Evolution and development Flashcards
What 3 things does all development ultimately depend?
Differential gene expression, morphogenesis and cell communication
How did evolution affect Hox genes?
Started with a common bilateral ancestor in the Cambrian, and later descendants modified it. The Hom-C complex got duplicated over millions of years
What is modularity?
Developmental events occur as modules in space and time
What are anatomical modules?
A module of an anatomical feature, like a hand. A hand develops in context of the limb
What are molecular modules?
Genes working in conjunction with transcription factors and other genes
Are gene regulatory networks modules?
Yes, they are molecular modules
What is co-option?
A module can be copied and reused for another feature
How did co-option happen in stickleback fish?
The pelvic spine is absent in freshwater sticklebacks, since the enhancer has been altered in the freshwater fish so it isn’t expressed. But the gene that is involved in the expression of the spine (Pitx1) is intact and perfectly functional
What are the 4 evolutionary mechanisms of developmental changes?
Heterotopy
Heterochrony
Heterometry
Heterotypy
What is heterotopy?
The location of the expression of the gene/molecule has changed (feathers and scales)
What is heterochrony?
The timing of the expression of the gene/molecule has changed (length of digits)
What is heterometry?
The amount of the expression of the gene/molecule has changed (loss of eyes in cave fish)
What is heterotypy?
The gene sequence has changed (mutation in Ubx stops insects from developing more than 6 legs)
