Marie-Hélène Chevallier

Isolation and characterization of microsatellite markers of an endangered tropical tree, Sideroxylon majus, and cross-species amplification in other Sapotaceae species

Sideroxylon majus (Sapotaceae) is an endangered endemic tree of La Réunion Island that has suffered from human actions. It is present in small and isolated populations that encounter severe difficulties to regenerate. To have powerful tools for population genetic studies, we have isolated and characterized 14 polymorphic microsatellite markers from S. majus. The 14 loci were tested on 57 individuals from 6 populations. The number of alleles per locus varied from 2 to 20, with an average of 11.8. The observed and expected heterozygosity levels ranged from 0.053 to 1.000, and 0.116 to 0.917, respectively. Six of the 14 loci deviated from Hardy–Weinberg equilibrium. These polymorphic microsatellite markers constitute new tools to study the genetic diversity and spatial genetic structure of S. majus. The cross-species amplifications indicate that most of these loci can be used to investigate population genetic structure in S. grandiflorum, S. boutonianum and S. sessiliflorum. These studies will provide useful results for the elaboration of effective conservation strategies.

Microsatellites in the Tree Foetidia mauritiana (Lecythidaceae) and Utility in Other Foetidia Taxa from the Mascarene Islands

Premise of the study: Polymorphic markers were required for a native tree of the Mascarene Islands, Foetidia mauritiana (Lecythidaceae), to investigate the effects of fragmentation of lowland tropical habitats on tree mating systems and on gene flow. Methods and Results: Using microsatellite enrichment and next-generation sequencing, we identified 13 microsatellite loci (dinucleotide repeats). They were highly polymorphic in 121 trees sampled in the largest three populations on Réunion, revealing 2–17 different alleles per locus. Furthermore, they were found to be polymorphic in conspecific populations on Mauritius and in F. rodriguesiana from Rodrigues. Conclusions: These results indicate the utility of these markers to investigate genetic diversity, mating systems, and gene flow in a genus native to the biodiversity hotspot of Madagascar and the Indian Ocean islands.

Isolation and Characterization of Microsatellite Markers for Mimusops balata (Sapotaceae) and Cross-Amplification in Other Mimusops Species

Mimusops balata (Sapotaceae) is an endemic tree species from La Réunion and Mauritius. Like many species growing in lowland forests in La Réunion, it has suffered from human disturbances. We developed twelve microsatellite markers for M. balata and tested cross-amplification in five other Mimusops species to have powerful tools for genetic diversity studies. Genotyping peaks were of very low quality for two loci and were consequently abandoned for the genetic diversity analyses. Ten microsatellite loci were tested on 34 individuals of M. balata from two natural populations. The number of alleles per locus ranged from one to seven. The observed and expected heterozygosity levels varied from 0.000 to 0.823, and from 0.000 to 0.812 respectively. Two loci deviated from the Hardy-Weinberg equilibrium. The presence of null alleles was detected for one of these two loci. Nine to ten loci cross-amplified reliably in Mauritian species, for the other three species, four to six loci show successful amplifications. These polymorphic microsatellite markers are now available for population genetic investigations in Mimusops species aiming to establish accurate guidelines for conservation managers.