CIE Spotlight: Differential genotypic effects of sexual trait size on offspring mating success and viability

Kerry F.

Kerry F.

Title: Differential genotypic effects of sexual trait size on offspring mating success and viability

Authors: Polak, Michal; Fanson, Kerry V.; Taylor, Phillip W.; Yap, Sarsha

Source: BEHAVIORAL ECOLOGY, 27 (2):444-451, MAR-APR 2016

Brief summary of the paper: Indicator models of sexual selection predict that females mating with the most ornamented males should produce offspring with enhanced expression of fitness-related traits, such as overall vigor and viability. Empirical support for this prediction, however, is limited.

We quantified the effects of a heritable and condition-dependent secondary sexual trait on offspring performance traits in Drosophila bipectinata Duda (Diptera: Drosophilidae). Forty-eight genetic (isofemale) lines were extracted from a natural population, reared in a common environment, and characterized in terms of sex comb size.

We measured pupal viability and adult mating success among the progeny of the 5 lines with the largest combs (high line category) and the 5 lines with the smallest combs (low line category). The high line category produced offspring that were significantly more viable than the low line category, and this advantage held across 2 developmental temperatures. In contrast, there was no effect of line category on male mating success, although at the individual-level, comb size was significantly positively correlated with mating success.

Our results indicate that the relative size of the D. bipectinata sex comb taps genotypic properties that enhance offspring fitness in a trait-specific manner. Thus, distinct proximate mechanisms likely underlie relationships between secondary sexual trait expression and different performance traits in offspring, offering a possible explanation for inconsistent support for the existence of indirect benefits in sexual selection.