AP Bio Unit 7

evolution

1. descent with modification

2. change in the genetic composition of a population from gen to gen

natural selection

individuals with certain inherited traits tend to survive and reproduce better due to those specific traits

improves the match between the organism and the environment

artificial selection

breeding to encourage the occurrence of desirable traits

homology

similarity in characteristics resulting from a shared ancestry

embryology

structures present in embryos can explain the similarities in different species

fossils

indicate structural similarities between different species and document the formation of new species

biogeography

study of the past and present geographical distributions of species

genetic drift

chance events alter allele frequency

• founder effect - few individuals isolate from larger population and establish a new population

• bottleneck effect - population is reduced by natural disasters/human actions

gene flow

transfer of alleles between population from migration and mating

• genetic variation - differences in the individuals composition of their genes

• geographic variation - differences in the gene pools of geographically separate populations

Hardy-Weinberg

frequencies of alleles and genotypes remain constant for each generation of a non-evolving species

five conditions

1. NO mutations

2. random mating

3. NO natural selection

4. large population size

5. NO gene flow

HW equation

p + q = 1

p² + 2pq + q² = 1

• p= frequency of dominant allele (A or AA)

• q= frequency of recessive allele (a or aa)

• pq= frequency of heterozygous (Aa)

relative fitness

contribution an individual makes to the gene pool in relation to their ability to survive in their environment

directional selection

favors one extreme of genes in a population

disruptive selection

favors both extremes of genes in a population

stabilizing selection

favors intermediate genes in a pool to maintain a stable trait and prevent genetic variation

sexual selection

individuals with certain characteristics are more likely to obtain a mate

sexual dimorphism

differences between secondary sex characteristics of males and females

intrasexual selection

competition amongst one sex for a mate

intersexual selection

one sex is picky in their mate selection of the other sex

heterozygote advantage

better reproductive success of heterozygotes

adaptive radiation

period in which organisms form many new species whose adaptations fill different niches

punctuated equilibrium

long periods in which a species undergoes little change interrupted by brief periods of sudden change

reproductive isolation

biological factors that impede members of 2 species from producing viable, fertile offspring

postzygotic barrier

reproductive barrier that prevents hybrid zygotes from developing

1. reduced hybrid viability (genes of parents impair development/survival)

2. reduced hybrid fertility (hybrid is sterile due to parents chromosomes)

3. hybrid breakdown (when hybrids mate, offspring are feeble/sterile)

hybrid

offspring resulting from the mating of 2 different species

prezygotic barrier

reproductive barrier that hinders the fertilization between species

1. habitat isolation

2. temporal isolation (breed at different times/seasons)

3. behavioral isolation (courtship rituals differ)

4. mechanical isolation (morphological differences)

5. gamete isolation (sperm can’t fertilize the egg)

morphological

body shape/features

ecological

by ecological niche (in comparison to another species and their surroundings)

biological

by inbreeding of its members

allopatric speciation

when a species is geographically isolated from original population

sympatric speciation

when a species is isolated with NO geographical barriers

phylogeny

evolutionary history of a species/group of organisms

phylogenic tree - triangles

a branching diagram representing the evolutionary history of organisms

taxonomy

naming and classifying forms of life

taxon

unit of taxonomy at any given level of classification

cladistics - squares

organisms are placed into groups called clades based on common descent

clade

groups of species that includes an ancestral and ALL its descents

monophyletic group

a common ancestor + ALL its descendants

paraphyletic group

a common ancestor + SOME of its descendants

polyphyletic group

derived from 2+ ancestors

outgroup

group that is least closely related to the other organisms

ancestral character

character shared by members of a certain clade originated in an ancestor that is not a member of that clade

derived character

character that is new/unique to a certain clade

levels of classification

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Miller and Urey Experiment

atmosphere can spontaneously produce organic molecules

protocell

abiotic precursor of living cells had internal chemistry that was different from its surroundings

RNA world

life on earth began with an RNA molecule that could copy itself

ribozymes

an enzyme that made copies of RNA created early life

formation of life

1. earth formation

2. oldest cells (unicellular)

3. photosynthetic bacteria (releases O2)

4. aerobic respiration

5. eukaryotic organisms

6. sexual reproduction

7. multicellular algae

cambrian explosion

brief time in history when there was an explosion of land and water diversity