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Recurrent camouflaged invasions and dispersal of an Asian freshwater gastropod in tropical Africa.

Van Bocxlaer B, Clewing C, Mongindo Etimosundja JP, Kankonda A, Wembo Ndeo O, Albrecht C - BMC Evol. Biol. (2015)

Bottom Line: Assessing ecological and evolutionary consequences of invasions simultaneously may therefore be the most effective approach to study taxa with complex invasion histories.Finally, the results of geographic modeling indicate that cryptic M. tuberculata invasions occurred primarily in densely populated areas.We draw suggestions for more effective conservation strategies from our integrated approach.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32 (IFZ), D-35392, Giessen, Germany. bert.vanbocxlaer@ugent.be.

ABSTRACT

Background: Non-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.

Results: Molecular 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.

Conclusions: We 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.

Show MeSH
Non-metric multidimensional scaling of morphologically-scored, AfricanMelanoides tuberculatapopulations. Morph codes are provided for invasive morphs, whereas native African morphs are lumped. Morphs CDI and LMI belong to clade 1, whereas all other material belongs to clade 2, illustrating that despite a deep phylogenetic split morphological overlap exists between both clades. Our study is the first to find morphological overlap between native and invasive M. tuberculata morphs, which hampers separating them based on shell morphology alone. The solid black circle indicates the position of lab-bred F1 individuals of morph CDI; * indicates the position of organically coated CDI specimens that were not bleached before assessment.
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Fig5: Non-metric multidimensional scaling of morphologically-scored, AfricanMelanoides tuberculatapopulations. Morph codes are provided for invasive morphs, whereas native African morphs are lumped. Morphs CDI and LMI belong to clade 1, whereas all other material belongs to clade 2, illustrating that despite a deep phylogenetic split morphological overlap exists between both clades. Our study is the first to find morphological overlap between native and invasive M. tuberculata morphs, which hampers separating them based on shell morphology alone. The solid black circle indicates the position of lab-bred F1 individuals of morph CDI; * indicates the position of organically coated CDI specimens that were not bleached before assessment.

Mentions: Ordination of morphological characters of native and invasive M. tuberculata in morphospace resulted in limited stress (8.99), which suggests a reliable ordination result. This result confirmed the observations mentioned above (Figure 5) and that the invasive BIT morph of M. tuberculata displays limited morphological variability in comparison to CDI and LMI morphs. On a continental scale, an overlap exists in morphological variation displayed by native and invasive M. tuberculata morphs (Figure 5), although some of the overlapping populations belong to deeply divergent clades (Figure 2).Figure 5


Recurrent camouflaged invasions and dispersal of an Asian freshwater gastropod in tropical Africa.

Van Bocxlaer B, Clewing C, Mongindo Etimosundja JP, Kankonda A, Wembo Ndeo O, Albrecht C - BMC Evol. Biol. (2015)

Non-metric multidimensional scaling of morphologically-scored, AfricanMelanoides tuberculatapopulations. Morph codes are provided for invasive morphs, whereas native African morphs are lumped. Morphs CDI and LMI belong to clade 1, whereas all other material belongs to clade 2, illustrating that despite a deep phylogenetic split morphological overlap exists between both clades. Our study is the first to find morphological overlap between native and invasive M. tuberculata morphs, which hampers separating them based on shell morphology alone. The solid black circle indicates the position of lab-bred F1 individuals of morph CDI; * indicates the position of organically coated CDI specimens that were not bleached before assessment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4373078&req=5

Fig5: Non-metric multidimensional scaling of morphologically-scored, AfricanMelanoides tuberculatapopulations. Morph codes are provided for invasive morphs, whereas native African morphs are lumped. Morphs CDI and LMI belong to clade 1, whereas all other material belongs to clade 2, illustrating that despite a deep phylogenetic split morphological overlap exists between both clades. Our study is the first to find morphological overlap between native and invasive M. tuberculata morphs, which hampers separating them based on shell morphology alone. The solid black circle indicates the position of lab-bred F1 individuals of morph CDI; * indicates the position of organically coated CDI specimens that were not bleached before assessment.
Mentions: Ordination of morphological characters of native and invasive M. tuberculata in morphospace resulted in limited stress (8.99), which suggests a reliable ordination result. This result confirmed the observations mentioned above (Figure 5) and that the invasive BIT morph of M. tuberculata displays limited morphological variability in comparison to CDI and LMI morphs. On a continental scale, an overlap exists in morphological variation displayed by native and invasive M. tuberculata morphs (Figure 5), although some of the overlapping populations belong to deeply divergent clades (Figure 2).Figure 5

Bottom Line: Assessing ecological and evolutionary consequences of invasions simultaneously may therefore be the most effective approach to study taxa with complex invasion histories.Finally, the results of geographic modeling indicate that cryptic M. tuberculata invasions occurred primarily in densely populated areas.We draw suggestions for more effective conservation strategies from our integrated approach.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32 (IFZ), D-35392, Giessen, Germany. bert.vanbocxlaer@ugent.be.

ABSTRACT

Background: Non-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.

Results: Molecular 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.

Conclusions: We 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.

Show MeSH