Climatic niche differences between diploid and tetraploid cytotypes of Chamerion angustifolium (Onagraceae)

Premise of the study: Polyploidy—the possession of more than two copies of each chromosome in the nucleus—is common in flowering plants. Polyploid plants can occupy different geographic ranges than their diploid progenitors, but the factors responsible for maintaining these range differences are poorly understood. Polyploidy can have significant physiological consequences, and the present study aims to determine whether previously described physiological differences between cytotypes are correlated with climatic niches and geographic distributions. Methods: Prior research indicates that tetraploid Chamerion angustifolium (Onagraceae) are more tolerant of drought and less tolerant of freezing than diploids, which suggests that they should occupy a niche that is warmer and drier than that of diploids. We extracted climate data for 134 C. angustifolium populations classified as pure diploid, pure tetraploid, or mixed-ploidy. We compared climatic conditions between these population categori...