Speciation by genome duplication: Repeated origins and genomic composition of the recently formed allopolyploid species Mimulus peregrinus.
Whole genome duplication (polyploidization) is a mechanism of "instantaneous" species formation that has played a major role in the evolutionary history of plants. Much of what we know about the early evolution of polyploids is based upon studies of a handful of recently formed species. A new polyploid hybrid (allopolyploid) species Mimulus peregrinus, formed within the last 140 years, was recently discovered on the Scottish mainland and corroborated by chromosome counts. Here, using targeted, high-depth sequencing of 1200 genic regions, we confirm the parental origins of this new species from M. x robertsii, a sterile triploid hybrid between the two introduced species M. guttatus and M. luteus that are naturalized and widespread in the United Kingdom. We also report a new population of M. peregrinus on the Orkney Islands and demonstrate that populations on the Scottish mainland and Orkney Islands arose independently via genome duplication from local populations of M. x robertsii. Our data raise the possibility that some alleles are already being lost in the evolving M. peregrinus genomes. The recent origins of a new species of the ecological model genus Mimulus via allopolyploidization provide a powerful opportunity to explore the early stages of hybridization and genome duplication in naturally evolved lineages.
Biological and Environmental Sciences, University of Stirling, Stirling, FK9 4LA, United Kingdom.
Mario
M
Vallejo-Marín
School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, United Kingdom.
Richard J A
RJA
Buggs
Biology Department, Whitman College, Walla Walla, Washington, 99362.
Arielle M
AM
Cooley
Department of Biology, College of William and Mary, Williamsburg, Virginia, 23185.
Joshua R
JR
Puzey
D032461:Chromosomes, Plant; D020440:Gene Duplication; D049810:Genetic Speciation; D018745:Genome, Plant; D006824:Hybridization, Genetic; D058865:Introduced Species; D032241:Mimulus / Q000235:genetics*; D011123:Polyploidy; D006113:United Kingdom
Hybridization; invasive species; plant speciation; polyploidy; whole genome duplication