Phylogeographic patterns and possible incipient domestication of Jacaratia mexicana A. DC. (Caricaceae) in Mexico

Jacaratia mexicana A. DC. (Caricaceae) is a tropical tree distributed throughout Mexico and Mesoamerica. Some evidence in Mexico indicates the presence of an incipient domestication process in this species. Phylogeographical analyses can potentially determine contemporary patterns of gene flow, isolation between population lineages, as well as historical processes such as population bottlenecks or expansions on their geographical areas. In this study we reconstruct the phylogeographical patterns in populations of J. mexicana A. DC., in order to find differences between genetic variation among wild and cultivated populations utilizing chloroplast DNA and nuclear DNA sequences. We generate a Bayesian phylogenetic tree, to estimate the divergence time between clades using calibrated mutation rates. We also infer the demographic history of these populations using neutrality tests among wild and cultivated accessions. We identified higher levels of haplotype and nucleotide diversity for the cpDNA and ITS types in wild populations than in domesticated populations. These results indicate a reduction of genetic diversity derived from human selection on domestication traits. Neutrality test suggests population expansion detected by the significant negative values of Fu's Fs in the cultivated populations of this specie. These process results in an excess of rare polymorphism with the fixation of certain advantageous mutation throughout time, this implication are in accordance with the role of the strong selection in the fruit traits of J. mexicana. The dated phylogeny constructed with BEAST program indicated a dispersion pattern for the J. mexicana ancestors across the South Pacific and South Eastern populations during the late Pliocene. Posterior dispersion and divergence in the clades from Central Mexico and North Pacific are in agreement with the episodes of mountain-building in different regions of Mexico.