Presentation on theme: "Evolution = change over time. Evolution Individuals do NOT evolve! Populations evolve. Evolution occurs at conception, when new combinations of DNA are."— Presentation transcript:
Evolution Individuals do NOT evolve! Populations evolve. Evolution occurs at conception, when new combinations of DNA are made. – The only role you have left in evolution will be when you have children!
Jean-Baptiste Lamarck (1744-1829) 3 ideas of Lamarck: 1.Organisms desired to change and better themselves. 2.The law of use and disuse. 3.The inheritance of acquired traits.
Darwin and Wallace: Similar ideas, different places & times Both founders of the theory of evolution
Alfred Russell Wallace Was also voyaging and observing similar things that Darwin was seeing. He sent an essay to Darwin, and Darwin published their ideas in a paper on the theory of evolution.
Darwin’s Ideas Darwin proposed evolution occurred through the process of Natural Selection. “Survival of the Fittest” means the organism that has traits that are more suitable to the environment will survive and reproduce. The principles of Natural Selection are:
1. Organisms have more offspring than is needed to replace themselves.
2. There is a variation of traits amongst the offspring.
3. Some of these traits are better suited to the environment than others.
4. The offspring that possess these favorable traits will survive and reproduce.
5. These favorable traits will be passed on to future generations.
Adaptations A favorable trait that makes an organism more likely or “fit” to survive. – **Traits are controlled by genes.
Adaptations 1.Mimicry – An individual gains an advantage by looking like the individuals of a different species. "Red touch yellow, kills a fellow. Red touch black, venom they lack.“ Scarlet king snake and coral snake.
Evidence for Evolution 1.Fossil record 2.Anatomical 3.Embryological 4.DNA 5.Artificial Selection
Evidence for Evolution Fossil record: Fossils show change over time.
Anatomical Evidence Homologous structures: – A common limb that has evolved to perform a different function. – Ex: Bird wing, human arm, elephant leg all have the same bones
Analogous structure: Different structures that perform the same function Ex: Bird wing, grasshopper wing
Vestigial structures: A structure that is reduced in function. (snake hips)
Embryological evidence: Comparing the embryos of different species can give clues to evolutionary relationships.
DNA Evidence: Comparing DNA of organisms can show hidden relationships. (scrub jays)
Mechanisms of Evolution: Evolution occurs when the genes in a population change. *Populations evolve, individuals don’t! Basic mechanisms of evolutionary change. 1.Natural Selection 2.Mutations 3.Genetic Drift 4.Migration
Mechanisms of Evolution: 1.Mutations: Changes in DNA sequences that result from environmental factors (ex: radiation or chemicals) or just by chance.
Mechanisms of Evolution 2.Genetic Drift: A random change in allele frequencies that cause changes in populations. – By chance, some individuals leave behind more offspring than others. The genes of the next generation are the genes of the "lucky" ones, not necessarily the healthier or "better" individuals.
Mechanisms of Evolution 3.Migration or Gene Flow: When new individuals enter or leave a population. As a result the allele frequencies change.
Speciation: a new species is created. Species- A group of organisms that breed with one another and produce fertile offspring.
How do new species form? 1.Geographic isolation: occurs when a natural physical barrier separates a population and t 1.Geographic isolation: occurs when a natural physical barrier separates a population and they evolve separate from each other. – Ex: Body of water, landslides, mountains, deserts
How do new species form? 2. Reproductive Isolation occurs when formerly interbreeding population can no longer breed and produce fertile offspring. – Geographic isolation can lead to reproductive isolation.
1. Mechanical- Failure due to physical interference