Long-term evolution of quantitative traits in the Drosophila melanogaster species subgroup

Abstract

Quantitative genetics aims at untangling the genetic and environmental effects on phenotypic variation. Trait heritability, which summarizes the relative importance of genetic effects, is estimated at the intraspecific level, but theory predicts that heritability could influence long-term evolution of quantitative traits. The phylogenetic signal concept bears resemblance to heritability and it has often been called species-level heritability. Under certain conditions, such as trait neutrality or contribution to phylogenesis, within-species heritability and between-species phylogenetic signal should be correlated. Here, we investigate the potential relationship between these two concepts by examining the evolution of multiple morphological traits for which heritability has been estimated in Drosophila melanogaster. Specifically, we analysed 42 morphological traits in both sexes on a phylogeny inferred from 22 nuclear genes for nine species of the melanogaster subgroup. We used Pagel's λ as a measurement of phylogenetic signal because it is the least influenced by the number of analysed taxa. Pigmentation traits showed the strongest concordance with the phylogeny, but no correlation was found between phylogenetic signal and heritability estimates mined from the literature. We obtained data for multiple climatic variables inferred from the geographical distribution of each species. Phylogenetic regression of quantitative traits on climatic variables showed a significantly positive correlation with heritability. Convergent selection, the response to which depends on the trait heritability, may have led to the null association between phylogenetic signal and heritability for morphological traits in Drosophila. We discuss the possible causes of discrepancy between both statistics and caution against their confusion in evolutionary biology.

Spatial variation in avian bill size is associated with temperature extremes in a major radiation of Australian passerines

“…In contrast to the effect of phylogeny on bill size per se , associations between relative bill size and climate extremes showed no phylogenetic signal among closely related species. Given the possible associations between phylogenetic signal (species-level heritability) and short-term heritability, this might suggest that observed climate-related bill size patterns occurred independently within species in response to local conditions, although attempts to demonstrate such links have typically not found that that is a clear association [ 58 ].…”

Character evolution of modern eupolypods supports the assignment of the fossil fern Cretacifilix fungiformis to Dryopteridaceae

“…The lack of phylogenetic signals found for nearly all the examined characters at family and genus ranks in both suborders Aspleniineae and Polypodiineae is arguably caused by several evolutionary processes which include fluctuations in the rate of evolution over time (Pagel, 1999), strong stabilizing selection, regular divergent selection (Revell et al, 2008), adaptive radiations in which close relatives rapidly diversify to fill new niches (Kamilar and Cooper, 2013), or high frequency of homoplasy (Voyta et al, 2022;Yassin et al, 2022). Consistently with a multi-factor hypothesis, a previous study utilizing a smaller dataset of eupolypod II (Sundue and Rothfels, 2014) retrieved moderate to low values of homoplasy for most of the characters studied.…”