Transcript Extinction in the Modern World

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