Spatially varying selection shapes life history clines among populations of Drosophila melanogaster from sub‐Saharan Africa

Abstract

Clines in life history traits, presumably driven by spatially varying selection, are widespread. Major latitudinal clines have been observed, for example, in Drosophila melanogaster, an ancestrally tropical insect from Africa that has colonized temperate habitats on multiple continents. Yet, how geographic factors other than latitude, such as altitude or longitude, affect life history in this species remains poorly understood. Moreover, most previous work has been performed on derived European, American and Australian populations, but whether life history also varies predictably with geography in the ancestral Afro-tropical range has not been investigated systematically. Here, we have examined life history variation among populations of D. melanogaster from sub-Saharan Africa. Viability and reproductive diapause did not vary with geography, but body size increased with altitude, latitude and longitude. Early fecundity covaried positively with altitude and latitude, whereas lifespan showed the opposite trend. Examination of genetic variance-covariance matrices revealed geographic differentiation also in trade-off structure, and QST-FST analysis showed that life history differentiation among populations is likely shaped by selection. Together, our results suggest that geographic and/or climatic factors drive adaptive phenotypic differentiation among ancestral African populations and confirm the widely held notion that latitude and altitude represent parallel gradients.

Mid-day siesta in natural populations of D. melanogaster from Africa exhibits an altitudinal cline and is regulated by splicing of a thermosensitive intron in the period clock gene

“…The majority of the findings presented in this report are based on flies from Cameroon and Kenya because for both countries numerous independent lines from relatively low (range is 78-561 m; herein referred to as low altitude group) and high (range is 2169-2506 m; herein referred to as high altitude group) altitudes were available—prior studies have used even less extreme altitude ranges then used here for defining low and high altitude groups for D. melanogaster from sub-Saharan Africa; e.g., [31]. In addition, flies from Cameroon (west cost) and Kenya (east coast) differ significantly in longitude, and evidence based on genetic structure suggests that the ancestral range of D. melanogaster was eastern Africa followed by a more recent expansion west, indicating that flies from the west and east have significantly different life-histories [23, 24].…”

Life history evolution and cellular mechanisms associated with increased size in high‐altitude Drosophila

“…2014; Fabian et al. 2015). Highland Ethiopian D. melanogaster constitutes a clear example of the dramatic phenotypes that can arise at high altitude, exhibiting unique features relative to known diversity in D. melanogaster (David and Capy 1988), including the largest naturally occurring body and wing size phenotypes described for this species.…”

A clinal polymorphism in the insulin signaling transcription factorfoxocontributes to life‐history adaptation inDrosophila*

“…For some traits, clinal patterns have been observed in a parallel fashion on multiple continents, but there can also be major differences among continents (e.g., see discussion in Fabian et al. ); for example, contrasting predictions have been made for viability (van ‘t Land et al. ), starvation resistance (Karan et al.…”