evolution exam 2

complex adaptation

a set of co-expressed traits that experience selection for a common function

novel trait

new physical, behavioral, or physiological characteristics in a population or organism that were not present in previous generations

promiscuous/multifunctional protein

a protein that can perform more than one function

gene recruitment

The duplicate copy of a promiscuous protein experiences a mutation in one of its regulatory regions. This will cause evolution to act on the gene in a new context. These mutations continue to accumulate, leading to complex adaptations.

regulatory network

systems of interacting cellular components.

antagonistic pleiotropy

some traits may be advantageous but have negative knock-on effects

two-fold cost of sex

Sexually-reproducing populations are half as efficient as asexual populations in terms of reproductive output

muller’s ratchet

Offspring of asexual reproduction simply inherit all the genes from their parent, so if a bad mutation occurs, offspring are 100% likely to inherit it.

anisogamy

Most organisms experience sexual reproduction where the male and female gametes are different sizes

intersexual selection

Individuals of one sex choose among individuals of another sex → females choosing males or males choosing females

direct benefits

food, protections, nest sites, help raising young

indirect benefits

Mating with a male who has high fitness in their environment indirectly benefits the female by increasing the likelihood that her offspring will survive in that same environment

sensory bias hypothesis

trait preferences evolve based on preexisting sensory tendencies

cryptic female choice

refers to the fact that some female organisms can store and separate sperm after mating

antagonistic coevolution

happens when traits that increase the reproductive success of one sex impose costs on the other, and each sex evolves counter-adaptations in response

taxa

any group of organisms at any level of classification (e.g., species, genus, kingdom)

branch

connect nodes to nodes, or nodes to tips. These represent evolutionary lineages over time

node

branching point in the tree. These represent divergence among taxa. *Represent a single taxon splitting into two.

tips

The ends of a branch. These represent a specific taxon

monophyletic

(clade) a group that includes a common ancestor and all of its descendants

polyphyletic

grouping of taxa that do not share an immediate common ancestor

paraphyletic

includes a common ancestor but only some of its decedents

outgroup

determine which traits are ancestral and which are derived

synapomorphy

Traits that are shared only by taxa in a clade

homoplasy

a trait that is shared by taxa but not because of shared descent

convergent evolution

the independent origin of similar traits in separate evolutionary lineages

polytomy

An internal node in a phylogeny with more than two branches that indicates we do not have enough information to determine branching order

parsimony

The simplest phylogeny, the one with the fewest evolutionary changes, is likely the correct one.