Abstract Hybridization is common among plant species and presents many challenges for conservation. One emerging issue is unrecognized hybrids being mistaken for rare species and receiving conservation management that may not be warranted. Here, we used genome-wide single nucleotide polymorphism (SNP) markers to test hybridization hypotheses for three threatened species in Western Australia: Eucalyptus crispata, E. leprophloia, and E. pruiniramis. All three were suspected hybrids arising from one shared parent, E. accedens, and three other species, E. arachnaea subsp. arachnaea, E. zopherophloia, and E. loxophleba subsp. loxophleba, respectively. Results confirmed hybrid origins for E. crispata and E. leprophloia as hypothesized, although an additional hybrid combination was detected within E. leprophloia. In all combinations, clonality and hybrid class testing determined that most populations exist as singleton F1 individuals scattered across the landscape, with few backcrosses. Consequently, these taxa do not represent stabilized hybrid species but transient hybrids resulting from rare reproductive events between their parental taxa. Here, we recommend taxonomic revision as nothotaxa and re-assessment of their conservation status. In contrast, E. pruiniramis showed no signal of hybrid origin, supporting its continued recognition as a valid, conservation-listed species. These varied outcomes highlight the value of using molecular data for clarifying hybrid status to inform appropriate conservation actions and resourcing.
Binks et al. (Mon,) studied this question.