Repeated sampling detects gene flow in a flightless ground beetle in a fragmented landscape

Area of Science:

• Evolutionary Biology
• Population Genetics
• Ecology

Background:

• Secondary clines naturally decrease in steepness over time due to uninterrupted gene flow.
• Temporally repeated sampling of populations within a cline enables the study of gene flow dynamics.

Purpose of the Study:

• To reinvestigate an allozyme gradient in Carabus auronitens populations 15-20 years after initial recording.
• To estimate the amount of ongoing gene flow and its effect on clinal variation.

Main Methods:

• Allozyme variation at the Est-1 locus was analyzed in 977 Carabus auronitens individuals from 29 sites.
• Data collected in 2005-2006 was compared to previous findings from 1985-1994.

Main Results:

• Both historical and recent data sets exhibited clinal variation in Carabus auronitens populations.
• A significant decrease in the steepness of the allozyme cline was observed over the 15-20 year period.
• The estimated average gene flow per generation was 0.6% per population.

Conclusions:

• Ongoing gene flow in the flightless ground beetle Carabus auronitens has resulted in a less pronounced cline.
• Landscape fragmentation remained stable, but migration and gene flow were facilitated by numerous hedgerows.
• Hedgerows are crucial for inter-population migration and potential future range shifts of forest insects.