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EVOLUTION Who is Charles Darwin? Where were the founding ideas of Evolution? What is evolution? Where are the Galapagos Islands? “change EVOLUTION over time” Well tested and supported idea You do not have to agree with a theory Evidence THEORY to support Born Feb 12th, 1809 England After college visited many continents as a part of the crew on the HMS Beagle Naturalist Observed diversity in organisms CHARLES DARWIN https://www.youtube.com/watch?v=xOl0tHVV6Ck “characteristics of many animals and plants varied from one island to the next.” – Charles Darwin GALAPAGOS ISLANDS https://www.youtube.com/watch?v=NKG2qH8778U https://www.youtube.com/watch?v=-FT3FU2XOgo PEOPLE DIDN’T BELIEVE THAT THINGS CHANGED… WHAT DOES THIS HAVE TO DO WITH CHARLES DARWIN AND EVOLUTION? Two geologists who recognized that the Earth changes Rocks form/change slowly (rock cycle) Many forces at work Proposed that the Earth had to be older than previously thought CHARLES LYELL JAMES HUTTON 1795 Present events events help to explain past Processes Change are ongoing does occur CHARLES LYELL JAMES HUTTON 1795 Can living organisms change as well? If so…they would change slowly…over time DARWIN CONSIDERS THIS… Early theory of evolution Species descend from others Living things change over time LAMARCK “selective use or disuse of organs, organisms acquired or lost traits in a lifetime. Traits can be passed to offspring…over time this leads to a change in a species.” 1) Tendency towards perfection (birds want to fly) 2) Use/Disuse (front legs to wings) 3) Inheritance of acquired traits LAMARCK’S PRINCIPLES There were issues with Lamarck’s principles…but it was a start. Adaptation Inheritance LAMARCK’S PRINCIPLES Individual differences among species… NATURAL VARIATION Nature’s own variations. Darwin considered this and decided that species naturally have genetic differences. ARTIFICIAL SELECTION Fitness- ability of an individual to survive and reproduce Adaptation- inherited (behavior or physical) trait that increases an organisms chance of survival. FITNESS ADAPTATION “Survival of the fittest”- individuals that are better suited for the environment are more likely to survive and therefore reproduce passing off genetic variances to their offspring. NATURAL SELECTION https://www.youtube.com/watch?v=AMtT5_AQmLg Vestigial Fossil organs record https://www.youtube.com/watch?v=OAfw3akpRe8 https://www.youtube.com/watch?v=GOKW_7KajCU Homologous body Geographic distribution structures of species EVIDENCE FOR EVOLUTION Galapagos finches Individual traits suggest specific niches for birds and give indicators of feeding habits and habitats. https://www.youtube.com/watch?v=l25MBq8T77w BIRD ADAPTATIONS https://www.youtube.com/watch?v=XzHQ5-lYvrk Gene Pool- Combined genetic combination of an entire population. -combinations of alleles (A,B,O,AB blood types), (eye colors etc.) How often do you see those traits?- Relative frequency GENES AND VARIATION Blood Type and Rh United States Frequency % of U.S. Population O+ 1 in 3 37.4% O- 1 in 15 6.6% A+ 1 in 3 35.7% A- 1 in 6 6.3% B+ 1 in 12 8.5% B- 1 in 67 1.5% AB+ 1 in 29 3.4% AB- 1 in 167 0.6% 1) Genetic shufflingrandom draw of genetic traits during meiosis. Crossing over. 8.4 million combos of genes in 23 chromosomes. 2) Mutations https://www.youtube.com/watch?v=qVmusHZtQms HOW DOES A POPULATION GAIN GENETIC VARIATION? Review Single gene (controlled by a gene with two alleles) Widows Peak Poly gene (controlled by two or more genes with multiple geno/phenotype possibilities) Height, eye color, skin color. SINGLE GENE VS. POLY GENE TRAITS selection acts on phenotypes not so much genotypes Nat Evolution acts on populations not individuals What factors can change the frequency of alleles in a population? 16-2 NATURAL SELECTION AND POPULATIONS Adding cards to the deck Removing cards from the deck (AKA- deaths without reproducing, individuals producing an abundance of offspring) FACTORS THAT AFFECT ALLELE FREQUENCY Simpler to calculate and understand Coloration in an organism… Allele could altogether disappear Adaptations that enhance traits will survive SINGLE GENE FREQUENCY More complicated to predict Ex. height POLY GENE FREQUENCY Selection at one end of the curve increases due to higher fitness. DIRECTIONAL SELECTION Individuals at the center (norm) of curve have a higher fitness than the ends of the curve. Ex. Baby weight STABILIZING SELECTION Individuals at high/low extreme of curve have a higher fitness that in the middle (norm) DISRUPTIVE SELECTION Random change in allele frequency Can cause an allele to become more or less common over time GENETIC DRIFT Allele frequency is constant Population is not evolving GENETIC EQUILIBRIUM In order to have genetic equilibrium… 1- No mutations 2- No natural selection 3-Random 4-Large mating population 5-No movement into or out of population HARDY-WEINBERG PRINCIPLE Formation of a new species Organisms that breed with one another and produce fertile offspring. Common gene pool SPECIATION As new species evolve populations become reproductively isolated from one another REPRODUCTIVE ISOLATION Species have different behavioral practices such as mating song, and technique so they don’t reproduce together. BEHAVIORAL ISOLATION Reproduction is isolated due to a physical barrier such as water, a landform (mountains) etc. GEOGRAPHIC ISOLATION Reproduction is isolated due to different reproduction dates/times. (spring/fall) TEMPORAL ISOLATION