1. Evolution and Classification
Spring 2018

2. Evolution of Populations
Evolution is a change in the frequency of alleles in a population over time.
3 sources of genetic variation
Mutations- Change in genetic material of a cell
Genetic Recombination- During sexual reproduction, each chromosome in a pair moves independently during meiosis
Lateral Gene Transfer- passing of genes from one organism to another (not including offspring)

3. Hardy-Weinberg Principle
Allele frequencies will remain constant, or have genetic equilibrium
Unless factors cause those frequencies to change.
The Hardy-Weinberg Principle holds under these conditions:
Random Mating
Very Large Population
No movement in or out of a population
No mutations
No natural selection

4. The Fossil Record The Fossil Record- Collections of fossils
Organized to provide evidence about the history of life on Earth
Includes how organisms have changed over time

5. Classification
In the 1730’s, Carlos Linnaeus, a Swedish botanist, developed a two word naming system called binomial nomenclature-
First part of the name is the genus
Second part of the name is referring to the species

6. Classification Linnaeus also developed a classification system
It included seven hierarchical taxa:
Kingdom
Phylum
Class
Order
Family
Genus
Species

7. Classification
Sometimes classification keys are used to identify organisms by traits that are visible
However, scientists today now look at how closely members of groups are related.
Phylogeny- the study of how living and extinct organisms are related to one another.
Clade- A group of species that includes a single common ancestor and all descendants of that ancestor.

8. Classification Cladogram- Derived character-
descendants
Cladogram-
A diagram that links groups of organisms by showing evolutionary lines
Aka lineages
Branches from common ancestors
Derived character-
A trait that arose in the most recent common ancestor of a particular lineage and passed to its descendants.
Splitting events
Ancestral lineage