From discovery to extinction? Phylogeography and niche modelling of a newly described dragonfly

The preservation of genetic diversity is a central goal in conservation. General theoretical frameworks such as the central–marginal hypothesis (CMH) often inform conservation strategies, but species with specialized habitat requirements or restricted distributions may not fit this model, hampering the delimitation of conservation units. We studied Onychogomphus cazuma, a recently described dragonfly endemic to Spain and restricted to thermal springs, to define a conservation framework. We aimed to (1) identify patterns of haplotypic structure through a phylogeographic analysis based on the mitochondrial marker cox2, (2) assess the role of philopatry in population structure through a capture-mark-recapture experiment, and (3) evaluate population-level extinction risk using ecological niche models under different climatic scenarios. A star-like haplotype network was observed, with seven population-specific haplotypes lacking a clearly structured geographic pattern, and philopatry was not detected. Ecological niche models predicted a drastic reduction in suitable habitat under future climate scenarios. The haplotypic diversity pattern is compatible with several demographic scenarios, such as a founder effect from an extinct source or a severe genetic bottleneck followed by population expansion. The presence of population-specific haplotypes indicates some degree of recent confinement, despite ongoing gene flow as suggested by the lack of geographic structure. The lack of clear central and peripheral population differentiation indicates that the CMH is not applicable to O. cazuma. Although three management units are tentatively proposed, projected habitat collapse implies that O. cazuma should be conserved as a single, highly vulnerable unit. Our results highlight the role of phylogeographic inference to design conservation strategies beyond generalized assumptions about population genetic patterns. For endemic species or those restricted to highly specific habitats, conservation efforts should prioritise preserving all populations.