AP Bio: Evolution (unit 7)

2024 AP Bio Evolution Unit

Early Earth Conditions

Early Earth Conditions

Reducing atmosphere (electron-adding) containing CO2, CH4, NH3, H2O, N2, and H2.

Elements Needed for Life

Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N).

Fossil Sources

Sedimentary rocks, amber, and frozen mammals.

Incomplete Fossil Record

Due to improper conditions for fossilization, limited discoveries, loss of fossils, and how some fossils are favored for the conditions of fossilization

Half-Life

Time for a parent isotope to decay by 50% into a stable daughter isotope

Radiometric Dating

Technique to determine age by measuring radioactive isotopes and decay products.

Continental Drift

Movement of landmasses from Pangaea over time.

Miller-Urey Experiment

Demonstrated biomolecules can form spontaneously under the conditions of the early Earth’s atmosphere

Haploid Gametes

Reproductive cells with a single set of chromosomes.

Haploid

Cells containing one set of chromosomes

Diploid

Cells containing two sets of chromosomes.

Protobionts/Protocells

the first cell-like structures formed from organic molecules.

aggregates of abiotically produced organic molecules surrounded by a membrane

Protists

Simple eukaryotic organisms not classified as plants, animals, or fungi.

Cambrian Explosion

Rapid evolution period caused by UV light mutations, marked by increased diversity.

birthed true multicellularity and differentiation, the root of modern invertebrates

Endosymbiosis Model

Explains evolution of eukaryotic organelles from engulfed prokaryotes.

Phylogenetic Tree

Diagram showing evolutionary relationships among species.

Species

a group of organisms that can breed and produce fertile offspring

Taxon

a hierarchical classification level

Homologous Similarities

Similar traits (phenotype and genetic) due to shared ancestry.

Analogous Similarities

Similar traits due to convergent evolution, not shared ancestry.

Parsimony/”occam’s razor”

Simplest explanation is often the most likely to be true.

Eukaryka

Domain including organisms with true nuclei. Single-celled organisms, plants, fungi, animals.

Archaea

Diverse prokaryotic organisms in various (usually extreme) environments.

Eubacteria

most known prokaryotes, distinct from archaea.

Theory of Use and Disuse

parts of the body that are used extensively become bigger and stronger, while those that aren’t used as often deteriorate

Lamarck’s Theory

the inheritance of acquired characteristics; organisms can pass on their modified characteristics to the offspring

Natural Selection

Process where organisms with advantageous traits survive and reproduce, leading to gradual changes over generations

Vestigial Structures

Remnants of features that served a function in ancestors.

Comparative Embryonic Development

Similarities in early development among different species.

Microevolution

Small-scale evolutionary changes within populations.

Artificial Selection

humans select for desired traits instead of natural ones

Evidence for evolution

biogeography, the fossil record, index fossils, homologous structures, vestigial structures, comparative embryology

Gene Flow

Transfer of alleles between populations. Usually has to do with immigration or emigration.

Genetic Drift

Random changes in allele frequencies in a population.

Directional Selection

Favors one extreme variant in a population.

Disruptive Selection

Favors variants at both ends of the distribution

Stabilizing Selection

Preserves intermediate variants and removes extremes.

Nonrandom/assortative mating

selecting a mate based on phenotype, giving that phenotype an advantage

Sexual Selection

Preference for certain traits in mates by females, leads to sexual dimorphism.

Allopatric Speciation

Speciation due to geographic/reproductive isolation.

Sympatric Speciation

Speciation without geographic change.

Reproductive Isolation

Mechanisms preventing species from interbreeding.

geographic isolation

species are separated by physical geography and cannot reproduce with each other

habitat/ecological isolation

species are in the same area but in different habitats

temporal isolation

species have different mating cycles

behavioral isolation

species have different mating rituals

mechanical isolation

morphological differences (parts don’t fit)

prevention of gamete fusion

gametes of different species don’t fuse well/don’t work well in the reproductive tract

hybrid invariability

hybrid adults don’t survive well in nature

hybrid infertiity

hybrid adults are sterile or have reduced fertility

hybrid vigor

crossbred individuals exhibit improved or enhanced biological qualities, such as growth rate, fertility, and resistance to disease compared to their purebred counterparts.

Gradualism

Evolution occurs slowly over long periods.

Punctuated Equilibrium

Evolution occurs in rapid bursts with long periods of stability.

h-w allele frequency equation

p+q=1

h-w genotype frequency equation

p²+2pq+q²=1

Hardy-Weinberg Equilibrium

Large population, no random mating, mutations, immigration, emigration, or natural selection

null hypothesis

a general default position; assumes that there is no relationship between the 2+ phenomena.

Founder effect

when a few individuals become isolated from a larger population, they may establish a new gene pool and population that’s different from the source population

Bottleneck effect

when a population passes through an event that reduces its size (sudden environment change, natural disaster, etc.)

population

a group of organisms of the same species living in the same geographic area at the same time, producing fertile offspring