Species diversity and speciation mechanisms in Crenicichla (Neotropical cichlids)

This thesis contributes to the knowledge of the species diversity of the Crenicichla lacustris sp. group in the La Plata River basin with description of three new species. Speciation mechanisms within two different species flocks from the middle Paraná/Iguazu and Uruguay Rivers were studied with a phylogenomic approach applying a novel genotyping method based on a Double-Digest Restriction site Adjacent DNA (ddRAD) sequencing. Our results support a repeated origin of morphological species being evolved several times sympatrically and independently in different drainages. A considerable role of hybridization/introgression as an evolutionary force was also proposed. The thesis further uncovers biogeographic aspects of the southern part of Brazilian shield and adjacent coastal rivers