Conservation of taxonomically difficult species: The case of the Australian orchid, Microtis angusii

As species are the common currency for conservation efforts, their accurate description is essential for efficient preservation of biological diversity. The genus Microtis (Orchidaceae) is typified by a paucity of consistent morphological characters, confounding taxonomic attempts. We report the results of a study of the conservation genetics of the recently discovered, endangered Australian orchid species M. angusii (Jones). This species was known only from one small population, with identification of further populations hampered by taxonomic difficulties. We used a combination of 122 AFLP markers and DNA sequence variation in the ribosomal ITS gene region to investigate the population genetic structure of the type population of M. angusii. Six further putative M. angusii populations were also analysed with these markers. Two of these populations showed high genetic affinity to M. angusii, bearing identical ITS sequences. Both the type and a second population were invariable across all AFLP loci. The third population, 3 km distant, showed minor genetic differentiation. These two new populations warrant immediate protection. Phylogenetic relationships between M. angusii and close relatives revealed its genetic affiliation to an unidentified, more distant population, and to the species M. unifolia. Given the propensity in Microtis for both selfing and clonality, mechanisms that both reduce within population variability and promote divergence between isolated populations, we recommend an extended study of both the genetic structure and breeding systems in the M. angusii/M. unifolia group, in order to ensure that the protection provided is both adequate and justified.