8.Development - Development phenotypic plasticity The...

This preview shows page 1 - 2 out of 6 pages.

Development & phenotypic plasticity The “nature/nurture” debate •It makes no sense to argue that a behavior is solely the product of genes or solely the product of environment –ingredients/recipe analogy •Developmental program: genetic code that determines how the organism will develop over the course of the lifetime, in response to a range of environmental stimuli Sources of behavioral variation in a population: Genetic differences between individuals Exposure to different environmental influences (in current situation, or in earlier phase of development) Examples of types of environmental input: •the other genes in the genome •amount of blood sugar transmitted from mother to fetus •amount of bullying received on the playground •nutrition •amount of physical contact with parents during childhood Different environmental inputs will cause different phenotypic outputs, even in the same individual/genotype! The same gene will be expressed differently depending on what other genes are in the genome How can big behavioral changes result from small genetic or environmental changes? •Hox genes: recipes for proteins called “transcription factors”: they switch other genes on and off by attaching themselves to “promoter” regions of DNA •Most genes aren’t activated till many of their promotors have attracted transcription factors •small changes in promotors affect tendency to attract transcription factors, which makes genes either more or less active •same gene can be reused many places and at different times, by putting different promoters next to it - so it is turned on and off at different points in the life cycle •by switching the same genes on and off in different patterns, you can produce big phenotypic changes without having new genes: –a change in one promoter can cause a cascade of effects Isn’t this genetic determinism?

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture