Landscape genetic connectivity in a riparian foundation tree is jointly driven by climatic gradients and river networks

摘要: Fremont cottonwood (Populus fremonti) is a foundation riparian tree species that drives community structure and ecosystem processes in southwestern U.S. ecosystems. Despite its ecological importance, little known about the environmental shape genetic diversity, structure, landscape connectivity. Here, we combined molecular analyses of 82 populations including 1312 individual trees dispersed over species' geographical distribution. We reduced data set to 40 743 individuals eliminate admixture with sibling species, used multivariate restricted optimization reciprocal causal modeling evaluate effects river network connectivity climatic gradients on gene flow. Our results confirmed following: First, flow jointly controlled by seasonal precipitation. Second, facilitated mid-sized large rivers, resisted small streams terrestrial uplands, resistance decreasing size. Third, differentiation increases cumulative differences winter spring suggest ongoing fragmentation habitats will lead loss landscape-level connectivity, leading increased inbreeding concomitant diversity species. These cascade much larger organisms, some which are threatened endangered.