EVOLUTION Definition A gradual change over a period

EVOLUTION Definition - A gradual change over a period of time

What is a theory? • Theories are statements or models that have been tested and confirmed many times • They explain a wide variety of data and observations • They can be used to make predictions

What is a theory? • They are not absolute, they serve as a model of understanding for the world and can be changed as the world view changes • The term "Theory" does not express doubt.

Charles Darwin • Naturalist that observed many species • Made many trips to the Galapagos Islands • Observed finches, mockingbirds, tortoises • Wrote the Origin of Species

Theory of Evolution by Natural Selection 1. Variation exists among individuals in a species

Theory of Evolution by Natural Selection 2. Individuals of species will compete for resources (food and space) called Struggle for Existence (Competition)

Theory of Evolution by Natural Selection 3. Some competition would lead to the death of some individuals, while others would survive. This is called Survival of the Fittest

• An adaptation is an inherited trait that helps an organism survive and reproduce in its environment. • As natural selection repeats from generation to generation, these adaptations become more common, and new adaptations may arise. • Over time, the population becomes better adapted to the environment. Adaptation

p 22 How do species change over time? • Adaptations are variations that help a species survive and reproduce. • At first, adaptations are rare. As more of the species survive and reproduce, the number of individuals with the adaptation will increase. • Other adaptations are inherited behaviors that help an organism find food, protect itself, or reproduce.

Theory of Evolution by Natural Selection 4. Individuals that had advantageous variations are more likely to survive and reproduce. Variations come from mutations and sex reproduction. 5. This process he describes came to be known as Natural Selection.

What happens to species as the environment changes? • All organisms have traits that allow them to survive in specific environments. • If the environment changes, a species is more likely to survive if it has genetic variation, which results in a variation of traits. • If no individuals have traits that help them to survive and reproduce in the changed environment, a species will become extinct.

What happens to species as the environment changes? • Extinction occurs when all members of a species have died. • Greater competition, new predators, and the loss of habitat are examples of environmental changes that can lead to extinction. • Because a natural disaster can destroy resources quickly, organisms may die no matter what adaptations they have. • The fossil record shows that many species have become extinct in the history of life on Earth.

Decent with Modifications Darwin noted that all the finches on the Galapagos Island looked about the same except for the shape of their beak. His observations lead to the conclusion that all the finches were descendants of the same original population. The shape of the beaks were adaptations for eating a particular type of food

Darwin’s Finches

Summary of Darwin’s Theory of Natural Selection • Organisms differ; variation is inherited • Organisms produce more offspring than survive • Organisms compete for resources • Organisms with advantages survive to pass those advantages to their children • Species alive today are descended with modifications from common ancestors

Evidence Supporting Natural Selection 1. 2. 3. 4. 5. Fossil Evidence Comparative Anatomy (Structural) Embryonic Development Geographic Distribution Biochemistry

Evidence of Evolution Fossil Evidence • Fossils are remains of once living organisms • Fossils at bottom are older than fossils at top

Evidence of Evolution Comparative Anatomy • Homologous Structures structures that are embryological similar, but have different functions, the wing of a bird and the forearm of a human

Evidence of Evolution • Vestigial Structures – structure that lost most or all of function do to lack of use • Examples- Wisdom Teeth and Appendix

Evidence of Evolution • Early Embryonic Development is similar which implies they are related, having a common ancestor

Geographical Evidence • Similar organisms from different locations were products of different lines of evolutionary descent

Evidence of Evolution Biochemical • Biochemistry and DNA – by comparing DNA sequences of organisms shows common ancestry

Genetic Variation There are two primary sources of genetic variation: • Mutations are changes in the DNA. A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations. • Sex Reproduction can introduce new gene combinations into a population. This genetic shuffling is another important source of genetic variation

Genetic Variation • Genetic variation and the Environment influence Natural Selection • The environment determines which traits are favorable for survival

Modern Theory of Evolution • Darwin’s theory relied on natural selection as the only known mechanism. • Inherited genetic variation from parent to offspring gives organisms a better chance of survival • Favorable genes increase in number within a population • Traits with low survival value decrease

Natural Selection is responsible for Antibiotic Resistance Bacteria and Pesticide Resistance in Foods

Antibiotic resistance is the ability of bacteria or other microbes to resist the effects of an antibiotic

10 most dangerous antibioticresistant bacteria

MRSA

Pesticide Resistance defined as an inheritable genetic change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control

Phylogenetic Tree or Cladogram

Phylogenetic Tree • Phylogeny is the evolutionary history of a kind of organism • The tree is a branching diagram or tree showing the evolutionary relationships among various biological species based upon the physical and/or genetic characteristics

Answer is 4