Theory of Evolution

Theory of Evolution

Intro • Today we are going to start a unit on evolution • It is important to note that everything that we will be discussing today in the classroom will be based in biology and scientific principles • In order to be respectful to all people’s beliefs and ideas • I would also ask you to stick to the principals of biology

What is Evolution • Has anyone ever heard about evolution before? • What is the idea of evolution? • Where have you heard the term evolution before?

What is Evolution • Evolution is the change over time of inherited traits in a population • It is a hotly debated topic • It is a relatively simple definition, however it has many different aspects to it

History of Evolution • Many years ago there were different ideas of how the organisms on planet earth came to be • People believed that organisms always the way that they currently saw them • They did not have the ability to observe populations, see interactions between species or see other ecosystems

History of Evolution • Since people were so used to the fact that the world did not change, many people were skeptical of the new ideas of evolution • Many of the scientists that believed the world was slowly changing were ridiculed, mocked and/or punished

Jean Baptiste Lamarck • Jean Baptiste Lamarck was the first biologist to propose the idea that populations of organisms change over time • His ideas were considered radical for the time that they were introduced

Jean Baptiste Lamarck • Lamarck had the idea that most organisms passed on their traits based on use and disuse • He believed that organisms changed over time based on their use and disuse of certain characteristics

Jean Baptiste Lamarck • A good example of this would be a giraffe • Lamarck would believe that a giraffe originally started out as a short necked animal • Over time the giraffe stretched its neck to get food • Over time the giraffe grew a longer neck and passed it on to its offspring

Disproving Lamarck • While Lamarck had the right ideas that organisms change, he did not have the right method of change • Just by using or not using a trait does not ensure it will be passed on to the next generation • A runt in a litter of puppies would demonstrate this

Disproving Lamarck • Just because an organism really wants a trait and may use it does not ensure the trait will be passed on • You can think about several things in your own life that may apply

Darwin • However a few years later in the 1830’s a young biologist set sail on a voyage on the HMS Beagle • Charles Darwin’s voyage was one of the most important events in biology

Darwin • He sailed around the world for five years making observations where ever he went • One place that had particular impact on him was the Galapagos Islands • It was there that he started to form the first ideas of evolution

Darwin • http://www.joost.com/36ziwbw/#/?noScroll=true&video_info=36ziwbw

Natural Selection • Darwin found on his journey that certain animals were better suited for their environments than other animals • Darwin found that some of these animals were better suited to survival than others

Natural Selection • Darwin believed that certain animals were better suited to survival and that helped them live and have offspring • Those animals that lived and had offspring would be the ones that you see in the world • This idea was called natural selection

Natural Selection • Natural selection can only happen when one organism has an increased chance to spread its genes • The probability that an organism will pass on its genes to the next generation is referred to as fitness

Natural Selection • An organism that has an increase in fitness have a larger chance of passing on their genes • An organism that has a decrease in fitness has a smaller chance of passing on their genes

Overproduction • There are also several other things that Darwin noticed during his travels that helped form his opinion of natural selection • One of the things he noticed was the number of offspring that were produced

Overproduction • Most animals can produce more offspring than can survive to maturity • This means that some of the offspring will die when they are young • The offspring that will die are ones that will not be passing their genes on in the gene pool

Overproduction • The idea that some offspring do not survive to maturity and cannot contribute their combination of genes is called overproduction • Examples of this would be wild octopus • More octopus are produced each year than can survive

Genetic Variation • Darwin also noticed that within a population there are a difference in traits • The difference in traits creates a full range of traits within a species • This is easy to observe in any population

Genetic Variation • The range of traits within a population helps determine how natural selection proceeds • Natural selection tends to select for certain traits and have certain other traits die out • The range in traits is called genetic variation

Genetic Variation • The range in traits allows for a species to survive if some traits are not variable • If deer with large antlers are hunted and killed easier, there will be deer that have small antlers that would survive • If there were no variation among deer, none would survive

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Adaptation • Some of the variations help an organism survive in an environment • These variations tend to become more frequent in a population • The more frequent that trait is in a population, the better chance that population will survive

Adaptation • A trait that makes an individual more likely to survive in an environment is called an adaptation • Something like thick fur in a cold environment is a successful adaptation • Something like thick fur in a warm environment is not a successful adaptation

Adaptation • Remember an adaptation is a something that is passed down from the parents • Adaptations are not something that is spontaneous or planned by the organism

Theory of Evolution