Brachyplatystoma platynemum is a catfish species widely distributed in the Amazon basin. Despite being considered of little commercial interest, the decline in other fish populations has contributed to the increase in the catches of this species. The structure, population genetic variability, and evolutionary process that have driven the diversification of this species are presently unknown. Considering that, in order to better understand the genetic structure of this species, we analyzed individuals from seven locations of the Amazon basin using eight molecular markers: control region and cytochrome b mtDNA sequences, and a set of six nuclear microsatellite loci. The results show high levels of haplotype diversity and point to the occurrence of two structured populations (Amazon River and the Madeira River) with high values for FST. Divergence time estimates based on mtDNA indicated that these populations diverged about 1.0 Mya (0.2–2.5 Mya 95% HPD) using cytochrome b and 1.4 Mya (0.2–2.7 Mya 95% HPD) using control region. During that time, the influence of climate changes and hydrological events such as sea level oscillations and drainage isolation as a result of geological processes in the Pleistocene may have contributed to the current structure of B. platynemum populations, as well as of differences in water chemistry in Madeira River. The strong genetic structure and the time of genetic divergence estimated for the groups may indicate the existence of strong structure populations of B. platynemum in the Amazon basin.
• Premise of the study: Microsatellite loci were developed for tucumã of Amazonas (Astrocaryum aculeatum), and cross‐species amplification was performed in six other Arecaceae, to investigate genetic diversity and population structure and to provide support for natural populations management.• Methods and Results: Fourteen microsatellite loci were isolated from a microsatellite‐enriched genomic library and used to characterize two wild populations of tucumã of Amazonas (Manaus and Manicoré cities). The investigated loci displayed high polymorphism for both A. aculeatum populations, with a mean observed heterozygosity of 0.498. Amplification rates ranging from 50% to 93% were found for four Astrocaryum species and two additional species of Arecaceae.• Conclusions: The information derived from the microsatellite markers developed here provides significant gains in conserved allelic richness and supports the implementation of several molecular breeding strategies for the Amazonian tucumã.
Anopheles darlingi is a major human malaria vector in the Neotropics. Twenty-four polymorphic microsatellite loci were isolated and characterized in 21-32 individuals collected in Coari (Amazonas, Brazil). The number of alleles per locus ranged from 4 to 11 (average of 7.667). The observed heterozygosity (H O ) varied between 0.037 and 0.833 (average of 0.500), while the expected heterozygosity (H E ) ranged from 0.177 to 0.871 (average of 0.723). Thirteen loci showed a significant deviation from HWE. No linkage disequilibrium was found between the loci.Keywords Anopheles darlingi Á Microsatellites Á Malaria vector Á Amazon Basin Anopheles (Nyssorhynchus) darlingi is the major and the most anthropophilic and endophagic malaria vector in the Brazilian Amazon Basin (Tadei et al. 1998). It is also a significant vector in other countries in South America such as Peru, Colombia and Suriname (Vittor et al. 2006). Although morphology and genetics variation had been described suggesting that A. darlingi is a species complex (Freitas-Sibajev et al. 1995), morphometric and genetic analyses using isozymes, RAPD and ITS2 demonstrated the existence of a single species (Manguin et al. 1999). Studies using mitochondrial and nuclear DNA markers provide support for moderate level of population genetic structure (Mirabello and Conn 2006;Scarpassa and Conn 2007;Mirabello et al. 2008).Eight microsatellite loci were characterized (Conn et al. 2001) but the development of new markers would improve genetic population studies, gene mapping and QTL analysis in this vector. This study reports the isolation and characterization of new 24 microsatellite markers for A. darlingi and cross-amplification in three con-generic species.A genomic library enriched with microsatellite DNA of A. darlingi was constructed (Billotte et al. 1999) from the Genomic DNA extracted (Wilkerson et al. 1995) using a pool of 10 A. darlingi adult specimens newly hatched and unfed collected in Coari, Amazonas, Brazil. The DNA was digested with RsaI restriction enzyme (Invitrogen), and linked to RSA21 and RSA25 adapters. Microsatellite DNA fragments were selected by hybridization with (CT) 8 and (GT) 8 repeats biotin-linked probes and recovered with streptavidin-linked particles (Promega). Selected fragments were linked into a pGEM-T vector (Promega), transformed into Escherichia coli XL1-blue competent cells and inoculated into plates with X-Gal/IPTG/LB agar. After the growth at 37°C the white colonies were transferred onto
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