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Title: Temperature gradient affects differentiation of gene expression and SNP allele frequencies in the dominant Lake Baikal zooplankton species
Abstract

Local adaptation and phenotypic plasticity are main mechanisms of organisms’ resilience in changing environments. Both are affected by gene flow and are expected to be weak in zooplankton populations inhabiting large continuous water bodies and strongly affected by currents. Lake Baikal, the deepest and one of the coldest lakes on Earth, experienced epilimnion temperature increase during the last 100 years, exposing Baikal's zooplankton to novel selective pressures. We obtained a partial transcriptome ofEpischura baikalensis(Copepoda: Calanoida), the dominant component of Baikal's zooplankton, and estimatedSNPallele frequencies and transcript abundances in samples from regions of Baikal that differ in multiyear average surface temperatures. The strongest signal in bothSNPand transcript abundance differentiation is theSWNEgradient along the 600+ km long axis of the lake, suggesting isolation by distance.SNPdifferentiation is stronger for nonsynonymous than synonymousSNPs and is paralleled by differential survival during a laboratory exposure to increased temperature, indicating directional selection operating on the temperature gradient. Transcript abundance, generally collinear with theSNPdifferentiation, shows samples from the warmest, less deep location clustering together with the southernmost samples. Differential expression is more frequent among transcripts orthologous to candidate thermal response genes previously identified in model arthropods, including genes encoding cytoskeleton proteins, heat‐shock proteins, proteases, enzymes of central energy metabolism, lipid and antioxidant pathways. We conclude that the pivotal endemic zooplankton species in Lake Baikal exists under temperature‐mediated selection and possesses both genetic variation and plasticity to respond to novel temperature‐related environmental pressures.

 
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NSF-PAR ID:
10081525
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Molecular Ecology
Volume:
27
Issue:
11
ISSN:
0962-1083
Page Range / eLocation ID:
p. 2544-2559
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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