Parallel evolution of site‐specific changes in divergent caribou lineages

Abstract

The parallel evolution of phenotypes or traits within or between species provides important insight into the basic mechanisms of evolution. Genetic and genomic advances have allowed investigations into the genetic underpinnings of parallel evolution and the independent evolution of similar traits in sympatric species. Parallel evolution may best be exemplified among species where multiple genetic lineages, descended from a common ancestor, colonized analogous environmental niches, and converged on a genotypic or phenotypic trait. Modern North American caribou (Rangifer tarandus) originated from three ancestral sources separated during the Last Glacial Maximum (LGM): the Beringian–Eurasian lineage (BEL), the North American lineage (NAL), and the High Arctic lineage (HAL). Historical introgression between the NAL and the BEL has been found throughout Ontario and eastern Manitoba. In this study, we first characterized the functional differentiation in the cytochrome‐b (cytB) gene by identifying nonsynonymous changes. Second, the caribou lineages were used as a direct means to assess site‐specific parallel changes among lineages. There was greater functional diversity within the NAL despite the BEL having greater neutral diversity. The patterns of amino acid substitutions occurring within different lineages supported the parallel evolution of cytB amino acid substitutions suggesting different selective pressures among lineages. This study highlights the independent evolution of identical amino acid substitutions within a wide‐ranging mammal species that have diversified from different ancestral haplogroups and where ecological niches can invoke parallel evolution.

Drainage-structuring of ancestral variation and a common functional pathway shape limited genomic convergence in natural high- and low-predation guppies

“…While, there are many definitions of genetic convergence (or parallelism) [2], here we use it broadly to describe selection acting at any of three levels: on the same mutations (eg. [7][8][9]); different mutations affecting the same genes (eg. [10][11][12]); or different genes in the same functional pathways (eg.…”

Selective sweep analysis reveals extensive parallel selection traits between large white and Duroc pigs

“…From the perspective of population genetics, the genomic patterns shaped by similar selection directions between populations could be termed as parallel selection signatures. So far, the traits underlying parallel selection have been reported in several species, such as herring (Lamichhaney et al., 2017) and caribou (Horn et al., 2018). In pigs, Frantz et al.…”

Major diversification of caribou shaped by glacial cycles before the Last Glacial Maximum

“…We used 33 whole-genome sequences and over 1,800 mitochondrial control region sequences to investigate genomic structure, patterns of introgression, and diversification in caribou from different regions of north-western North America. Overall genomic structure shows separation between individuals from different DUs, although with a few exceptions: boreal caribou from the Northwest Territories are not most closely related with the boreal caribou from Cold Lake (Figure 5 and 7), a reflection of parallel evolution of ecotype inferred previously (Horn et al, 2018;Polfus et al, 2017;. Northern mountain caribou have sub-structuring within them, notably Itcha-Ilgachuz and Aishihik are well separated in the PCA (Figure 5 and 6b).…”

“…Boreal caribou are generally considered to belong to the woodland subspecies and are more sedentary than barren-ground caribou. However, caribou that show typical boreal caribou sedentary behaviour in central Northwest Territories belong to the BEL, suggesting parallel phenotypic evolution (Horn et al, 2018;Polfus et al, 2017;. Northern mountain caribou (DU7) are found in the Yukon, western Northwest Territories, and in northern and central British Columbia.…”