Habitat differentiation between diploid and tetraploid Galax urceolata (Diapensiaceae)

Polyploid plants are typically geographically separated from their diploid progenitors, but it is rarely known whether this segregation is maintained by habitat differentiation or by selection against triploid hybrids. We tested for habitat differentiation between diploid and tetraploid populations of Galax urceolata in the southeastern United States by comparing the abundance and richness of vegetation associated with their respective habitats and testing for spatial autocorrelation in the distributions of diploid and tetraploid plants. Diploid and tetraploid habitats did not differ with respect to plant species richness. Herbaceous plants were 500% more common in tetraploid than diploid populations, while shrubs and trees were more common in diploid populations. Differences were found for the relative abundances of the most common species, with three species being significantly more prevalent in tetraploid than diploid populations. Spatial patchiness was detected for diploids and tetraploids, on a scale of 25 km. These results provide evidence for habitat differentiation, which may contribute to the maintenance of spatial separation between diploid and tetraploid G. urceolata.