Early Theories of Evolution Lamarckian Theory (1744-1824) Lamarck believed living things: changed over time adapted to their environment

3 Hypotheses 1. A desire to change An inborn urge to better themselves Ex. Birds desired to fly → wings

2. Use and Disuse Organism could alter body shape by using their bodies in new ways Ex. Snakes, giraffes

3. Passing on of traits If an animal acquired a trait during its lifetime, it could pass the change on to its offspring Ex. Weightlifter’s muscles

All of the above are fallacies associated with evolution

Charles Darwin 1809-1892 1831 traveled around the world and collected plant and animal species on the HMS Beagle Published On the Origin of Species by Means of Natural Selection in 1859

Chapter 15 Evolution 15.1 Darwin’s Theory of Natural Selection The Galápagos Islands Darwin began to collect mockingbirds, finches, and other animals on the four islands. He noticed that the different islands seemed to have their own, slightly different varieties of animals.

Darwin Continued His Studies Chapter 15 Evolution 15.1 Darwin’s Theory of Natural Selection Darwin Continued His Studies Darwin hypothesized that new species could appear gradually through small changes in ancestral species. Darwin inferred that if humans could change species by artificial selection, then perhaps the same process could work in nature.

Artificial selection: the process of directed breeding to produce offspring with desirable traits

Natural Selection: theory that organisms best adapted to the environment will out compete those who aren’t and will survive

4 Basic Principles 1. Individuals in a population show variations 2. Variations can be inherited

3. Organisms have more offspring than can survive on available resources 4. Variations that increase reproductive success will have a greater chance of being passed on

Evolution: cumulative changes in groups of organisms through time Groups evolve, not individuals

Darwin’s theory of natural selection is not synonymous with evolution. Chapter 15 Evolution 15.1 Darwin’s Theory of Natural Selection Darwin’s theory of natural selection is not synonymous with evolution. It is a means of explaining how evolution works.

Theory of Evolution: all organisms on Earth have descended from a common ancestor

15.2 Evidence of Evolution Support for Evolution 1. The fossil record Chapter 15 Evolution 15.2 Evidence of Evolution Support for Evolution 1. The fossil record Fossils provide a record of species that lived long ago. Fossils show that ancient species share similarities with species that now live on Earth. Glyptodont Armadillo

Archaeopteryx

Fossil has characteristics that classify it as a bird, but retained several obvious dinosaur characteristics

Convergent vs. Divergent Evolution (Background) https://www.youtube.com/watch?v=4-QL-4z0y1U

Support for Evolution 2. Comparative Anatomy Homologous structures: anatomically similar structures inherited from a common ancestor

The structures may move in different ways, but they share similar construction

Ex. Bird wings and reptile limbs

https://www.youtube.com/watch?v=V15KKXfj2Mg

predicts that features of ancestors that no Chapter 15 Evolution 15.2 Evidence of Evolution Vestigial Structures Structures that are the reduced forms of functional structures in other organisms. Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost.

Other examples?

Kiwi Bird

Chapter 15 Evolution 15.2 Evidence of Evolution Analogous structures can be used for the same purpose and can be superficially similar in construction, but are not inherited from a common ancestor.

Show that functionally similar features can evolve independently in similar environments

https://www.youtube.com/watch?v=dXEBCa4OHV4

3. Comparative Embryology Chapter 15 Evolution 15.2 Evidence of Evolution 3. Comparative Embryology Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms.

4. Comparative Biochemistry Chapter 15 Evolution 15.2 Evidence of Evolution 4. Comparative Biochemistry Common ancestry can be seen in DNA and amino acid sequences

5. Geographic Distribution Chapter 15 Evolution 15.2 Evidence of Evolution 5. Geographic Distribution The distribution of plants and animals that Darwin saw first suggested evolution to Darwin. Rabbit Mara

Evolution is intimately linked with climate and geological forces. Chapter 15 Evolution 15.2 Evidence of Evolution Patterns of migration were critical to Darwin when he was developing his theory. Evolution is intimately linked with climate and geological forces.

Usually measured by number of healthy offspring Chapter 15 Evolution 15.2 Evidence of Evolution Types of Adaptation An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success. Fitness is a measure of the relative contribution an individual trait makes to the next generation. Usually measured by number of healthy offspring

Camouflage: allows an organism to blend in with its environment Chapter 15 Evolution 15.2 Evidence of Evolution Camouflage: allows an organism to blend in with its environment Allows organisms to become almost invisible to predators Leafy sea dragon

Camouflage

One species evolves to resemble another species. Chapter 15 Evolution 15.2 Evidence of Evolution Mimicry One species evolves to resemble another species. Western coral snake California king snake

Consequences of Adaptations Chapter 15 Evolution 15.2 Evidence of Evolution Consequences of Adaptations Some features of an organism might be consequences of other evolved characteristics. They do not increase reproductive success. Features likely arose as an unavoidable consequence of prior evolutionary change.