Travel with your kin ship! Insights from genetic sibship among settlers of a coral damselfish

Preliminary insight into parental contributions to Japanese eel (Anguilla japonica) preleptocephali spawned on different nights

Parentage sibship-inference analyses were conducted using mtDNA sequencing and six microsatellite genotypes of 182 Japanese eel preleptocephali that were collected from one net-tow near the West Mariana Ridge in May 2014. At least 328 parents were involved in producing the 182 preleptocephali, and several parents may have spawned a few times during 3 days of a spawning period. Half-sibs suggested that a few parents mated with 1-3 partners, indicating that the Japanese eel can form spawning aggregations in which several parents mate with each other in the ocean.

Dongsha Atoll is an important stepping-stone that promotes regional genetic connectivity in the South China Sea

Background

Understanding region-wide patterns of larval connectivity and gene flow is crucial for managing and conserving marine biodiversity. Dongsha Atoll National Park (DANP), located in the northern South China Sea (SCS), was established in 2007 to study and conserve this diverse and remote coral atoll. However, the role of Dongsha Atoll in connectivity throughout the SCS is seldom studied. In this study, we aim to evaluate the role of DANP in conserving regional marine biodiversity.

Methods

In total, 206 samples across nine marine species were collected and sequenced from Dongsha Atoll, and these data were combined with available sequence data from each of these nine species archived in the Genomic Observatories Metadatabase (GEOME). Together, these data provide the most extensive population genetic analysis of a single marine protected area. We evaluate metapopulation structure for each species by using a coalescent sampler, selecting among panmixia, stepping-stone, and island models of connectivity in a likelihood-based framework. We then completed a heuristic graph theoretical analysis based on maximum dispersal distance to get a sense of Dongsha’s centrality within the SCS.

Results

Our dataset yielded 111 unique haplotypes across all taxa at DANP, 58% of which were not sampled elsewhere. Analysis of metapopulation structure showed that five out of nine species have strong regional connectivity across the SCS such that their gene pools are effectively panmictic (mean pelagic larval duration (PLD) = 78 days, sd = 60 days); while four species have stepping-stone metapopulation structure, indicating that larvae are exchanged primarily between nearby populations (mean PLD = 37 days, sd = 15 days). For all but one species, Dongsha was ranked within the top 15 out of 115 large reefs in the South China Sea for betweenness centrality. Thus, for most species, Dongsha Atoll provides an essential link for maintaining stepping-stone gene flow across the SCS.

Conclusions

This multispecies study provides the most comprehensive examination of the role of Dongsha Atoll in marine connectivity in the South China Sea to date. Combining new and existing population genetic data for nine coral reef species in the region with a graph theoretical analysis, this study provides evidence that Dongsha Atoll is an important hub for sustaining connectivity for the majority of coral-reef species in the region.