Development of microsatellite markers for the neotropical tree species Dipteryx alata (Fabaceae).

PREMISE OF THE STUDY: Microsatellite markers were developed for the population genetic analyses of the neotropical tree Dipteryx alata (Fabaceae). METHODS AND RESULTS: Microsatellites were developed from a genomic shotgun library. Polymorphism at each microsatellite loci was analyzed based on 94 individuals from three populations. Eight loci amplified successfully and presented one to 10 alleles, and expected heterozygosities ranged from 0.097 to 0.862. Four loci also amplified in Pterodon emarginatus and presented similar polymorphism. CONCLUSION: The eight microsatellite primer pairs are potentially suitable for population genetic studies and successfully amplified in another Fabaceae species.

Landscape conservation genetics of Dipteryx alata ("baru" tree: Fabaceae) from Cerrado region of central Brazil.

In this paper random amplified polymorphic DNA (RAPD) was used to evaluate the degree of among-population differentiation and associated spatial patterns of genetic divergence for Dipteryx alata Vogel populations from Cerrado region of central Brazil, furnishing support for future programs of conservation of this species. We analyzed patterns of genetic and spatial population structure using 45 RAPD loci scored for 309 trees, sampled from five different regions with two populations each. Genetic structure analysis suggested that panmixia null hypothesis can be rejected, with significant among-population components of 15%. Hierarchical partition by Analysis of Molecular Variance (AMOVA) shows that 5% of genetic variation is within regions, whereas 10% of variation is among regions, and these results were confirmed by a Bayesian analyses on HICKORY. The Mantel correlogram revealed that this divergence is spatially structured, so that local populations situated at short geographic distances could not be considered independent units for conservation and management. However, genetic discontinuities among populations were found in the northwest and southeast parts of the study area, corresponding to regions of recent socio-economic expansion and high population density, respectively. Taking both geographic distances and genetic discontinuities into account it is possible to establish a group of population to be conserved, covering most of D. alata geographic distribution and congruent with previously established priority areas for conservation in the Cerrado region.

RAPD variation and population genetic structure of Physalaemus cuvieri (Anura: Leptodactylidae) in Central Brazil.

Studies about the organization of the genetic variability and population structure in natural populations are used either to understand microevolutionary processes or the effects of isolation by human-inducted landscape modifications. In this paper, we analyzed patterns of genetic population structure using 126 RAPD loci scored for 214 individuals of Physalaemus cuvieri, sampled from 18 local populations. Around 97% of these loci were polymorphic. The among-population variation component (Phi(ST)) obtained by AMOVA was equal to 0.101 and theta B obtained using a Bayesian approach for dominant markers was 0.103. Genetic divergence, analyzed by Mantel spatial correlogram, revealed only a short-distance significant correlation between genetic and geographic distances. This is expected if low levels of population differentiation, due to high abundance buffering the effect of stochastic processes, are combined with low spatially restricted gene flow. Although this may be consistent with the current knowledge of species' biology, the spatial distribution of local populations observed in this study also suggest that, at least in part, recent human occupation and habitat fragmentation may also explain part of the interpopulational component of the genetic variation.