Panmixia across elevation in thermally sensitive Andean dung beetles. Issue 9 (12th April 2020)

• Record Type: Journal Article
• Authors: Linck, Ethan B.; Celi, Jorge E.; Sheldon, Kimberly S.
• Is Part Of: Ecology and evolution. Volume 10:Issue 9(2020)
• Page Start: 4143
• Page End: 4155
• Publication Date: 2020-04-12
• Subjects: climatic variability hypothesis -- Ecuador -- isolation by environment -- mountain passes -- Scarabaeinae -- tropics; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.6185
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Janzen's seasonality hypothesis predicts that organisms inhabiting environments with limited climatic variability will evolve a reduced thermal tolerance breadth compared with organisms experiencing greater climatic variability. In turn, narrow tolerance breadth may select against dispersal across strong temperature gradients, such as those found across elevation. This can result in narrow elevational ranges and generate a pattern of isolation by environment or neutral genetic differentiation correlated with environmental variables that are independent of geographic distance. We tested for signatures of isolation by environment across elevation using genome‐wide SNP data from five species of Andean dung beetles (subfamily Scarabaeinae) with well‐characterized, narrow thermal physiologies, and narrow elevational distributions. Contrary to our expectations, we found no evidence of population genetic structure associated with elevation and little signal of isolation by environment. Further, elevational ranges for four of five species appear to be at equilibrium and show no decay of genetic diversity at range limits. Taken together, these results suggest physiological constraints on dispersal may primarily operate outside of a stable realized niche and point to a lower bound on the spatial scale of local adaptation. Abstract : We use genomic data to ask whether dispersal is reduced across elevation relative to within elevation in five species of Andean dung beetle. Contrary to a downstream prediction of Daniel Janzen's "mountain passes" hypothesis, we find high gene flow across the elevational ranges of all species.