Sexual selection and population divergence I: The influence of socially flexible cuticular hydrocarbon expression in male field crickets (Teleogryllus oceanicus)

Abstract

Debates about how coevolution of sexual traits and preferences might promote evolutionary diversification have permeated speciation research for over a century. Recent work demonstrates that the expression of such traits can be sensitive to variation in the social environment. Here we examined social flexibility in a sexually selected male traitcuticular hydrocarbon (CHC) profiles -in the field cricket Teleogryllus oceanicus and tested whether population genetic divergence predicts the extent or direction of social flexibility in allopatric populations. We manipulated male crickets' social environments during rearing and then characterised CHC profiles. CHC signatures varied considerably across populations and also in response to the social environment, but our prediction that increased social flexibility would be selected in more recently founded populations exposed to fluctuating

Sexual selection and population divergence II. Divergence in different sexual traits and signal modalities in field crickets (Teleogryllus oceanicus )

“…These are archived on the Dryad Digital Repository (doi:10.5061/dryad.tb552). Detailed methodological descriptions for microsatellite, calling song and CHC analyses are provided in Pascoal et al (2016), so we briefly summarize the procedures below. Detailed methodological descriptions for microsatellite, calling song and CHC analyses are provided in Pascoal et al (2016), so we briefly summarize the procedures below.…”

“…We previously reared crickets in a common garden environment in the lab and recorded the calling songs of between 18 and 21 adult males per population (Bailey and Macleod 2014;Pascoal et al 2016). Stock populations experienced at least two generations of lab rearing, thereby reducing the potential for maternal effects arising from field conditions.…”

“…We previously analyzed the CHC profiles of 768 adult male crickets between the ages of 7 and 10 days posteclosion (Pascoal et al 2016). Frozen crickets were thawed and immersed in 4 mL of HPLC-grade hexane (Fisher Scientific) for 5 minutes.…”

“…Wing (n = 755) and CHC (n = 768) traits were quantified from the same individuals in the previously described experiment, which examined social environment effects, while calling song traits were quantified from a different set of individuals (n = 137) (Pascoal et al 2016). Wing (n = 755) and CHC (n = 768) traits were quantified from the same individuals in the previously described experiment, which examined social environment effects, while calling song traits were quantified from a different set of individuals (n = 137) (Pascoal et al 2016).…”

“…Wing (n = 755) and CHC (n = 768) traits were quantified from the same individuals in the previously described experiment, which examined social environment effects, while calling song traits were quantified from a different set of individuals (n = 137) (Pascoal et al 2016). The five CHC traits comprised the first five PCs based on the same extraction implemented in Pascoal et al (2016), which cumulatively explained 71.9% of variation in CHC profiles (PC1 = 38.4%, PC2 = 16.5%, PC3 = 7.3%, PC4 = 5.1%, PC5 = 4.6%). We chose these traits because they were found to be the main targets of selection in a multivariate selection analysis of calling song in the closely related sister species T. commodus (Brooks et al 2005).…”