The duration of an organism's daily exposure to light, considered especially with regard to the effect of the exposure on growth and development.
For most animals the seasonally changing pattern of day length provides the most accurate year-on-year index of time and many fish use the increasing and decreasing components of this light cycle to coordinate development. In order to use light in this way, however, firstly the light must be perceived, secondly, day length change must in some way be measured and lastly, this information must be transduced into a suitable 'message' for integration by the newoendocrine cascade which initiates and then modulates development. Photoperiod is the ability of organisms to and use the body length as an anticipatory cue to time seasonal events in their life histories. Photoperiodism is especially important in initiating physiological and developmental processes that are typically irrevocable and that culminate at a future time or at a distant place; the further away in space or time, the more likely a seasonal event is initiated by photoperiod. A wide variety of animals from diverse take use the day length or photoperiod as an anticipatory cue to make seasonal preparations. Photoperiod is most useful in predicting environmental conditions in the future or at distant localities; photoperiod provides a go/ no-go signal that initiates a usually irrevocable cascade of physiological and development processes that cuminate in reproduction, dormancy and migration. Day length provides a highly reliable calendar that animals can use to anticipate and prepare for seasonal change. Unlike temperature and rainfall, day length at a given spot on earth is the same today as it was on this date 10 or 10,000 years ago.


Likes:
Thanks:
HaHa: 
Reply With Quote
















