Genetic structure of red-handed howler monkey populations in the fragmented landscape of Eastern Brazilian Amazonia

We genotyped 15 microsatellite loci in order to evaluate the effects of habitat fragmentation, caused by flooding of the Tucuruí reservoir, on the genetic structure of Alouatta belzebul in eastern Amazonia. The analysis included two populations sampled in 1984, representing both margins of the Tocantins river, and three populations sampled 18 years later. Minimal differences in the diversity levels between present-day (Ho = 0.62-0.69 and AR = 6.07-7.21) and pre-flooding (Ho = 0.60-0.62 and AR = 6.27-6.77) populations indicated there was no significant loss of genetic variability, possibly because of successful management strategies applied during the flooding. The changes observed were limited to shifts in the composition of alleles, which presumably reflect the admixture of subpopulations during flooding. Given this, there were significant differences in the Rst values (p = 0.05) in all but one between-site comparison. Both present-day and original populations showed a deficit of heterozygotes, which suggests that this may be typical of the species, at least at a local level, perhaps because of specific ecological characteristics. The relatively large number of private alleles recorded in all populations may be a consequence of the Wahlund effect resulting from population admixture or a process of expansion rather than the loss of rare alleles through genetic drift. Additionally, the levels of genetic variability observed in this study were higher than those reported for other species of Neotropical primates, suggesting good fitness levels in these A. belzebul populations. Regular genetic monitoring of remnant populations, especially on islands, should nevertheless be an integral component of long-term management strategies.

Assessing the genetic structure of Oryza glumaepatula populations with isozyme markers

To assess the genetic diversity and genetic structure parameters, nine populations of Oryza glumaepatula from the Amazon biome, four from the Pantanal biome, and one collected at Rio Xingu, Mato Grosso, totaling 14 populations and 333 individuals were studied with isozyme markers. Six loci were evaluated showing a moderate allozyme variability (A = 1.21, P = 20.7%, H_o = 0.005, H_e = 0.060). The populations from the Pantanal biome showed higher diversity levels than the Amazon biome. High genetic differentiation among the populations, expected for self-fertilizing species, was observed (F_ST=0.763), with lower differentiation found among the Pantanal populations (F_ST=0.501). The average apparent outcrossing rate was higher for the Pantanal populations (t _a = 0.092) than for the Amazonian populations (t _a = 0.003), while the average for the 14 populations was 0.047, in accordance with a self-fertilization mating system.

Can Lutjanus purpureus (South red snapper) be "legally" considered a red snapper (Lutjanus campechanus)?

Red snappers (Lutjanus purpureus in Brazil and Lutjanus campechanus in USA and Gulf of Mexico) are both under clear effect of overfishing. Because of their high morphological similarity it has already been suggested that they could possibly be considered as a single species. To investigate the degree of similarity and the genetic structure of red snapper populations we constructed a common dataset of partial D-loop mtDNA sequences of L. purpureus from Brazil (Amapá, Pará and Maranhão) and L. campechanus from the Atlantic coast of the USA (Florida, Louisiana and Mississippi). Phylogenetic and population genetic analyses surprisingly depicted high similarity between L. campechanus and L. purpureus, compatible with the hypothesis of a single species of red snapper for the Western Atlantic Ocean. These preliminary but very curious findings open an important discussion regarding the legislation involved on the capture of this overexploited fish resources as well as regarding their taxonomy.

Estruturação morfológica e gênica das populações de Corallus hortulanus (Linnaeus, 1758) (Serpentes, Boidae) ao sul da bacia Amazônica, Brasil

Corallus hortulanus é uma espécie conhecida por apresentar grande variação no padrão de coloração e desenho, além de apresentar a maior distribuição geográfica e ecológica dentre as serpentes Neotropicais. O objetivo deste trabalho foi determinar a variação morfológica nos padrões de cor e desenho, verificar se estes padrões estão relacionados à presença dos rios amazônicos, verificar o grau de estruturação genética entre as populações de C. hortulanus ao longo de sua distribuição e verificar se os principais interflúvios ao sul da bacia amazônica representam populações geneticamente estruturadas. Foram analisados as cores e desenhos de 125 espécimes e geradas 103 sequências de Citb e 38 de COI. Um total de seis morfotipos foram descritos para as populações ao sul do Rio Amazonas. Verificou-se que os rios ao sul do Rio Amazonas apresentaram um padrão misto, onde Tocantins, Xingu e Madeira não influenciaram na estruturação genética, enquanto que os rios Purus e Tapajós se apresentaram como barreira geográfica para as populações de C. hortulanus, sendo que apenas em um caso a estruturação é encontrada em todas as análises (Purus).