Data from: Molecular phenotyping of maternally mediated parallel adaptive divergence within Rana arvalis and Rana temporaria

When similar selection acts on the same traits in multiple species or
populations, parallel evolution can result in similar phenotypic changes,
yet the underlying molecular architecture of parallel phenotypic
divergence can be variable. Maternal effects can influence evolution at
ecological timescales and facilitate local adaptation, but their
contribution to parallel adaptive divergence is unclear. In this study, we
(i) tested for variation in embryonic acid tolerance in a common garden
experiment and (ii) used molecular phenotyping of egg coats to investigate
the molecular basis of maternally mediated parallel adaptive divergence in
two amphibian species (Rana arvalis and Rana temporaria). Our results on
three R. arvalis and two R. temporaria populations show that adaptive
divergence in embryonic acid tolerance is mediated via maternally derived
egg coats in both species. We find extensive polymorphism in egg jelly
coat glycoproteins within both species and that acid-tolerant clutches
have more negatively charged egg jelly – indicating that the glycosylation
status of the jelly coat proteins is under divergent selection in
acidified environments, likely due to its impact on jelly water balance.
Overall, these data provide evidence for parallel mechanisms of adaptive
divergence in two species. Our study highlights the importance of studying
intraspecific molecular variation in egg coats and, specifically, their
glycoproteins, to increase understanding of underlying forces maintaining
variation in jelly coats.