Sex‐specific plasticity of growth and maturation size in a spider: implications for sexual size dimorphism

Abstract

Sex‐specific plasticity in body size has been recently proposed to cause intraspecific patterns of variation in sexual size dimorphism (SSD). We reared juvenile male and female Mediterranean tarantulas (Lycosa tarantula) under two feeding regimes and monitored their growth until maturation. Selection gradients calculated across studies show how maturation size is under net stabilizing selection in females and under directional selection in males. This pattern was used to predict that body size should be more canalized in females than in males. As expected, feeding affected male but not female maturation size. The sex‐specific response of maturation size was related to a dramatic divergence between subadult male and female growth pathways. These results demonstrate the existence of sex‐specific canalization and resource allocation to maturation size in this species, which causes variation in SSD depending on developmental conditions consistent with the differential‐plasticity hypothesis explaining Rensch's Rule.

Fecundity and sexual size dimorphism of wolf spiders (Araneae: Lycosidae) along an elevational gradient in the Arctic

“…This is in agreement with the hypothesis that female terrestrial arthropods are more plastic than males in response to environmental variation (reviewed in ) and supports the notion (Foellmer and Moya-Laraño 2007), in general, male-biased SSD appears to arise from sexual selection ) while fecundity selection supports larger females (Prenter et al 1999;. However, SSD and selection for it can also be mediated by sex-specific differences in growth in response to external factors (Uhl et al 2004;Fernández-Montreveta and Moya-Laraño 2007;reviewed in Stillwell et al 2010). show that physiological difference between the sexes in plasticity of growth rate and development time can be ultimately responsible for differences in adult body size.…”

Sexual selection explains sex-specific growth plasticity and positive allometry for sexual size dimorphism in a reef fish

“…Indeed, several studies on polygynous species illustrate that males display more pronounced changes in growth rate and body size in response to food supply compared with females, subsequently driving a pattern of positive allometry for SSD (e.g. Badyaev 2002;Bonduriansky 2007;Fernández-Montraveta & Moya-larañ o 2007). In the present study, however, we illustrate that males (i.e.…”

Sex Differences in Phenotypic Plasticity Affect Variation in Sexual Size Dimorphism in Insects: From Physiology to Evolution

“…Among tests of the adaptive canalization hypothesis, some researchers predict that traits under the strongest directional selection should be most canalized (least plastic) (51), but others (including us) predict that plasticity should be least for traits under the strongest stabilizing selection. These ideas were initially developed to explain variation in canalization among traits within one sex—stabilizing selection should favor canalization, and thus reduced plasticity (compared to the average trait in an organism), of morphological traits (such as genitalia) that must match between males and females (40), since deviation from the average phenotype can have substantial negative fitness consequences (85, 125)—but the argument applies equally to other traits (including body size) and to differences between sexes (57). In contrast, the condition dependence hypothesis predicts that traits under the strongest directional selection will exhibit greater sensitivity to environmental conditions, and thus be the most plastic, relative to other traits (22, 23, 27).…”