Genetic consequences of interglacial isolation in a steppe bird

Area of Science:

• Evolutionary Biology
• Quaternary Paleoclimatology
• Population Genetics

Background:

• Pleistocene glacial cycles influenced species' historical evolution and distribution.
• Steppe-associated taxa may exhibit different evolutionary patterns compared to temperate species.
• The little bustard (Tetrax tetrax) is a Palaearctic steppe bird potentially impacted by these cycles.

Purpose of the Study:

• To evaluate the evolutionary patterns of steppe vegetation-associated taxa during Pleistocene climate changes.
• To assess the genetic diversity and population structure of the little bustard (Tetrax tetrax) in response to glacial cycles.
• To test the hypothesis of isolation during interglacials and expansion during glacials in a steppe bird.

Main Methods:

• Molecular genetic data analysis.
• Mismatch distribution analyses to infer population expansion events.
• Coalescent-based methods to model historical population dynamics.

Main Results:

• Extremely low genetic diversity and differentiation observed among eight little bustard populations in Spain and France.
• Evidence of population expansions during cooling periods before and after the last interglacial period.
• Glacial expansions led to significant admixture in Western Europe, linked to interglacial refugia.

Conclusions:

• The little bustard's genetic patterns align with a model of Pleistocene cycle impacts.
• Low between-population genetic differentiation results from short interglacial isolation and long glacial exchange.
• This study provides insights into the evolutionary consequences of climate change on steppe species.