Influence of Mating Systems, Contemporary Niches, and Historical Demography on the Genetic Patterns of Flagship Plants From the Amazonian Cangas

ABSTRACT

Genetic diversity is shaped by multiple factors, including life‐history traits, contemporary range distributions, niche constraints, and historical demography. The interplay of these drivers remains largely unexplored, particularly at scales proven to be relevant to conservation management of tropical biodiversity hotspots. Here, we investigate the relative contribution of each of these factors in shaping the current patterns of genetic diversity of 13 plant species occurring in Carajás, Southeastern Amazon, Brazil. We further test whether species associated with iron‐rich substrates in Carajás, known as cangas, share a common demographic history despite their differences in life‐history traits, distributions, and niches. We found that inbreeding levels are likely determined by mating systems, while both observed and expected heterozygosity were negatively associated with niche marginality. Surprisingly, distribution range and niche breadth had no effects on genetic parameters, likely due to the absence of correlations with ecological specialization. Demographic reconstructions revealed a lack of synchronous population histories across co‐distributed cangas plants, which likely reflects variation in the diversified life‐history traits affecting the timing of their responses to past climatic changes. Our results offer valuable insights into future demographic trends of cangas ‐associated species, refining predictions on the fate of species in the face of anthropogenic pressures such as habitat loss and climate change. Our data further contribute to subsidizing analyses to determine priority areas and species for conservation.