Abstract: Pocillopora damicornis represents one of the best-studied reef-building coral species, characterized by high levels of eco-phenotypic variation and a confusing life history. Multiple modes of reproduction and recent instances of cryptic speciation have been acknowledged from different geographic locations thus challenging the taxonomic status of P. damicornis. Multiple cryptic lineages may well explain the reproductive flexibility reported across the species global distribution range; however, the delimitation of the cryptics is arduous due to the lack of congruence amongst morphological characters, mitochondrial phylogenies and nuclear genealogies.
I herein apply the “Unified Species Concept” (USC; DeQueiroz 2007) to delimit genetically distinct yet morphologically cryptic lineages within the P. damicornis species complex by combining evidence from morphological, genetic, reproductive and symbiont data. According to the USC, species are defined as separately evolving metapopulation lineages. Multiple sources of evidence therefore (i.e. criteria associated with previously accepted species concepts) are used in synergy to assess metapopulation boundaries. Molecular phylogenies inferred from mitochondrial markers (CR, ORF) were congruent with morphological groups suggesting at least five independently evolving lineages. In contrast, nuclear markers (HSP70, ITS2) recovered sharp genetic discontinuities among only three of these lineages. The combined additional evidence inferred from: microsatellite genotyping, gross morphology, associated Symbiodinium clades and reproductive mode and timing of populations suggested that introgressive hybridization may be the cause of the low resolution power observed in the nuclear regions.
In light of multiple evidence, I propose that the lineages recovered in P. damicornis sensu lato represents different stages along the species genealogical continuum and are therefore difficult to resolve on the basis of a single species concept. The USC appears to be a suitable approach in organisms where cryptic speciation and hybridization mask classic taxonomic identification and is here suggested as an important conceptual improvement in categorizing ambiguous taxa. This is especially important in P. damicornis lineages where the misinterpretation of distinct species as ecomorphs in the past led to the confusing patterns reported for its biology and ecology.
Biography: Sebastian is originally from Germany where he started his career at the University of Bielefeld before continuing his studies at the University of Oldenburg with a focus on marine biodiversity. After some initial work on coral reefs during his studies at the University of the West Indies, Trinidad and Tobago, he conducted a master thesis on coral recruitment in North Sulawesi, Indonesia. This thesis was in collaboration with the Centre for Marine Ecology (ZMT), Bremen and the Universitas Sam Ratulangi in Manado, Indonesia. In 2009 Sebastian enrolled as a PhD student at the University of Tasmania (UTas), were he is associated with the Institute for Marine and Antarctic Studies (IMAS). Conducting his thesis in close collaboration with the Australian Institute for Marine Science (AIMS) he is based in Townsville. Sebastian’s research aims to understand the ecological and evolutionary significance of different life histories in corals and the role they may play for speciation.