Agenda Quiz Trade and Grade Ally gatorz Natural Selection Notes Worksheet Exit Ticket

Mutations Review Mutations occur all the time. They can either be GOOD, BAD, or HAVE NO EFFECT. An example of a good mutation: A cheetah got a mutation that made their legs a little longer and they can run faster. An example of a bad mutation: A bird had a mutation that made them call at a sound frequency that predators can hear easily. An example of a mutation that has no effect: A codon that was supposed to be translated CAA gets translated as CAG. They both still produce glutamine.

What really makes a mutation good? Key Point #1: A mutation is good if it increases an organisms fitness. Fitness: Science words- ability to pass on genes Normal words- has lots of babies!!!

NOT GOOD BECAUSE OF THE ENVIRONMENT. Important! Some traits can increase fitness in one environment but not another Having extra fur might be helpful in the north pole… but it would not be helpful in the desert. NOT GOOD BECAUSE OF THE ENVIRONMENT. Make sure to note that we’ll be discussing “goodness” in more depth tomorrow.

So what?.... What happens to bad mutations over time? What happens to good mutations over time?

Natural Selection Key Point #2: Natural selection is the process by which…. traits caused by good mutations become more common in a population over time and Traits caused by bad mutations become less common in a population over time.

Natural Selection Example -In any population, there are differences between species. For example - These fish are different sizes, shapes and speeds.

Natural Selection -Organisms with helpful traits such as being fast, survive better in their environment than slow fish. Since they are alive longer they have more time to have babies and spread their genes!

Natural Selection -Over time, only the organisms with the good genes (in this example, fast fish) will survive and reproduce and the new population of fish will have lots of fast fish!!!! Ancestors (Great-Grandparents) New population of fish

1. traits caused by good mutations become more common in a population over time A good mutation gives an organism an advantage that lets it produce more offspring. Many organisms will be born with the mutation, and it will become more common in the population. REALLY IMPORTANT!!!

2. Traits caused by bad mutations become less common in a population over time. A bad mutation gives an organism a disadvantage that causes it to produce fewer offspring. Few organisms will be born with the mutation, and it will become less common in the population. REALLY IMPORTANT!!!

In other words… Natural selection is survival of the fittest Remember!! Fittest (has the most babies!!!)

Natural Selection Question 1 Koalas have hands and feet that allow them to have a good grip on tree branches (they eat leaves and branches) RANDOM MUTATION YES, DUH. CUZ THE KOALA CAN SPEND MORE TIME UP IN THE TREE EATING THAT GOOD GOOD. INCREASE IN AN ENVIRONMENT WHERE THE KOALA WASN’T ALL UP IN THE TREE The environment had trees with eucalyptus trees that have leaves up high. It was helpful to hang out up there because you can avoid predators on the bottom level and eat a bunch of leaves up top.

Natural Selection Question 1 Koalas have hands and feet that allow them to have a good grip on tree branches (they eat leaves and branches) What caused this trait? Is this beneficial to the koala? Why? What about the environment makes it beneficial? What will happen to this trait in the population? In what environment would this trait not be helpful? RANDOM MUTATION YES, DUH. CUZ THE KOALA CAN SPEND MORE TIME UP IN THE TREE EATING THAT GOOD GOOD. INCREASE IN AN ENVIRONMENT WHERE THE KOALA WASN’T ALL UP IN THE TREE The environment had trees with eucalyptus trees that have leaves up high. It was helpful to hang out up there because you can avoid predators on the bottom level and eat a bunch of leaves up top.

Natural Selection Question 2 Wolves developed thick fur in the desert. RANDOM MUTATIONS NO DECREASE IF THE WOLF WAS SOMEWHERE UP NORTH IT IS WARM IN THE DESERT.

Natural Selection Question 2 Wolves developed thick fur in the desert. What caused this trait? Is this beneficial to the wolf? Why? What about this environment makes it harmful? What will happen to this trait in the population? In what environment would this trait be helpful? RANDOM MUTATIONS NO DECREASE IF THE WOLF WAS SOMEWHERE UP NORTH IT IS WARM IN THE DESERT.

Adaptation Key Point 3: When a good mutation becomes extremely common in a population it is called an adaptation Adaptation: heritable traits that increases an organism’s fitness in its environment. Re: bullet point #1, I just want to MENTION that adaptations result from the accumulation of many many mutations over a long period of time. That’s the meat and potatoes of tomorrow’s lecture, and I’m not covering it today. I just want them to have heard it before, so tomorrow is not coming at them completely out of the blue. Today’s lecture, by contrast, focuses on teaching students how to tell whether something is an adaptation or not.

Break It Down Stop! Biology time!!! OK, that’s a really long and difficult to understand definition. Let’s break it down.

“Adaptations are heritable traits…” Heritable: passed on through genes; inherited from parents. To be an adaptation, a trait MUST be heritable Not all traits are heritable! Heritable traits: eye color, hair color, skin color, height, hairiness Non-heritable traits: tattoos, favorite type of music, hairstyle, learned knowledge There are three sorts of adaptations: structural, physiological (can perform new ability), behavioral.

And they must INCREASE FITNESS in the environment increase fitness: allow an organism to have more babies!!!!!! Live longer (more common) More attractive

Adaptation Examples: Moth Coloring Bird Wing

Adaptation Examples: Secreting Slime Making venom Bioluminescence

Adaptation Examples: Goosebumps is a reflex behavior Reflex behavior = controlled by autonomic nervous system Voluntary behavior = controlled by brain So instincts such as migration are considered to be voluntary, even though birds will almost never refuse to migrate. (But they could! For example, if injured.) NOTE THAT ADAPTATIONS OCCUR IN HUMANS, NOT JUST ANIMALS!!! Goosebumps is a reflex behavior Migration is a voluntary behavior

The Point Make a checklist. Is the trait… Heritable? Going to increase fitness in a specific environment? If your answer to either of these questions is “no,” then the trait is NOT AN ADAPTATION.

Example: Crocodile Teeth Crocodiles have sharp, pointed teeth. The shape of their teeth is heritable. Having sharp, pointed teeth helps them to survive in their specific environment. So, it is an adaptation. How does it help them survive? Ask students.

Non-Example: Favorite Food Favorite food is not heritable. Your parents’ favorite food does not have any bearing on your favorite food. Favorite food does not help you survive. So, your favorite food is not an adaptation. Note that even if one of these two were true, it STILL would not be an adaptation. At end of this side, get someone to pass out whiteboards and markers. Or use ActivExpressions if you have them.