Comparative studies on the structure of an upland African stream ecosystem

Upland stream systems have been extensively investigated in Europe, North America and Australasia and many of the central ideas concerning their function are based on these systems. One central paradigm, the river continuum concept is ultimately derived from those North American streams whose catchments remain forested with native vegetation. Streams of the tropics may or may not fit the model. They have been little studied. The Amani Nature Reserve in the East Usambara Mountains of north-eastern Tanzania offers an opportunity to bring these naturally forested systems to the attention of the ecological community. This article describes a comparison made between two lengths of the River Dodwe in this area. The work was carried out by a group of postgraduate students from eighteen European and African countries with advice from five staff members, as part of a course organised by the Tropical Biology Association. Rigorous efforts were made to standardise techniques, in a situation where equipment and laboratory facilities were very basic, through a management structure and deliberate allocation of work to specialists in each area.The article offers a summary of invertebrate communities found in the stream and its biomass. Crabs seem to be the key organism in both sections of the streams

Madagascan day geckos (Phelsuma spp.) exhibit differing responses along a gradient of land-use change

Madagascar is a key priority for global conservation efforts, as much of its diverse and highly endemic biota is threatened by deforestation. Despite this threat, there are limited data on the responses and tolerances of herpetofaunal species to landscape change. This study investigated the response of Madagascan day geckos (Phelsuma spp.) to deforestation in Nosy Be, Madagascar. We selected six sites along a gradient of land-use change: two in Sambirano rainforest (“Forest”), two in secondary, fragmented forest (“Fragment”), and two in agricultural plantations (“Orchard” and “Cropland”). We conducted a series of time-constrained searches at each site. The mean encounter rate of Phelsuma geckos (geckos detected per person/hour) was greater in agricultural sites than Forest sites, but no difference was detected between Forest and Fragment or Fragment and agricultural areas. Three species were encountered more frequently in agricultural land than forested sites, but this was not true for Phelsuma seippi, an endangered species on the IUCN Red List. These results suggest that adaptive, generalist species may benefit from anthropogenic land-use change, whereas specialist species will suffer. Our study emphasizes the importance of extending research beyond the borders of protected forests to include anthropogenically disturbed areas

Comparative studies on the structure of an upland African stream ecosystem

Upland stream systems have been extensively investigated in Europe,North America and Australasia and many of the central ideas concerningtheir function are based on these systems. One central paradigm, the rivercontinuum concept (Vannote et al. 1980) is ultimately derived from thoseNorth American streams whose catchments remain forested with nativevegetation

Hiding deep in the trees: discovery of divergent mitochondrial lineages in Malagasy chameleons of the <I>Calumma nasutum </I>group

NatuurwetenskappePlant- en DierkundePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Gecko phylogeography in the Western Indian Ocean region: the oldest clade of Ebenavia inunguis lives on the youngest island

Hawlitschek O, Toussaint EFA, Gehring P-S, et al. Gecko phylogeography in the Western Indian Ocean region: the oldest clade of Ebenavia inunguis lives on the youngest island. JOURNAL OF BIOGEOGRAPHY. 2017;44(2):409-420.AimWe studied the gecko genus Ebenavia to reconstruct its colonization history, test for anthropogenic versus natural dispersal out of Madagascar, and correlate divergence date estimates of our phylogeny with geological age estimates of islands in the region. LocationMadagascar and surrounding islands of the Western Indian Ocean (Comoros, Mayotte, Mauritius, Pemba). MethodsWe reconstructed the phylogeny of Ebenavia covering its entire geographical range using a molecular data set of three mitochondrial and two nuclear markers. We estimated divergence times based on calibrations using (1) previously calculated mutation rates of mitochondrial markers, (2) a combination of these rates with old or (3) young geological age estimates for some of the islands inhabited by the genus, and (4) an independent data set with fossil outgroup calibration points. ResultsEbenavia inunguis, one of two recognized species of the genus, comprises multiple ancient evolutionary lineages. The earliest divergence within this complex (Miocene, 13-20Ma; 95% credibility interval [CI]: 4-29Ma) separates the population of the Comoros Islands, excluding Mayotte, from all other lineages. The age estimates for island lineages coincide with the geological age estimates of the islands except for Grand Comoro, where the age of the local clade (3-5Ma; 95% CI: 2-7Ma) significantly predates the estimated island age (05Ma). A clade from north Madagascar+Mayotte+Pemba is estimated to have diverged from an eastern Malagasy clade in the Miocene. Main ConclusionsOur results suggest that Grand Comoro Island is geologically older than previously estimated. The islands of the Comoros and Pemba were probably colonized via natural dispersal out of Madagascar (>1000km in the case of Pemba). Mauritius was most likely colonized only recently from eastern Madagascar via human translocation