Pseudo-parallel patterns of disjunctions in an Arctic-alpine plant lineage

Disjunct distributions have intrigued biologists for centuries. Investigating these biogeographic patterns provides insight into speciation and biodiversity at multiple spatial and phylogenetic scales. Some disjunctions have been intensively studied, yet others have been largely overlooked and remain poorly understood. Among the lesser-known disjunction patterns is that between the mountain ranges of western North America. Flora and fauna endemic to the mountains of this region provide important systems for investigating causes and results of disjunctions, given the relatively recent geological formation of this area and the intense climatic fluctuations that have occurred since its formation. In Micranthes (Saxifragaceae), which has high rates of montane endemism, two species, M. bryophora and M. tolmiei, show this biogeographical pattern. By reconstructing a time-calibrated phylogeny based on 518 low-copy nuclear markers and including multiple populations of each species from the Coas...