Myrtaceae richness and distribution across the Atlantic Forest Domain are constrained by geoclimatic variables

Myrtaceae family presents high species richness in the Atlantic Forest Domain (AFD) of South America, which is considered a world biodiversity hotspot. Evidence indicates that the vegetation composition of the AFD changes from the northern to the southern portion of its territory. We aimed at understanding patterns of Myrtaceae species richness and composition throughout the AFD, underlying geoclimatic variables responsible for Myrtaceae biodiversity distribution. Thus, our study intends to shed light on the relationship between landscape and climate variation to Myrtaceae species richness and composition. We created a matrix of Myrtaceae species occurrence across 57 sites throughout the AFD and extracted geoclimatic co-variables for these sites to predict Myrtaceae diversity and distribution. We explored Myrtaceae composition descriptively through richness and Jaccard dissimilarity index. We employed a generalized linear model and a redundancy analysis (RDA) approach depicting the variations of Myrtaceae richness and distribution related to co-variables. We found 977 Myrtaceae occurrences representing 299 species belonging to 16 genera. The average dissimilarity between locations was 94.5%. Elevation, distance from the ocean, duration of water excess period in days, mean diurnal temperature range, precipitation of wettest month, severity of the water deficit period, and temperature seasonality were the main co-variables that predict the variation in Myrtaceae richness and composition. Our study contributes to understanding biogeographic and evolutionary patterns of Myrtaceae in the Neotropics, providing valuable information for conservation decisions against an overwhelming conjuncture of threats across AFD.