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Investigating the developmental and gene regulatory basis of color diversification in cichlid fish : A framework for evolutionary developmental studies in the Midas cichlid species complex (Amphilophus spp.)

Investigating the developmental and gene regulatory basis of color diversification in cichlid fish : A framework for evolutionary developmental studies in the Midas cichlid species complex (Amphilophus spp.)

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SEFTON, Margaret, 2017. Investigating the developmental and gene regulatory basis of color diversification in cichlid fish : A framework for evolutionary developmental studies in the Midas cichlid species complex (Amphilophus spp.) [Dissertation]. Konstanz: University of Konstanz

@phdthesis{Sefton2017Inves-44054, title={Investigating the developmental and gene regulatory basis of color diversification in cichlid fish : A framework for evolutionary developmental studies in the Midas cichlid species complex (Amphilophus spp.)}, year={2017}, author={Sefton, Margaret}, address={Konstanz}, school={Universität Konstanz} }

Sefton, Margaret 2018-11-28T12:01:49Z With their explosive speciation and astounding levels of diversity, cichlid fishes are an excellent model system for the study of the relationship between genotype and phenotype. In particular, the recent radiations of the Midas cichlids represent an opportunity to examine the molecular basis of rapid adaptive diversification and phenotypic change. In this thesis, I propose a framework in which the Midas cichlids can be used as a model for future research using an evo-devo approach. In its chapters, the suitability of this group for evo-devo studies is assessed, and methods to facilitate future research are outlined. Finally, an empirical study into the regulatory basis of morphological change is conducted, identifying target genes for future research.<br />Chapter I defines a developmental staging system for the Midas cichlid species complex (Amphilophus spp.). The first seven days following fertilization are described in detail, providing an important framework for future studies in cichlid evolution and development. The morphogenesis of key innovations found in the Midas cichlid, including adhesive glands and chromatophore development, were noted in detail. Six main developmental periods are defined - the zygote, cleavage, blastula, gastrula, segmentation, and post-hatching periods. Using these ontogenetic landmarks, development in the Midas cichlid was compared to that of other teleosts such as zebrafish and medaka. Additionally, we tested for the effects of temperature on the rate of development. Compared to the zebrafish, early development in Midas cichlids proceeds slowly, and is highly sensitive to changes in temperature. Overall, this chapter provides an outline of standardized developmental landmarks, facilitating both comparative studies of ontogeny and functional experiments using transgenesis and genome editing techniques.<br />For the first time in a Neotropical cichlid species, a method for producing transgenic Midas cichlids is outlined in Chapter II. Protocols used in zebrafish and other model teleosts were adapted for use in the Midas cichlid – a crucial step in establishing this species complex as a model for evolutionary developmental studies. Using optimized microinjection protocols and Tol2 transposon-mediated transgenesis, this chapter describes the generation of a stable transgenic line of Midas cichlids. F1 fish with ubiquitously-expressed fluorescence were produced by inserting the ubi::eGFP plasmid construct, combining the ubiquitin promoter region with the gene for enhanced GFP (eGFP), into the Midas genome.<br />In Chapter III, gene regulation is characterized among African cichlid species. Using RNA sequencing, genome-wide expression patterns were examined in three unpaired fin types (anal, dorsal and caudal fins) in five African cichlid species. The species examined in this study (Oreochromis niloticus, Neolamprologus brichardi, Astatotilapia burtoni, Metriaclima zebra and Pundamilia nyererei) represent both species within the Haplochromine lineage, which is known as a textbook example of an adaptive radiation, as well as more distantly-related, non-radiating species. Within this context, we describe general patterns of cis-regulatory evolution and identify target genes associated with color patterning and fin morphology which can be examined in future research using techniques developed in the previous chapters.<br />In summary, this thesis establishes a framework in which evo-devo studies can be carried out in cichlid fishes. Future research using an evolutionary developmental approach will contribute to a greater understanding of the link between genotype and phenotype and the role of cis-regulatory changes in the generation of adaptive diversity. 2017 2018-11-28T12:01:49Z Investigating the developmental and gene regulatory basis of color diversification in cichlid fish : A framework for evolutionary developmental studies in the Midas cichlid species complex (Amphilophus spp.) Sefton, Margaret eng terms-of-use

Dateiabrufe seit 28.11.2018 (Informationen über die Zugriffsstatistik)

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