Sex on the edge: reproductive patterns across the geographic range of the Syrrhopodon involutus (Calymperaceae) complex

Abstract In seed plants, populations located at the margins of species distributions are often characterized by reduced sexual reproduction and an increased reliance asexual reproduction. The degree to which this pattern applies to reproductive traits in haploid–dominant, non–seed plants was assessed in the Syrrhopodon involutus Schwaeg complex, a group of closely related tropical mosses with unisexual gametophytes. The second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA was sequenced for samples from throughout the range of the Syrrhopodon involutus Schwaeg complex and a maximum likelihood analysis was performed on the sequence data to infer phylogenetic history. Reproductive data were collected from 270 herbarium vouchers representing at least 337 individuals, and analyzed to test for geographic or phylogenetic differences in sex expression and sexual reproduction. Female sex expression was significantly lower among marginally distributed individuals compared to individuals collected ...