Radiation im Fluss. Mechanismen der Artenbildung bei viviparen Süßwasserschnecken endemisch im Kaek River, Thailand
Evolution, Anthropologie
Zusammenfassung der Projektergebnisse
The main objective of this study was to investigate the freshwater gastropods Brotia from the Kaek River with its high morphological diversity, potentially being a new model organism for speciation in invertebrates. This riverine setting is especially interesting with multiple environmental factors acting on radiation and speciation. We investigated morphological characteristics, habitat preferences as well as inter- and intraspecific differences of Brotia. We used an evolutionary systematic approach to look deeper into the interconnectedness and relationships of shell size and shape, radula morphology and reproduction in concert with ecological factors and sophisticated genetical methods, combining mtDNA with innovative ddRAD techniques. The project aimed to answer basic questions in evolutionary biology and biogeography. The morphological results reveal some degree of species specific characteristics of Brotia taxa in the Kaek River drainage. Shell morphology generally varies from slender and highly turreted shells to small and globular ones. Nevertheless, this is not a clear bimodal distribution of shell shapes, instead we find every possible transitional form between these two extremes. Neither habitat nor location in the headwaters or lower river courses seem to have any impact on the specifics of shell shapes. The same is true for the radula morphology and potential substrate correlation. Contrary to the hypothesis held earlier, we find no indication for trophic specialization with respect to the shape of the radula and its dentition among the Kaek River species assemblage. In addition, the analysis of the brood pouch content as a proxy for a species specific reproductive system show not significant results either. In contrast, the molecular phylogenetic data suggest a geographical clustering of Brotia species along the river course, with Brotia species typically occurring either in the headwater region versus those in the middle/lower courses, respectively. This pattern is found analyzing molecular characterisics in two mitochondrial genes. In addition, our preliminary results regarding a multilocus next generation sequencing approach also hint in this direction – a somewhat unexpected result, as the mtDNA data revealed no clear picture in other respect (possibly due to genetic artefacts, such e.g. incomplete lineage sorting, but also potentiall due to hybridization). The analysis of our sophisticated ddRAD dataset is still under construction. We hope the calculation of the resulting trees will be finished in 2020.
Projektbezogene Publikationen (Auswahl)
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2016. Riverine radiation or relict remainder? Evaluating speciation in Brotia species endemic to the Kaek River, Thailand. Talk: p47, In: Tan Shau Hwai, A., Yasin, Z., Teh Chiew Peng, C. & Mohd Razalli, N. (eds.), The 19th International Congress of Unitas Malacologica. World Congress of Malacology 2016. 18-24 July 2016, Penang, Malaysia. Unity in Diversity. Program & Abstract Book. Unitas Malacologica, Penang
Lentge-Maaß, N. & Glaubrecht, M.
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2017. Speciation in endemic freshwater gastropods from the Kaek River, Thailand. Poster, Society for Molecular Biology & Evolution Annual Meeting 2017, 2-6 July 2017, Austin, Texas, USA
Lentge-Maaß, N. & Glaubrecht, M.
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2019. Go with the flow? Diversity and speciation in endemic freshwater gastropods in the Kaek River, Thailand. Talk, World Congress of Malacology 2019, 11-16 August 2019, Pacific Grove, California, USA
Lentge-Maaß, N. & Glaubrecht, M.
