Gene diversity and mode of reproduction in the brooded larvae of the coral Heteroxenia fuscescens

Population genetics assessment of two pocilloporid coral species from the northern red sea: Implications for urbanized reef sustainability

Understanding the genetic makeup of key coral species is vital for effective coral reef management, as heightened genetic diversity directly influences long-term survival and resilience against environmental changes. This study focused on two widespread Indo-Pacific branching corals, Pocillopora damicornis (referred as Pocillopora cf. damicornis (as identified only morphologically) and Seriatopora hystrix, by genotyping 222 and 195 colonies, respectively, from 10 sites in the northern Gulf of Eilat, Red Sea, using six and five microsatellite markers, respectively. Both species exhibited low observed heterozygosity (0.47 for P. cf. damicornis, 0.32 for S. hystrix) and similar expected heterozygosity (0.576 for P. cf. damicornis, 0.578 for S. hystrix). Pocillopora cf. damicornis showed minimal deviations from Hardy-Weinberg equilibrium (HWE) and low but positive F values, indicating high gene flow, while S. hystrix exhibited higher diversion from HWE and positive F values, suggesting isolation by distance and possible non-random mating or genetic drift. As the Gulf of Eilat undergoes rapid urbanization, this study highlights the anthropogenic impacts on the population genetics of key ecosystem engineering species and emphasizes the importance of managing genetics of Marine Protected Areas while implementing active coral reef restoration. The differences in reproductive traits between the two species (S. hystrix being a brooder, while P. cf. damicornis a broadcast spawner), underscore the need for sustainable population genetics management of the coral reefs for the future and resilience of the coral reef ecosystem of the northern Red Sea region.

Yaron Fuchs: Exploring the mysterious mixture of life and death

Fuchs studies how cell death controls stem cell-driven processes.

Maternal-larval population genetic traits in Stylophora pistillata, a hermaphroditic brooding coral species

Aspects of maternal-planula larval genetics in the monoecious scleractinian coral Stylophora pistillata (Red Sea, Eilat) were studied by amplified fragment length polymorphism (AFLP) methodology in two successive reproductive seasons. In total, 293 planulae and 10 adult colonies were analyzed. In June 2006, 147 planulae were collected from 10 shallow water colonies. In March, April and June 2007, 146 additional planulae were sampled from five of the ten 2006 sampled colonies. All AFLP products showed unalike band profiles indicating a fully sexual production pattern. We used 181 and 210 putative AFLP loci, of which the overall level of polymorphism in 2006 was 92 and 99  % in 2007 (respectively). Differences were also observed between 2006 and 2007 reproductive seasons in terms of total average gene diversity (0.191 vs. 0.247, respectively), suggesting fast turnover of sperm donor genotypes. In addition, increased numbers of potential sperm donor colonies in the vicinity of gravid females showed no impact on genetic differentiation levels in released larvae. UPGMA tree revealed clustering of maternal genotypes and their offspring, suggesting, as expected, high relatedness between planulae and their mothers. In addition, the average heterozygosity of each group of siblings was persistently lower than heterozygosity calculated for the respective maternal colony, suggesting the possibility of partial inbreeding. This trend of reduced genetic heterogeneity in Stylophora pistillata is an alarming sign for populations residing in the northern Red Sea coral reefs.

Employing of the amplified fragment length polymorphism (AFLP) methodology as an efficient population genetic tool for symbiotic cnidarians

Although the use of molecular markers in population genetics of marine organisms is increasingly employed, methodologic limitations still hampered the research for some taxa, such as symbiotic cnidarians, including scleractinian corals. The development of molecular tools in scleractinian corals' studies is faced with a list of obstacles, such as high cost, labor, time consuming, contamination with foreign DNA, and markers with low resolution. The AFLP (amplified fragment length polymorphism) method, overcomes most of the obstacles listed above except of the difficulty of contamination by algal symbiont DNA. We compared the implication of two pre-DNA extraction treatments to obtain coral DNA free of algal contaminations, termed as CPEM, cell population enriched method, and TTEM, total tissue extraction method. The CPEM process result in pure coral DNA for all samples, but is time consuming, whereas in the TTEM process, approximately 25% to 18% of the samples are still contaminated by algal DNA. However, algal DNA contaminations in the PCR at 2.5 x 10(-1) ng level (approximately 100 algal cells) and below, did not amplify any new AFLP band or peak for neither radioactive nor florescence analyses. Therefore, even the TTEM process may be used because it is faster, easier to handle, and easily employed on a large amount of samples, with minimal contamination artifacts. When correctly employed, both methods are applicable to wide experimental manipulations.