Questions

Page 15- #2

Page 19- #1-3

Extinction in the Modern World

Section 1.3

Humans and the Rate of Extinction

The earth is roughly 4.5 billion years old

The oldest homo sapien fossil discovered is 200 000 years old

Humans have been around for a short time – but have had a significant impact!

http://www.brainpop.com/ (population growth)

A brief history of extinction

There have been 5 mass extinctions in earth’s history

The most famous (but not the biggest) happened 65 million years ago when the dinosaurs were wiped out.

Mass extinctions occurred before humans existed

But the causes were much different – asteroids, volcanoes, etc.

Other causes of extinction include; competition for food, climate changes, etc.

In modern times, human activities are the major causes of extinction.

Effects of Extinction

The number of species in an ecosystem is called the biological diversity or biodiversity of the ecosystem.

The reduction in biodiversity caused by extinction can cause a “domino effect” in ecosystems

Ex. Sea otters

Genetic Diversity

Variety within a population is essential for the ability of that species to cope with environmental change

An organism’s ability to adapt to environmental change determines how well it will survive in the long run

Video (natural selection)

Q & A

Q-The “domino effect” is describing what kind of phenomenon? Give an example of an animal that has been effected this way.

The domino effect refers to the reduction of biodiversity in an ecosystem thus resulting in a change of the food chain. Ex: killer whales and sea otters

The greater the diversity of genes in a population, the greater the chances that some individuals will possess the genes needed to survive under conditions of environmental stress.

What are some examples of environmental stress??

Habitat Fragmentation

Road construction, house construction, etc. causes animal habitats to become fragmented or broken up into smaller pieces

Habitat destruction is the number one cause of species extinction and endangerment

Part 1: Genes

All physical characteristics are determined by genes

Genes are sections of DNA that show up as visible traits – eye colour, hair colour, etc.

Genes are found on chromosomes

Each healthy human has 46 chromosomes, or 23 pairs

Each cell in your body has two copies of each chromosome – one from your mother and one from your father

Crash Course – Heredity

Activity #1

Let’s see how genetically diverse our classroom is.

Let’s figure out what your number is.

Hopefully, we will be incredibly diverse

With a partner- figure out your traits

What are the Characteristics of the Class Population?

Fill out the genetic traits sheetUse the genetic wheel to determine your

genetic numberThere are 128 possibilities of the seven

traitsHow diverse is this population?Can you think of an 8th trait that would set

individuals apart?

Why is genetic Diversity Important?

Activity 2 Split into two teams: Each Person has to pick 10 characteristics Once the game starts you can’t change anything

about yourselfIf anyone has the characteristic that I read out

they are “dead” and will sit downThe object of the game is to have at least one

person on your team “alive” at the end

I Will Survive ! (Activity 2)

Tall (<6’) Short (>5’) Average (5’-6’) Brown Hair Blonde Red Hair Blue eyes Brown eyes Green Eyes Hazel eyes Light skinned Dark skinned Medium Toned Can Curl Tongue Can’t curl Tongue Wiggle Ears Can’t Wiggle Ears Left handed Right Handed Can Cross eyes Can-not cross eyes Run Fast Run Slow Climb Trees Good eye-sight Bad eye-sight Can’t Climb Trees Good Communicators Introverted (shy) Extroverted (outgoing) Never Gets Sick Get Sick A lot Small feet Big Feet Double Jointed Not Double Jointed Good Problem Solvers Good Fixers Swimmer Skater Athlete Singer Musician/ Artist Writer Dancer Can arch eyebrows Can’t Arch Eyebrows Widows Peak Hairline No Widows Peak Hair Line Curly Hair Straight Hair

Did any characteristics wipe out more people than others?

Let’s try the game again, this time you can make any changes to yourself that you like

Did you do better this time?Key Point: the more diverse your team is,

the greater your chance of survival!

Part 1: Continued

Populations of some species have become so small or fragmented that they have lost much of their original genetic diversity.

If these populations are suddenly subjected to stress there may not be any individuals with the genes that will allow them to survive the stress

Part 1: Continued

In a healthy population there is a wide variety of genes that combine in many different ways – Result=> diverse population

If the population is suddenly subjected to stress, (disease or environmental change) genetic variety = more likely that at least some individuals will be adapted to survive

http://www.brainpop.com/ (human evolution)

What Else Affects Survival?

http://www.brainpop.com/ (mutation)http://www.brainpop.com/ (mass

extinction)