Date of Award:

5-1-1979

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biology

Department name when degree awarded

Life Sciences:Biology

Committee Chair(s)

James A. Gessaman

Committee

James A. Gessaman

Committee

Keith L. Dixon

Committee

LeGrande C. Ellis

Abstract

1. Photoperiods of 12 or 15 hr duration stimulate testicular growth in captive black-billed magpies (Pica pica hudsonia) at both 2 and 20°C; 9-hr photoperiods do not initiate growth at 20°C. 2. Cold temperatures (2°C) inhibit testicular development at 12-hr photoperiods; a slight inhibition occurs at 15-hr photo-periods. The inhibitory effect of cold temperatures on testicular growth in magpies at 12-hr photoperiods is greater than in any species similarly investigated. 3. An estimate of the effect of cold temperature on vernal testicular growth in wild magpies is calculated, and the adaptive value of temperature modulation of photoperiodically induced testicular growth is discussed.

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