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Nunatak colonization by flightless beetles

Jiang, Luke1; Kavanaugh, David2; Kavanaugh, Jeffrey3; Schoville, Sean1

Research facility: Juneau Icefield Research Program
Published Jul 14, 2026 on Dryad. https://doi.org/10.5061/dryad.5hqbzkhmn

Data files

Abstract

The process of recolonizing alpine habitats following ice retreat remains poorly understood. We examined the dispersal of a flightless ground beetle, Nebria lituyae, into and between nunatak habitats of the Juneau Icefield using genetic data. Eleven populations were sampled, for a total of 161 individuals. We measured genetic diversity at a mitochondrial gene (COI) and in the nuclear genome using genotype-by-sequencing (GBS) to identify 2931 single nucleotide variants (SNPs). We measured genomic diversity and performed analyses to determine population structure and the pattern of evolutionary divergence. We infer that most nunatak populations were colonized by a single external population, given their genetic similarity and relative divergence; genetic diversity was generally preserved in nuclear genomes, with a stronger reduction in mitochondrial diversity. However, two nunatak sites have many unique alleles, suggesting independent colonization from distinct sources.  We find evidence of very recent migration to one of these nunatak populations, suggesting a dynamic process of movement through time.