Phylogeography of the palm Syagrus coronata (Martius) Beccari (Arecaceae): distribution in the “Caatinga” and Atlantic forest domains

Abstract

The palm species Syagrus coronata (Mart.) Becc. shows widespread geographic distribution in the “Caatinga” (seasonally dry tropical forest biome) and Atlantic forest domains (rain forest biome), which suggests that environmental variation in the two domains may have modeled the distribution of S. coronata, generating a distinct phylogeographic scenario. This study assessed the phylogeographic structure of S. coronata in the “Caatinga” and Atlantic forest domains using 181 sequences of the trnH-psbA intergenic spacer from samples spread in ten localities. Genealogical relationships between the haplotypes were estimated using the median-joining method, and spatial analysis of molecular variance was performed using SAMOVA software. The results revealed ten haplotypes, some of which were unique to either the “Caatinga” or the Atlantic forest domain, and analysis of the spatial molecular variance revealed four groups, showing genetic structure (FST = 0.56, P < 0.0001; FCT = 0.51, P < 0.0001), with 51.22% variation between the groups. Remarkably, an inverted sequence of 13 bp was observed in the position 296–308 bp and using the sequence of Cocos nucifera L. as a reference, it was observed that the ancestor type was typical of the “Caatinga” domain and inverted type of the Atlantic forest domain. The results show that S. coronata presents a phylogeographic structuring distributed in the “Caatinga” and Atlantic forest domains. “Caatinga” domain as an ancient refuge and Atlantic forest domain as a regional center of diversification and the São Francisco River had an important role in promoting diversification in the “Caatinga” domain.