Thermal adaptation and acclimation of ectotherms from differing aquatic climates

Area of Science:

• Ecology
• Evolutionary Biology
• Genetics

Background:

• Ectothermic aquatic organisms face thermal stress, necessitating adaptation and acclimation mechanisms.
• Understanding these mechanisms is crucial for predicting species' responses to climate change.

Purpose of the Study:

• To investigate thermal adaptation in redband trout (Oncorhynchus mykiss gairdneri) from contrasting desert and montane populations.
• To elucidate the heat shock response and identify genetic markers associated with thermal stress survival.

Main Methods:

• Common-garden experiment with controlled thermal stress.
• Analysis of heat shock gene expression and heat shock protein (Hsp) production.
• Genomewide association study using over 10,000 SNPs.

Main Results:

• Desert trout exhibited a lower heat shock response compared to montane trout, suggesting evolved adaptive mechanisms.
• Montane trout showed higher Hsp induction, improving short-term survival but incurring physiological costs.
• Multiple SNPs, including Hsp47, were significantly associated with survival under thermal stress, with Hsp47 being a strong candidate for desert adaptation.

Conclusions:

• Redband trout populations display distinct adaptive strategies for thermal stress.
• Desert populations may possess alternative, cost-effective mechanisms for thermal tolerance.
• Identified SNPs can aid in predicting species' adaptive potential under climate change scenarios.