Selection signatures along environmental gradients during a damselfly range expansion

Description

Insect distributions are shifting rapidly in response to climate change and are undergoing rapid evolutionary change. We investigate the molecular signatures underlying local adaptation in the damselfly, Ischnura elegans, which is undergoing rapid range-expansion in Europe. I. elegans is an emerging model species for examining eco-evolutionary processes in nature. Using a landscape genomic approach combined with generalised dissimilarity modelling (GDM), we detect selection signatures on loci via allelic frequency change along environmental gradients. We analyse >13 000 Single Nucleotide Polymorphisms (SNPs), derived from Restriction-site Associated DNA sequencing (RADseq), in 426 individuals from 25 sites spanning the I. elegans distribution in Sweden, including its expanding northern range edge. Environmental association analysis (EAA) and the magnitude of allele frequency change along the range expansion gradient revealed significant signatures of selection in relation to high maximum summer temperature, high mean annual precipitation, and low wind speeds at the range edge. SNP annotations with significant signatures of selection revealed gene functions associated with ongoing range expansion, including heat shock proteins, ion transport and visual processes, which have implications for the thermal stress response, salinity tolerance and mate discrimination, respectively. We also identified environmental thresholds where climate-mediated selection is likely to be strong, and indicate that I. elegans is rapidly adapting to the climatic environment during its current and ongoing range expansion. Our findings empirically validate an integrative approach for detecting spatially explicit signatures of local adaptation along environmental gradients during range expansion. 

Period	18 Aug 2018 → 22 Aug 2018
Event title	European Society for Evolutionary Biology (ESEB): II Joint Congress on Evolutionary Biology
Event type	Conference
Location	Montpellier, FranceShow on map
Degree of Recognition	International