Condition dependence of sexually dimorphic colouration and longevity in the ambush bug Phymata americana

Abstract

Sexually selected traits that are costly are predicted to be more condition dependent than nonsexually selected traits. Assuming resource limitation, increased allocation to a sexually selected trait may also come at a cost to other fitness components. To test these predictions, we varied adult food ration to manipulate condition in the colour dimorphic bug, Phymata americana. We compared the degree of condition dependence in a sexually selected trait expressed in males to a nonsexually selected trait expressed in males and females. We also evaluated the effects of condition on longevity of both sexes. We found that the expression of these colour pattern traits was strongly influenced by both diet and age. As expected, the strength of condition dependence was much more pronounced in the sexually selected, male‐limited trait but the nonsexual trait also exhibited significant condition dependence in both sexes. The sexually selected male trait also exhibited a higher coefficient of phenotypic variation than the nonsexually selected trait in males and females. Diet had contrasting effects on male and female longevity; increased food availability had positive effects on female lifespan but these effects were not detected in males, suggesting that males allocated limited resources preferentially to sexually selected traits. These results are consistent with the expectation that optimal allocation to various fitness components differs between the sexes.

Condition Dependence of a Multicomponent Sexual Display Trait in Drosophila serrata

“…Unfortunately, many of these studies suffered from a number of shortcomings, and compelling manipulative evidence that sexual traits exhibit heightened condition dependence is limited (Cotton et al 2004). Although some of the concerns raised by Cotton et al (2004) have been addressed in several recent studies (e.g., Bonduriansky and Rowe 2005;Kemp and Rutowski 2007;Siitari et al 2007;Kemp 2008;Peters et al 2008;Punzalan et al 2008;McGuigan 2009;Smith and Greig 2010;Tibbetts 2010;Wyman et al 2010), conspicuous gaps in our knowledge remain. For example, the standard experimental approach compares the extent of condition-dependent expression of sexual traits with that of one or more nonsexual traits.…”

“…For example, the standard experimental approach compares the extent of condition-dependent expression of sexual traits with that of one or more nonsexual traits. As nonsexual traits, such comparisons often employ the homologous traits in females or other nonsexual traits in males, on the presumption that directional selection is weaker or absent on them (but see Punzalan et al 2008;McGuigan 2009). While useful, such comparisons often rest on an untested assumption concerning the strength of selection on these traits and therefore cannot be used to estimate the relationship between the strengths of condition dependence and selection.…”

Comparing the intersex genetic correlation for fitness across novel environments in the fruit fly, Drosophila serrata

“…We also observed a negative r w FM in corn, possibly reflecting sexually antagonistic effects peculiar to this environment. Although it is unclear as to the underlying proximate causes of such effects, they may correspond to the variation in the availability of (or ability to assimilate) limited resources; sex-specific nutritional and energetic requirements can generate sex differences in allocation to components of fitness that is ultimately environment dependent (Hunt et al, 2004;Maklakov et al, 2008;Punzalan et al, 2008; also see Judge et al, 2008). That r w FM was more positive in the yeast environment in our case (as compared to Delcourt et al (2009), who used a population long adapted to this environment) is also consistent with an increasing proportion of sexually antagonistic genetic variation as adaptation proceeds.…”

Condition-dependent ejaculate size and composition in a ladybird beetle

“…The extent of condition dependence in sexually selected traits is a key issue for sexual selection research (Zahavi 1975;Iwasa & Pomiankowski 1994;Rowe & Houle 1996). Following a series of environmental manipulations of condition, there is now considerable empirical evidence for condition dependence in several types of sexually selected traits, including secondary sexual morphology, ornaments and pigmentation, and acoustic signals (Andersson 1994;Cotton et al 2004 and references therein; Bonduriansky & Rowe 2005;Punzalan et al 2008). Recent evidence suggests that male ejaculates are also sexually selected (Eberhard & Cordero 1995;Ramm et al 2007;Simmons & Kotiaho 2007;Martin-Coello et al 2009;Wigby et al 2009) and costly (e.g.…”