Climate outweighs native vs. non-native range-effects for genetics and common garden performance of a cosmopolitan weed

Comparing genetic diversity, genetic differentiation and performance between native and non-native populations has advanced our knowledge of contemporary evolution and its ecological consequences. However, such between-range comparisons can be complicated by high among-population variation within native and non-native ranges. For example, native vs. non-native comparisons between small and non-representative subsets of populations for species with very large distributions have the potential to mislead because they may not sufficiently account for within-range adaptation to climatic conditions, and demographic history that may lead to non-adaptive evolution. We used the cosmopolitan weed Conyza canadensis to study the interplay of adaptive and demographic processes across, to our knowledge, the broadest climatic gradient yet investigated in this context. To examine the distribution of genetic diversity, we genotyped 26 native and 26 non-native populations at 12 microsatellite loci. Furth...