Abstract
Selection for secondary sexual trait (SST) elaboration may increase intralocus sexual conflict over the optimal values of traits expressed from shared genomes. This conflict can reduce female fitness, and the resulting gender load can be exacerbated by environmental stress, with consequences for a population's ability to adapt to novel environments. However, how the evolution of SSTs interacts with environment in determining female fitness is not well understood. Here, we investigated this question using replicate lines of bulb mites selected for increased or decreased prevalence of a male SST—thickened legs used as weapons. The fitness of females from these lines was measured at a temperature to which the mites were adapted (24°C), as well as at two novel temperatures: 18°C and 28°C. We found the prevalence of the SST interacted with temperature in determining female fecundity. At 28°C, females from populations with high SST prevalence were less fecund than females from populations in which the SST was rare, but the reverse was true at 18°C. Thus, a novel environment does not universally depress female fitness more in populations with a high degree of sexually selected dimorphism. We discuss possible consequences of the interaction we detected for adaptation to novel environments.
Highlights
Sexual selection arises through competition for mates and leads to the evolution of costly traits that facilitate this competition, such as weapons, aggressive behaviors, sexual ornaments, and displays to attract the opposite sex (Anderson 1994)
We found that selection direction and temperature interacted significantly in their effect on female fecundity: females from the S-lines were more fecund than females from the F-lines at 28°C, but at 18°C the situation was reversed (Table 1; Fig. 1)
Previous work had demonstrated that selection for the secondary sexual trait (SST) in these lines resulted in a correlated decrease in female fitness (Plesnar-Bielak et al 2014), which is consistent with the widespread sexually antagonistic pleiotropy associated with the evolution of SSTs (Cox and Calsbeek 2009; Harano et al 2010)
Summary
Sexual selection arises through competition for mates and leads to the evolution of costly traits that facilitate this competition, such as weapons, aggressive behaviors, sexual ornaments, and displays to attract the opposite sex (Anderson 1994). Intense research on IASC over the past two decades has demonstrated that it is pervasive among taxa and has implications for a wide range of fundamental evolutionary processes including the maintenance of genetic variation (Rice and Chippindale 2001; Connallon and Clark 2012; Rostant et al 2015), speciation (Parker and Partridge 1998; Rice and Chippindale 2002), the evolution of gene expression (Ellegren and Parsch 2007) and of sex chromosomes (Rice 1984; Kraak and Pen 2002; van Doorn and Kirkpatrick 2007), sex allocation (Alonzo and Sinervo 2001), sexual selection (Pischedda and Chippindale 2006; Brommer et al 2007), and aging (Vieira et al 2000; Bonduriansky et al 2008) Given their role in shaping gender load, the evolution of SSTs is likely to affect all of these processes. We investigated how the environment modulates female fitness in lines selected for the presence or absence of an SST in the male-dimorphic bulb mite Rhizoglyphus robini
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
