BackgroundNon-indigenous taxa currently represent a large fraction of the species and biomass of freshwater ecosystems. The accumulation of invasive taxa in combination with other stressors in these ecosystems may alter the habitats to which native taxa are adapted, which could elicit evolutionary changes in native populations and their ecological interactions. Assessing ecological and evolutionary consequences of invasions simultaneously may therefore be the most effective approach to study taxa with complex invasion histories. Here we apply such an integrated approach to the cerithioid gastropod Melanoides tuberculata, a model system in invasion biology.ResultsMolecular phylogenetics and ancestral range reconstructions allowed us to identify several independent Asian invasions in Lakes Malawi and Tanganyika, the Congo River, Nigeria and Cameroon. Some invasive M. tuberculata populations display much variation in shell morphology, and overlap in morphospace with M. tuberculata populations native to Africa. Experiments confirmed great ecophenotyic plasticity in some invasive populations, which, in combination with the overlap in disparity with native populations, masks invaders and their dispersal through Africa. Finally, the results of geographic modeling indicate that cryptic M. tuberculata invasions occurred primarily in densely populated areas.ConclusionsWe reveal the continental nature of invasions of Asian M. tuberculata to Africa. Several of the affected ecosystems have high endemicity in Cerithioidea: Lake Tanganyika has an unparalleled diversity in freshwater cerithioids (>10 endemic genera) and the Congo Basin and Lake Malawi are home to the two largest endemic species clusters of Melanoides in Africa (~12 and ~8 species, respectively). Cerithioids perform ecologically important functions in the benthic ecosystems of African freshwaters, but invaders and ecosystem change pose risks to their native diversity. We draw suggestions for more effective conservation strategies from our integrated approach.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0296-2) contains supplementary material, which is available to authorized users.
Freshwater ecosystems provide many services such as moderation of the local microclimate and a source of water and food for riparian communities. It is also a
Decapod crustaceans are one of the dominant faunal components of most tropical streams. However, several aspects concerning their biology and ecology are poorly known, especially in intertropical Africa. The aim of this study was to investigate the production of the atyid shrimps in Masanga Mabe, an equatorial lowland forest stream of Kisangani region. Samplings were undertaken biweekly from September 2000 to August 2003 with Surber net in four study sites. A total of 14,878 atyid shrimps specimens were sampled, measured for carapace length, weighted and identified. Atyid production was estimated by size frequency method according to sites (1, 2 and 3). Atyid composition showed the existence of two species: C. africana (Caridina africana) Kingsley 1882 and C. togoensis (Caridina togoensis) Hilgendorf 1893. Specific production ranged from 1.35 g·DM·m
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