Unraveling Reticulate Evolution in (Cactaceae) From Southern Mexico.

The process of hybridization occurs in approximately 40% of vascular plants, and this exchange of genetic material between non-conspecific individuals occurs unequally among plant lineages, being more frequent in certain groups such as (Cactaceae). This genus is known for multiple taxonomic controversies due to widespread polyploidy and probable hybrid origin of several of its species. Southern Mexico species of this genus have been poorly studied despite their great diversity in regions such as the Tehuacán-Cuicatlán Valley which contains around 12% of recognized Mexico's native species. In this work, we focus on testing the hybrid status of two putative hybrids from this region, and , and estimate if hybridization occurs among sampled southern opuntias using two newly identified nuclear intron markers to construct phylogenetic networks with HyDe and Dsuite and perform invariant analysis under the coalescent model with HyDe and Dsuite. For the test of hybrid origin in , our results could not recover hybridization as proposed in the literature, but we found introgression into individuals involving and . Regarding , we identified as probable parental species, supported by our analysis, which sustains the previous hybridization hypothesis between and clades. Finally, we suggest new hybridization and introgression cases among southern Mexican species involving and as parental species of and .