Divergent lineages in a young species: the case of Datilillo (Yucca valida), a broadly distributed plant from the Baja California Peninsula

Abstract

ABSTRACTPremiseGlobally, barriers triggered by climatic events have caused habitats fragmentation and populations divergence. One example are the oscillations of the Quaternary, which had an important role in the historical distribution of wildlife across North America. Notably, diverse plant species from the Baja California Peninsula, located in western North America, exhibit strong genetic structure and highly concordant differentiated lineages across their ranges, as they were isolated during the Last Interglacial and became genetically differentiated over time. A representative taxon of this Peninsula is the genusYucca, withYucca validahaving the widest range. Although Y. valida is a dominant species, there is an extensive distribution discontinuity between 26° N and 27° N, where any individuals have been identified, suggesting restricted gene flow rates; moreover, the historical distribution models indicate a substantial reduction in its range during the Last Interglacial, making it an interesting model for studying genetic differentiation.MethodsWe examined the phylogeography ofY. validathroughout its range to identify the number of genetic lineages, quantify their genetic differentiation, reconstruct their demographic history and estimate the species’ age.Key resultsWe assembled 4,411 SNPs from 147 plants, identifying three allopatric lineages. Our analyses supported that the accumulation of genetic differentiation was driven by genetic drift. We estimated an age under one million years old for the last common ancestor ofY. validaand its sister species.ConclusionsThe drivers of genetic divergence in Y. valida have been historical climate changes, limited dispersal capacity, and an extensive geographical range gap.