Genetic variation but weak genetic covariation between pre‐ and post‐copulatory episodes of sexual selection inDrosophila melanogaster

Abstract

When females mate polyandrously, male reproductive success depends both on the male's ability to attain matings and on his ability to outcompete rival males in the fertilization of ova post-copulation. Increased investment in ejaculate components may trade off with investment in precopulatory traits due to resource allocation. Alternatively, pre- and post-copulatory traits could be positively related if individuals can afford to invest heavily in traits advantageous at both episodes of selection. There is empirical evidence for both positive and negative associations between pre- and post-copulatory episodes, but little is known about the genetic basis of these correlations. In this study, we measured morphological, chemical and behavioural precopulatory male traits and investigated their relationship with measures of male fitness (male mating success, remating inhibition and offensive sperm competitiveness) across 40 isofemale lines of Drosophila melanogaster. We found significant variation among isofemale lines, indicating a genetic basis for most of the traits investigated. However, we found weak evidence for genetic correlations between precopulatory traits and our indices of male fitness. Moreover, pre- and post-copulatory episodes of selection were uncorrelated, suggesting selection may act independently at the different episodes to maximize male reproductive success.

Costs and benefits of giant sperm and sperm storage organs in Drosophila melanogaster

“…Here, however, we did not find an association between sperm length and premating success, in concordance with Droge‐Young, Manier, Lüpold, Belote, and Pitnick () and Travers et al. (). It is possible that precopulatory and post‐copulatory effort trade off in D. melanogaster (Filice & Dukas, ) and that both are so costly that males may invest in only one or the other.…”

“…However, most studies in other species have found that precopulatory success is a good predictor of post-copulatory outcome (Evans, Zane, Francescato, & Pilastro, 2003;Hosken, Taylor, Hoyle, Higgins, & Wedell, 2008;Lewis & Austad, 1994;Polak & Simmons, 2009;Sbilordo & Martin, 2014;McDonald, Spurgin, Fairfield, Richardson, Pizzari, 2017), although it matters which traits are considered (Ala- . Here, however, we did not find an association between sperm length and premating success, in concordance with Droge-Young, Manier, Lüpold, Belote, and Pitnick (2012) and Travers et al (2016). It is possible that precopulatory and post-copulatory effort trade off in D. melanogaster (Filice & Dukas, 2019) and that both are so costly that males may invest in only one or the other.…”

“…Do males with long sperm also have higher precopulatory success (increased attractiveness, mating success), fecundity, or viability? Sperm size could be correlated with these traits due to genetic linkage with viability alleles (Gilbert & Uetz, 2016;Head, Hunt, Jennions, & Brooks, 2005;Svobodová et al, 2018), or there may be significant tradeoffs (Ball & Parker, 1996;Dines et al, 2015;Foo, Simmons, Peters, Rhodes, 2018), or even no relationship (Travers, Garcia-Gonzalez, & Simmons, 2016), depending on a range of ecological factors (Evans & Garcia-Gonzalez, 2016;Lüpold, Tomkins, Simmons, & Fitzpatrick, 2014;Parker, Lessells, & Simmons, 2013;Simmons, Lüpold, & Fitzpatrick, 2017). In addition, do females benefit from bearing SRs that select for longer sperm, or does cryptic female choice carry a cost?…”

Sexual coloration and sperm performance in the Australian painted dragon lizard, Ctenophorus pictus

“…Alternatively, some studies demonstrate that the same individuals can have both large weapons or bright colours and competitive ejaculates (i.e. additive relationship; Evans et al ., ; Pilastro et al ., ; Malo et al ., ; Locatello et al ., ; Hosken et al ., ), and others have found no such relationship (Pischedda & Rice, ; Lewis et al ., ; Travers et al ., ). Parker et al .…”

“…Alternatively, some studies demonstrate that the same individuals can have both large weapons or bright colours and competitive ejaculates (i.e. additive relationship; Evans et al, 2003;Pilastro et al, 2004;Malo et al, 2005;Locatello et al, 2006;Hosken et al, 2008), and others have found no such relationship (Pischedda & Rice, 2012;Lewis et al, 2013;Travers et al, 2016). Parker et al (2013) suggested, based on theoretical analyses, that the degree to which males are able to monopolize access to females via precopulatory sexual selection (sensu Emlen & Oring, 1977) may determine the strength and direction of this trade-off among species.…”