82 research outputs found
Resource competition between macrobenthic epifauna and infauna in a Kenyan Avicennia marina mangrove forest
Resource competition between macrobenthic epifauna in a Kenyan <i>Avicennia marina</i> mangrove forest
A cage exclusion experiment was used to examine the interaction between the epibenthos (permanent and visiting) and the macroinfauna of a high intertidal Kenyan Avicennia marina mangrove sediment. Densities of Oligochaeta (families Tubificidae and Enchytraeidae), Amphipoda, Insecta larvae, Polychaeta and macro-Nematoda, and a broad range of environmental factors were followed over 5 mo of caging. A significant increase of amphipod and insect larvae densities in the cages indicated a positive exclusion effect, while no such effect was observed for oligochaetes (Tubificidae in particular), polychaetes or macronematodes. Resource competitive interactions were a plausible explanation for the status of the amphipod community. This was supported by the parallel positive exclusion effect detected of microalgal densities. It is therefore hypothesized that competition for microalgae and deposited food sources is the determining structuring force exerted by the epibenthos on the macrobenthic infauna. However, the presence of epibenthic predation can not be excluded
Relative contribution of neutral and deterministic processes in shaping fruit-feeding butterfly assemblages in Afrotropical forests
The unified neutral theory of biodiversity and biogeography has gained the status of a quantitative null model for explaining patterns in ecological (meta)communities. The theory assumes that individuals of trophically similar species are functionally equivalent. We empirically evaluate the relative contribution of neutral and deterministic processes in shaping fruit-feeding butterfly assemblages in three tropical forests in Africa, using both direct (confronting the neutral model with species abundance data) and indirect approaches (testing the predictions of neutral theory using data other than species abundance distributions). Abundance data were obtained by sampling butterflies using banana baited traps set at the forest canopy and understorey strata. Our results indicate a clear consistency in the kind of species or species groups observed at either the canopy or understorey in the three studied communities. Furthermore, we found significant correlation between some flight-related morphological traits and species abundance at the forest canopy, but not at the understorey. Neutral theory’s contribution to explaining our data lies largely in identifying dispersal limitation as a key process regulating fruit-feeding butterfly community structure. Our study illustrates that using species abundance data alone in evaluating neutral theory can be informative, but is insufficient. Species-level information such as habitat preference, host plants, geographical distribution, and phylogeny is essential in elucidating the processes that regulate biodiversity community structures and patterns
Assessing Conservation Values: Biodiversity and Endemicity in Tropical Land Use Systems
Despite an increasing amount of data on the effects of tropical land use on continental forest fauna and flora, it is debatable whether the choice of the indicator variables allows for a proper evaluation of the role of modified habitats in mitigating the global biodiversity crisis. While many single-taxon studies have highlighted that species with narrow geographic ranges especially suffer from habitat modification, there is no multi-taxa study available which consistently focuses on geographic range composition of the studied indicator groups. We compiled geographic range data for 180 bird, 119 butterfly, 204 tree and 219 understorey plant species sampled along a gradient of habitat modification ranging from near-primary forest through young secondary forest and agroforestry systems to annual crops in the southwestern lowlands of Cameroon. We found very similar patterns of declining species richness with increasing habitat modification between taxon-specific groups of similar geographic range categories. At the 8 km2 spatial level, estimated richness of endemic species declined in all groups by 21% (birds) to 91% (trees) from forests to annual crops, while estimated richness of widespread species increased by +101% (trees) to +275% (understorey plants), or remained stable (- 2%, butterflies). Even traditional agroforestry systems lost estimated endemic species richness by - 18% (birds) to - 90% (understorey plants). Endemic species richness of one taxon explained between 37% and 57% of others (positive correlations) and taxon-specific richness in widespread species explained up to 76% of variation in richness of endemic species (negative correlations). The key implication of this study is that the range size aspect is fundamental in assessments of conservation value via species inventory data from modified habitats. The study also suggests that even ecologically friendly agricultural matrices may be of much lower value for tropical conservation than indicated by mere biodiversity value
Systematics and historical biogeography of the old world butterfly subtribe Mycalesina (Lepidoptera: Nymphalidae: Satyrinae)
Habitat Preferences of Butterflies in the Bumbuna Forest, Northern Sierra Leone
The habitat preferences of the butterfly fauna were studied in the Bumbuna Forest Reserve in northern Sierra Leone. The intact forest reserve and a secondary forest regrowth, disturbed as a result of slash-and-burn agriculture, were compared to savanna habitats. Of the 290 specimens collected, 195 butterfly species were included, of which significant proportion were Nymphalidae. Of the 147 forest species, 111 (75.5%) showed preferences for the forest habitats, while 70 (47.6%) and 34 (23.1%) preferred disturbed and savannah habitats, respectively. Numerically, a comparable proportion of savannah species were recorded in the 18 disturbed (73.9%) and 16 savannah habitats (63.2%). Accumulated species richness and diversity indices were lower in the disturbed habitats compared to the forest reserve, but lowest in the savanna habitats. However, a large proportion of forest species, especially those with either a more restricted geographic range or species for which no information on geographic distribution was available, were exclusively captured in the forest patches. The survey indicated the presence of a rich butterfly fauna, which should be systematically collected for further research and study in order to build a good taxonomic database for Sierra Leone
Continuing effectiveness of serogroup A meningococcal conjugate vaccine, Chad, 2013.
In 2011, vaccination with a serogroup A meningococcal polysaccharide conjugate vaccine was implemented in 3 of 23 regions in Chad. Cases of meningitis declined dramatically in vaccinated areas, but an epidemic continued in the rest of Chad. In 2012, the remaining Chad population was vaccinated, and the epidemic was halted
Resource competition between macrobenthic epifauna and infauna in a Kenyan Avicennia marina mangrove forest.
Taxonomy and identification of Lohora Moore (Lepidoptera : Satyrinae), the Sulawesi bush browns
A dichotomous key and revisional notes are presented for all 17 known species of Lohora Moore, a genus of satyrine butterflies endemic to the Sulawesi Region (Indonesia). Detailed information on primary type material of all taxa is included, together with description of a new species, L. anna, from Lore Lindu National Park previously misidentified in the literature as L. deianira (Hewitson). The recognition of some species, notably a complex centred on L. transiens (Fruhstorfer) that includes L. anna, sp. nov., is difficult and the rank of certain other taxa is problematic. A detailed revision remains necessary if this, the major endemic radiation of butterflies on Sulawesi, is to be better understood
The butterfly fauna of the Noyau Central, Lama Forest (Republic of Benin), with notes on its ecological composition and geographic distribution
The Noyau Central (c. 4777 ha) in south-central Benin is the largest remaining natural forest within the Dahomey Gap. Based on field work conducted in 1998, a preliminary list of 83 butterfly species is presented for this largely unknown core area of the Lama Forest. Forty butterfly species were documented for the first time in Benin. Forty-one are true lowland forest specie, not found in savanna. Overall species richness was higher in clearings, than in closed forest. However, a high proportion of forest species, especially those with a more restricted geographic range, were exclusively captured in the forest patches. Because other forest areas in Benin are much smaller, the Noyau Central is likely to contribute critically to the conservation of the country's butterfly fauna
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