333 research outputs found

    Response of wet forest butterflies to selective logging in Kalakad–Mundanthurai Tiger Reserve: Implications for conservation

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    The butterfly fauna of an unlogged wet evergreen site in Kalakad–Mundanthurai Tiger Reserve was compared with that of an adjoining 30-year-old selectively logged site. Comparison of the vegetation structure of both sites showed that the canopy was less contiguous and the ground cover was higher in the logged site. Species richness, abundance, and diversity of butterflies were higher in the selectively logged site. Species abundance in both forests types fitted log series distribution, which indicates that only a small portion of the assemblage occur in high abundance. Examination of habitat usage by the butterflies showed that the logged forest harbored a greater number of ubiquitous species along with the wet forest assemblage. Few species like Idea malabarica showed restraint in logged site, while there was a release of few other species in logged site. Implications of these results for butterfly conservation are discussed

    Breeding systems and pollination modes of understorey shrubs in a medium elevation wet evergreen forest, southern Western Ghats, India

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    This study on the reproductive biology and pollination modes of 22 species of understorey shrubs in 11 families was conducted in a medium elevation wet evergreen forest in the southern Western Ghats of India from 1994 to 1997. We evaluated whether this assemblage was predominantly outcrossing as in other tropical forests, and whether mating systems are related to pollination mode. We assessed whether species were hermaphrodites, dioecious or monecious. We assessed the breeding systems of each species with hand self pollinations. About 55% of the species produced small white and inconspicuous flowers. The majority of the flowers opened at dawn and was visited by diurnal pollinators. The proportion of dioecious and monoecious species was lower than for other tropical forests. Among the hermaphrodites, the majority had mixed mating systems. Therefore the overall levels of obligate outcrossers (37%) were low compared with other tropical forests. We recognized 7 pollination modes: social bees, solitary bees, diverse insects, flies, sunbird, sphingid moth and Xylocopa sp. Among these the social bees, flies and diverse insects visited more species than the other groups. Species pollinated by flies and diverse insects tended to be significantly more outcrossing than those pollinated by bees and other solitary pollinators

    Dispersal modes of tree species in the wet forests of southern Western Ghats

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    Dispersal modes of tree species in a wet evergreen forest at Kakachi in the Kalakad–Mundanthurai Tiger Reserve, southern India are described here. Frugivore visitors to 82 tree species were observed. Biotic agents involved in seed dispersal and seed predation were six species of birds and five species of mammals. Birddispersed species were the most common species (59%), followed by mammal-dispersed species (26%). Primates were less important than bats and civets in seed dispersal. Fifteen per cent of the species had no apparent adaptation for abiotic dispersal (mechanically dispersed) except one wind-dispersed species. Many bird-dispersed species occurred at low density but the total density of bird-dispersed species compares with that of mammal and mechanically dispersed species. Edge or gap habitat species were less abundant than the closed forest ones in all three types of dispersal modes. Species level comparison with other wet forest sites indicates a high degree of similarity between Kakachi and La Selva in central America

    Avian blood parasites in an endangered columbid: Leucocytozoon marchouxi in the Mauritian Pink Pigeon Columba mayeri

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    There is increasing evidence that pathogens can play a significant role in species decline. This study of a complete free-living species reveals a cost of blood parasitism to an endangered host, the Pink Pigeon Columba mayeri, endemic to Mauritius. We investigated the prevalence and effect of infection of the blood parasite, Leucocytozoon marchouxi, in the free-living Pink Pigeon population. Overall, L. marchouxi infection prevalence detected was 18·3%. Juveniles were more likely to be infected than older birds and there was geographical variation in infection prevalence. Survival of birds infected with L. marchouxi was lower than that of uninfected birds to 90 days post-sampling. This study suggests that while common haematozoa are well tolerated in healthy adults, these parasites may have greater pathogenic potential in susceptible juveniles. The study is unusual given its completeness of species sampling (96%) within a short time-period, the accurate host age data, and its focus on blood parasites in a threatened bird species. Species for which long-term life-history data are available for every individual serve as valuable models for dissecting the contribution of particular pathogens to species decline

    Does haemosporidian infection affect hematological and biochemical profiles of the endangered Black-fronted piping-guan (Aburria jacutinga)?

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    Infectious diseases can cause deleterious effects on bird species, leading to population decline and extinction. Haemosporidia can be recognized by their negative effects on host fitness, including reproductive success and immune responses. In captivity, outbreaks of haemosporidian infection have been observed in birds in zoos and aviaries. The endemic Brazilian Atlantic rainforest species Aburria jacutinga is one of the most endangered species in the Cracidae family, and wild populations of this species are currently found mainly in conservation areas in only two Brazilian states. In this study, we aimed to evaluate the effects of avian haemosporidia on hematological and biochemical parameters in two captive populations of A. jacutinga. Forty-two animals were assessed, and the haemosporidian prevalence was similar for males and females. The occurrence of haemosporidian infection in captive A. jacutinga observed in this study was similar to results found in other captive and wild birds in Brazil. We found three different lineages of haemosporidia. Two lineages were identified as Plasmodium sp., one of which was previously detected in Europe and Asia, and the other is a new lineage closely related to P. gallinaceum. A new third lineage was identified as Haemoproteus sp. We found no significant differences in hematological and biochemical values between infected and non-infected birds, and the haemosporidian lineage did not seem to have an impact on the clinical and physiological parameters of A. jacutinga. This is the first report on an evaluation of natural haemosporidian infections diagnosed by microscopic and molecular methods in A. jacutinga by hematology, blood biochemistry, and serum protein values. Determining physiological parameters, occurrence and an estimation of the impact of haemosporidia in endangered avian species may contribute to the management of species rehabilitation and conservation

    Seaweeds in two oceans: beta-diversity

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    Several species assembly mechanisms have been proposed to structure ecological communities. We assess the biogeography of seaweeds along 2,900 km of South Africa’s coastline in relation to a thermal gradient produced by the Agulhas Current, and contrast this with the environmental structure created by the Benguela Current. We subdivided the coastline into “bioregions” to examine the regional patterning. To investigate the assembly mechanisms, we decomposed Sørensen’s b-diversity into “turnover” (bsim) and “nestedness-resultant” (bsne) dissimilarities, and used distance-based redundancy analysis (db-RDA) to relate them to the Euclidean thermal difference, dE, and geographical distance. Moran’s eigenvector maps (MEM) were used as an additional set of spatial constraints. Variation partitioning was then used to find the relative strengths of thermal and spatially-structured thermal drivers. Spatial and environmental predictors explained 97.9% of the total variation in bsim and the thermal gradient accounted for 84.2% of this combined pool. bsim was the major component of overall b-diversity in the Agulhas Current region, suggesting niche influences (environmental sorting) as dominant assembly process there. The much weaker thermal gradient in the Benguela Current-influenced region resulted in a high amount of bsne that could indicate neutral assembly processes. The intensification of upwelling during the mid-Pliocene 4.6–3.2 Ma (i.e., historical factors) were likely responsible for setting up the strong disjunction between the species-poor west coast and species-rich south and east coast floras, and this separation continues to maintain two systems of community structuring mechanisms in the Atlantic and Indian Ocean influenced sides of South Africa
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