Sexual Selection on male cuticular hydrocarbons via male–male competition and female choice

Abstract

Traditional views of sexual selection assumed that male–male competition and female mate choice work in harmony, selecting upon the same traits in the same direction. However, we now know that this is not always the case and that these two mechanisms often impose conflicting selection on male sexual traits. Cuticular hydrocarbons (CHCs) have been shown to be linked to both social dominance and male attractiveness in several insect species. However, although several studies have estimated the strength and form of sexual selection imposed on male CHCs by female mate choice, none have established whether these chemical traits are also subject to sexual selection via male–male competition. Using a multivariate selection analysis, we estimate and compare sexual selection exerted by male–male competition and female mate choice on male CHC composition in the broad‐horned flour beetle Gnatocerus cornutus. We show that male–male competition exerts strong linear selection on both overall CHC abundance and body size in males, while female mate choice exerts a mixture of linear and nonlinear selection, targeting not just the overall amount of CHCs expressed but the relative abundance of specific hydrocarbons as well. We discuss the potential implications of this antagonistic selection with regard to male reproductive success.

Hairstreak butterflies (Lepidoptera, Lycaenidae) and evolution of their male secondary sexual organs

“…Such dimorphisms probably indicate different reproductive strategies among conspecific males (e.g. Bonduriansky, ; Lane et al., ; Weir et al., ) and are unlikely to be related to selection for species recognition. If correct, then a ventral hindwing scent pouch with androconia may be selected for species recognition in some species (e.g.…”

Phenotypic integration and the evolution of signal repertoires: A case study of treefrog acoustic communication

“…Phenotypic integration studies of signal repertoires may improve the understanding of the causes and consequences of the evolution of multiple signals because, as argued above for the traits of individual signals, measures of integration across signals quantify the potential constraints that act on the independent evolution of different signal types. The characteristics of different signals within a repertoire may be expected to covary positively to some extent if their production is controlled by a common morphological apparatus or physiological mechanism (Podos, 1997;Podos, Lahti, & Moseley, 2009), yet they may also be subject to conflicting selection pressures to optimize signaling in different contexts, for instance when certain magnitudes of signal characteristics are effective in one context but ineffective in another (Lane, Dickinson, Tregenza, & House, 2016;Leitão & Riebel, 2003;Moore & Moore, 1999) or if both signals draw from the same pool of energetic resources (Shutler, 2011). Nevertheless, while a growing number of studies are quantifying the complexity and interrelationships between components of animal (and plant;Junker et al, 2017) signals (Bertram, Fitzsimmons, McAuley, Rundle, & Gorelick, 2012;Blankers, Gray, & Matthias Hennig, 2017;Hebets et al, 2016;Moore, 1997;Pitchers et al, 2013), relatively little is known about the integration of characteristics across the signals in the repertoire (Wilkins, Shizuka, Joseph, Hubbard, & Safran, 2015).…”

Experimental evidence for the role of sexual selection in the evolution of cuticular hydrocarbons in the dung beetle, Onthophagus taurus

“…This previous study did not find evidence of female choice acting on PC1, indicating that female choice may not have played a significant role in the evolution of male PC1 scores found here. Cuticular hydrocarbons are associated with male dominance in some insects (Roux, Sreng, Provost, Roux, & Clement, ; Thomas & Simmons, ), and importantly, the form of sexual selection imposed on CHCs can differ for female mate choice versus male contest competition (Lane, Dickinson, Tregenza, & House, ). Mating success and fighting success appear to be uncorrelated in male O. taurus (McCullough & Simmons, ), and consequently, any selection on CHCs imposed by male contest competition could differ to that imposed by female mate choice.…”