Similar but different: Revealing the relative roles of species‐traits versus biome properties structuring genetic variation in South American marsh rats

Aim: Wetland habitats, and the ecological restrictions imposed by them,
structure patterns of genetic variation in constituent taxa. As
such, genetic variation may reflect properties of the specific
biomes species inhabit, or shared life history traits among
species may result in similar genetic structure. We evaluated these
hypotheses jointly by quantifying the similarity of genetic
structure in three South American marsh rat species (Holochilus),
and test how genetic variation in each species relates to
biome‐specific environmental space and historical stability. Location:
South America. Taxon: Rodentia. Methods: Using complementary analyses
(Mantel tests, dbRDA, Procrustes, covariance structure of allele
frequencies and environmental niche models [ENMs])
with 8,000–32,000 SNPs per species, we quantified the association
between genomic variation and geographic and/or environmental
differences. Results: Significant association between genetic variation
and geography was identified for all species. Similarity in the
strength of the association suggests connectivity patterns
dictated by shared species‐traits predominate at the biome scale.
However, substantial amounts of genetic variation are not
explained by geography. Focusing on this portion of the variance,
we demonstrate a significant quantitative association between
genetic variation and the environmental space of a biome, and a
qualitative association with varying regional stability.
Specifically, historically stable areas estimated from ecological
niche models are correlated with local levels of
geographic structuring, suggesting that local biome‐specific
histories affect population isolation/ connectivity.