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NICHE AND RANGE SIZE PATTERNS SUGGEST THAT SPECIATION BEGINS IN SMALL, ECOLOGICALLY DIVERGED POPULATIONS IN NORTH AMERICAN MONKEYFLOWERS ( MIMULUS SPP .)
Author(s) -
Grossenbacher Dena L.,
Veloz Samuel D.,
Sexton Jason P.
Publication year - 2014
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12355
Subject(s) - biology , sympatric speciation , parapatric speciation , genetic algorithm , niche , range (aeronautics) , ecological niche , ecological speciation , niche differentiation , character displacement , sympatry , niche segregation , ecology , sister group , evolutionary biology , reproductive isolation , clade , habitat , phylogenetics , gene flow , population , genetic variation , materials science , demography , sociology , composite material , gene , biochemistry
Closely related species (e.g., sister taxa) often occupy very different ecological niches and can exhibit large differences in geographic distributions despite their shared evolutionary history. Budding speciation is one process that may partially explain how differences in niche and distribution characteristics may rapidly evolve. Budding speciation is the process through which new species form as initially small colonizing populations that acquire reproductive isolation. This mode of species formation predicts that, at the time of speciation, sister species should have highly asymmetrical distributions. We tested this hypothesis in North American monkeyflowers, a diverse clade with a robust phylogeny, using data on geographical ranges, climate, and plant community attributes. We found that recently diverged sister pairs have highly asymmetrical ranges and niche breadths, relative to older sister pairs. Additionally, we found that sister species occupy distinct environmental niche positions, and that 80% of sister species have completely or partially overlapping distributions (i.e., are broadly sympatric). Together, these results suggest that budding speciation has occurred frequently in Mimulus , that it has likely taken place both inside the range and on the range periphery, and that observed divergences in habitat and resource use could be associated with speciation in small populations.