Biochemical genetic variation, intraspecific genetic structure and postglacial evolution of select north European vertebrate species

• Analysis of the tempo and mode of intraspecific differentiation provides important information for understanding subspeciation, for construction of taxonomic hierarchies within a species and for management of genetic variation in natural populations.The present thesis describes the genetic structure of natural populations of willow grouse (Lagopus tagopus L.), rock ptarmigan (Lagopus mutus L.), red deer (Cervus ebaphus L.), fourhorn sculpin (Myoxocephalus quadricornis L.), and perch (Perea fluviatilis L.) in the recently (within 8.000 years) deglaciated Scandinavian region, studied by analysis of allozyme variation at multiple loci.The amount of genetic variation within these species was similar to previously reported means for each particular vertebrate group, except for the perch which has an extremely low level of genetic variation. All species, except perch, show a complex population genetic structure. The magnitude of genetic differentiation between populations indicates that the majority of population structures are of postglacial origin. Differentiation potentially indicating divergence times in excess of the timespan available for postglacial evolution was only observed between two Scandinavian red deer subspecies.In red deer and willow grouse, the distribution of genetic variability does not support the currently applied subspecies classifications. Taxonomic subspecies either show very little absolute genetic differentiation as for the red deer, or do not represent a general subdivision of the genetic variation within the species, as for the willow grouse. This discrepancy emphazises that morphological characters may fail to depict the evolutionary relationships among populations.Temporal variation in the genetic structure was found in willow grouse and fourhorn sculpin. This may reflect an unstable demographic structure due to population density changes in willow grouse, and lack of temporally stationary breeding units in fourhorn sculpin.In addition, a comparison was made of the genetic structure of marine, anadromous, and freshwater fishes from Scandinavia and North America, by a nested gene diversity analysis of published allele frequency data for biochemical loci. Large differences in the intraspecific distribution of genetic variability was found between marine and freshwater fish. Species with geographical barriers between localities have consistently higher levels of intraspecific genetic differentiation, as expected if migration is important in determining the genetic structure of populations.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Evolution (biologi)

Populationsgenetik

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