Climatic niche evolution is faster in sympatric than allopatric lineages of the butterfly genusPyrgus

Abstract

Understanding how speciation relates to ecological divergence has long fascinated biologists. It is assumed that ecological divergence is essential to sympatric speciation, as a mechanism to avoid competition and eventually lead to reproductive isolation, while divergence in allopatry is not necessarily associated with niche differentiation. The impact of the spatial context of divergence on the evolutionary rates of abiotic dimensions of the ecological niche has rarely been explored for an entire clade. Here, we compare the magnitude of climatic niche shifts between sympatric versus allopatric divergence of lineages in butterflies. By combining next-generation sequencing, parametric biogeography and ecological niche analyses applied to a genus-wide phylogeny of Palaearctic Pyrgus butterflies, we compare evolutionary rates along eight climatic dimensions across sister lineages that diverged in large-scale sympatry versus allopatry. In order to examine the possible effects of the spatial scale at which sympatry is defined, we considered three sets of biogeographic assignments, ranging from narrow to broad definition. Our findings suggest higher rates of niche evolution along all climatic dimensions for sister lineages that diverge in sympatry, when using a narrow delineation of biogeographic areas. This result contrasts with significantly lower rates of climatic niche evolution found in cases of allopatric speciation, despite the biogeographic regions defined here being characterized by significantly different climates. Higher rates in allopatry are retrieved when biogeographic areas are too widely defined-in such a case allopatric events may be recorded as sympatric. Our results reveal the macro-evolutionary significance of abiotic niche differentiation involved in speciation processes within biogeographic regions, and illustrate the importance of the spatial scale chosen to define areas when applying parametric biogeographic analyses.

Geography of speciation affects rate of trait divergence in haemulid fishes

“…Our results partially agree with those of Pitteloud et al [85] in Pyrgus butterflies in which they found higher rates of niche evolution along climatic dimensions for sister lineages that diverge in sympatry. Haemulids are an ecologically diverse group of reef and shore fishes in the tropical Western Atlantic and the Eastern Pacific.…”

Phylogeography of a widespread lizard complex reflects patterns of both geographic and ecological isolation

“…Recent studies highlighting the strength and ubiquity of isolation by environment (Sexton et al, ; Wang & Bradburd, ) have typically focused on finer scales, mostly at the level of recent population differentiation. Although some studies have demonstrated relatively high lability in environmental niche traits between closely related species (Peterson et al, ; Warren et al, ), few have demonstrated environmental niche divergence as a major factor promoting broader phylogeographic divergence or speciation (but see Cooney, Seddon, & Tobias, ; Pitteloud et al, ). Here, we find evidence for lineage diversification related to both geographic isolation and environmental niche evolution in an abundant and widespread lizard group that otherwise exhibits fairly strong niche and morphological conservatism.…”

Testing Host-Plant Driven Speciation in Phytophagous Insects: A Phylogenetic Perspective

“…Geography and ecology are always closely intertwined in speciation scenarios. There have been several studies that have investigated geographic range expansion in herbivorous insects (Becerra, Venable 1999;Slove, Janz 2011); climate induced host shifts (see Winkler, Mitter, Scheffer 2009;Nyman et al 2012 for reviews and recent studies since then Sanchez-Guillen et al 2016;Lisa De-Silva et al 2017;Owen et al 2017;Pitteloud et al 2017;Sahoo et al 2017) and climate driven diversification dynamics (Kergoat et al 2018, Letsch et al 2018.…”