Flower morphology variation in five species of Penstemon (Plantaginaceae) displaying Hymenoptera pollination syndrome

Background: Geographic distance promotes phenotypic variation by facilitating environmental distance, limiting gene flow, and exposing plants to different pollen vectors. Therefore, understanding how plant morphology changes across a geographic range improves our of the drivers morphological diversification both on macro- micro-evolutionary scale.
 Questions: 1) How do location abiotic factors affect flower between populations? 2) Is there pattern variation? 3) does yearly in temperature precipitation within populations?
 Studied species: Penstemon albidus, P. fruticosus, glandulosus, speciosus, whippleanus
 Study site dates: The continental USA, summers 2017 2018
 Methods: Fifty-seven populations 496 individuals were selected at random measure ten floral traits. Bioclimatic variables extracted from WorldClim database NOAA. Linear models, partial least squares regression, Mantel tests canonical correlation analysis used analyze data.
 Results: alone explained significant portion two species, while others, did not vary despite large distances. albidus whippleanus flowers increase size south-north, glandulosus speciosus exhibited an east-west increasing trend. Additionally, mean annual was most important variable influencing glandulosusflower morphology.
 Conclusions: facilitates isolation-by-distance isolation-by-phenology as well differences populations; however, other such pollinators might be keeping morphologically homogeneous distance.