THE EVOLUTION OF SPERM-ALLOCATION STRATEGIES AND THE DEGREE OF SPERM COMPETITION

Evolution ◽  
2005 ◽  
Vol 59 (3) ◽  
pp. 492 ◽  
Author(s):  
Paul D. Williams ◽  
Troy Day ◽  
Erin Cameron
Evolution ◽  
2005 ◽  
Vol 59 (3) ◽  
pp. 492-499 ◽  
Author(s):  
Paul D. Williams ◽  
Troy Day ◽  
Erin Cameron

Author(s):  
Zachariah Wylde ◽  
Angela Crean ◽  
Russell Bonduriansky

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.


Ethology ◽  
2015 ◽  
Vol 121 (5) ◽  
pp. 451-461 ◽  
Author(s):  
Solana Abraham ◽  
M. Teresa Vera ◽  
Diana Pérez-Staples

2006 ◽  
Vol 274 (1607) ◽  
pp. 209-217 ◽  
Author(s):  
Leif Engqvist ◽  
Klaus Reinhold

Sperm competition theory predicts that when males are certain of sperm competition, they should decrease sperm investment in matings with an increasing number of competing ejaculates. How males should allocate sperm when competing with differently sized ejaculates, however, has not yet been examined. Here, we report the outcomes of two models assuming variation in males' sperm reserves and males being faced with different amounts of competing sperm. In the first ‘spawning model’, two males compete instantaneously and both are able to assess the sperm competitive ability of each other. In the second ‘sperm storage model’, males are sequentially confronted with situations involving different levels of sperm competition, for instance different amounts of sperm already stored by the female mating partner. In both of the models, we found that optimal sperm allocation will strongly depend on the size of the male's sperm reserve. Males should always invest maximally in competition with other males that are equally strong competitors. That is, for males with small sperm reserves, our model predicts a negative correlation between sperm allocation and sperm competition intensity, whereas for males with large sperm reserves, this correlation is predicted to be positive.


2015 ◽  
Vol 109 ◽  
pp. 81-87 ◽  
Author(s):  
Alicia Jarrige ◽  
Dennis Riemann ◽  
Marlène Goubault ◽  
Tim Schmoll

2008 ◽  
Vol 172 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Lutz Fromhage ◽  
John M. McNamara ◽  
Alasdair I. Houston

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