Chapter 4 Outline
The Physiology of Immature Animals Always Differs from That of Adults
Introduction to Phenotypic Plasticity and Epigenetics
Phenotypic Plasticity during Development
- Environmental effects during development may arise from programmed responses to the environment or may be forced by chemical or physical necessity
- Insect polyphenic development underlies some of the most dramatic cases of phenotypic plasticity
- Other animals besides insects also sometimes exhibit polyphenic development
Epigenetics
- Two major mechanisms of epigenetic marking are DNA methylation and covalent modification of histone proteins
- Epigenetic inheritance can be within an individual or transgenerational
- Epigenetic marking plays a key role in tissue differentiation during ordinary development
- Evidence increasingly points to epigenetic control of polyphenic development
- Epigenetic marking may account for lifelong effects of early-life stress