Ancient mtDNA diversity reveals specific population development of wild horses in Switzerland after the Last Glacial Maximum.

This research explores the changes in the population of wild horses in Switzerland, from about 41,000 to 5,000 years ago, during an era marked by major environmental changes. Tracing the mitochondrial DNA from archaeological horse remains, the study revealed substantial genetic diversification among horse populations living during and immediately after the Last Glacial Maximum (LGM) and a highly diverse population expansion following the retreat of ice.

Overview

The study is a detailed investigation into regional scale population dynamics, with a focus on wild horses in Switzerland and covering a timespan of approximately 41,000 to 5,000 years ago. This era was marked by significant environmental shifts that influenced the genetic and population trends in wild horses in the region, such as the Last Glacial Maximum (LGM), steppe vegetation, afforestation, and the commencement of human agricultural activities.

Methodology

• The researchers examined 92 archaeological horse remains obtained from nine different sites, primarily surrounding the Swiss Jura Mountains.
• The mitochondrial d-loop, a non-coding region of mitochondrial DNA, was used to study matrilineal population dynamics. The team assembled 240 base pairs of the mitochondrial d-loop for examination.
• The researchers applied FST values for gauging the extent of genetic differentiation in the horse populations during and immediately after the LGM.

Findings

• The results indicate a high level of genetic differentiation amongst the horse populations that existed during the LGM and immediately after.
• Once the glaciers retreated, a genetically diverse population expanded, as indicated by significantly negative results for Tajima’s D, Fu’s FS, and mismatch analyses.
• Interestingly, this population trend differed from the pattern observed in Asia during the same period, where horse populations declined post-LGM.

Significance

• This research provides a comprehensive regional view of wild horse population trends, highlighting distinct patterns of colonisation and genetic diversity between successive populations.
• The study’s findings deviate from the larger Eurasian trend, highlighting the effects of environmental changes at regional scales.
• Understanding these animal population dynamics can provide valuable insights into past environmental changes and their impacts on biodiversity. Such understandings can be leveraged to create informed conservation strategies.