BIOL150 Chapter Notes - Chapter 8: Reciprocal Altruism, Circadian Clock, Stepfamily
20 Jul 2016
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Document Summary
Ultimate means the entire population, proximate narrows down to individual organism. Migration is defined as the long distance movement of a population associated with a change of seasons. Piloting is the use of familiar landmarks: offspring follows parents and memorize route from there, homing pigeons uses piloting to navigate final stages of a journey home. Compass orientation is movement that is oriented in a specific direction: migratory birds like whooping canes appear to use sun during the day and stars at night. Birds must have an internal clock that defines morning, noon and evening since the sun is at different positions every time. Circadian clock maintains 24-hour rhythm of chemical activity. On clear nights, birds can use north star to find magnetic north. On cloudy days and where stars or the sun isn"t available, birds appear to orient using earth"s magnetic field. One hypothesis says birds can detect magnetism by their visual system.
