A morphological trait involved in reproductive isolation between Drosophila sister species is sensitive to temperature

Abstract

Phenotypic plasticity, the capacity for one genotype to generate multiple phenotypes in response to environmental variation, is a pervasive feature of biological systems (Debat & David, 2001;Klingenberg, 2019). The connection between plasticity and speciation is multifaceted (Lafuente & Beldade, 2019). On the one hand, plasticity can be heritable and modified by selection. On the other hand, plasticity can favor adaptation and speciation. As animals colonize novel habitats or face changing climate conditions, the phenotypic traits that are optimal for fitness are usually different from those experienced in the ancestral population. Waddington was among the first to suggest that organisms may solve this challenge by phenotypic plasticity first and later on by genetic fixation of what was previously an environmentally induced phenotypic trait (a process he called "genetic assimilation"; Waddington, 1942). According to several authors, the trait variations enabled by plasticity can initiate and accelerate the pace of adaptive evolution and promote morphological diversification. This central idea is at the basis of the "flexible stem hypothesis"

Temperature and sex shape reproductive barriers in a climate change hotspot

“…Either type can emerge before or after zygote formation, but intrinsic barriers are considered robust to environmental context (per the examples above), whereas extrinsic barriers rely on environmental factors for their maintenance. Temperature, for example, maintains prezygotic barriers between fruit fly species by shaping differences in thermal niche (Matute et al, 2009) or morphological plasticity in genitalia (Peluffo et al, 2021). The distinction between intrinsic and extrinsic barriers can be blurred, however, if strengths of intrinsic barriers vary environmentally.…”