Contrasting adaptive genetic consequences of stream insects under changing climate

Area of Science:

• Ecology and Evolutionary Biology
• Climate Change Impact Assessment
• Freshwater Biodiversity

Background:

• Climate change is degrading freshwater biodiversity, with impacts on neutral genetic diversity well-studied.
• The role of adaptive genetic evolution, including evolutionary rescue, in population responses to climate change remains largely overlooked.
• Understanding these adaptive processes is crucial for predicting species' long-term survival in changing environments.

Purpose of the Study:

• To develop and apply a modeling approach to project both adaptive and neutral genetic diversity of stream insects under climate change.
• To investigate the potential for evolutionary rescue in response to projected hydrological and thermal shifts.
• To assess species-specific differences in adaptive genetic responses and their implications for watershed genetic diversity.

Main Methods:

• Utilized empirical neutral and putative adaptive genetic loci data for four stream insect species.
• Employed ecological niche models (ENMs) integrated with a distributed hydrological-thermal simulation model.
• Projected hydraulic and thermal variables under various climate change scenarios (GCMs and RCPs) for near and far future periods.

Main Results:

• Projected increases in annual water temperature across future periods.
• Ephemera japonica showed potential for evolutionary rescue, retaining adaptive genetic diversity despite habitat shifts.
• Hydropsyche albicephala experienced significant habitat decline and reduced watershed genetic diversity; other species showed homogenized genetic structures and decreased gamma diversity.

Conclusions:

• Evolutionary rescue potential varies significantly among species, contingent on their capacity for local adaptation.
• Climate change impacts on freshwater insect genetic diversity are species-specific, with potential for both resilience and decline.
• The study highlights the importance of considering adaptive evolution in conservation strategies for freshwater ecosystems.