Inferring the Past and Present Connectivity Across the Range of a North American Leaf Beetle: Combining Ecological Niche Modeling and a Geographically Explicit Model of Coalescence

Abstract

The leaf beetle Chrysomela aeneicollis occurs across Western North America, either at high elevation or in small, isolated populations along the coast, and thus has a highly fragmented distribution. DNA sequence data (three loci) were collected from five regions across the species range. Population connectivity was examined using traditional ecological niche modeling, which suggested that gene flow could occur among regions now and in the past. We developed geographically explicit coalescence models of sequence evolution that incorporated a two-dimensional representation of the hypothesized ranges suggested by the niche-modeling estimates. We simulated sequence data according to these models and compared them to observed sequences to identify most probable scenarios regarding the migration history of C. aeneicollis. Our results disagreed with initial niche-modeling estimates by clearly rejecting recent connectivity among regions, and were instead most consistent with a long period of range fragmentation, extending well beyond the last glacial maximum. This application of geographically explicit models of coalescence has highlighted some limitations of the use of climatic variables for predicting the present and past range of a species and has explained aspects of the Pleistocene evolutionary history of a cold-adapted organism in Western North America. K E Y W O R D S :Chrysomela aeneicollis, coalescent simulations, leaf beetle, phylogeography, PHYLOGEOSIM, range fragmentation.

Ecological niche modelling and coalescent simulations to explore the recent geographical range history of five widespread bumblebee species in Europe

“…A similar observation has been observed in Dellicour et al . (), highlighting the limitations of the ENM approach for estimating current and past species ranges. From a practical point of view, a main issue in ENM based range estimates is the availability of past environmental data.…”

“…In bumblebees, it has been suggested that determining habitat suitability, which is analogous to the ENM approach, can be used as a baseline approach for understanding species-specific responses to climate change (Herrera et al, 2014;Lecocq et al, 2015a;Rasmont et al, 2015). Coalescence-based genetic models have been combined with ENM in numerous studies (Carstens & Richards, 2007;Shepard & Burbrink, 2008Solomon et al, 2008;Bagley et al, 2013;Dellicour et al, 2014a). More recently, there have been studies (e.g.…”

Contrasting genetic patterns between two coexisting Eleutherococcus species in northern China

“…Hence, it is hard to find cryptic refugia as well as microhabitats differences between codistributed species (Dellicour et al. , ). Although habitats of the two Eleutherococcus species overlap at a regional scale, the small‐scale niche differences (e.g., altitude) are ignored by the current simulations due to the low resolution of ancient climate data.…”

Comparative phylogeography of five bumblebees: impact of range fragmentation, range size and diet specialization

“…This pattern is indeed often observed in insects (e.g. Dellicour et al ., ; Quinzin & Mardulyn, ) and other animals (Zink & Barrowclough, ; Peters, Bolender & Pearce, ), probably due to the smaller effective population size associated with the mitochondrial genome (stronger genetic drift) and to a history of recurrent adaptive selection (Bazin, Glémin & Galtier, ).…”