This site is 100% ad supported. Please add an exception to adblock for this site.

Ch1, 23 LIFE


undefined, object
copy deck
1) species change over time

2) natural selection causes the changes
1) process by which adaptive traits are aqcquired by evolutionary mechanisms

2) traits that enhance the survival & reproductive success of their bearers
population genetics
-apply Mendel's laws to populations of orgs
gene pool
the sum of all alleles in a population
autotrophs ; heterotrophs
-self-feeders ; other-feeders
group w/ a recent common ancestor
- a specific type; no natural interbreeding
the scientific study of the diversity of organisms
under systematics, classifying organisms
- a hypothesis that describes the history of descent from a common ancestor of a group of organisms

- phylogenetic tree – each node / split = speciation event
features shared by 2 + species from a common ancestor
derived trait
a trait that differs from its ancestral form
convergent evolution
traits that were independently evolved become superficially similar b/c of similar selective pressures
evolutionary reversal
reverting back to ancestor state from derived state
homoplastic traits / homoplasies
traits that are similar not b/c of inheritance from common ancestor
ancestral traits vs derived traits
only traits in ingroup are derived; ancestral traits in ingroups and outgroups
Evolutionary Agents causing HWE deviation
1) Mutations
2) Migration
3) Genetic Drift
4) Nonrandom Mating
5) Natural Selection
-are rare for each loci, but so many loci that there may be a few mutations in each zygote
produces gene flow
genetic drift
the random loss of indivs and the alleles they possess
population bottlenecks
occasional periods a normally large pop. may go thru when only a small # of indivs. survive

-may increase/decrease an allele freq lots by chance being a bigger factor
founder effect
a few indivs colonize region;
resulting change in genetic variation
nonrandom mating
-like x like or like x unlike
-ie 2 flowers - pin (long stigma, short stamen/anther), thrum (short stigma, long stamen/anther)
natural selection
when some indivs contribute more offspring to the next generation than others, changing allele freqs

-fitness - contribution of one relative to the phenotype of another
natural selection, quantified 3 ways
1) stabilizing selection - avg. favored
2) directional selection - R or L
3) distruptive selection - both extremes
stabilizing selection
-favors average indivs
-reduces variation
direction selection
-indivs of one extreme are favored
disruptive selection
indivs at both extremes favored
-results in bimodal distribution
-ie bill sizes in black-bellied seedcracker of W. Africa

Deck Info