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Restingas are sandy coastal plains that stand between the sea and the Brazilian Atlantic forest mountains. The predominant restinga vegetation type in northern Rio de Janeiro, Brazil, is characterized by the formation of islands that begins with colonization by some pioneer herbs and/or woody plants. Pioneer plants are stress-resistant and nurse many other less-resistant plant species. Determining the spatiotemporal variation in the dynamics of nurse plants is essential to understand the ecological functioning of restingas as a whole. The goal of this study was to analyze the spatiotemporal variation in population dynamics of the nurse bromeliad Aechmea nudicaulis. We monitored A. nudicaulis ramets in different habitats, microhabitats, and years. We analyzed the spatiotemporal variation in demographic traits and in population growth rate. Results showed young ramet traits were more variable at the microhabitat level, and when variable, vegetative ramet traits varied at all spatiotemporal scales. Overall, λ values indicated that A. nudicaulis basically remained spatiotemporally stable as most of the λ values did not significantly differ from unity. Hence, the stability of A. nudicaulis in different microhabitats and habitats in the restinga may create several settlement opportunities for many other less-resistant species.

Habitat selection by directional growth of plants has previously been investigated but field evidence for this phenomenon is extremely scarce. In this study we demonstrate directional clonal growth in Aechmea nudicaulis, a monocarpic, perennial bromeliad native to spatially heterogeneous sandy coastal plains (restinga) in Brazil. This habitat is characterized by a matrix of bare sand with interspersed vegetation islands. Due to very high soil surface temperatures and other stress factors such as drought, A. nudicaulis can only germinate inside vegetation islands. Nevertheless, this species is very common on bare sand. In this study we tested the hypothesis that clonal fragments occurring at the border and inside vegetation islands show habitat selection by growing preferentially towards the bare sand habitat (i.e. away from the center of vegetation islands).We randomly chose 116 clonal fragments in two distinct micro-environments (inside vegetation islands, and in the border area between bare sand and vegetation islands) in the natural habitat of A. nudicaulis and measured their growth direction in relation to the island center. We measured the growth directions of entire clonal fragments (defined as the line that connects the oldest and the youngest ramets of a clonal fragment) as well as the growth direction of the youngest internode on each fragment (the growth direction of the youngest ramet in relation to its parent ramet). We used Monte Carlo simulations to test for deviations from randomness in the growth direction of clonal fragments and individual internodes. The clonal fragments of A. nudicaulis showed a significant tendency to grow away from the center of vegetation islands. In other words, the main growth direction of clonal fragments growing inside vegetation islands or at the border between bare sand and vegetation islands was preferentially directed towards bare sand environments. Individual internodes at the border of vegetation islands also exhibited this tendency to grow towards the outside of vegetation islands, but internodes growing inside vegetation islands did not show directional growth. These results provide the first field evidence for habitat selection through directional growth of a clonal plant species.

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OBJECTIVE:To assess incidence and predictors of fi rst pregnancy among women with HIV/AIDS. METHODS:Prospective cohort study was conducted in Rio de Janeiro, southeastern Brazil, between 1996 and2003. This study comprised 225 women with HIV/AIDS followed up until their fi rst pregnancy or fi rst censored event (hysterectomy, tubal ligation, menopause, 50 years of age, loss to follow-up, death or the end of December 2003). Pregnancy and abortion rates were estimated, and Cox proportional hazards models were used to identify baseline characteristics associated with pregnancy risk. RESULTS:The women were followed up for 565 person/years with a median follow-up of 3 years per women. The mean age was 32 years (SD: 7), and 54.7% were white. There were 60 pregnancies in 39 women, and 18 were terminated (induced abortions), accounting for a rate of 6.9% and 2.1% women/ year, respectively. Repeated pregnancies occurred in 33.3% of the women (13/39). Higher pregnancy risk was seen among younger women (HR=3.42; 95%CI: 1.69;6.95) and those living with their partners (HR=1.89; 95%CI: 1.00;3.57). Lower pregnancy risk was associated with higher education level (HR=0.43; 95%CI: 0.19;0.99) and use of antiretroviral therapy (HR=061; 95%CI: 0.31;1.17). CONCLUSIONS:Lower pregnancy rates were found in our cohort than in the general population. Sociodemographic characteristics should be taken into consideration in the management of reproductive health in HIV-positive childbearing age women. Reproductive and family planning counseling must be incorporated into HIV/AIDS programs for women to help preventing HIV transmission to their partners and offspring.

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Sex-linked meiotic drive genes are expected to spread quickly in populations and may cause their extinction because of the lack of one sex. Theoretically, the most general evolutionary response to these genes is the spread of autosomal suppressors of meiotic drive because of Fisher's Principle, a mechanism of natural selection that would correct uneven sexual proportions. Such adaptive response depends on heritable autosomal variation for sexual proportion, which seems to be lacking in most species with chromosomal sex-determination. Natural populations of Drosophila mediopunctata bear sex-ratio X chromosomes ('SR'), an X-Y meiotic drive system that leads to female bias. In this paper we show that sexual proportion is highly heritable (h2 = 41 per cent) in experimental populations of this species because of autosomal genes, thus fulfilling the conditions for adaptive evolution of sexual proportion. The spread of autosomal suppressors is expected to have a dual effect on sexual proportion, reducing both the female excess in the progenies of SR/Y males and the frequency of SR chromosomes. Hence, prior to the spread of their suppressors, SR chromosomes presumably attained a high frequency in natural populations of D. mediopunctata, causing a strong female bias.

Although plant demography, genetics and reproduction are inter-related processes, few studies on rare tropical plants have attempted to integrate them. We used an integrated approach to study two endangered Neoregelia spp. from the Brazilian Atlantic Forest. The floral phenotypes of N. ibitipocensis and N. oligantha are similar, and both species are visited and pollinated only by bumblebees. Flowers of N. ibitipocensis secrete copious nectar, which bees can access only by forcing the corolla to open, whereas flowers of N. oligantha are nectarless. Neoregelia ibitipocensis is self-incompatible and pollen-limited, whereas N. oligantha is self-compatible and sets fruits spontaneously. Population growth rates indicate an increasing population size for both species, although to a lesser extent for N. oligantha. Genetic diversity as a whole was moderate; Bayesian analysis indicated a spatially structured cluster for N. ibitipocensis populations, and genetic diversity was scattered across the distribution of N. oligantha. Despite these differences, vegetative reproduction via clonal growth was the main component of population structuring in both species. Limited seed production in N. ibitipocensis and the risk of genetic drift in N. oligantha seem to be the main threats to their persistence.