Genomic structural variation rescues a classic biological invader from a population bottleneck

Area of Science:

• Genomics
• Invasion Biology
• Conservation Genetics

Background:

• Invasive species often face population bottlenecks, posing a paradox for their successful spread.
• The brown treesnake (Boiga irregularis) in Guam is an example of an invasive species that survived a severe bottleneck.

Purpose of the Study:

• To investigate the genomic mechanisms enabling invasive species to overcome population bottlenecks.
• To understand how the brown treesnake population in Guam maintained diversity despite extreme bottlenecks.

Main Methods:

• Genome-wide analysis of the brown treesnake population in Guam.
• Identification and characterization of genomic structural variants (SVs) and single-nucleotide variants (SNVs).
• Analysis of SV distribution and enrichment in functional genomic regions.

Main Results:

• The brown treesnake population experienced an extreme bottleneck, with extensive runs of homozygosity.
• Nearly 19,000 structural variants were identified, impacting a larger portion of the genome than SNVs.
• Structural variant density was highest in gene promoters, particularly in genes related to adaptive immunity and olfaction.

Conclusions:

• Genomic structural variants provide substantial genetic diversity, enabling invasive species to adapt and avoid inbreeding depression.
• Rapid evolution of gene-linked diversity through SVs in critical regions can rescue populations.
• Findings have significant implications for understanding invasion dynamics and informing conservation strategies.