Octocorallia (primarily soft corals and gorgonians) occur in cold-water environments as well as in tropical seas and can form a major component of reef communities. Because of their... Show more Octocorallia (primarily soft corals and gorgonians) occur in cold-water environments as well as in tropical seas and can form a major component of reef communities. Because of their abundance and three-dimensional structure octocorals are an important habitat for symbiotic species such as crustaceans, worms, fishes and molluscs. Among the latter group are snails of the family Ovulidae, obligate associates of octocorals. Ovulid snails have adapted their morphological appearance to avoid predation. They can either be perfectly camouflaged or ambiguously coloured to advertise their toxic properties. It was therefore expected that these morphological adaptations would have an evolutionary background, which would corresponds with that of their octocoral hosts. In this thesis the evolutionary history of the Ovulidae and Octocorallia are examined within and between both taxa by using a multifaceted approach, consisting of (calibrated) phylogenetic and co-evolutionary analyses, taxonomic revisions and coral bioactivity research. The results show that snails and octocorals did not coevolve, but that the evolutionary history between both groups is best described as sequential evolution in which the host affects the symbiont but not vice versa. Show less
Introduction: The major climatic oscillations during the Quaternary Ice Age heavily influenced the distribution of species and left their mark on intraspecific genetic diversity. Past range shifts... Show moreIntroduction: The major climatic oscillations during the Quaternary Ice Age heavily influenced the distribution of species and left their mark on intraspecific genetic diversity. Past range shifts can be reconstructed with the aid of species distribution modeling and phylogeographical analyses. We test the responses of the different members of the genus Triturus (i.e. the marbled and crested newts) as the climate shifted from the previous glacial period (the Last Glacial Maximum, similar to 21 Ka) to the current interglacial.Results: We present the results of a dense mitochondrial DNA phylogeography (visualizing genetic diversity within and divergence among populations) and species distribution modeling (using two different climate simulations) for the nine Triturus species on composite maps.Conclusions: The combined use of species distribution modeling and mitochondrial phylogeography provides insight in the glacial contraction and postglacial expansion of Triturus. The combined use of the two independent techniques yields a more complete understanding of the historical biogeography of Triturus than both approaches would on their own. Triturus newts generally conform to the 'southern richness and northern purity' paradigm, but we also find more intricate patterns, such as the absence of genetic variation and suitable area at the Last Glacial Maximum (T. dobrogicus), an 'extra-Mediterranean' refugium in the Carpathian Basin (T. cristatus), and areas where species displaced one another postglacially (e. g. T. macedonicus and western T. karelinii). We provide a biogeographical scenario for Triturus, showing the positions of glacial refugia, the regions that were postglacially colonized and the areas where species displaced one another as they shifted their ranges. Show less
