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

Insert Graph of Height

4' 3'' 4' 6'' 4' 9" 5' 5' 3" 5' 6" 5' 9" 6' 6' 3"0

2

4

6

8

10

12

# Of People

# Of People

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