BIOL 101 Chapter Assigned Readings: Reading Notes
Document Summary
Some organisms can change their appearance, physiology, and development in response to changes in the environment. A genotype is not a blueprint and what results as a final form is the product of both hardwired developmental processes combined with the effect pf external factors such as temperature, interactions, or nutrition. Phenotypic plasticity evolves by selecting for complete phenotypes and hardwired reaction norms. There are gene regulation mechanisms that respond to changing environmental conditions, and these regulatory mechanisms and the genes they effect are what are selected for in the evolution of phenotypic plasticity. The first view is an example of adaptive phenotypic plasticity, and the second is an example of genotype by environment interactions. A species of vertebrae gives rise to another species on average once every million years. , just published reports on just such an apparent case in cichlid fishes from.
