Parallel divergent adaptation along replicated altitudinal gradients in Alpine trout

Area of Science:

• Evolutionary biology
• Population genetics
• Ecology

Background:

• European trout (Salmo trutta species complex) inhabit diverse European river systems, from lowlands to alpine streams.
• Distinct evolutionary lineages exist within major river systems, with some genetic diversity persisting despite human-mediated translocations.
• Investigating adaptive divergence is crucial for understanding trout resilience and adaptation.

Purpose of the Study:

• To investigate adaptive genetic divergence among European trout populations across major drainages.
• To assess adaptive divergence along altitudinal gradients within rivers.
• To explore the interplay of divergent selection and gene flow in trout adaptation.

Main Methods:

• Employed Amplified Fragment Length Polymorphism (AFLP)-based genome scans.
• Analyzed genetic markers to detect signatures of divergent selection.
• Compared genetic divergence patterns between drainages and along altitudinal transects.

Main Results:

• Divergent selection was stronger between major drainages compared to within-drainage altitudinal transects.
• Evidence of parallel adaptive changes was observed at approximately 2% of markers along altitudinal gradients.
• Altitudinal divergence suggests altitude is a significant factor in local adaptation.

Conclusions:

• Adaptive genetic divergence is prevalent in European trout, both between and within river systems.
• Alpine trout serve as a valuable model for studying adaptation to climate gradients.
• Further research can elucidate the roles of divergent selection and gene flow in adaptation.