Evolution

Evolution- the development of new organisms from pre-existing organisms over time. Why does it happen?

Evolution- the development of new organisms form pre-existing organisms over time. Why does it happen? So that organisms can survive changing environments (food, shelter, reproduction).

Adaptation vs. Acclimatization Adaptation – Change in a population over time. Example – whales loosing walking limbs Acclimatization – Change in an individual in its lifetime. Example: 40° in the Fall and 40° in the Spring

Best Supported Argument: Evolution! “Thanks so Much! I would just like to thank a few people that made it possible for my explanation…”

Georges Cuvier Charles Lyell Observed changes in fossil layers of rock Surmised that layers were different due to catastrophes (floods, ice ages) CATASTROPHISM Charles Lyell Geologic processes that shaped the Earth’s surface in the past are still at work today. “we find no vestige of a beginning, no prospect of an end.” - Hutton UNIFORMITARIANISM

Lamarck: Inheritance of Acquired Traits

Use and Disuse Body parts used to get along in the environment get stronger and larger Those that aren’t used, deteriorate.

Inheritance of Acquired Characteristics Modifications acquired during an organism’s lifetime could be passed on to their offspring. Example: A weightlifter’s child could be born with a more muscular anatomy.

Charles Darwin Developed the Theory of Evolution by means of Natural Selection and Descent with Modification

What is a Scientific theory? Everyday vs. Scientific Theories Everyday – an opinion “My theory is that gas prices are going up because the gas stations are trying to make more money.” Scientific - An extensively tested, well supported explanation. “The theory of evolution states that over loooong periods of time, organisms change to fit their environment.”

Development of Theory of Natural Selection Darwin observed 12 species of finches Noted differences in beaks and how that correlated to food choice

Natural Selection Some individuals are better adapted to their environment. These individuals survive and reproduce (pass on their genes)

Descent with Modification Supposed that all organisms were related to an ancient ancestor

Tree of Life Common Descent: All organisms on Earth descended from a common ancestor 4 billion years ago.

Tree of Life Diagram represented a system of natural history. Ancestors at the bottom, descendants at the top. What does this remind you of?

Family Pedigree

Common Ancestor An organism that is a shared ancestor (relative) between two or more different species.

Cladogram/Phylogenetic Tree A diagram showing the evolution of species, including common ancestors. A B C

Cladogram/Phylogenetic Tree Where is the common ancestor between crocodiles and birds? Where is the common ancestor among birds, reptiles, and mammals? Where is the common ancestor among all of the organisms? A B C

Human Evolution

Four Main Parts of Evolution by Natural Selection: 1. Overproduction- a population produces more offspring than can survive. 2. Genetic Variation- within a population individuals have different traits. 3. Struggle to Survive- if there is no competition there is no impetus to change. 4. Differential Reproduction- if you are better adapted, you will live longer an reproduce more.

Overproduction Sea Turtles Hatching

Genetic Variation The genes within a population contains differences. Are you exactly the same as the person next to you?

Variation exists among members of a species.

Again. . . why does variety persist?

Allele Frequency The proportion of gene copies of a given allele in a population. A change in allele frequency results in small evolutionary changes (microevlolution)

Gene Pool All of the genes of the reproductively active members of a population.

Out of the gene pool?

Struggle to Survive

Struggle to survive Individuals must compete with each other for resources. Food, water, mates, etc. Male Caribou fight for the right to breed with a female Caribou.

Differential Reproduction Only the individuals with the best adaptations to their environment will survive competition. Only the survivors will be able to reproduce and pass on their genes.

Differential Reproduction Moths who were darker were better adapted to live on sooty trees.

Differential Reproduction

What supports the Theory of Evolution? 1. Direct Observation 2. Fossil record 3. Homologous structures 4. genetic/and or biochemical similarities

Direct Observations Evolution of drug resistant viruses and antibiotic resistant bacteria Peppered moths during Industrial Revolution.

Fossil Record Skeletons and other preserved remains that show the changes in species over time. Superposition- Where the fossil is in the ground help us determine which are older and newer species.

Homologous Structures Forelimbs of mammals that are now used for a variety of purposes, such as flying in bats and swimming in whale, but were present and used in a common ancestor for walking. Homologous Structures have the a similar form, but different functions.

Genetic similarities All life forms use the same genetic language of DNA and RNA. Example- Amino acid sequences coding for hemoglobin in primate species shows great similarities

Types of Natural Selection Directional Stabilizing Disruptive

Directional Selection Natural selection where the most extreme form of a trait is favored and becomes common. Birds of paradise

Stabilizing Selection Natural selection where the average form of the trait is favored and is more common.

Disruptive Selection Natural selection where two extreme forms of a trait are selected.

Artificial Selection It has led to offspring through successive generations that can be very different in appearance and behavior from their distant ancestors. Organisms with certain traits are bred repeatedly until population has only that trait Example- Dogs, Corn, Broccoli, Cows, etc.

Artificial Selection

These chickens cannot stand or move.

Cow selectively bred for extra meat (muscle) Cow selectively bred for extra meat (muscle). Usually cannot stand for more than a few minutes or walk more than a few steps.

Artificial Selection