Niche Shifts, Hybridization, Polyploidy and Geographic Parthenogenesis in Western North American Hawthorns (Crataegus subg. Sanguineae, Rosaceae)

We compare biogeographic and morphological parameters of two agamic complexes western North American hawthorns so as to evaluate possible explanations the differences in range between sexually reproducing taxa their apomictic sister taxa. have documented range, breeding system, morphology, leaf vascular architecture, niche breadth these hawthorns, for which phylogenetic relationships ploidy levels are known. Species distribution data from herbarium specimens online databases were analyzed order ranges climate niches described by bioclimatic variables. Flow cytometry level system. Voucher provided morphometric that using uni- multivariate methods. Members black-fruited taxonomic sections Crataegus subg. Sanguineae (sections Douglasianae, Salignae) previously been identified hybrids. They presumptively self-fertile polyploids with pseudogamous gametophytic apomixis. Their morphologies, geographic ranges, characteristics resemble those diploid, sexual parent or intermediate them other parent, one both partially sympatric tetraploid apomicts red-fruited C. Americanae much wider distributions. Comparing Douglasianae Salignae suggests parthenogenesis (larger sizes apomicts, compared taxa) may less do adaptation than it does reproductive assurance pseudogamously self-compatible Greater allopolyploids diploids similarly be more due parental traits effects genome duplication per se.