Population genomics and taxonomy solve a conservation conundrum in the Balearic paleoendemic Femeniasia balearica

A robust understanding of taxonomy, distribution and intraspecific genetic diversity is crucial for the conservation of narrow endemic species, which face a higher risk of extinction, especially in insular systems. Here, we study the monotypic plant genus Femeniasia (Asteraceae), narrowly endemic to the Balearic Islands. Only four populations are known for the sole species of this genus, Femeniasia balearica: three on the island of Menorca, where it is considered native and endemic, and one recently discovered on the island of Mallorca, suspected to be the result of a recent anthropogenic introduction. The latter population poses a conservation conundrum: if introduced, it may not merit the same conservation status as native populations; if native, it would be of high biogeographic and conservation interest. To solve this problem and gain an in-depth understanding of diversity and differentiation across the distribution of F. balearica, we conducted phylogenetic and divergence time inference for F. balearica and its relatives based on plastid DNA, phylogenomic, population genomic and coalescent-based demographic analysis of F. balearica populations based on genotyping-by-sequencing (GBS), and a morphological study. Our findings revealed a divergence dating back to the Pliocene, and significant morphological and genetic differentiation between Mallorcan and Menorcan populations, which supports an old presence of F. balearica on Mallorca. As a result, the Mallorcan population is herein described as F. balearica subsp. majoricensis. The combined study of intraspecific genetic diversity and taxonomy proved fundamental in identifying natural populations of taxonomic, biogeographic and evolutionary relevance. Our findings should prompt a reconsideration of the conservation and management strategies of Femeniasia.