If gene flow between populations is sufficiently high, then beneficial variation may spread quickly and potentially allow for rapid adaptive responses to changing environments. Distinguishing between these scenarios is crucial to understand the capacity of populations to adapt rapidly to environmental change. In response to a shared selection pressure, populations may adapt through the migration of beneficial alleles or through independent mutations that result in the evolution of convergent phenotypes. Our findings underscore how allelic dominance can shape the geographic extent and rate of convergent adaptation in response to rapidly changing environments. Simulations show that if annual snow cover dramatically declined in the same population, then the predicted selective increase in frequency of the now beneficial winter-brown Agouti allele is likely to be extremely slow due to the same masking effect. However, the PNW haplotype does occur at low frequency in a winter-white population from Montana, consistent with the spread of a locally deleterious recessive variant that is masked from selection when rare. Genome sequencing of a winter-brown snowshoe hare from Alaska shows that it lacks the winter-brown PNW haplotype, reflecting a history of convergent phenotypic evolution. Our phylogeographic analyses revealed deep structure and limited gene flow between PNW and more northern Boreal populations, where winter-brown camouflage is rare along the range edge. In coastal Pacific Northwest (PNW) populations, winter-brown camouflage is known to be determined by a recessive haplotype at the Agouti pigmentation gene. We used extensive range-wide genomic data to 1) resolve broad-scale patterns of population structure and gene flow and 2) investigate the factors shaping the origins and distribution of winter-brown camouflage variation. In some warmer climates, hares have evolved brown winter camouflage – an adaptation that may spread under climate change. Snowshoe hares ( Lepus americanus) typically molt into white winter coats to remain camouflaged against snow. Determining how different populations adapt to similar environments is fundamental to understanding the limits of adaptation under changing environments.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |