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Description: |
xv, 150 leaves : illustrations ; 29 cm |
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Dissertation Note: |
Ph. D. Texas A & M University 1990 |
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Bibliography Note: |
Includes bibliographical references. |
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General Note: |
"Major subject: Veterinary physiology." |
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Summary, Etc. Note: |
Abstract: The reproductive biology of the coyote was studied over a five year period (1985-1990). Serum concentrations of reproductive hormones and behavior profiles obtained from mature and immature male and female coyotes demonstrated that the immature female is physiologically and behaviorally capable of reproducing her first reproductive season and that the immature male is physiologically capable of reproducing, but does not exhibit the sexual behavior necessary for reproduction. No significant difference was found in serum concentrations of reproductive hormones in mature and immature females. In mature males serum concentrations of testosterone, FSH, and LH were doubled and sperm counts were ten fold higher than observed in the immature males. The male sexual behavior may require higher levels of testosterone than was found in the immature males, and, with respect to reproduction, physiological maturity precedes behavioral maturation. A study of the dominant/subordinate relationship demonstrated that there are three classes of female coyotes: Dominant females that cycle and produce live young; subordinate females that cycle but do not bear young due to a delay in the onset of proestrus, the LH surge and estrus; and subordinate females that do not cycle demonstrating no preovulatory surges of LH, FSH, and estrogen and no vaginal estrus. Subordination was associated with an alteration in the secretion of reproductive hormones resulting in a loss of fecundity in the female coyote. There was a general correlation between serum LH concentrations and in vitro basal LH release in coyotes of the same gender as a function of seasonal reproductive activity. When the slopes of the LH responses to GnRH (ng LH released/log concentration of GnRH) were used as an indication of pituitary sensitivity, there was an increase in sensitivity in the females during the reproductive season and no change in GnRH sensitivity in the males between the reproductive and nonreproductive seasons. The administration of naltrexone, an opioid antagonist, abolished behavior hierarchy in the female coyote, influencing the timing of estrus and the behavior enabling them to exhibit sexual behavior and produce live pups. |
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Name Added Entry: |
Amoss, Max S., degree supervisor. |