Changes in Developmental Rate and Timing

Notes

• Subtopic: Changes in Rate and Timing of Development In evolutionary developmental biology, changes in the rate and timing of an organism's development can lead to significant evolutionary differences. These changes can be categorized into two main types: those affecting the onset of reproductive traits and those affecting the onset of somatic traits. These developmental changes can either be accelerated or delayed when compared to an ancestral species. • Subtopic: Categories of Developmental Changes 1. **Recapitulation**: In this category, reproduction occurs relatively later in somatic development in the descendant species. 2. **Paedomorphosis**: Here, reproduction occurs relatively earlier in somatic development, resulting in a body that retains juvenile characteristics when sexually mature. - **Acceleration**: Somatic traits develop faster. - **Hypermorphosis**: Reproductive traits are delayed. - **Progenesis**: Reproductive traits develop faster. - **Neoteny**: Somatic traits are delayed. • Subtopic: Example of Neoteny - The Axolotl The axolotl, a species of salamander, is a classic example of neoteny. They reach sexual maturity while their somatic traits are delayed, which i...