Forecasting effects of climate changes on the population genetic structure of Anacardium occidentale in the Cerrado biome, Brazil.

There has been a continuous interest in understanding the patterns of genetic diversity in natural populations because of the role of intraspecific genetic diversity as the basis of all evolutionary change and thus, its potential effects on population persistence when facing environmental changes. Here, we provided the first description of genetic diversity distribution and population structure of Anacardium occidentale L. (cashew) from the Brazilian Cerrado, one of the most economically important tropical crops in the world. We applied Bayesian clustering approaches (STRUCTURE and POPS) that allow predicting the effects of future climatic changes on the population genetic structure of A. occidentale. We identified distinct genetic groups corresponding to the southwestern, central, and northern regions of the species' range. The characterized genetic clusters will disappear under future climate change scenarios, leading to a homogenization of genetic variability across the landscape. Our findings suggest a high likelihood for the loss of genetic diversity, which in turn will reduce the evolutionary potential of the species to cope with predicted future climatic changes. Results from this study may help develop management strategies to conserve the genetic diversity and structure of natural cashew populations.

Genetic analysis of a local population of Oryza glumaepatula using SSR markers: implications for management and conservation programs.

Knowledge of natural diversity and population structures of wild species, which might be related to cultivated species, is fundamental for conservation and breeding purposes. In this study, a genetic characterization of a large population of Oryza glumaepatula, occurring in a 10 km(2) area located at Tamengo Basin (Paraguay River, Brazil), was performed using SSR markers. This population is annually dragged from the river to permit navigation; one goal of this study was to examine the impact of this removal on genetic variability. From 18 polymorphic SSR markers, a total of 190 alleles were detected in a sample of 126 individuals, with an average of 10.3 alleles/locus, and a H(e) of 0.67. The five QTL-related markers showed an average H(e) value of 0.56, while the remaining 13 markers detected an average estimate of 0.70. An apparent outcrossing rate of 30%, a high proportion of alleles at low frequencies (56%), and the presence of exclusive alleles (9.5%) were found, with strong evidence of the establishment of individuals from different populations upstream in the Paraguay River. For conservation purposes, the river drag has no effect on the population. However, periodical seed collection from the Corumbá population can preserve part of the genetic variability present in upstream populations reducing the need for upriver collecting expeditions.

Macroevolutionary dynamics and comparative methods of morphological diversification

Among the comparative approaches that have been used to understand the patterns of morphologicaldiversification, those related to the detection and evaluation of large-scale evolutionary trends have recentlybeen highlighted. A new method known as the analysis of skewness (ANSKEW) allows partitioning betweenthe passive and driven trends associated with the random occupation of a bounded morphological spaceand a single morphological attractor, respectively. This partitioning provides a better understanding of therelative role of processes that occur at distinct hierarchical levels associated with the macroevolutionarytrends of morphological diversification. In this paper, we used this new approach to understand the patternsof morphological diversification in Erodiscini (Coleoptera, Curculionidae, Otidocephalinae) beetles. Whengenera were used as subclades, ANSKEW revealed that 19.9% of the body size variation in the Erodiscini wasattributable to driven trends, i.e., a morphological attractor, whereas 80.1% of the variation was attributableto the occupation of different adaptive zones by distinct subclades (a passive process), with the passivecomponents being significant (based on 5,000 bootstrap samples). This simple approach to partitioningprovided insights into the intrinsic dynamics of body size evolution in this group without the need to considerexplicit phylogenetic structures. Such analyses could provide a starting point for further evaluation of adaptivevariation at multiple hierarchical levels and of the processes underlying the relationship between variationin body size and other ecological, physiological and behavioral aspects.