Der Einfluss physiologischer Variation auf die geographischen Verbreitungsgrenzen parapatrischer, kryptischer Arten
Zusammenfassung der Projektergebnisse
In this project we focused on three species of the snail Melampus, formerly though to be just one species: M. bidentatus. Because they are so morphologically similar, few comparisons have been made to understand their differences, especially what drives their different geographical ranges. To better understand how these species differ, we examined morphological characteristics, genomic sequences, and gene expression changes in response to changes in temperature and salinity. All of this is intended to better understand how subtle variation among species can alter their response to the environment, and in turn change where they are found in nature. In the first part, we used morphological comparisons, published field surveys, and decades of taxonomic literature to define and name the three cryptic species. What was formerly Melampus bidentatus is now: M. bidentatus, M. jaumei, and M. gundlachi. Morphological comparisons revealed that these species are not outwardly different, despite deep genetic divisions. Whole-mitochondrial genome sequencing was next used to show that they are highly genetically divergent at all genes in the mitochondria, and that faster rates of sequence evolution might be associated with greater frequency of gene order changes. Lastly, we measured both metabolites and expressed genes to understand the joint response of M. jaumei to salinity and temperature. Surprisingly, we find that response to cold is very different depending on acclimation to different salinities. This suggests that geographical range could be shaped strongly by these two aspects of the environment. This last part of the project has also identified a set of candidate genes associated with cold and salinity response. These will be instrumental in future work to screen for environmental stress, to better understand what shapes geographical range, and to understand the evolution of cold tolerance.
Projektbezogene Publikationen (Auswahl)
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Molecular Species Delimitation and Morphometry in the Melampus bidentatus (Panpulmonata, Ellobiidae) Cryptic Species Complex. Bulletin of the Society of Systematic Biologists, 2(2).
Inäbnit, Thomas; Tiedemann, Ralph & Dennis, Alice
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Mitochondrial genomes of three Melampus species (Ellobiidae; Gastropoda) and a proposed mitochondrial control region for Euthyneura.
Inäbnit, Thomas; Tiedemann, Ralph & Dennis, Alice B.
