Horst Wilkens

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The genetic basis of vertebrate morphological evolution has traditionally been very difficult to examine in naturally occurring populations. Here we describe the generation of a genome-wide linkage map to allow quantitative trait analysis of evolutionarily derived morphologies in the Mexican cave tetra, a species that has, in a series of independent caves,(More)
Astyanax fasciatus has become a model organism for the study of regressive and adaptive evolution in cave animals. To fully understand these processes, it is important to have background information on the systematics and phylogeography of surface and cave populations of this species. Here we investigate the phylogeography of A. fasciatus in North and(More)
A study of genetic diversity at microsatellite loci and the mitochondrial DNA (mtDNA) cytochrome b gene was carried out to assess genetic relationships among four Mexican cave (Pachon, Sabinos, Tinaja, Chica) and four surface populations of Astyanax fasciatus (Characidae) from northeast Mexico and the Yucatan. With the exception of Chica, the cave(More)
Cave fish provide a model system for exploring the genetic basis of regressive evolution. A proposal that regressive evolution (for example, eye loss) may result from pleiotropy, by selection on constructive traits (for example, improved taste) has received considerable recent interest as it contradicts the theory that regressive evolution results from(More)
We investigated differentiation processes in the Neotropical fish Astyanax that represents a model system for examining adaptation to caves, including regressive evolution. In particular, we analyzed microsatellite and mitochondrial data of seven cave and seven surface populations from Mexico to test whether the evolution of the cave fish represents a case(More)
The nocturnal Mexican catfish Rhamdia laticauda (Pimelodidae, Teleostei) is the surface sister species of a number of cave species. Comparison between two of them, R. zongolicensis and R. reddelli, reveals an intermediate state of reduction of the biologically functionless eyes, melanin pigmentation and the negative phototactic behavior. The surface species(More)
Astyanax has become an important model system for evolutionary studies of cave animals. We investigated correlations of population genetic patterns revealed by microsatellite data and phylogeographic patterns shown by mitochondrial DNA sequences in Mexican cave and surface fish of the genus Astyanax (Characidae, Teleostei) to improve the understanding of(More)
In the present study we have analyzed the integrity and expression of the alphaA-crystallin gene, that codes for a major structural component of the lens, in a blind cave form of the teleostean fish, Astyanax fasciatus. This is the first alphaA-crystallin gene cloned from a teleostean fish. Sequence comparison of this cave-form gene with its epigean(More)
The early morphogenesis of the degenerate eyes of the Mexican cave fish Astyanax fasciatus and of its conspecific epigean ancestor has been studied comparatively using light- and electron-microscopical techniques; the transcription of the opsin gene has been analysed during early ontogeny in both populations by in situ hybridization. The opsin protein is an(More)
The river-dwelling fishes of Astyanax fasciatus and their derivatives from Pachon and Micos caves in Mexico were collected. By comparing red (r007) and green (g103) opsin gene sequences from the three populations, we found a high frequency of C-->T changes in r007 and g103 of the eyed Micos fishes presumably due to spontaneous cytosine methylation or(More)