Levels of Classification Most living things have been classified based on their physical and behavioral characteristics. There are 7 levels of classification: Kingdom-Phylum-Class-Order-Family-Genus- Species The kingdom level is the most broad and the species level is the most specific. There are 6 kingdoms- Archaebacteria, Eubacteria, Protists, Fungi, Plants and Animals. Living things are typically referred to using their genus and species names. Humans are Homo sapiens. Homo is our genus name and sapien is our species name.

Dichotomous Key If you don’t know the classification of a species, you can use the clues of a dichotomous key to help you.

Populations A population is a group of organisms of the same species that inhabit the same area at the same time. Most populations grow either exponentially or logistically. Exponential growth occurs when resources are plentiful and the reproduction rate is greater than the death rate. Logistic growth occurs if there are limited resources. Growth of the population plateaus when its carrying capacity is reached. The number of organisms will continue to hover around the carrying capacity (will go above it and below it and above it and below it …).

What is the Carrying Capacity for this population of rabbits?

Population Genetics The genetics of a population will remain stable unless one or more of the following events occur. The genetics of a population will remain stable unless one or more of the following events occur. Mutation= random changes in the DNA Mutation= random changes in the DNA Natural Selection= survival of the fittest Natural Selection= survival of the fittest(certain genotypic groups are targeted because they are not able to survive as well as others) Gene Flow= movement of alleles into or out of a population (immigration or emigration) Gene Flow= movement of alleles into or out of a population (immigration or emigration) Genetic drift= changes in the alleles of a population due to random events (i.e. natural disaster or epidemic) Genetic drift= changes in the alleles of a population due to random events (i.e. natural disaster or epidemic) Non-random mating Non-random mating Small population size= Allele frequencies change more drastically in small populations. Small population size= Allele frequencies change more drastically in small populations.

Each colored line represents a different genetic drift event acting on a population. Notice that the smallest population experiences the greatest change in allele frequency over time and the largest population experiences the least change in allele frequency over time.

Measuring the Genetics of a Population The Hardy-Weinberg equation calculates genetic variety in a population. The Hardy-Weinberg equation calculates genetic variety in a population. The H-W equation is: The H-W equation is: p 2 + 2pq + q 2 = 1 (or 100%) q 2 = the frequency of homozygous recessive individuals. 2pq = the frequency of heterozygous individuals. p 2 = the frequency of homozygous dominant individuals. If the allele frequencies change from 1 generation to the next, the population has evolved.

Human Impact on Populations Humans can impact populations in a variety of ways: Selective breeding Deforestation Pesticide and fertilizer use Invasive species Antibiotics Burning fossil fuels/global warming

Evidence of Common Ancestry Charles Darwin came up with the theory that all living things can be traced back to the same original ancestor. Charles Darwin came up with the theory that all living things can be traced back to the same original ancestor. The evidence that supports this theory includes: The evidence that supports this theory includes: – Fossils – DNA/proteins – Embryo structure – Comparative anatomy (homologous features) – Vestigial structures

Fossils

Embryos

Homologous Features

Vestigial organs

Cladogram A cladogram is a diagram that shows the evolutionary relationship among different species. A cladogram is a diagram that shows the evolutionary relationship among different species. As an organism evolves, there is a new branch on the cladogram. As an organism evolves, there is a new branch on the cladogram. Organisms with similar characteristics (DNA, structure, behavior) are placed more closely on the cladogram. Organisms with similar characteristics (DNA, structure, behavior) are placed more closely on the cladogram. Characteristics that evolve between species are called derived characters. Characteristics that evolve between species are called derived characters.

Variations of Cladograms

LampreyFrogBird Dog MacaqueHuman

Create a Cladogram using the Pictures Place a “+” if the characteristic is present and a “-” if it is absent Organism Characteristic JawsLimbsHairLungs Opposable thumb Upright, erect posture Turtle Gorilla Human Lamprey Caecilian Lamprey Cat TOTAL