10.5061/DRYAD.5QFTTDZ1H
Popovic, Iva
0000-0001-6582-4236
University of Queensland
Riginos, Cynthia
0000-0002-5485-4197
University of Queensland
Comparative genomics reveals divergent thermal selection in warm- and
cold-tolerant marine mussels
Dryad
dataset
2019
2019-12-17T00:00:00Z
2019-12-17T00:00:00Z
en
161670221 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Investigating the history of natural selection among closely related
species can elucidate how genomes diverge in response to disparate
environmental pressures. Molecular evolutionary approaches can be
integrated with knowledge of gene functions to examine how evolutionary
divergence may affect ecologically-relevant traits such as temperature
tolerance and species distribution limits. Here, we integrate
transcriptome-wide analyses of molecular evolution with knowledge from
physiological studies to develop hypotheses regarding the functional
classes of genes under positive selection in one of the world’s most
widespread invasive species, the warm-tolerant marine mussel Mytilus
galloprovincialis. Based on existing physiological information, we test
the hypothesis that genomic functions previously linked to divergent
temperature adaptation at the whole-organism level show accelerated
molecular divergence between warm-adapted M. galloprovincialis and
cold-adapted congeners. Combined results from codon model tests and
analyses of polymorphism and divergence reveal that divergent selection
has affected genomic functions previously associated with species-specific
expression responses to heat stress, namely oxidative stress defense and
cytoskeletal stabilisation. Examining specific loci implicated in thermal
tolerance among Mytilus species (based on interspecific biochemical or
expression patterns), we find close functional similarities between known
thermotolerance candidate genes under positive selection and positively
selected loci under predicted genomic functions (those associated with
divergent expression responses). Taken together, our findings suggest a
contribution of temperature-dependent selection in the molecular
divergence between warm- and cold-adapted Mytilus species that is largely
consistent with results from physiological studies. More broadly, this
study provides an example of how independent experimental evidence from
ecophysiological investigations can inform evolutionary hypotheses about
molecular adaptation in closely related non-model species.