepidoptera Pyralidae

Sperm competition theory predicts that males are adapted for success in sperm competition by the production of large numbers of sperm. This is supported by both inter– and intraspecific studies showing that males mating under high sperm competition risk increase investment in sperm production. Such an increase in sperm production is an advantage if sperm mix randomly or if sperm displacement occurs. When two males mate with the same female, the measurement of the proportion of eggs fertilized by the second male to mate (termed P 2 ) has been used to help elucidate sperm competition mechanisms. P 2 is usually quoted as a mean value, with little attention being paid to its variance, although P 2 estimates are notoriously variable. By predicting an expected variance for P 2 , additional information on sperm competition mechanisms may be obtained. Here we present a technique for analysing the variance in P 2 when a given mechanism of P 2 is assumed. We apply this technique to P 2 data collected from Plodia interpunctella (Lepidoptera, Pyralidae), assuming a ‘fair raffle’ mechanism of sperm competition. We compare observed distributions of P 2 with theoretical distributions generated assuming random mixing of two ejaculates drawn randomly from a population of known mean and variance in sperm numbers. Ejaculates of known size were obtained by counting the number of sperm ejaculated by males mating for the first (large ejaculate) or second (small ejaculate) time. Females either received two small or one small and one large ejaculate, and the distribution of P 2 (estimated using the sterile male technique) was compared with our theoretical predictions. The observed variance in P 2 was greater than our model prediction, thus we conclude that sperm from P. interpunctella do not mix randomly before fertilization.

scholarly journals Phenotypic engineering of sperm-production rate confirms evolutionary predictions of sperm competition theory

2013 ◽  
Vol 280 (1757) ◽  
pp. 20122711 ◽  
Author(s):  
Kiyono Sekii ◽  
Dita B. Vizoso ◽  
Georg Kuales ◽  
Katrien De Mulder ◽  
Peter Ladurner ◽  
...  
Keyword(s):  
Sperm Competition ◽  
Production Rate ◽  
Sperm Production ◽  
Competition Theory ◽  
Phenotypic Engineering

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.

scholarly journals Casanovas are liars: behavioral syndromes, sperm competition risk, and the evolution of deceptive male mating behavior in live-bearing fishes

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 75 ◽  
Author(s):  
David Bierbach ◽  
Amber M Makowicz ◽  
Ingo Schlupp ◽  
Holger Geupel ◽  
Bruno Streit ◽  
...  
Keyword(s):  
Mate Choice ◽  
Sexual Activity ◽  
Sperm Competition ◽  
Evolutionary Significance ◽  
Behavioral Syndromes ◽  
Male Mating ◽  
Data Set ◽  
Poecilia Mexicana ◽  
Audience Effects ◽  
Sperm Competition Risk

Male reproductive biology can by characterized through competition over mates as well as mate choice. Multiple mating and male mate choice copying, especially in internally fertilizing species, set the stage for increased sperm competition, i.e., sperm of two or more males can compete for fertilization of the female’s ova. In the internally fertilizing fish Poecilia mexicana, males respond to the presence of rivals with reduced expression of mating preferences (audience effect), thereby lowering the risk of by-standing rivals copying their mate choice. Also, males interact initially more with a non-preferred female when observed by a rival, which has been interpreted in previous studies as a strategy to mislead rivals, again reducing sperm competition risk (SCR). Nevertheless, species might differ consistently in their expression of aggressive and reproductive behaviors, possibly due to varying levels of SCR. In the current study, we present a unique data set comprising ten poeciliid species (in two cases including multiple populations) and ask whether species can be characterized through consistent differences in the expression of aggression, sexual activity and changes in mate choice under increased SCR. We found consistent species-specific differences in aggressive behavior, sexual activity as well as in the level of misleading behavior, while decreased preference expression under increased SCR was a general feature of all but one species examined. Furthermore, mean sexual activity correlated positively with the occurrence of potentially misleading behavior. An alternative explanation for audience effects would be that males attempt to avoid aggressive encounters, which would predict stronger audience effects in more aggressive species. We demonstrate a positive correlation between mean aggressiveness and sexual activity (suggesting a hormonal link as a mechanistic explanation), but did not detect a correlation between aggressiveness and audience effects. Suites of correlated behavioral tendencies are termed behavioral syndromes, and our present study provides correlational evidence for the evolutionary significance of SCR in shaping a behavioral syndrome at the species level across poeciliid taxa.

scholarly journals Imminent risk of predation reduces the relative strength of postcopulatory sexual selection in the guppy

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200076
Author(s):  
Alexandra Glavaschi ◽  
Silvia Cattelan ◽  
Alessandro Grapputo ◽  
Andrea Pilastro
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Repeated Measures ◽  
Poecilia Reticulata ◽  
Male Reproductive Success ◽  
Sperm Production ◽  
Postcopulatory Sexual Selection ◽  
Repeated Measures Design ◽  
Risk Of Predation ◽  
Livebearing Fish

Fifty years of research on sperm competition has led to a very good understanding of the interspecific variation in sperm production traits. The reasons why this variation is often very large within populations have been less investigated. We suggest that the interaction between fluctuating environmental conditions and polyandry is a key phenomenon explaining such variation. We focus here on imminent predation risk (IPR). IPR impacts significantly several aspects of prey behaviour and reproduction, and it is expected to influence the operation of sexual selection before and after mating. We estimated the effect of IPR on the male opportunity for pre- and postcopulatory sexual selection in guppies ( Poecilia reticulata ), a livebearing fish where females prefer colourful males and mate multiply. We used a repeated-measures design, in which males were allowed to mate with different females either under IPR or in a predator-free condition. We found that IPR increased the total opportunity for sexual selection and reduced the relative contribution of postcopulatory sexual selection to male reproductive success. IPR is inherently variable and our results suggest that interspecific reproductive interference by predators may contribute towards maintaining the variation in sperm production within populations. This article is part of the theme issue ‘Fifty years of sperm competition'.

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