Molecular Tools for Species Identification and Population Assessment of Marine Organisms

Abstract

Sessile or site attached marine species rely on the dispersal of their pelagic larvae to ensure the exchange of reproductive individuals within and among subpopulations. The resultant and continued mixing of genetic identities constitutes their population connectivity and can ensure resilience against disturbance, disease or local extinctions. Studies focusing on population connectivity in centers of high biodiversity are particularly needed to protect and sustain these ecosystems in light of global climate change and increasing anthropogenic impacts from growing coastal populations and fisheries. Coral reef organisms, like anemonefishes and their host sea anemones, are ideal candidates to study the dynamics of larval dispersal, as adults are site attached and adult migration therefore does not factor in genetic mixing. The overarching aim of this thesis is to develop, test and apply molecular markers in the study of different aspects of genetic and biological diversity in anemonefishes and their obligate symbiont sea anemone partners in the Indo-Malay Archipelago, adding to the body of scientific evidence needed to support biodiversity conservation in this biodiversity hotspot . Specifically, the study furthers our understanding of connectivity in anemonefishes by presenting single species population genetic studies for, Amphiprion perideraion (Chapter I) and A. sandaracinos (Chapter II), where species specific structures are discussed in detail to highlight differences despite the highly similar life history and ecology of these fishes. This data is used as a basis for a multispecies approach to connectivity in anemonefishes by identifying and scaling regional barriers to geneflow among congeners (Amphiprion perideraion, A. sandaracinos, A. clarkii and A. ocellaris), making these results more accessible for application and implementation driven fields of research. By applying a comparative intergenomic (mitochondrial and nuclear markers) and an intrageneric (four species) approach, the mechanisms shaping genetic diversity in natural populations of anemonefishes are addressed and the variability in the system is explored.The impact of host specialization (generalist vs. specialist) and the length of the pelagic larval phase are tentatively discussed in light of the overall genetic structure that could be detected for each species. To heed the close association between anemonefishes and their sea anemone host, two mitochondrial and one nuclear marker are investigated as to their potential to delineate and identify species within the Actiniaria (Chapter III). Following a fourth research aim to study connectivity and diversity in host sea anemones, the attempted development of a set of polymorphic microsatellite loci is shown (Chapter IV).