Phylogeography and ecological niche modelling in Eugenia uniflora (Myrtaceae) suggest distinct vegetational responses to climate change between the southern and the northern Atlantic Forest

In this study, we evaluate phylogeographic patterns and predictions of ecological niche modelling (ENM) for Eugenia uniflora (Myrtaceae), a widely distributed taxon in the Atlantic forest domain, to understand the effect of past climatic oscillations on the demographic history of this species. An analysis of phylogeographic population structure and demography was conducted on E. uniflora from 46 localities in natural environments across the distribution range of the species based on three plastid markers. ENM was also performed to predict suitable environments and areas of dramatic decrease in future suitability for the species under distinct representative concentration pathways (RCPs). Eugenia uniflora exhibited higher haplotype and nucleotide diversity in the southern part of its distribution than in the northern part. Two divergent lineages were revealed in the phylogenetic analysis of haplotypes, with an estimated divergence at c. 4.9 Mya. The populations in the northern and central regions of the range probably experienced population growth, whereas populations in the southern region are marked by historical demographic stability. ENM results indicate that the distribution of E. uniflora was fragmented in cool periods and was broader and more connected during warm periods during Pleistocene. The results suggest distinct evolutionary histories in southern to northern populations, indicating region‐specific responses to changes.