Niche conservatism for ecological preference in the Louisiana iris species complex

Spatial and temporal environmental variation influences evolutionary processes such as divergence among populations and species. In the present study, we investigated the patterns of niche evolution for the Louisiana irises, as well as the phylogenetic relationship between these species. Using BEAST, a species phylogeny was generated for the Louisiana irises aiming to test the hypothesis of whether niche conservatism has played an important role for this species complex. Species distribution models were constructed for present day distributions to determine the environmental factors that contribute to species ranges. Tests of niche similarity were performed to evaluate whether niche conservatism is apparent within this species complex. We demonstrate that the Louisiana iris species complex is a monophyletic clade with Iris brevicaulis and Iris fulva as being sister to each other. The differences observed among the iris species with respect to the associated environmental factors suggest that these components have an effect on the distributions and habitats occupied. Furthermore, tests of niche similarity indicate niche conservatism for all species comparisons. Working at the species level and assessing the various factors that can influence differentiation, the present study obtained a more complete picture of the ecological and evolutionary history of this species complex across the geographical and ecological range. (C) 2016 The Linnean Society of London,