From Genes to Traits

complex adaptation

A suite of coexpression traits that experience selection together. Phenotypes are complex when influenced by many environmental and genetic factors and when multiple components must be expressed together for the traits to function.

regulatory network

A system of interacting genetic elements functioning like a circuit board—responding to signals with output that controls activation of other genes during development or the cell cycle.

• Regulatory networks are often involved in complex adaptations

Hox genes

Encode transcription factors that determine the identity of body parts along the head-to-tail body axis.

Horizontal gene transfer

The exchange of genetic information between individuals because bacteria and archaea don’t have a nucleus

gene recruitment

The co-option of a particular gene or network for different functions as a result of a mutation.

gene duplication

• Paralog: there are two copies of the same gene; one copy can continue to perform as normal, whereas the other can acquire new mutations and potentially gain new function

• Once there are 2 copies, they can divide the labor of the original gene.

can accumulate mutations faster

Paralog

two copies of the same gene; one copy can continue to perform as normal, whereas the other can acquire new mutations and potentially gain new function

Promiscuous Protein

protein capable of carrying out more than one function

Pleiotropy

When a single locus affects two or more apparently unrelated phenotypic traits.

Mutations can also be pleiotropic—altering an organism in more than one way.

Antagonistic pleiotropy

A single gene controls two or more traits, and atleast one trait is beneficial and the other trait is harmful.

convergent evolution

The independent evolution of two different lineages into a similar form

• Same traits, not stemming from a common ancestor

• Result of similar selection pressures, such as the same environment.

parallel evolution

The independent evolution of similar traits in multiple lineages, starting from a similar ancestral condition.

• Cave fish developing pale skin in comparison to the surface population.

homoplasy

Similar traits due to a common ancestry

deep homology

A condition in which the growth and development of traits across lineages result from underlying genetic mechanisms inherited from a common ancestor.