EVOLUTION =

EVOLUTION = Change Over Time!

Evolution: Big QUESTIONS HOW do Living Things CHANGE? WHY do some organisms survive and others DIE OFF?

The Evolution Revolution EVIDENCE FOR EVOLUTION Fossils and the Fossil Record Radioactive Dating Measuring the radioactive decay rate (half-life) of elements found in fossils The remains or evidence of a living thing and the fossil evidence that scientists have collected

FOSSILS & DATING Fossils provide actual dates of when organisms lived Radioactive Material Decay TIME

Fossil Record 99% of all species that have existed are now extinct Only 10% of all remains are able to be collected and examined as fossils The fossil record may be incomplete, but it is all we have!

Fossils Body Fossils: made from body parts of the organism. bones, claws, teeth, etc… Trace Fossils: made from things left behind Footprints, nests, dung, tooth/claw markings, impressions, etc… Useful for learning about different organisms: where and when they lived Helpful in learning about common ancestors Predicting Continental drift Understanding extinct species’ diet, physical traits, and habitat.

Radioactive Dating Isotopes: Variants of elements with same # of protons but different # of neutrons, many having unstable nuclei. Ex: C12C14 Carbon 14- radioactive isotope with a short half-life that can be used to date newer rocks, or the remains of living things like wood, bones, leather, and plant fragments All living things have the same ratio of C12 to C14 as the air we breathe At the time of death, as time goes on, the amount of C14 an organism has decreases by half. Ex: 5,730 year half-life of C14 Half-life: in an isotope the time it takes for half the atoms in a given mass to decay. The ratio between the amount of original isotope and decay can be used to estimate the age of a sample. Number of years total time of decay ------------------------ = -------------------------- Isotope’s half life number of half lives

The Evolution Revolution EVIDENCE FOR EVOLUTION Law of Superposition and Index Fossils In a series of sedimentary rock layers, the youngest rocks lie on top of older rocks

Index Fossils Help in dating other fossils found in the same sedimentary layer. If an unknown fossil is found near a fossil from a known era then you can assume the two organisms were from the same time

The Evolution Revolution EVIDENCE FOR EVOLUTION BODY STRUCTURES- Living organisms have similar body parts showing a relationship Random, spontaneous changes in the genetic code. Mutations Anatomical Evidence for Change

Mutations and Adaptations MUTATION-random genetic change ADAPTATION-When the mutation assists in survival and is passed onto offspring Homologous structures: structures are similar but have different function, and point to a common ancestor Analogous Structures are similar in function but different anatomically and organisms are not related. Arises when different species live in similar habitats and deal with the same environmental pressures.

Homologous vs. Analogous

The Evolution Revolution EVIDENCE FOR EVOLUTION Embryology The study of developing organisms

Embryology Can you tell the bird from the human?

HOW do Living Things CHANGE? How did the giraffe's neck get so long?

survive and others DIE OFF? WHY do some organisms survive and others DIE OFF? Jean Baptist LAMARCK vs. Charles DARWIN

Neck grows because it needs the food up in the trees! HOW do Living Things CHANGE? Jean Baptiste LAMARCK (1744-1829) Environment changes thus creating a NEED to change, so over time the giraffe’s neck gets longer Neck grows because it needs the food up in the trees!

shorter necked animals are Charles DARWIN (1809-1882) Survival of the Fittest: The ability to pass genes onto offspring. The less “fit” organism will die off (extinction is a part of evolution) The best suited for the environment will: Survive and get food Find a mate Pass on genes Neck is long because shorter necked animals are not as successful!

Who’s theory is widely accepted in the scientific community? Darwin: Theory of Natural Section (Imagine a population of Beetles) There is a variation of traits: ex. The same species of beetle can be brown or green. 2. Not all organisms get to reproduce: ex. The green beetles tend to get eaten more often and so few survive to reproduce.

3. Basic Genetics (heredity): ex 3. Basic Genetics (heredity): ex. The beetles that survive pass their genes, thus certain traits are more frequent in the population 4. Extinction: ex. The green beetle is less “fit” so that population dies out.

survive and others DIE OFF? WHY do some organisms survive and others DIE OFF? Mechanisms of Change: Natural Selection: process by which favorable traits are passed on and those genotypes associated with the favored trait will increase in frequency in the next generation. Those traits that provide an advantage will be inherited, or passed on and others will phase out or go extinct. Examples of Natural Selection: Peppered Moth: Before the industrial Revolution the whiter moth was more abundant in the population, but as more coal was burned the tree bark that the moth lived on turned black thus allowing the black moths to become more abundant in frequency.

Mechanisms of Change continued…. Mutations: Can be useful, harmful, or neutral to a population, and not all mutations matter to evolution. Useful Mutation: helps organism survive in environment (adaptation) Harmful Mutation: organism is not suitable for environment Neutral Mutation: does not harm or help organism.

Mechanisms of change continued…. Migration: when a population of different species move to new locations and create genetic variation.

Mechanisms of change continued… Genetic Drift: chance changes of a population from generation to generation.