Local adaptation to current but not future climate in seasonally dry tropical forests: population genomic evidence in a neotropical legume tree

Neotropical seasonally dry biomes are amongst the world's most threatened ecosystems and are predicted to lose more biodiver-sity with climate change. The capacity of natural populations to respond to these changes depends on their genetic variation, butis poorly understood in most Neotropical seasonally dry forest species. Here, we used genome-wide single nucleotide polymor-phism (SNP) data for 109 individuals across 12 Colombian populations of Enterolobium cyclocarpum, a widespread deciduouslegume tree found in seasonally dry tropical forests, human-disturbed and open landscapes from Central and Northern SouthAmerica, to (1) explore population structure across the landscape, (2) determine local adaptation to heat and drought stress, and(3) assess genomic offset and adaptive potential under future climate change. Our results suggest clear genomic differentiationamong regions and populations, as well as an uneven spatial distribution of adaptive alleles associated with drought and heatstress, together suggesting different degrees of local adaptation to climate across the landscape. Furthermore, all regions investi-gated (i.e., Caribbean, inter-Andean valleys, and Orinoquía) showed limited adaptive potential under future climate change sce-narios. For some regions, gene flow may help buffer the effects of environmental change by bringing in adaptive alleles, however,this will likely be insufficient to counteract predicted mal-adaptation in certain regions, such as in the Orinoquía. Our resultssuggest that both barriers to gene flow (e.g., orography) and varying heat and drought stress conditions have shaped the genomiccomposition and adaptive potential of the species. Enterolobium cyclocarpum populations have adapted locally to current cli-mate, but this adaptation may not be sufficient to cope with future climate change, particularly where population connectivity islow. Our findings have relevance for the conservation of species in highly threatened Neotropical biomes, such as seasonally drytropical forests, which are expected to experience rising temperatures and greater drought under future climate change.