AP Biology Unit 7: Evolution

Phylogeny is the evolutionary history of a species or group of related species. It provides important information about similar characteristics in closely related species.

Taxonomy is the ordered division and naming of organisms.

Binomial nomenclature, published by Carl Linneaus in the 18th century. The first part of the name is the genus, and the second part is the specific epithet, which is unique for each species within the genus.

Domain, kingdom, phylum, class, order, family, genus, and species

A phylogenetic tree represents a hypothesis about evolutionary relationships. They show patterns of descent and do not indicate when species evolved or how much change occurred in a lineage.

A branch point represents the divergence of two species.

Sister taxa are groups that share an immediate common ancestor.

Similarity due to shared ancestry. EX: Bat and bird wings are homologous as forelimbs

Similarity due to convergent evolution. EX: Bat and bird wings are analogous as functional wings

When similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages

Analogous structures or molecular sequences that evolved independently

A group of species that includes an ancestral species and all its descendants

A clade that consists of the ancestor species and all its descendants

A grouping that consists of an ancestral species and some, but not all, of the descendants

A grouping that consists of various species with different ancestors

A character that originated in an ancestor of the taxon

An evolutionary novelty unique to a particular clade

A molecular clock uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change.

Charles Darwin proposed the idea of evolution by natural selection. He is known for Darwin’s Finches, where he found differences in beaks of 13 species of finches on the Galapagos Islands.

When a new population is started by only a few individuals. Some rare alleles may be at high frequency and others may be missing. Skew the gene pool of the new population.

When a larger population is drastically reduced by a disaster, leading to a loss of variation where some alleles may be eliminated altogether. Narrows the gene pool. EX: All cheetahs share a small number of alleles, <1% diversity

A hypothetical, non-evolving population that preserves allele frequencies and serves as a model to measure if forces are acting on a population. If allele frequencies change, population is not in equilibrium and evolution is occurring.

(Frequencies must add to 100%)
For alleles: p + q = 1

For individuals: p² + 2pq + q² = 1

Where the environment favors one extreme

Where species have similar body and colorations, but are distinct biological species because their songs and other behaviors are different enough to prevent interbreeding.

Pre-zygotic barriers impede on mating or hinder fertilization if mating occurs. Habitat, temporal, behavior, mechanical, and gametic isolation

Post-zygotic barriers prevent hybrid zygote from developing into a viable, fertile adult. Reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

“Other country”, where populations evolve independently due to a geographic separation, such as migration or a physical barrier

“Same country”, where populations evolve independently due to isolation even though members of population remain in contact. The causes for this isolation are chromosomal changes (polyploidy) and non-random mating.

Evolution of many diversely adapted species when introduced to various new environmental challenges and opportunities. Many ecological niches open. EX: Darwin’s finches, mammals

Mutation creates variation and changes DNA sequence. Types: Point mutation, duplications, translocations

Individuals are selected. Populations evolve.

Heterozygotes have a greater fitness because they maintain both alleles in the population. EX: Sickle cell anemia where heterozygotes are protected against malaria

Changes in gene frequencies from 1 generation to another because of chance events