EEB386H1 Lecture Notes - Lecture 6: Hypothalamus, T-Cell Receptor, Photoperiodism
14 Aug 2014
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Document Summary
C. capensis breeds in the hudson bay lowlands. 100 frost- free days to complete breeding and moult. Hpg- axis seasonal breeding of birds is regulated by the hypothalamic- pituitary- gonadal axis (hpg- axis) Chases and fighting) also activates sexual behavior (ex. Song and courtship behavior) ex. In fall, it is insensitive, but sensitivity increases when threshold daylength reached increasing daylength in spring stimulates gonadotropin secretion (ex. Photoperiod seasonal change in daylength is main predictive cue for timing of breeding, moult, and migration. Modifiers include: rainfall, temperature, social stimuli (ex. Male song) replacement of the old integument with new integument. Humphrey and parkes distinguished the predominany plumage type (basic) from another plumage that is carried for a shorter time (alternate) In many birds, basic and alternate are the same as non- breeding and breeding plumage. Moult with no seasonal change. Most birds have the same plumage year- round complete moult post- breeding simply renews the plumage, especially wing feathers.
