Bellwork 430 Put your phone up Week 429
Bellwork: 4/30 Put your phone up Week 4/29 – 5/3 1. 2. 3. Grab the new unit book What do you know about Charles Darwin? Ancestors of the polar bear had a brown coat but today they have a white coat. Why? What initiated the change?
1. 2. 3. 4. Today: Bellwork Presentations Unit 7, Part I Notes Peppered Moths
Materials • Unit book • Worksheet
This Week: • Monday: Presentations • Tues/Wed: Unit 7 Pt. 1 Notes, Peppered Moths • Thursday: Pt. 2 & 3 Notes & Microevolution Packet • Friday: Pt. 4 Notes & Video
Homework • Peppered Moth Worksheet • Due Thursday
Unit VII: Evolution
Part I: Intro to Evolution
Intro ? • Ancestors of the polar bear had a brown coat but today they have a white coat. Why? What initiated the change?
Important Dates • Darwin – published his theory of evolution: 1859 • Mendel – published that his parents pass on their offspring discrete heritable factors: 1866 • Hershey and Chase Experiment - discovery of DNA as genetic material: 1952 • Watson & Crick DNA structure: 1953
Jean La. Mark’s Ideas • One of the first to develop a theory of evolution • Reasoned that organisms must adapt to their environment • Inheritance of acquired characteristics • Organisms develop certain characteristics during their lifetime & pass them on to their offspring • Example: Giraffe’s long neck (due to stretching to reach leaves)
Ideas from Geology • Charles Lyell – geologist • Suggested Earth is far older than originally thought • Evidence: • Slow & gradual geological processes occur over long periods of time cause enormous changes to Earth • Examples: • Building of mountains • Creation of canyons
Malthus & Population Dynamics • Observed more babies born than people dying • Suggests human population growing at a rapid rate • Maintain this pace, eventually run out of food & living space
THINK • How might Malthus’ ideas be applied to plants and animals?
Darwin Influenced by Malthus Idea • Applied Malthus ideas to plant and animal population • Plant and animal populations typically do not become overpopulated • Suggests certain factors keep population in check • Disease • Availability of food and other resources
Charles Darwin • Darwin took a voyage on the HMS Beagle in 1831 • Purpose of voyage: map the topography of South American coastline • As a naturalist, his job was to record and collect the plants & animals of South America • From these observations: developed his theory of evolution which was publish in “Origin of Species” in 1859
2 Key Ideas Published in “Origin of Species” 1. Descent with Modification 2. Natural Selection
Descent With Modification • Originated from common ancestor • Descendants of that ancestor spread into various habitats and accumulated modifications • Modifications were adaptations that allowed them to live successfully in that environment • Occurred over millions of years • Descent with modification was driven by natural selection
Natural Selection • Within population compete for resources • Examples: • Food • Water • Shelter
Natural Selection • Individual variation within the population
Natural Selection • Ones with the “most fit traits” compete best for resources
Natural Selection • Those that effectively compete survive and pass traits to offspring • Individuals cannot evolve, only populations can • Mating necessary
Natural Selection • Leads to adaptation – individuals best suited for the environment survive
3 Key Components to Natural Selection 1. Genetic Variation 2. Reproduction 3. Environmental Pressure – selection of desirable trait
Evidence of Natural Selection • Darwin’s Finches • Dominance of particular beak shape & size based on food source
Evidence of Natural Selection • Antibiotic Resistance • Drug resistance in the bacterium Staphylococcus aureus – creating MRSA (methicillin-resistant S. aureus) • Created by bacteria that are overexposed to antibiotic • Few bacteria resistance – survived antibiotic treatment • Over time, resistant strain of bacterium became more common
THINK • Why is reproduction critical to natural selection & descent with modification?
THINK • Examining the picture of finches, what was the… 1. Genetic variation? 2. Environmental Pressure?
THINK • Why is the statement “He has evolved into a fine guitarist” not biologically accurate?
Summary • Over millions of years, the average length of the giraffes’ necks have increased. During the time that this change was taking place, food close to the ground became relatively scarce, but there were always plenty of leaves on the higher branches of trees. Provide the most likely explanation for giraffes’ long neck… 1. According to La. Mark 2. According to Darwin
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