Biology Chapters 12-14

Evolution

change in allele frequencies in a populations gene pool over time

“Descent with modification”

all species are connected by a common ancestor and change over generations; this creates the “Tree of LIfe”

Cuvier

Fossils show extinction

Hutton & Lyell

Earth changes slowly (uniformitarianism), meaning Earth is very old

Lamarck’s two ideas

Use and disuse: organs used get stronger

Inheritance of acquired traits

gained during life are passed to offspring

Darwin’s voyage

Visited the galapagos islands, noticed adaptations in finches and tortoises

Descent with modification

All life shares ancestry but has diverged

Natural selection

Traits that improve survival/reproduction increase in the population

Adaptations

heritable traits improving survival/reproductive success

Artificial

humans choose traits

Natural Selection

Traits that improve survival/reproduction increase in the population

Darwin’s 5 observations & 3 inferences (from E. Mayr)

Obs: Populations overproduce, traits vary, traits are heritable, resources are limited, individuals differ in survival

Inf: Survival isn’t random, traits help survival, traits become more common over time

Artificial selection

humans choose traits

Natural selection

environment “chooses” traits, doesn’t have a goal works with what’s already there

Modern synthesis

fusion on natural selection and genetics

Mutations are a source of..

new traits

3 Domains of life

Bacteria, Archea, Eukarya (Woese)

Fossil Record

Shows changes in species over time

Biogeography

Species on islands resemble nearby mainland species

Anatomical Homology

same structure, different function (human arm, bat wing)

Developmental Homology

Embryos look similar

Molecular Homology

DNA similarities

Form

In sediment, amber, ice, etc.

Relative dating

Deeper = older

Radiometric dating

based on decay of radioactive elements

Plate tectonics

Influence species’ locations

Species distribution

tells us about historical separation

Homologous structures

same ancestry, different function

Vestigal structures

no longer used (human tailbone)

Convergent evolution

Unrelated species evolve similar traits

Molecular clocks

measure mutation rate to estimate evolutionary time

Gene pool

all alleles in a population

HW Equilibrium

Allele frequencies stay constant IF no mutation, no migration (gene flow), large population, random mating, no natural selection

HW Equation

p²+2pq+q²=1 ; p: dominant allele frequency, q: recessive allele frequency

Directional Selection

One extreme favored

Disruptive Selection

Both extremes favoted

Stabalizing selection

average is favored

Intrasexual

competition between males

Intersexual

females choose mates

Systemantics

science of classifying organisims

Phylogenetics

Evolutionary relationships

Taxonomy

naming and classifying organisms

Taxonomic Hierarchy (largest to smallest)

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Cladistics

method using shared traits to show ancestry