Evolution Evolution refers to observable biological changes in a population (or larger group of related organisms) over time; i.e. from one generation to the next. A population is a group of organisms of the same species that interact and interbreed with each other.

Important Evolution Vocabulary Gene – a segment of DNA that holds the information for determining a trait. Gene pool – all of the genes of all of the members of a population. Population - a group of reproducing individuals of the same species in the same area (same gene pool). Alleles are different forms of the same gene (for example, different colors of beetle forewings)

Microevolution vs. Macroevolution Microevolution – changes to the gene pool of a single population. Changes can occur over a short period of time. Example – differences between dog breeds Are different dog breeds different species?

Microevolution vs. Macroevolution Macroevolution – changes and patterns over a long period of time that result in the origin of new species. Usually refers to a group larger than a single population (ex: birds) Example – the evolution of birds from dinosaurs Transitional Species

Both Microevolution and macroevolution are dependent upon genetic mutation and the exchange of genes, but also a super competitive environment with scarce resources.

Microevolution When allele frequencies (relative abundance of alleles of a given gene in a population) change in a population, microevolution occurs. Natural populations are never in genetic equilibrium. (genetic equilibrium = no change) Six processes of microevolution (small- scale changes in a population's allele frequencies) prevent genetic equilibrium: Four processes of microevolution: 1. Mutation

1. Mutation A mutation is a permanent small-scale change in an organism's DNA. For Example: ACCGA -> AGCGA Mutations are the primary source of new alleles

2. Gene Flow Gene flow is the migration of individuals and their genes among populations

3. Genetic Drift Genetic drift is the random change in allele frequencies over generations.

Genetic Drift Continued: Small populations repopulating The Bottleneck Effect: The Founder Effect:

4. Natural Selection (i.e. Environmental Sifting) Natural selection: In a given environment, differential survival and reproduction among individuals of a population that vary in details of shared, inherited traits. Any trait that enhances an individual’s fitness (ability to survive and reproduce in a particular environment) is called an adaptive trait. Survival of the fittest?

How do these organism’s traits increase their fitness?

5. Artificial selection In artificial selection humans choose which traits are passed on. Why did Charles Darwin spend the first third of On the Origin of Species explaining and providing examples of artificial selection (selective breeding)?

6. Sexual selection In sexual selection certain traits are preferentially chosen by mates. Sexual selection was Charles Darwin’s other original idea for an evolutionary mechanism.

Microevolution Review Use your COLORED PENCILS to fill out the microevolution worksheet See previous 4 slides

Patterns of Macroevolution Over long periods of time, we can observe repeating patterns that happen to many different groups of organisms. Coevolution Predator and prey Host and parasite Pollinator and flower Schistoma (blood fluke)

Patterns of Macroevolution Over long periods of time, we can observe repeating patterns that happen to many different groups of organisms. Stasis A lineage exists for millions of years with little or no change (e.g. Bdelloid Rotifers and Coelacanths).

Patterns of Macroevolution Over long periods of time, we can observe repeating patterns that happen to many different groups of organisms. Adaptive radiation A burst of speciation that occurs when a lineage encounters a new set of niches.

Evidence for Evolution Macroevolution occurs over very long periods of time. What evidence do we have to show that it occurs? Observations of microevolution Light color is adaptive in areas of low pollution; dark color is adaptive in areas of high pollution.

Evidence for Evolution Macroevolution occurs over very long periods of time. What evidence do we have to show that it occurs? Fossil Evidence Archaeopteryx Fossils of whale ancestors

Homologous Structures-similar body parts that reflect a shared ancestry

Evidence for Evolution Macroevolution occurs over very long periods of time. What evidence do we have to show that it occurs? Molecular Evidence (DNA and proteins)

Evidence for Evolution Macroevolution occurs over very long periods of time. What evidence do we have to show that it occurs? Vestigial Structures