Aluana Gonçalves de Abreu

Genetic structure and gene flow among Brazilian populations of Heliothis virescens (Lepidoptera: Noctuidae).

ABSTRACT Population genetic studies are essential to the better application of pest management strategies, including the monitoring of the evolution of resistance to insecticides and genetically modified plants. Bacillus thuringiensis Berliner (Bt) crops have been instrumental in controlling tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), a pest that has developed resistance to many common insecticides once used for its management. In our study, microsatellite markers were applied to investigate the genetic structure and patterns of gene flow among Brazilian populations of H. virescens from cotton, Gossypium hirsutum L., and soybean, Glycine max (L.) Merr., fields, aiming to propose means to improve its management in the field. In total, 127 alleles were found across nine microsatellites loci for 205 individuals from 12 localities. Low levels of gene flow and moderate to great genetic structure were found for these populations. Host plant association, crop growing season, and geographic origin were not responsible for the genetic structuring among Brazilian populations of H. virescens. Other factors, such as demographic history and seasonal variability of intrapopulation genetic variation, were suggested to be molding the current pattern of genetic variability distribution.

Species delimitation of Cattleya coccinea and C. mantiqueirae (Orchidaceae): insights from phylogenetic and population genetics analyses

The high-altitude Southeastern Brazilian Cattleya coccinea clade includes two taxonomically challenging species, Cattleya coccinea and Cattleya mantiqueirae, the latter considered restricted to the mountain range of Serra da Mantiqueira. To hypothesize the existence of evolutionary independent lineages corresponding to these species, we inferred phylogenetic relationships and described patterns of population genetic diversity and structure of populations from six localities based on ISSR and cpDNA sequence data. Results do not support the species C. coccinea and C. mantiqueirae as previously circumscribed. Most analyses recovered southwestern and northeastern groups along the two mountain ranges, suggesting geography rather than morphology as an important criteria for species delimitation. However, due to the lack of information on the type locality of C. coccinea and the topological complexity of the southwestern area, the taxonomic circumscription of C. coccinea and C. mantiqueirae must be evaluated by additional population sampling. We also propose that the northeastern group comprise at least one distinct species. Also, specimens from Lima Duarte from Serra da Mantiqueira clearly do not belong to neither of the two groups and demand further investigation concerning a possible hybridization scenario of C. coccinea/C. mantiqueirae and C. brevipedunculata. Population genetic patterns of variation are in agreement with pollination observations for this group and with a drift-selection model of speciation. Owing to the high genetic differences among populations, with low levels of variation within populations, conservation priorities should favour protecting as many populations as possible.

Genetic diversity of Gossypium barbadense from the central Brazilian Amazon

The Amazon Basin is a center of diversity of Gossypium barbadense and the strategy for conservation of this genetic resource depends on the knowledge of the diversity maintained in Amazonas State. During two expeditions, in 2012 and 2014, plants were collected in ten municipalities in the state of Amazonas, in the central Brazilian Amazon region. The molecular diversity was estimated by SSR markers for 50 samples collected in 2012. The morphological diversity of 24 plants collected in 2014 was assessed ex situ and compared to that of 50 plants of the same and other cotton varieties from other Brazilian states. Most of plants evaluated in situ in Amazonas had purple petioles and veins (82%), associated to medicinal use, and kidney seeds (78%). The ex situ morphological analysies showed that G. barbadense plants from the Amazonas state: i) presented higher similarity to cotton plants from other northern Brazilian states, and ii) were grouped separately from those of other northern Brazilian states by descriptor analysis. Both the molecular (H=0.41) and morphological (H=0.38±0.02) diversity among the collected plants was considered intermediary. Our study indicates the distinctiveness of Amazon cottons, and contributes to demonstrate the discrimination power of multicategorical traits.