EVOLUTION EVOLUTION Change Over Time Evolution Big QUESTIONS
EVOLUTION =
EVOLUTION = Change Over Time!
Evolution: Big QUESTIONS
The Evolution Revolution EVIDENCE FOR EVOLUTION Fossils and the Fossil Record The remains or evidence of a living thing and the fossil evidence that scientists have collected Radioactive Dating Measuring the radioactive decay rate (half-life) of elements found in fossils
FOSSILS & DATING Radioactive Material Decay TIME n Fossils provide actual dates of when organisms lived
Fossil Record n 99% of all species that have existed are now extinct n Only 10% of all remains are able to be collected and examined as fossils n The fossil record may be incomplete, but it is all we have!
Fossils n Useful for learning about different organisms: where and when they lived n Helpful in learning about common ancestors n Predicting Continental drift n Understanding extinct species’ diet, physical traits, and habitat. 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…
Radioactive Dating n Isotopes: Variants of elements with same # of protons but different # of neutrons, many having unstable nuclei. Ex: C 12 C 14 n 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 n All living things have the same ratio of C 12 to C 14 as the air we breathe n At the time of death, as time goes on, the amount of C 14 an organism has decreases by half. Ex: 5, 730 year half-life of C 14 n Half-life: in an isotope the time it takes for half the atoms in a given mass to decay. n 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 n Help in dating other fossils found in the same sedimentary layer. n 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 Anatomical Evidence Mutations for Change Ran S RE sp o d o m U T C U R T , n ta BO DY S c s m n h an nis eo u a g r o g n i g s Liv e y s g d o b e in t i l ar n et m i s e he v a i h c a c g n ode wi p a r ts s h o i p. h s r e l a ti o n
Mutations and Adaptations n MUTATION-random genetic change n ADAPTATION-When the mutation assists in survival and is passed onto offspring n Homologous structures: structures are similar but have different function, and point to a common ancestor n 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 s d e v tu d y o el o p f o rg an i s i n g ms
Embryology n Can you tell the bird from the human?
Jean Baptist LAMARCK vs. Charles DARWIN
n. Jean Baptiste LAMARCK (17441829) n. Environment changes thus creating a NEED to change, so over time the giraffe’s neck gets longer
n. Charles DARWIN (1809 -1882) n Survival of the Fittest: The ability to pass genes onto offspring. n. The less “fit” organism will die off (extinction is a part of evolution) n. The best suited for the environment will: • Survive and get food • Find a mate • Pass on genes
Who’s theory is widely accepted in the scientific community? Darwin: Theory of Natural Section (Imagine a population of Beetles) 1. 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. 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.
n Mechanisms of Change: n 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.
Mechanisms of Change continued…. n Mutations: Can be useful, harmful, or neutral to a population, and not all mutations matter to evolution. n Useful Mutation: helps organism survive in environment (adaptation) n Harmful Mutation: organism is not suitable for environment n Neutral Mutation: does not harm or help organism.
Mechanisms of change continued…. n Migration: when a population of different species move to new locations and create genetic variation.
Mechanisms of change continued… n Genetic Drift: chance changes of a population from generation to generation.
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