BIO-8 Lecture Notes - Lecture 21: Photoperiodism, Henry David Thoreau, Commercial Fishing
Document Summary
The right timing of life history events is critical so behavior and physiology match changing environmental conditions. Organisms rely of various indirect, environmental cues. Photoperiod: the amount of light that occurs each day; provides a cue for many events in the life histories of virtually all organisms. In michigan, water fleas (daphnia) enter diapause in mid- September when the photoperiod declines to less than 12 hours of sunlight. Related species in alaska diapause in august when the photoperiod declines to less than 20 hours of sunlight. These photo-sensitivities are related to environmental temp; the photoperiod is related to decline of temps below a hospitable threshold. Fluctuations in resource availability often determine the timing of life history events. Metamorphosis occurs when a larva changes into juvenile or an adult. Like many amphibians, the barking treefrog undergoes metamorphosis. Individuals with high food resources can metamorphose at a relatively.
