16.4 – Molecular EvolutionChapter 17 – Evolution of Populations17.4 Molecular Evolution

16.4 – Molecular EvolutionWarm Up (solo)

What types of reproductive isolation may have been important in Galapagos finch species? Explain. Explain how a finch that feeds only on insects might have evolved.

16.4 – Molecular EvolutionDevelopmental Genes & Body Plans Key Question: How may HOX genes be involved in evolutionary change?

16.4 – Molecular EvolutionWhat are Hox genes? Hox genes determine which parts of an embryo develop arms, legs, or wings.

Also control the size/shape of these structures Hox genes are homologous—

They shape the bodies of almost all animals (common ancestry)

16.4 – Molecular Evolution

16.4 – Molecular EvolutionHox Genes & Evolution Small changes in HOX gene activity during embryological development can produce large changes in adult animals Insects & Crustaceans are related to ancient common ancestors that had dozens of legs.

Insects have 3 pairs of leg? What happened to all the extra legs? Mutation in a single Hox gene, Ubx, turned off the growth of some legs.

A change in ONE hox gene major evolutionary difference!

16.4 – Molecular Evolution

16.4 – Molecular EvolutionTiming is Everything! Each part of an embryo starts to grow at a certain time, grows for a specific time, and stops growing at a specific time. Small changes in starting/stopping times can make a big difference in organisms! Small timing changes can make the difference between long, thin fingers and short, stubby toes!