Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [76]-86).

Thesis (M.S.)--Ohio State University, 2005. / Includes bibliographical references (leaves 86-98). Available online via OhioLINK's ETD Center

Thesis--Groningen. / Summary in English and Dutch. "Stellingen" inserted. Bibliography: p. 120-129.

No description available.

I examine some of the ecological and evolutionary implications of body size in hermit crabs, with special emphasis on the upper intertidal species Clibanarius digueti. In Chapter 1 I show that body size had a far greater effect than species identity on desiccation tolerance for shell-less individuals of C. digueti, Paguristes anahuacus, Pagurus lepidus, and Phimochirus roseus. In contrast with other intertidal taxa, there was no correlation between the upper tidal limit of a species and the expected desiccation tolerance of an average-sized, shell-less individual of that species. This suggests that the gastropod shell that normally houses the hermit crab is sufficient to eliminate desiccation as a community-structuring force in this guild. Clibanarius digueti exhibits strong sexual dimorphism in body size, with almost no overlap in size between adult males and females. In Chapter 2 I show that sexual differences in the intensity of selection on size favor this dimorphism. Specifically, male mating success depended more strongly on body size than did female fecundity. In fact, the rate of increase in fecundity with body size equalled the lowest previously recorded for decapod crustaceans, suggesting that sexual size dimorphism in this species may depend more on weak fecundity selection on females than on strong sexual selection on males. Documenting contemporary selection on a character, however, is not the same as documenting that selection caused the character to evolve. Chapter 3 presents the first empirical test in a single species (C. digueti) of the hypothesis that sexual size dimorphism represents an evolutionary response to sexual differences in selection on size. The test is based on a general model that predicts crab body size as a function of shell limitations, shell fit and body size. Both males and females occupied optimally sized shells of non-preferred species, but the greater the desirability of a shell species, the greater the tendency for males to occupy tighter-fitting shells than females. Males also apparently suffere higher mortality than similarly-sized females. According to the general model, these results agree with the hypothesis that differential selection is causally involved in the evolution of sexual size dimorphism, and contradict the alternative hypothesis that energetic constraints on females produce the dimorphism.

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

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.