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Habitat fragmentation is considered an important threat to biodiversity, increasing species exposure to edge effects. The Brazilian Cerrado savanna is considered a biodiversity hotspot and has been converted to small, isolated fragments due to human activities. Ant communities and colony survivorship are known to be affected by edge effects in Cerrado, but to date there is no information on the genetic diversity of ant colonies at the edge of fragmented areas. Here, we investigate if colony genetic diversity and structure of Odontomachus chelifer (Latreille) ants (Hymenoptera: Formicidae) are subject to edge effects in a Cerrado reserve in southeast Brazil. Using microsatellites, we evaluated the number of breeders (queens and males) and the genetic diversity in O. chelifer colonies located in the interior versus edge of a Cerrado fragment. All O. chelifer nests had multiple queens, which presented a low mating frequency. The number of breeders and most estimates of genetic diversity did not differ between colonies at the edge versus interior of the fragment. Genetic structure was not influenced by nest location as well. However, we detected a small and positive increase in the observed heterozygosity in colonies located at fragment edges. High heterozygosity is thought to be particularly important in fast-changing environments, such as edges, providing an advantage for genetic diversity. Further investigation is needed to assess in greater detail how habitat loss affects O. chelifer biology. Our study is a first step toward elucidating edge effects on genetic diversity of ant colonies, a topic still poorly explored in tropical environments. [ABSTRACT FROM AUTHOR]

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We studied the Red-billed Currasow (Crax blumenbachii) in Vale Natural Reserve, Linhares, Espírito Santo State, Brazil, using camera traps. We found the Red-billed Curassow present in the entire area of the reserve (~ 22,000 ha) during 40 months of camera trapping (2005-2008). Most records were of single individuals, especially males, but pairs and even groups of individuals were also recorded. Males were paired with one and two females, suggesting polygyny in the species. The species was recorded throughout the day with one peak from 0500 to 0600 hrs and another after 1600 hrs. The daily activity pattern was similar for males and females. The number and widespread nature of the records suggests the local population of this species may be higher than previously thought. [ABSTRACT FROM AUTHOR]

The tuco-tuco das dunas (Ctenomys flamarioni) is a subterranean rodent endemic to sand-dune ecosystems along the southern coast of Brazil. We studied 3 populations that differed in the degree of human impact, and used direct and indirect methods to assess demographic and genetic information. Field studies revealed a tendency toward a female-biased sex ratio, and sexual dimorphism in both weight and length in all 3 populations. This evidence supports a hypothesis of polygyny in C. flamarioni. Using 9 microsatellite loci, we explored patterns of variation and genetic structure among the populations. Our findings suggested that the Xangri-hi and Remanso populations, living in more-disturbed locations, could have experienced demographic reductions in population size, but not the Pinhal population. However, other factors such as a polygynous breeding system and the environmental instability that characterizes the coastal dunes may have influenced the observed pattern. Analysis of genetic structure revealed strong differentiation among populations, but no significant structure at the intrapopulation level, Nonsignificant values for the tested indices from assignment tests (FST, FIS, MAIc, and vAlc) over population showed no evidence of sex-biased dispersal. The same was observed from analyses of molecular variance. Nevertheless, lower pairwise FST and higher Nm values between males from Xangri-á and Remanso indicated greater gene flow among males, suggesting a slightly male-biased dispersal pattern. Significant differences in interpopulation dispersal patterns were clearer among females, with greater dispersal for females from Pinhal than those at Remanso and Xangri-lá. [ABSTRACT FROM AUTHOR]

Gnamptogenys striatula is a polygynous ant species, in which all workers are potentially able to mate. The reproductive status, relatedness and pedigree relationships among nestmate queens and winged females in a Brazilian population were investigated. We collected all the sexual females of 12 colonies (2–44 queens per colony, plus 2–18 winged females in 3 colonies). Dissections revealed that 98% of the queens were inseminated and that the queens in the most polygynous colonies did not lay equal numbers of eggs. The sexual females and a sample of the population were genotyped using eight microsatellite markers. Relatedness among nestmate queens was among the highest recorded to date (0.65±0.25), and tests of pedigree relationship showed that they were likely to be full-sisters, and sometimes cousins. Mated winged females were always full-sisters, the estimated genetically effective queen numbers were low and tests of pedigree relationship showed that only a few queens in the colony could be the mothers. These results suggest that the high queen-queen relatedness in polygynous colonies of G. striatula is maintained by an unusual mechanism: winged females are mostly produced by only one or a few queens, and these groups of full-sisters are recruited back into their original nest after mating. [ABSTRACT FROM AUTHOR]

A polymorphic microsatellite locus was isolated and characterized fromPolybia paulista, one of the most common polygynic, swarm-founding social wasps in Brazil. Three other microsatellite loci for which the primer sets were originally developed in independent-founding paper wasps also showed polymorphism in the size of amplification products inP. paulista. [ABSTRACT FROM AUTHOR]

Social insects face strong selection from parasites because the conditions of group living often favor the transmission of infection among nestmates. However, there is little detailed information on the effects of parasite infection in the host species. Workers of Polybia species, neotropical swarm-founding wasps, are commonly infected by gregarines, protozoans that are exclusively parasitic on invertebrates. Previous studies showed that high rates of gregarine infection in workers of Polybia occidentalis (Olivier) have negative effects on their colony performance. However, the effect of seasonality on infection rates throughout the year or between wet and dry seasons has not been examined. Host-parasite interactions cannot be understood without consideration of the overall population dynamic. We compared rates of gregarine infection in workers of Polybia paulista (Ihering) between wet and dry seasons and among months. The 35% rate was by far the highest of the four wet seasons sampled, but the rates declined in the mid-wet season and were very low during the dry season. Strong seasonal differences in infection rates were also observed between the dry and wet seasons. Several potential factors affecting the seasonal differences are discussed.