Summary
Heterochrony and microRNA pathways such as let-7 control when developmental events occur.
In depth
Heterochronic genes in C. elegans (lin-4, let-7, lin-28) control larval stage transitions. Segmentation clock in somitogenesis. Neoteny and progenesis create evolutionary changes.
Timing mechanisms include clocks and sequential gene expression. Heterochronic changes (earlier or later development) cause evolutionary shifts in form.
Key idea: when something happens in development can matter as much as what happens.
Frequently asked questions
What is Developmental Timing?
Heterochrony and microRNA pathways such as let-7 control when developmental events occur.
Which area of biology covers Developmental Timing, and how advanced is it?
Developmental Timing is one of the 54 topics in Developmental Biology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Metamorphosis in Amphibians, Somites, Model Organisms in Development.
Can you give an example of Developmental Timing?
Humans retain juvenile features such as a flat face (neoteny).
What should I learn before Developmental Timing?
Work through the Beginner topics in Developmental Biology first, such as Fertilisation, Zygote, Embryo, then return to Developmental Timing. Advanced topics assume the Intermediate vocabulary.
What topics are related to Developmental Timing?
The closest topics to Developmental Timing are Metamorphosis in Amphibians, Somites, Model Organisms in Development, Hox Genes. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Developmental Timing?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Developmental Timing. To practise the whole of Developmental Biology, use the Developmental Biology quiz.
How is Developmental Timing different from Metamorphosis in Amphibians?
Developmental Timing: Heterochrony and microRNA pathways such as let-7 control when developmental events occur. Metamorphosis in Amphibians: Thyroid hormones trigger the tadpole to frog change, including tail loss and limb growth. Read both side by side and note what each one explains.
How should I study Developmental Timing step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Metamorphosis in Amphibians and explain the difference aloud. Finally, take the Developmental Biology quiz and come back to this page for any question you miss.