Evolution Evidence of Change Evidence for evolution Charles

Evolution: Evidence of Change

Evidence for evolution! Charles Darwin contributed enormously to our understanding of the process of evolution At the age of 22, Charles Darwin (1809 -1882) climbed aboard the H. M. S. Beagle, to sail the world for 5 years

The Voyage of the Beagle Africa and South America Mesmerized by the magnificent diversity of life on the planet. Each species perfectly suited for its own environment, and how much variety there was in lifestyle, appearance, and behaviour.

Theories of Evolutionary theory = foundation on which the rest of modern biological science is built Observing that evolution has occurred is relatively simple; we can see the physical similarities between species and the hard evidence that change has occurred. Explaining how and why evolution occurs is more difficult. Darwin sought a mechanism for these changes. He was influenced by his travels and the scientists who came before him

Carolus Linnaeus (1707 -1778) Father of Taxonomy Developed the modern system for naming and classifying organisms Based on the relatedness of Organisms Physical similarities, observable characteristics Hinted at the idea of common ancestors

Jean Baptiste de Lamarck (1744 -1829) Brought the idea of evolution to the forefront He realized that organisms adapted to their environments Lamarck’s theory is based on 3 ideas: Desire (the will) to change Use and Disuse Passing on acquired traits Knew nothing of genes or genetics, didn’t understand the how He’s known most famously for the giraffe neck stretch hypothesis

Darwin’s Other Influences Charles Lyell, geologist Earth is very old and has changed over time Farmers (and selective breeders) Artificial selection for desirable traits Thomas Malthus, economist An Essay on Population should grow exponentially but in reality, they remain stable due to war, famine and disease

Darwin’s Explanation Darwin called the physical traits and behaviors that help an organism survive and reproduce in its environment its fitness Fitness arises from a process called adaptation Fitness is not always about strength; it includes any characteristic that increases an organism’s chances of survival and reproduction New organism come from preexisting organisms; thus, each species has descended from the offspring of other species over time Darwin called this principle common descent Darwin didn’t know about DNA. His “How” was Natural Selection BUT we know now!!!

Where is DNA?

Deoxyribo. Nucleic Acid Basic structure of DNA includes: 1. Double helix 2. Sugar-phosphate backbone 3. Nitrogenous bases 4. Complementary base pairing

1. Double helix Two helices wound with one another

2. Sugar-phosphate backbone

3. Nitrogenous bases Adenine Guanine Thymine Cytosine

4. Complementary base pairing