Abstract
Quantifying the genetic diversity in natural populations is crucial to address ecological and evolutionary questions. Despite recent advances in whole-genome sequencing, microsatellite markers have remained one of the most powerful tools for a myriad of population genetic approaches. Here, we used the 454 sequencing technique to develop microsatellite loci in the fire coral Millepora platyphylla, an important reef-builder of Indo-Pacific reefs. We tested the cross-species amplification of these loci in five other species of the genus Millepora and analysed its success in correlation with the genetic distances between species using mitochondrial 16S sequences. We succeeded in discovering fifteen microsatellite loci in our target species M. platyphylla, among which twelve were polymorphic with 2–13 alleles and a mean observed heterozygosity of 0.411. Cross-species amplification in the five other Millepora species revealed a high probability of amplification success (71%) and polymorphism (59%) of the loci. Our results show no evidence of decreased heterozygosity with increasing genetic distance. However, only one locus enabled measures of genetic diversity in the Caribbean species M. complanata due to high proportions of null alleles for most of the microsatellites. This result indicates that our novel markers may only be useful for the Indo-Pacific species of Millepora. Measures of genetic diversity revealed significant linkage disequilibrium, moderate levels of observed heterozygosity (0.323–0.496) and heterozygote deficiencies for the Indo-Pacific species. The accessibility to new polymorphic microsatellite markers for hydrozoan Millepora species creates new opportunities for future research on processes driving the complexity of their colonisation success on many Indo-Pacific reefs.
Highlights
Coral reefs are increasingly threatened by chronic and acute stressors (Bellwood et al, 2004) and are expected to be highly vulnerable to future climate change due to rapidly increasingHow to cite this article Dubé et al (2017), Genetic diversity and differentiation in reef-building Millepora species, as revealed by crossspecies amplification of fifteen novel microsatellite loci
Our results show that most of our microsatellite markers are not useful to estimate the genetic diversity in the Caribbean species M. complanata due to the high proportion of null alleles
This study highlights the utility of cross-species amplification of microsatellites in assessing population genetics of the Millepora genus in the Indo-Pacific region
Summary
Coral reefs are increasingly threatened by chronic and acute stressors (Bellwood et al, 2004) and are expected to be highly vulnerable to future climate change due to rapidly increasingHow to cite this article Dubé et al (2017), Genetic diversity and differentiation in reef-building Millepora species, as revealed by crossspecies amplification of fifteen novel microsatellite loci. These anthropogenic disturbances can further change the biodiversity in coral reefs and may hamper their capacity to deliver important sources of ecosystem services to millions of people (Wilkinson, 2008; Cardinale et al, 2012). For long-live sessile organisms, such as reef-building corals, patterns of genetic diversity at both local and global scales are highly governed by the dispersal of sexual larvae (Baird, Guest & Willis, 2009; Harrison, 2011). The degree of genetic variation in partially clonal reef organisms is heavily influenced by the relative contribution from sexual and asexual reproduction for local population maintenance (e.g., Baums, Miller & Hellberg, 2006; Pinzón et al, 2012; Adjeroud et al, 2014). While our understanding of population genetics in scleractinian corals has improved considerably over the last decade, such information remains unavailable for Millepora hydrocorals (‘fire corals’)
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