Abstract booklet - gtö – Society for Tropical Ecology

80 PARALLEL SESSION HALL H IV | TROPICAL ISLAND BIODIVERSITYPARALLEL SESSION HALL H IV | TROPICAL ISLAND BIODIVERSITY 81ANT COMMUNITIES ON SMALL TROPICAL ISLANDS: EFFECTSOF ISLAND SIZE AND ISOLATION ARE OBSCURED BY HABITATDISTURBANCE AND ‘TRAMP’ ANT SPECIESCAN KEY FOOD RESOURCES EXPLAIN THE PRESENCE ANDABSENCE OF TWO MOUSE LEMURS (MICROCEBUS SPP.) INNORTHWESTERN MADAGASCAR?Akhmad Rizali 11Agroecology, Uni Göttingen, Göttingen, DE, arizali@gwdg.deSandra Thorén 1 , Sehen Lalandy 3 , Romule Rakotondravony 4 , UteRadespiel 1TUESDAY 16:30 Hall H IVComparisons among islands offer an opportunity to study the effects ofbiotic and abiotic factors on small, replicated biological communities. Smallerpopulation sizes on islands accelerate some ecological processes, which maydecrease the time needed for perturbations to affect community composition.We surveyed ants on 18 small tropical islands in Thousand Islands Archipelago(Indonesian name: Kepulauan Seribu) off Jakarta, Indonesia, to determine theeffects of island size, isolation from the mainland, and habitat disturbance onant community composition. Ants were sampled from the soil surface, leaf litterand vegetation in all habitat types on each island. Island size, isolation from themainland, and landuse patterns were quantified using GIS software. The presenceof settlements and of boat docks were used as indicators of anthropogenicdisturbance. The richness of ant communities and non-tramp ant species oneach island were analysed in relation to the islands’ physical characteristics andindicators of human disturbance. Forty-eight ant species from 5 subfamiliesand 28 genera were recorded from the archipelago, and approximately 20%of the ant species were well-known human-commensal ‘tramp’ species. Islandswith boat docks or human settlements had significantly more tramp speciesthan did islands lacking these indicators of anthropogenic disturbance, andthe diversity of non-tramp species decreased with habitat disturbance. Humandisturbance on islands in the Thousand Islands Archipelago promotes theintroduction and/or establishment of tramp species. Tramp species affectthe composition of insular ant communities, and expected biogeographicalpatterns of ant richness are masked. The island with the greatest estimatedspecies richness and the greatest number of unique ant species, Rambut Island,is a forested bird sanctuary, highlighting the importance of protected areas inpreserving the diversity of species-rich invertebrate faunas.1Institute of Zoology, University of Veterinary Medicine Hanover, Hannover, DE,thorensandra@gmail.com, 3 Faculty of Sciences, University of Antananarivo,Antananarivo, Madagascar, , , 4 Faculty of Sciences, University of Mahajanga,Mahajanga, Madagascar, ,Since essential resources may influence the distribution pattern of species,we investigate whether the distribution of food plants explains varyingabundances of M. murinus and M. ravelobensis in northwestern Madagascar.Therefore, we first identified potential key food plants for both species in threestudy sites and subsequently tested, if the distribution of these food plantscould explain the presence/absence of the mouse lemurs in another set of 18study sites. To identify key food plants we collected feeding data from 17 femaleM. murinus and 18 female M. ravelobensis, and botanical data from 9 plots and36 50m-transects. We identified seven and four potential key food plant speciesfor M. murinus and M. ravelobensis, respectively. However, the presence ofthese food plants could not be unambiguously linked to the presence/absenceof the two mouse lemurs in the 18 further sites. However, whenever one offour food plants of M. murinus was present; this mouse lemur was also present.In conclusion, the distribution of food resources might influence distributionpattern of M. murinus, but not of M. ravelobensis. The evolutionary implicationsof these findings will be discussed.TUESDAY 16:45 Hall H IVgtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö