Post-invasion selection acts on standing genetic variation despite a severe founding bottleneck

Area of Science:

• Evolutionary biology
• Genetics
• Ecology

Background:

• Invasive populations often exhibit reduced genetic diversity compared to native ranges.
• Despite bottlenecks, invasive species can adapt rapidly, leading to debate on the role of genetic diversity in adaptation.
• Understanding adaptation post-invasion is crucial for managing biological invasions.

Purpose of the Study:

• To investigate natural selection in the aftermath of a founding event using a 10-year time-series dataset of the invasive Asian honey bee (Apis cerana) in Australia.
• To determine if genetic bottlenecks constrain adaptation in invasive populations.
• To identify the source of genetic variation targeted by selection during early invasion stages.

Main Methods:

• Whole-genome resequencing of Apis cerana samples collected over a 10-year period.
• Analysis of genetic diversity and population expansion following the invasion's founding event.
• Detection of loci under positive selection and investigation of allele origins.

Main Results:

• The Australian Apis cerana population was founded by a single colony, experiencing a severe genetic bottleneck and loss of diversity.
• Despite the bottleneck, signatures of positive selection were detected in the early years post-invasion.
• Selection primarily acted on standing genetic variation introduced by the founders, not on new mutations.

Conclusions:

• Severe founding bottlenecks do not necessarily preclude rapid adaptation in invasive populations.
• Selection on standing genetic variation plays a significant role in the early adaptation of invasive species.
• This study highlights the importance of founder genetic variation for successful biological invasions.