EvolutionEvolution Science Department Post Falls High School
Evolution: What it is and isn’t! Evolution is both FACT and THEORY.
Evolution Evolution = a change Biological Evolution = a change in a population over time –Macroevolution = changes in a a population’s appearance over time –Microevolution = changes in a population Accepting these definitions, EVOLUTION is a FACT.
Theory of Evolution The Theory part of evolution is what is controversial. The theory describes HOW these population changes happen. Darwin and Lamarck are some of the key figures in the theory of evolution.
Parts of the Modern Theory of Evolution 1.Natural Selection 2.Genetic Drift 3.Mutations 4.Recombination These parts of evolution are what is controversial
Evidence for the Theory of Evolution Fossils: Sedimentary layers are chronological and can show sequences of species Embryology: similarities in embryos of vastly different species Homology: many organisms have related structures; Vestigial Organs: Human Tailbone, Appendix, and Whale Pelvis DNA and biochemical similarities
5 Major Misconceptions About Evolution Evolution has never been observed Evolution violates the 2nd law of thermodynamics There are no transitional fossils The theory of evolution says that life originated, and evolution proceeds, by random chance. Evolution is only a theory; it hasn’t been proved. Evolution results in better organisms
Natural Selection English Peppered Moths in the Industrial Revolution (coal burning)
Moth color appeared to change as surface of environment changed They both existed, just relative numbers were changed with majority matching environment
Genetic Drift A gradual shift in the gene frequencies of small populations (less than 10,000 individuals) Alteration of allele frequencies via chance Founder Effect Population Bottleneck
Founder Effect The difference between the gene pool of a population as a whole and that of a newly isolated population of the same species. Occurs when populations are started from a small number of pioneer individuals of an original population. Due to small sample size, the new population could have a much different genetic ratio than the original one.
Founder Effect “Dunkers” - German Baptist religious sect that settled in Franklin County, PA between 1719 and 1729. Type A blood % is 60%, U.S. = 42%; Germany=45% Amish of Lancaster, PA - high frequency of Dwarfism and polydactylism First humans to reach North America (across the Bering Straits land bridge) brought with them gene frequencies not representative of the Asiatic population
Population Bottleneck A population bottleneck is a period of time after which only a small number of the original population survive. As a consequence, a large amount of the original genetic variability may be lost by chance.
Population Bottleneck Elephant seal - hunted to near extinction in the 1800’s; only about 20 left in 1890’s. “Harem” style breeding means that one male could have fathered all of the elephant seals. Genetic analysis shows that all of the elephant seals today (30,000) are almost genetically identical.
Example of Genetic Drift Resulting in Evolution *Can* explain the different frequencies of blood types in different racial groups (isolation of small populations) Race/GroupABOAB U.S.42%10%45%3% Chinese31%28%34%7% Blackfoot76%---24%--- Navajo24%---76%---
Mutation leads to……. Sudden change in heredity (DNA, etc) Tail gene (mutation in only one gene leads to loss of the tail) Sickle-cell anemia (confers malaria resistance)
Variations, which become…… Differences in alleles present in the gene pool of a population
Adaptations, which lead to……. Differences in alleles present in the gene pool of a population
Change And what do we call change that occurs over time? Webster calls it evolution! Examples –Music –Electronics –Clothing
SummarySummary Mutations (sudden changes in heredity) cause variations in a species. Those more successful variations become the most common form in the population (are selected by Mother Nature)!
Natural Selection Those variations that enable organisms to better survive their environment and reproduce soon outnumber the other alleles Those that survive to reproduce pass on their variation of the allele to their offspring (resulting in more organisms exhibiting the variation!)
Contributors Lamarck Wallace Lyell Malthus Erasmus Darwin Charles Darwin
Lamarck’s Theory of Evolution French biologist who introduced the evolutionary theory called Lamarckism. Explains the Theory of Acquired Characteristics. Can it be? States that new traits in an organism develop because of a need created by the environment and are transmitted to offspring. An example of this would be if a primal fish, in order to survive, is obliged to swim, it will evolve a tail.
Charles Darwin (Early Life) Born to a wealthy family in England in 1809. Darwin’s father, Robert Darwin was a successful doctor. Darwin started school and did not do well. He was not interested in doing any work, instead he wanted answers to his questions about life. Finished school with little interest in college. Robert Darwin managed to get him into medical school. Darwin graduated and was asked to attend a voyage, which began his life long studies.
Do you want to take a voyage on the M.S.Beagle? You will travel all around the world looking at exotic animals and researching them. Your pay will be free room and board, and the experience of a lifetime.
Charles Darwin (The Voyage) In 1831 Darwin set out on The Beagle, a ship sent around the world to gather information. Darwin was assigned the job of the naturalist. Darwin collected natural specimens such as plants and animals. He discovered many things in the Galapagos Islands. Darwin returned to England in 1836.
Alfred Russel Wallace (1823-1913) In 1848, he made an expedition to the Amazon River with British naturalist Henry Walter Bates. From 1854-1862 he conducted research in the islands of Malaysia. Duplicated Darwin’s summaries During his trips he noted fundamental zoological differences between the animal species of Asia and those of Australia, and he placed the zoological dividing line-known as Wallace’s Line- between the Malay islands of Borneo and Celebes.
Does science have the only answers? No, certainly not!
CREATIONISM Some claim that Earth and the universe are relatively young, perhaps only 6,000 to 10,000 years old. Life was created by a supreme being in a specific sequence in a 6 day span
Scientists that have studied a giant crater full of star dust think the dust contains the basic chemicals for life. The idea that the scientists have is that the earth was seeded with the necessary elements for life came from the bombardment by comets and asteroids. The evolution process would take place through natural selection, much like Darwin’s theory.
Greek Creation Myth A variety of theories to chose from. Main theory: Gods started over again. Man became very corrupt. Zeus decided to flood the earth for nine days and nine nights. Son of Prometheus and daughter of Epumetheus were told to build an ark, and fill it with supplies.
After the flood the two survivors asked for humans to refill the earth. They were told to throw rocks behind their back, which then became humans. Humans filled the earth once again.
The Iroquois people And how they believe We evolved on earth. Humans came from a women who fell to earth from the “sky people”
At PFHS, we do not require you to believe in evolution. We present it as an example of a widely accepted scientific theory that you must learn. That knowledge makes you better able to understand the answers available to you and your belief system.
And it is required to be presented by the state of Idaho, State Achievement Standard 652.01.a