Limited connectivity and a phylogeographic break characterize populations of the pink anemonefish, Amphiprion perideraion, in the Indo-Malay Archipelago: inferences from a mitochondrial and microsatellite loci.

To enhance the understanding of larval dispersal in marine organisms, species with a sedentary adult stage and a pelagic larval phase of known duration constitute ideal candidates, because inferences can be made about the role of larval dispersal in population connectivity. Members of the immensely diverse marine fauna of the Indo-Malay Archipelago are of particular importance in this respect, as biodiversity conservation is becoming a large concern in this region. In this study, the genetic population structure of the pink anemonefish, Amphiprion perideraion, is analyzed by applying 10 microsatellite loci as well as sequences of the mitochondrial control region to also allow for a direct comparison of marker-derived results. Both marker systems detected a strong overall genetic structure (ΦST = 0.096, P < 0.0001; mean D est = 0.17; F ST = 0.015, P < 0.0001) and best supported regional groupings (ΦCT = 0.199 P < 0.0001; F CT = 0.018, P < 0.001) that suggested a differentiation of the Java Sea population from the rest of the archipelago. Differentiation of a New Guinea group was confirmed by both markers, but disagreed over the affinity of populations from west New Guinea. Mitochondrial data suggest higher connectivity among populations with fewer signals of regional substructure than microsatellite data. Considering the homogenizing effect of only a few migrants per generation on genetic differentiation between populations, marker-specific results have important implications for conservation efforts concerning this and similar species.

Interspecific, spatial and temporal variability of self-recruitment in anemonefishes.

Polymorphic microsatellite DNA parentage analysis was used to investigate the spatio-temporal variability of self-recruitment in populations of two anemonefishes: Amphiprion ocellaris and A. perideraion. Tissue samples of A. ocellaris (n = 364) and A. perideraion (n = 105) were collected from fringing reefs around two small islands (Barrang Lompo and Samalona) in Spermonde Archipelago, Indonesia. Specimens were genotyped based on seven microsatellite loci for A. ocellaris and five microsatellite loci for A. perideraion, and parentage assignment as well as site fidelity were calculated. Both species showed high levels of self-recruitment: 65.2% of juvenile A. ocellaris in Samalona were the progeny of parents from the same island, while on Barrang Lompo 47.4% of A. ocellaris and 46.9% of A. perideraion juveniles had parents from that island. Self-recruitment of A. ocellaris in Barrang Lompo varied from 44% to 52% between the two sampling periods. The site fidelity of A. ocellaris juveniles that returned to their reef site in Barang Lompo was up to 44%, while for A. perideraion up to 19%. In Samalona, the percentage of juveniles that returned to their natal reef site ranged from 8% to 11%. Exchange of progeny between the two study islands, located 7.5 km apart, was also detected via parentage assignments. The larger Samalona adult population of A. ocellaris was identified as the parents of 21% of Barrang Lompo juveniles, while the smaller adult population on Barrang Lompo were the parents of only 4% of Samalona juveniles. High self-recruitment and recruitment to nearby island reefs have important implications for management and conservation of anemonefishes. Small MPAs, preferably on every island/reef, should ensure that a part of the population is protected to enable replenishment by the highly localised recruitment behaviour observed in these species.

Contrasting patterns in species boundaries and evolution of anemonefishes (Amphiprioninae, Pomacentridae) in the centre of marine biodiversity.

Many species of coral reef fishes are distinguished by their colour patterns, but genetic studies have shown these are not always good predictors of genetic isolation and species boundaries. The genus Amphiprion comprises several species that have very similar colouration. Additionally, morphological characters are so variable, that sibling species can show a considerable overlap, making it difficult to differentiate them. In this study, we investigated the species boundaries between the sibling species pair A. ocellaris and A. percula (Subgenus Actinicola) and three closely related species of the subgenus Phalerebus (A. akallopisos, A. perideraion, A. sandaracinos) by phylogenetic analysis of mitochondrial cytochrome b and control region sequences. These two subgenera show strong differences in their patterns of species boundaries. Within the A. ocellaris/A. percula complex, five clades were found representing different geographic regions. Two major divergences both with genetic distances of 4-7% in cty b and 17-19% in the d-loop region indicate the presence of three instead of two deep evolutionary lineages. The species of the subgenus Phalerebus show three monophyletic clades, independent of the geographical location of origin, but concordant to the morphological species classification. The genetic distances between the Phalerebus species were 2-5% in cty b and 10-12% in the control region.

Geological history and oceanography of the Indo-Malay Archipelago shape the genetic population structure in the false clown anemonefish (Amphiprion ocellaris).

Like many fishes on coral reefs, the false clown anemonefish, Amphiprion ocellaris, has a life history with two different phases: adults are strongly site attached, whereas larvae are planktonic. Therefore, the larvae have the potential to disperse, but the degree of dispersal potential depends primarily on the period of the larval stage, which is only 8-12 days in A. ocellaris. In this study, we investigated the genetic population structure and gene flow in A. ocellaris across the Indo-Malay Archipelago by analysing a fragment of the mitochondrial control region. Population genetic analysis, using AMOVA, revealed a significant and high overall phi(ST)-value of 0.241 (P < 0.001), clearly showing limited gene flow. Haplotype network analysis detected eight distinct clades corresponding mainly to different geographical areas, which were most probably separated during sea level low stands in the Pleistocene. The distribution of the clades among the different populations indicated slow partial re-mixing mainly in the central region of the archipelago. Major surface currents seem to facilitate larval dispersal, indicated by higher connectivity along major surface currents in the region (e.g. Indonesian Throughflow). Four main groups were found by the hierarchical AMOVA within the archipelago. These different genetic lineages should be managed and protected as separate ornamental fishery stocks and resource contributing to the genetic diversity of the area. Regarding the high diversity and the differentiation among areas within the Indo-Malay Archipelago of A. ocellaris populations, the centre-of-origin theory is supported to be the main mechanism by which the high biodiversity evolved in this area.