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Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : [79]-88).

The evolutionary importance of genetic constraints has always been recognized by biologists, but very little data is available to quantitatively assess the role of constraints in shaping the biology of organisms. The field of quantitative genetics provides the tools necessary to study evolutionary constraints, mainly through the estimation of the matrix of additive genetic variance and covariance (the G matrix). The main goals of this Ph.D. dissertation were to study the persistence of constraints across environments and across species, to explore the consequences of constraints on species divergence, and to try to understand some morphological and life history characteristics of field crickets in light of genetic variation. Populations of seven wing-dimorphic cricket species from the genera Gryllus and Teleogryllus were sampled from the wild and reared in the laboratory. Using multiple statistical approaches to the comparison of G matrices, results revealed little variation in G matrices across species. Moreover, the relatively small effect of rearing environment and of the two wing morphologies on G were shown to be of the same magnitude as variation between species, therefore confirming the general constancy of genetic constraints through evolutionary time scales. Mean trait values, selection regimes and phylogenetic distances were all shown not to be predictors of G matrix variation. In agreement with the constraint hypothesis of quantitative genetic theory, morphological divergence between species was shown to be predictable from a reconstructed ancestral G matrix. In addition, information on genetic variation was used to explain various patterns relating to size, ovipositor length, wing morphology and diapause occurrence in field crickets. Overall, we suggest that genetic constraints, as described by quantitative genetics, have played a major role in shaping the observed biological diversity of field cricket species, a conclusion tha

Vocalization behavior of captive loggerhead shrikes was studied at the Avian Science and Conservation Centre of McGill University. In the first stage, calls of two pairs kept in indoor cages were individually recorded not only to catalogue these calls spectrographically and quantitatively but also to use them in identifying the birds sexually. Males vocalized 21 call figures for 16.50% of the observation time and females, 8 call figures for 2.64% of the observation time. Males contiguously delivered 1 to 11 bouts with a mean of 7.25 min for a rate of 6.06 bouts/h; females delivered 1 to 9 bouts with a mean of 4.07 min for a rate of 1.27 bouts/h. Males not only vocalized at a higher rate and longer than females, but also demonstrated trill calls which the females did not do. In the second stage, five pairs were paired in large outdoor breeding pens. Their calls were recorded and current visual displays observed in an effort to understand calls related to breeding behaviors. Two new calls figures vocalized by males as well as 2 call figures by young shrikes were recorded. Each male demonstrated distinctive calls that differed from those of other males during nest-site selection, nest building and copulation, but similar calls during food offering, aggressive and alarm behavior. Despite the call differences, all males performed similar visual displays during the above activities. Conversely, breeding females gave no calls, other than harsh calls during food offering, food begging, aggressive and alarm behaviors.

This thesis investigates the evolution of two secondary sexual characters in birds, large male body size and exaggerated male tail length. To determine whether the elaboration of these two characters is associated with two correlates of sexual selection intensity, mating system and parental care, I collected and examined morphological information for 1,990 species and natural history data for 745 species. Comparative studies should account for the problem of related species sharing similarities through common descent, so here I investigate associations with contrast scores that measure the variation radiating from unique ancestral nodes in a phylogeny. I show that greater polygyny correlates strongly with increasing male size but only slightly with longer male tail length, and that lesser paternal care correlates strongly with both traits. These results indicate that the evolution of increased male body size and exaggerated male tail length in birds is substantially influenced by the intensity of sexual selection.

Bibliography: leaves 274-289. / xiii, 289 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The mechanisms underlying the evolution of sexual size dimorphism in honeyeaters were investigated the Crescent Honeyeater, Phylidonyris pyrrhoptera. Ecological data was acquired at the Cromer Conservation Park, and Parndana, South Australia. / Thesis (Ph.D.)--Adelaide University, Dept. of Environmental Biology, 2001

Dissertation (Ph.D.)--Auburn University, / Abstract. Includes bibliographic references.

Thesis (Ph. D.)--Illinois State University, 1981. / Title from title page screen, viewed March 22, 2005. Dissertation Committee: Mathew J. Nadakavukaren (chair), John L. Frehn, Derek A. McCracken, Arlan R. Richardson, Fritz E. Schwalm. Includes bibliographical references (leaves 113-124) and abstract. Also available in print.

Thesis (Ph. D.)--Australian National University, 2003. / Title from PDF title page (viewed May 12, 2005). Includes bibliographical references.

Thesis (M.A.)--Texas State University--San Marcos, 2009. / Vita. Appendix: leaves 28-40. Includes bibliographical references (leaves 41-43). Also available on microfilm.