A molecular assessment of range expansion of the northern or virile crayfish (Orconectes virilis), crayfish-based community co-structure, and phylogeny of crayfish-affiliated symbionts

• Molecular assessment: crayfish and symbionts

• Author / Creator

  Williams, Bronwyn W.

• Geographical limits of a species’ range are determined in part by the environmental tolerances of that species, and also by its past and current ability to colonize new areas. Range shifts are a common occurrence in the evolutionary history of almost all taxa; however, anthropogenically-mediated activities have facilitated rapid changes in the distribution of many species directly (via introduction) or indirectly (via alteration in habitat or environment). Identification of the pathways underlying range expansion is critical if we are to understand the ecological and evolutionary potential of a species facing changing abiotic and biotic factors.
  The northern crayfish, Orconectes virilis (Hagen), has rapidly expanded its western range edge along several rivers in the prairies of North America. Although the spatial extent and timing of spread appear to indicate that the species has responded to a large-scale change in environmental conditions, several lines of evidence suggested that human-mediated introduction may also have played a role in range expansion of the species. The species is currently contiguously distributed along rivers across the Interior Plains, but is also found in several lakes and waterways disjunct from the core range. In this thesis I use phylogeographic analysis to identify two genetically distinct O. virilis haplogroups in the region. One haplogroup is spatially and genetically consistent with patterns expected from gradual post-glacial expansion; however, the second is suggestive of frequent and widespread introduction. I developed microsatellite markers that allowed me to assess fine-scale intra-river genetic patterns associated with spread of O. virilis. I found that genetic patterns were not consistent across rivers, and that recent range expansion has resulted from a combination of natural spread and human-mediated introduction.
  Two groups of crayfish-associated symbionts were found on O. virilis in the Interior Plains, branchiobdellidan worms and entocytherid ostracods. The distributions of these organisms suggest that factors affecting range limits differ among host and symbionts. Little is known of the ecology and evolution of these symbionts, not only in the Prairies, but also across their global distribution. My examination of phylogenetic patterns of North American branchiobdellidans provides the best supported evolutionary hypothesis of the order to date.

• Subjects / Keywords

  • Entocytheridae
  • Host-symbiont
  • Orconectes virilis
  • Branchiobdellida
  • Phylogeny
  • Range expansion

• Graduation date

  Fall 2012

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3PD2Z

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.