Gonadal steroid endocrinology of sea turtle reproduction /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Immature loggerhead, Caretta caretta, green, Chelonia mydas, and hawksbill, Eretmochelys imbricata. sea turtles had relatively low serum concentrations of testosterone (T), estradiol-17β (E2), and progesterone (Pro) during the prolonged maturation period in (possibly 50 years or more). However, immature males had significantly higher serum T than immature females and serum T increased significantly during "puberty" in male C. mydas. The results also suggest that T stimulates tail elongation, a secondary sexual characteristic, in males. Serum T concentrations were used to predict the sex of 218 immature C. caretta captured near Hutchinson Island, FL. The sex ratio (2.1 female: 1.0 male) was significantly different from a 1:1 ratio predicted by sex allocation theory. Adult male C. caretta possessed a prenuptial spermatogenic pattern that was positively correlated with increased serum T. Serum T remained high through migration and mating seasons suggesting that T could affect those behaviors. In contrast to adult females, adult male C. caretta may be reproductively active every year. Adult female C. caretta also possessed a prenuptial pattern of gonadal recrudescence coincident with gonadal steroid production. Females exhibited a significant elevation in serum E2 approximately 4-6 weeks prior to migration indicating increased vitellogenesis. Serum T increased immediately prior to migration, suggesting that T could affect migratory and/or mating behaviors. Caretta caretta have relatively high serum T, E2, and Pro during nesting if there is to be a subsequent ovulation, otherwise the concentrations of all three steroids are low. In female C. caretta and C. mydas. serum T was high at the time of nesting and then decreased during the periovulatory period when serum follicle-stimulating hormone (FSH), luteinizing hormone (LH) and Pro increases significantly, suggesting that FSH, LH and Pro may stimulate ovulation, whereas T is a likely candidate for mediating the hormonal surges associated with ovulation. The prenuptial gonadal cycles of C. caretta with temporally associated gonadal steroid production and reproductive behaviors indicate that marine adaptation may have facilitated the retention of a primitive reproductive cycle in sea turtles... |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Zoology." |
| Physical Description: | xv, 114 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |