Distribution and genetic variation of invasive crayfish of the genus Orconectes

Crayfish are an important part of European fauna, but since the 19th century native crayfish species have been largely influenced by biological invasions, when large number of their populations was dramatically reduced due to the introduction of the pathogen of the crayfish plague (oomycete Aphanomyces astaci) to Europe. Several North American crayfish species were then brought to the European continent to substitute lost populations of native crayfish, the most widespread being the spiny-cheek crayfish (Orconectes limosus), the signal crayfish (Pacifastacus leniusculus) and the red swamp crayfish (Procambarus clarkii). However, these crayfish can carry pathogen of the crayfish plague and therefore represent a serious threat to the native species. My work focused mostly on the spiny-cheek crayfish (O. limosus). Available literature data suggest that the species was brought to Europe only once, and all European individuals may be descendants of the founder population. However, other cases of introduction may not have been documented, and cannot be ruled out. The first aim of my thesis was to evaluate the haplotype variation of the spiny-cheek crayfish populations from Europe and North America. Mitochondrial gene for cytochrome c oxidase subunit 1 (COI) of selected O. limosus individuals from several..