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Pupal period and adult size in Drosophila melanogaster : a cautionary tale of contrasting correlations between two sexually dimorphic traits
Author(s) -
NUNNEY L.
Publication year - 2007
Publication title -
journal of evolutionary biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.289
H-Index - 128
eISSN - 1420-9101
pISSN - 1010-061X
DOI - 10.1111/j.1420-9101.2006.01214.x
Subject(s) - biology , sexual dimorphism , pupa , drosophila melanogaster , trait , drosophila (subgenus) , genetic correlation , evolutionary biology , period (music) , sexual selection , zoology , genetic variation , genetics , larva , ecology , gene , physics , computer science , acoustics , programming language
Sexual dimorphism (SD) is widespread, reflecting a resolution of genetic conflicts arising from sex‐specific differences in selection. However, genetic correlations among traits may constrain the evolution of SD. Drosophila melanogaster exhibits SD for pupal period (males longer) and adult weight (females heavier). This negative inter‐sex covariance between the traits contrasts with a significant intra‐sex positive genetic correlation ( r g = 0.95) estimated using lines selected for fast larval development. Path analysis indicated that within sexes the selection regime indirectly reduced adult weight which in turn reduced pupal period. A hypothesis is proposed for the evolution of SD whereby the trait ‘pupal period’ is divided into ‘intrinsic’ (correlated with body size) and ‘ecological’ (uncorrelated with body size) components, and (the larger) females eclose earlier than males size via a shortening of the ecological component, thus achieving the advantage of provisioning eggs prior to sexual maturity. This hypothesis avoids invoking successful ‘incompatible antagonistic selection’.