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

Abstract

Understanding the physiological and genetic basis of growth and body size variation has wide‐ranging implications, from cancer and metabolic disease to the genetics of complex traits. We examined the evolution of body and wing size in high‐altitude Drosophila melanogaster from Ethiopia, flies with larger size than any previously known population. Specifically, we sought to identify life history characteristics and cellular mechanisms that may have facilitated size evolution. We found that the large‐bodied Ethiopian flies laid significantly fewer but larger eggs relative to lowland, smaller‐bodied Zambian flies. The highland flies were found to achieve larger size in a similar developmental period, potentially aided by a reproductive strategy favoring greater provisioning of fewer offspring. At the cellular level, cell proliferation was a strong contributor to wing size evolution, but both thorax and wing size increases involved important changes in cell size. Nuclear size measurements were consistent with elevated somatic ploidy as an important mechanism of body size evolution. We discuss the significance of these results for the genetic basis of evolutionary changes in body and wing size in Ethiopian D. melanogaster.

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

“…Although not as well-studied as latitudinal clines, numerous phenotypic traits in animals, including Drosophila, exhibit altitudinal clines [26]. In this study we measured the wake-sleep patterns of D. melanogaster derived from natural populations captured at different altitudes from tropical regions of sub-Saharan Africa [23, 24, 27–29] (Additional file 1: Table S1). Over a wide range of temperatures D. melanogaster from high altitudes show a less robust mid-day siesta that is characterized by more fragmented sleep.…”

Evolution of ovipositor length inDrosophila suzukiiis driven by enhanced cell size expansion and anisotropic tissue reorganization

“…Hence, the more pronounced apical expansion of cells is not a general feature of D. suzukii development, but rather seems to be specific to its ovipositor. It has been suggested that a common mechanism for cell size expansion is polyploidy (29), which can be measured using nuclear size (30). However, in both species, we find no increase in nuclear area from 48 to 54 h APF (Fig.…”

Genetic and environmental canalization are not associated among altitudinally varying populations ofDrosophila melanogaster

“…Thus what has been lacking for studies testing evolutionary models of canalization is a model system with the relevant natural history that can be studied in a multivariate perspective. Lack et al (2016a), among other recent studies, demonstrated that populations of Drosophila melanogaster from sub-Saharan Africa recently adapted to a high-altitude environment via increased body size and wing morphology, among other traits (Pitchers et al, 2013; Lack et al, 2016a,b; Bastide et al, 2016; Fabian et al, 2015; Klepsatel et al, 2014). Intriguingly, the high-altitude population show a substantial increase in the frequency of qualitative mutational defects of wing morphology (Lack et al, 2016a).…”

“…Drosophila melanogaster strains used in the current study represent a subset of those from Lack et al (2016a,b). The high-altitude inbred strains were derived from flies collected in Fiche, Ethiopia at an altitude of 3070 m in December 2011.…”