Patterns of genetic structuring in the coral Pocillopora damicornis on reefs in East Africa

Petra Souter,Niklas Olsson,Oskar Henriksson,Mats Grahn

doi:10.1186/1472-6785-9-19

Petra Souter, Niklas Olsson + Show 2 more

Open Access

https://doi.org/10.1186/1472-6785-9-19

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Abstract

BackgroundStudies of population genetic structures provide an indication of direction and magnitude of larval transport and hence are an important component in the assessment of the ability of reefs to recover from severe disturbance. This paper reports data on population genetic structures in the coral Pocillopora damicornis from 26 reefs in Kenya and Tanzania.ResultsGene flow among reefs was found to be variable, with a significant overall genetic subdivision (FST = 0.023 ± 0.004 SE; p < 0.001), however, only 34% of all pairwise population comparisons showed significant differentiation. Panmixia could not be rejected between reefs separated by as much as 697 km, while other sites, separated by only a single kilometre, were found to be significantly differentiated. An analysis of molecular variance indicated that population genetic differentiation was significant only at the smaller spatial scale (< 10 km), whereas panmixia could not be rejected between groups of samples separated by over 100 km. Estimates of contemporary gene flow showed similar results, with numbers of first generation migrants within each population ranging from 0 to 4 (~5% of the total number of colonies sampled) and likely dispersal distances ranging between 5 and 500 km.ConclusionThis study showed that population differentiation in P. damicornis varied over spatial scales and that this variability occurred at both evolutionary and ecological time scales. This paradox is discussed in light of stochastic recruitment and small scale population structures found in other species of coral. The study also identifies potential source reefs, such as those within Mnemba Conservation area near Zanzibar and genetically isolated reefs such as those within Malindi Marine National Park and Reserve in northern Kenya.

Highlights

Studies of population genetic structures provide an indication of direction and magnitude of larval transport and are an important component in the assessment of the ability of reefs to recover from severe disturbance
The poor condition of many of these reefs is attributable to the extreme El Ninõ event in 1998, which functionally destroyed approximately 16% of the world's coral reefs through bleaching-induced mass mortality
The results obtained from the present study revealed a more disordered genetic structure with no significant correlations between genetic and geographic distances at either of the two spatial scales

Summary

Introduction

Studies of population genetic structures provide an indication of direction and magnitude of larval transport and are an important component in the assessment of the ability of reefs to recover from severe disturbance. This paper reports data on population genetic structures in the coral Pocillopora damicornis from 26 reefs in Kenya and Tanzania. In 2004, slightly more than 40% of the reefs affected by the El Ninõ showed signs of recovery. Most of these reefs were exposed to minimal anthropogenic influence either (page number not for citation purposes). The results from population genetic studies provides information that can be incorporated into marine protected areas management strategies [10]

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