Influence of phylogeny and ploidy on species ranges of North American angiosperms


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1. Species differ widely in the size and ecological characteristics of their geographic ranges. This variation reflects, in part, differences in ecological tolerance among taxa, but the influence of phylogeny and evolutionary divergence through genome duplication remains controversial.

2. Here, we examine the evolutionary sources of variation in species range area, latitudinal position and overlap, and six range climatic variables (maximum, minimum and breadth of temperature and precipitation) for North American angiosperms. We sampled two diploid and one polyploid species from each of 144 genera and examined sources of variation in a nested taxonomic analysis and congeneric species pairs comparison.

3. For all range characteristics studied, a significant portion of the variance among species (mean 53%, range 37–60%) was attributable to taxonomic membership above species (i.e. genus, family and order). Four of the seven range attributes were significantly correlated between diploid congeners (e.g. range area rs = 0.65) and between heteroploid (diploid and polyploid) congeners (e.g. range area rs = 0.62). The strength of correlations between heteroploid relatives was not consistently different than correlations between diploids.

4. No differences in mean range breadth (range area, temperature breadth, precipitation breadth) or climatological position (minimum and maximum temperature and precipitation) were observed between diploid and polyploid congeners. Polyploids were not more likely to occupy northern latitudinal positions and were no more displaced from diploids than other congeneric diploids.

5.Synthesis. Our results suggest that, at the scale of North America, the geographical and ecological aspects of species ranges are influenced by phylogenetic history. Furthermore, genome duplication does not cause or allow greater divergence in species range characteristics than occurs between related diploid species.