My study is directed towards understanding the pattern of evolution taking place among populations of Peromyscus inhabiting the islands of British Columbia. A standard morphological approach, as veil as karyotype and reproductive isolation analyses, have shown that a taxonomic revision of this faunal group is desirable. I have proposed such a revision. A discriminant analysis utilizing morphological measurements reveals the existence of two distinctive phenotypes within the islands surveyed. Breeding studies, involving 78 pairs of insular Peromyscus, indicate that reproductive isolation exists between the two morph groups. Furthermore, when given the choice the large and small morph groups prefer the company of their own type. Extensive phallic variation occurs among island populations but no suggestion of taxonomic relationships are discernible. Karyotype analysis reveals that there are two distinct karyotypic patterns. The karyotype correlates with the two morphotype classifications. The large morph has a high number of metacentric chromosomes and the small morph has a low number. The high metacentric number karyotype is identical to that possessed by the morphologically similar Peromyscus sitkehsis known to inhabit the islands to the north of the.study group. Karyotype variation within each of the tvo major divisions is minimal. I have proposed that the karyotypic differences between these two morphs is significant at the species level. The large morph should be considered as P. sitkensis and the small phenotype should remain as P. maniculatus. The degree and rapidity of evolution within these Peromyscus populations requires a broadening in the scope of some subspecific taxa. Change in subspecific nomenclature has been indicated. Additional studies of Peromyscus upon the adjacent mainland and Vancouver Island are required before meaningful relationships can be expressed between insular and mainland groups at the subspecific level. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

No description available.

No description available.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 31-35). Also available via the World Wide Web.

Effects of infections with sylvatic species Trichinella, T. nativa or T. pseudospiralis, on the diel locomotory activity and locomotory activity pattern of an indigenous rodent host, the deer mouse (Peromyscus maniculatus), were assessed in a familiar environment and during the process of familiarization in a novel environment. Infection with muscle-encapsulating T. nativa severely reduced overall locomotory activity and changed locomotory activity patterns in a dose dependent fashion. In contrast, T. pseudospiralis infection had no such effects on diel locomotory activity. Infection with these nonencapsulating nematodes also changed locomotory activity patterns, but effects were independent of inoculation dose. Trichinella pseudospiralis infection almost completely reversed the locomotory exploration patterns of mice. Both T. nativa- and T. pseudospiralis-infected mice spent more time in shelter than did sham-inoculated conspecifics. Biological characterization of these infections in deer mice revealed striking departures from the conventional course of infection as typified by synanthropic trichinellosis in laboratory mice, and provided further insight into the relationship between the major phases of infection and the observed behavioral changes. Altered behaviors of infected deer mice are discussed in terms of their consequences on host fitness and survival, as well as parasite transmission. The study establishes links between behavioral observations derived from synanthropic and laboratory rodent-T. spiralis host-parasite associations and their sylvatic counterparts. It provides the behavioral underpinnings for future assessments of the role of wild rodents in the transmission of sylvatic trichinelloses.

No description available.

Given the distribution and probable evolutionary history of the Peromyscus maniculatus species group, an interspecific comparison of microsatellite variation among these species would be logically based (at least initially) on primers isolated from the genome of a geographically central population of P. maniculatus. Additionally, as the species in the group are recently diverged, reasonably informative microsatellite data are likely to require analysis of a rapid evolving category of microsatellite loci. The initial phase of this research involved the isolation, characterization and assessment of variation for a panel of DNA microsatellites containing perfect dinucleotide repeats from a geographically central population of P. maniculatus. Theoretical predictions and empirical studies indicate that phylogenetic analyses based on microsatellite primers isolated from a focal species may be subject to ascertainment biases that can be expected to degrade the efficacy of this approach with increasing phylogenetic depth between the species from which the microsatellites were isolated and those to which these loci are being compared. Results of an analysis of allelic variation at 12 pure, dinucleotide microsatellite loci (isolated from P. maniculatus) are reported for samples of all species in the P. maniculatus species group and the sister taxon P. leucopus. Examined for the species in the P. maniculatus species group for which there is an a priori highly corroborated phylogeny, evidence of ascertainment bias was apparent only for one locus that was unique to P. maniculatus. Genealogical analyses of the data over all loci yielded inferred relationships that were entirely concordant with the a priori corroborated phylogeny for P. maniculatus, P. keeni, P. polionotus, P. melanotis and P. leucopus. Genealogical analyses of the previously unresolved relationships of P. keeni and P. sejugis consistently placed these as an independent sister-group between P. maniculatus and P. polionotus. The geographically improbable sister-group association of P. keeni and P. sejugis may be the result of an historical ancestral continuity or may reflect large-scale lineage sorting rather than true phylogenetic propinquity. These data suggest that, given the choice of an appropriate focal species, even relatively small sets of pure dinucleotide microsatellites can provide reliable population genetic and systematic implications for taxa with divergence times dating to the Pleistocene.

No description available.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 42-43). Also available via the World Wide Web.