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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 years old Humans have been around for a short time – but have had a significant impact! (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)(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 sheet Use the genetic wheel to determine your genetic number There are 128 possibilities of the seven traits How diverse is this population? Can you think of an 8 th 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 yourself If anyone has the characteristic that I read out they are “dead” and will sit down The object of the game is to have at least one person on your team “alive” at the end

I Will Survive ! (Activity 2) Tall ( 5’) Average (5’-6’) Brown Hair BlondeRed Hair Blue eyesBrown eyes Green Eyes Hazel eyes Light skinned Dark skinned Medium Toned Can Curl TongueCan’t curl Tongue Wiggle EarsCan’t Wiggle Ears Left handed Right Handed Can Cross eyesCan-not cross eyes Run FastRun SlowClimb Trees Good eye-sight Bad eye-sight Can’t Climb Trees Good Communicators Introverted (shy)Extroverted (outgoing) Never Gets SickGet Sick A lot Small feet Big Feet Double Jointed Not Double Jointed Good Problem Solvers Good Fixers Swimmer SkaterAthlete Singer Musician/ ArtistWriter Dancer Can arch eyebrowsCan’t Arch Eyebrows Widows Peak Hairline No Widows Peak Hair Line Curly HairStraight 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 (human evolution)

What Else Affects Survival? (mutation) (mass extinction)