Condition dependence of phenotypic integration and the evolvability of genitalic traits in a neriid fly

Abstract

The spectacular diversity of insect male genitalia, and their relative insensitivity to the environment, have long puzzled evolutionary biologists and taxonomists. We asked whether the unusual evolvability of male genitalia could be associated with low morphological integration of genitalic traits, by comparison with male somatic traits and female traits. We also asked whether this pattern was robust to variation in resource availability during development, which affects adult condition. To address these questions, we manipulated larval diet quality in a split-brood design and compared levels of integration of male and female genitalic and somatic traits in the neriid fly, Telostylinus angusticollis . We found that male genitalic traits were substantially less integrated than male somatic traits, and less integrated than female genitalic traits. Female genitalic traits were also less integrated than female somatic traits, but the difference was less pronounced than in males. However, integration of male genitalic traits was negatively condition-dependent, with high-condition males exhibiting lower trait integration than low-condition males. Finally, genitalic traits exhibited lower larval diet × family interactions than somatic traits. These results could help explain the unusually high evolvability of male genitalic traits in insects.

Morphological canalization, integration, and plasticity in response to population density inAbutilon theophrasti: Influences of soil conditions and growth stages

“…Despite much recent progress on this topic (Pigliucci & Preston, 2004; Schlosser & Wagner, 2004), most empirical studies have only studied patterns of phenotypic integration in a single environment (Pigliucci & Preston, 2004); but see (Liu et al., 2007; Pigliucci et al., 1995). In this study, we found an increase in coefficient of integration (CI) with density at 50 days, consistent with some studies (Gianoli, 2004; Schlichting, 1986; Wylde & Bonduriansky, 2020), suggesting the strength of phenotypic integration can increase with environmental stresses (García‐Verdugo et al., 2009; Gianoli, 2004; Schlichting, 1989a,b; Waitt & Levin, 1993). The increase in the number and strength of correlations among functionally correlated traits (phenotypic integration) is related to the extent of environmental stress (Gianoli, 2004; Schlichting, 1986) and endow plants the ability to effectively respond to such stress (Chapin III, 1991).…”

A comparison of two methods for estimating measurement repeatability in morphometric studies

“…We utilized a morphometric dataset on the neriid fly Telostylinus angusticollis that included 22 somatic and genitalic traits measured on individuals reared on nutrient-rich and nutrient-poor larval diets (Wylde & Bonduriansky, 2020). Eggs collected from stock flies were reared using a larval diet that is intermediate in nutrient concentration between the rich and poor diets, based on Sentinella et al (2013).…”

Morphological canalization, integration and plasticity in response to population density in Abutilon theophrasti: influences of soil conditions and growth stages

“…Despite much recent progress on this topic (Pigliucci & Preston, 2004;Schlosser & Wagner, 2004), most empirical studies have only studied patterns of phenotypic integration in a single environment (Pigliucci & Preston, 2004; but see Liu et al, 2007;Pigliucci et al , 1995). In this study, we found an increase in coefficient of integration (CI) with density at 50 d (Gianoli, 2004;Schlichting, 1986;Wylde & Bonduriansky, 2020), and decrease in the number of correlations (NC) with density at 70 d (Badyaev et al , 2005;Mallitt et al , 2010;Pigliucci & Kolodynska, 2002). The stage-dependence responses in CI suggested the strength of response of integration to density decreased over time.…”