Elucidation of the mechanism of action of selfish genetic elements is difficult outside species with well-defined genetics. Male-killing, the phenomenon whereby inherited bacteria kill male hosts during embryogenesis, is thus uncharacterized in mechanistic terms despite being common and important in insects. We characterized the prevalence, identity and source of the male-killing infection recently discovered in Drosophila melanogaster in Brazil. Male-killing was found to be present in 2.3% of flies from Recife, Brazil, and was uniquely associated with the presence of Spiroplasma infection. The identity of sequences across part of the 16S and across the 16S-23S ITS region indicated that the male-killing infection of D. melanogaster was very closely related to S. poulsonii, the source of the male-killing infection in willistoni group flies also found in South America. The sequences of two further protein-coding genes indicated the D. melanogaster infection to be most closely related to that found in D. nebulosa, from the willistoni group. Our data suggest that the establishment of D. melanogaster in South America was associated with the movement of male-killing bacteria between species.

During Paleogene the Neotropical region was mainly covered by rainforests and ancient Amazon (AM) and Atlantic Forest (AF) were continuous and interconnected. The Andean uplift and drastic climate changes along the Eocene/Miocene resulted in the formation of a drier area separating AM from AF. However, multiple evidences have indicated recurrent connections between Neotropical rainforests during Quaternary. In this study we predict biogeographical connections between Neotropical Forests during the last glacial maximum (LGM-21 ka) and establish the climatic conditions that favored such connections. We tested if the general climatic conditions suitable to both Amazon (AM) and AF were uniform across current Cerrado and Caatinga areas or did subsets of these climatic spaces have independent spatial displacements connecting specific regions of AM and AF. For these, 50 occurrence points equidistant in the climatic space were sampled along the western and eastern AM and northern and southern AF and used to built ecological niche models (ENM) for each region. Potential distributions were predicted for the current and the LGM climatic scenarios using an ensemble approach. The ENMs detected the disjunct distribution of the two Neotropical rainforests in the present and showed three Electronic supplementary material The online version of this article (main connections during LGM: (1) climate suitable to western AM were detected along the northern coast of Brazil, overlapping the putative distribution of northern AF; (2) climates suitable to southern AF, northern AF and western AM were detected along the area now occupied by southern limits of the Caatinga and (3) the climate suitable to southern AF was found at the south limits of the eastern AM. Our findings suggest that subsets of both AM and AF may be considered distinct biogeographical units as implied by different responses to climate changes.

We conducted an isozyme study in 22 populations of five Pleurothallis (Orchidaceae) species (12 loci in nine enzymatic systems). The genetic variability in all populations is surprisingly high (P = 58-83%, A = 2.1-3.8, H(e) = 0.25-0.43) in spite of the fact that the five species are pollinated by small flies whose behavior enables self-pollination. We suggest that self-incompatibility, inbreeding depression, and mechanical barriers that prevent self-pollination in these species are responsible for the maintainance of the high genetic variability. These traits are uncommon in Orchidaceae, but have been observed in these and some other species pollinated by flies or other pollinators with behavior that facilitates self-pollination. The genetic similarity among conspecific populations is also high for species with very short-range flying pollinators. Only one population of P. teres presented values of genetic similarity lower than usually observed in allopatric conspecific populations. Morphology, however, does not support its segregation as a new taxon. All species can be recognized by their enzymatic patterns, and the results agree with recently proposed taxonomic realignments. Conversely, the supposed affinities among these species based on floral morphology are not supported, and we hypothesize that it may be due to convergence in species with similar pollinators.

Understanding the evolutionary processes from recent demographic history is especially difficult for interstitial organisms due to their poorly known natural history. In this study, the genetic variation and population history of the four Ototyphlonemertes (Diesing in Sitz ber Math Nat Kl Akad Wiss Wien 46:413-416, 1863) species were evaluated from samples collected along the Brazilian coast (between 27°31 0 S and 13°00 0 W) in 2006. The mitochondrial region cytochrome c oxidase subunit 3 (COX3) is analyzed to assess the genetic variation of these dioecious species. Although these species have a sympatric distribution along the coast, our data suggest that their levels of differentiation and their demographic histories differ sharply. There is strong evidence of gene flow among demes in O. erneba and O. evelinae, and their level of structuring is much lower than for the other two species. Indeed, the COX3 fragment reveals cryptic lineages in O. lactea and O. parmula. The results seem to contradict the high genetic structuring and low intrapopulational variability expected with the ecological constriction and habitat discontinuity faced by these organisms, meaning that there might be gene flow among populations or their dispersal capability has been underestimated.

Aim  The aim of this study was to assess the causal mechanisms underlying populational subdivision in Drosophila gouveai, a cactophilic species associated with xeric vegetation enclaves in eastern Brazil. A secondary aim was to investigate the genetic effects of Pleistocene climatic fluctuations on these environments. Location  Dry vegetation enclaves within the limits of the Cerrado domain in eastern Brazil. Methods  We determined the mitochondrial DNA haplotypes of 55 individuals (representing 12 populations) based on sequence data of a 483‐bp fragment from the cytochrome c oxidase subunit II (COII) gene. Phylogenetic and coalescent analyses were used to test for the occurrence of demographic events and to infer the time of divergence amongst genetically independent groups. Results  Our analyses revealed the existence of two divergent subclades (G1 and G2) plus an introgressed clade restricted to the southernmost range of D. gouveai. Subclades G1 and G2 displayed genetic footprints of range expansion and segregated geographical distributions in south‐eastern and some central highland regions, east and west of the Paraná River valley. Molecular dating indicated that the main demographic and diversification events occurred in the late to middle Pleistocene. Main conclusions  The phylogeographical and genetic patterns observed for D. gouveai in this study are consistent with changes in the distribution of dry vegetation in eastern Brazil. All of the estimates obtained by molecular dating indicate that range expansion and isolation pre‐dated the Last Glacial Maximum, occurring during the late to middle Pleistocene, and were probably triggered by climatic changes during the Pleistocene. The current patchy geographical distribution and population subdivision in D. gouveai is apparently closely linked to these past events.

Population genetic structure and genetic diversity levels are important issues to understand population dynamics and to guide forest management plans. The Brazil nut tree (Bertholletia excelsa Bonpl.) is an endemic species, widely distributed through Amazonian upland forests and also an important species for the local extractive economy. Our aim was to analyze the genetic structure of Brazil nut trees at both fine and large scales throughout the Amazon Basin, contributing to the knowledge base on this species and to generate information to support plans for its conservation. We genotyped individuals from nine sites distributed in five regions of the Brazilian Amazon using 11 microsatellite loci. We found an excess of heterozygotes in most populations, with significant negative inbreeding coefficients (f) for five of them and the finescale structure, when present, was very small. These results, as a consequence of self-incompatibility, indicate that conservation plans for B. excelsa must include the maintenance of genetic diversity within populations to ensure viable amounts of seeds for both economic purposes and for the local persistence of the species.

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