Hybridization with mountain hares increases the functional allelic repertoire in brown hares

Abstract

Brown hares (Lepus europaeus Pallas) are able to hybridize with mountain hares (L. timidus Linnaeus) and produce fertile offspring, which results in cross-species gene flow. However, not much is known about the functional significance of this genetic introgression. Using targeted sequencing of candidate loci combined with mtDNA genotyping, we found the ancestral genetic diversity in the Finnish brown hare to be small, likely due to founder effect and range expansion, while gene flow from mountain hares constitutes an important source of functional genetic variability. Some of this variability, such as the alleles of the mountain hare thermogenin (uncoupling protein 1, UCP1), might have adaptive advantage for brown hares, whereas immunity-related MHC alleles are reciprocally exchanged and maintained via balancing selection. Our study offers a rare example where an expanding species can increase its allelic variability through hybridization with a congeneric native species, offering a route to shortcut evolutionary adaptation to the local environmental conditions.

Interspecific introgression of MHC genes in Triturus newts: Evidence from multiple contact zones

“…The evidence for MHC introgression in multiple Triturus hybrid zones provided here adds to a small set of recently published studies indicating that MHC introgression may be a widespread phenomenon. MHC introgression was reported in humans (Abi‐Rached et al, 2011 , MHC‐I), Alpine ibex (Grossen et al, 2014 , MHC‐II), Lacerta lizards (Sagonas et al, 2019 , MHC‐I), Lissotriton newts (Fijarczyk et al, 2018 ; Dudek et al, 2019 , both MHC classes) and hares (Pohjoismäki et al, 2021 , MHC‐II). MHC introgression, with various strengths of supporting evidence, was also suggested for penguins (Hibbets et al, 2020 , MHC‐II), fire‐bellied toads (de Cahsan et al, 2021 , MHC‐II), chickens (Manjula et al, 2021 , MHC region), and trouts (Talarico et al, 2021 , MHC‐II).…”

Ancient DNA of the Don-Hares Assumes the Existence of Two Distinct Mitochondrial Clades in Northeast Asia

“…Recent studies have suggested that hares represent a widespread radiation of species characterized by striking ecological adaptations and recurrent admixture [ 9 , 46 ]. Based on our preliminary mitochondrial genome data, we speculate the existence of ancient hybridization between L. tanaiticus and L. timidus at the end of the Late Pleistocene; the same as described for L. timidus and L. europaeus [ 9 , 11 , 12 ].…”

“…Nowadays, only four hare species inhabit northern Eurasia: brown hare ( L. europaeus ), mountain hare ( L. timidus ), Manchurian hare ( L. mandshuricus ), and Tolai hare ( L. tolai ). Previous studies demonstrated the existence of ancient genomic introgression between Lepus species, particularly between L. timidus and L. europaeus [ 9 , 10 , 11 , 12 ]. Moreover, the hybridization between those species might have an adaptive effect [ 9 , 11 ].…”

“…Previous studies demonstrated the existence of ancient genomic introgression between Lepus species, particularly between L. timidus and L. europaeus [ 9 , 10 , 11 , 12 ]. Moreover, the hybridization between those species might have an adaptive effect [ 9 , 11 ].…”

Mountain- and brown hare genetic polymorphisms to survey local adaptations and conservation status of the heath hare (Lepus timidus sylvaticus, Nilsson 1831)

“…Introgression may facilitate adaptation of the non-native brown hare to boreal prerequisites (e.g. seasonal shift to white winter pelage 3,7 , cold climate and/or pathogen resistance 9 ). This two-species complex thus offers an excellent model system for exploring how rapid, human-induced ecological change affects species including, their behavioural, demographic and evolutionary interactions over time.…”