Transcript VII. Natural Selection - Effingham County Schools

Mutation
A change in a DNA sequence, usually occurring because of errors in
replication or repair. Mutation is the ultimate source of genetic variation .
Migration or Gene FLow
The chance of an individual
migrating to another population and
sharing it’s genes there.
The drift over time of allele
frequencies in a population due to
random sampling effects forming
successive generations.
Genetic Drift
Natural Selection
A process of evolution in which traits that result in better fitness of an individual
survives to the next generation.
Charles Darwin
___________________
– credited with the theory of evolution
Evidence that supports the theory of
Evolution
•Fossil Records
•Geographic Distribution
•Ebryology
•Homologous Structures
•Vestigial Structures
•Biochemistry
•Artificial Selection
VII. Natural Selection- process by which organisms with
beneficial traits will more likely survive long enough to
reproduce and pass on those beneficial traits.
Natural Selection- Works much like artificial selection,
but the environment “selects” the best traits.
– A. Causes Survival of the fittest!
– B. Fitness is a result of adaptation.
• Fitness= the ability of an individual to survive
• Adaptation= an inherited characteristic that
increases the chance of survival
Natural selection– environment
“selects” traits
VIII. How does survival of the fittest
work?”
– The organism that is most capable
of surviving and passing its genes
on in an environment will do so.
– This will cause those genes to be
more dominant in a population.
IX. Darwins 5 Points
1. Variation– populations have
differences
– DNA mutations are the
ultimate source of variation in
organisms
– These mutations are part if
the organism’s genetics, and
are passed on to its offspring
1. Variation- dark
and light mice
What else can cause variation other
than mutations?
Migration- introduces new traits
and variation with in a population
IX. Darwins 5 Points
2. Some variations are
favorable
– Favorable variations
are those that give an
organism an
advantage to
reproduce in a certain
environment
2. Favorable Trait- dark color
IX. Darwins 5 Points
3. Overproduction –
More offspring are
produced than
survive
3. Overproduction
IX. Darwins 5 Points
3. Overproduction
– More offspring
are produced
than survive
IX. Darwins 5 Points
4. Adaptation –
those that survive
are the ones with
the favorable traits
4.Camoflague is
an adaptation
IX. Darwins 5 Points
5. Selection – the
population will
change over time as
a result of passing
inheritable traits
from adaptations
5. Natural selection
selects for the
darker mouse and
against the white
mouse
…And the
population will will
include darker mice
over time.
There are two variations in rabbits: some strictly eat grass and
some strictly eat berries and flowers. A drought occurs one
year, and the plants have difficulty producing any extras
(flowers, berries, etc.).They can only try and keep themselves
green. The rabbits have had babies all year long but many are
eaten by foxes or hawks. Due to the drought, many have starved
to death.
What rabbit will natural selection select AGAINST? ______________
FOR?______________
Population has variations.
Some variations are favorable.
More offspring are produced than survive._________________________________________
Those that survive have favorable traits.
A population will change over time.
1)There are 2 variations in worms: worms that eat at night (nocturnal) and worms that
eat during the day (diurnal). The birds eat during the day and seem to be eating ONLY
the diurnal worms. The nocturnal worms are in their burrows during this time. Each
spring when the worms reproduce, they have about 500 babies but only 100 of these
500 ever become old enough to reproduce.
a. What worm has natural selection selected AGAINST? ______________ FOR?
_____________
Darwin's 5 points: Identify the 5 points in the scenario above.
Population has variations.
_________________________________________________________________
Some variations are favorable.
_____________________________________________________________
More offspring are produced than
survive._________________________________________________
Those that survive have favorable traits.
____________________________________________________
A population will change over time.
________________________________________________________
2) There are 3 variations in polar bears: thick coats, thin coats and medium coats. It is
fall, soon to be winter. The temperatures are dropping rapidly and the bears must be
kept warm, or they will freeze to death. Many of the bears have had ~2 cubs each but
due to the extreme temperatures, many mothers only have one cub left.
a. What bear will natural selection select AGAINST? ______________ FOR?
______________
Darwin's 5 points: Identify the 5 points in the scenario above.
Population has variations.
_________________________________________________________________
Some variations are favorable.
_____________________________________________________________
More offspring are produced than
survive._________________________________________________
Those that survive have favorable traits.
____________________________________________________
A population will change over time.
________________________________________________________
3) In ostriches, there are 2 variations: ones that run fast and those that run slowly. The
fast birds can reach up to 40 miles an hour. Jackals love to eat ostrich, and they can
reach speeds of up to 35-40 miles per hour. A flock of ostrich will lay ~ 10 eggs (each
mother only lays 1), but many rodents break into the eggs and eat the fetus before they
hatch.
a. What ostrich will natural selection select AGAINST? __________ FOR?
_____________
Darwin's 5 points: Identify the 5 points in the scenario above.
Population has variations.
_________________________________________________________________
Some variations are favorable.
_____________________________________________________________
More offspring are produced than
survive._________________________________________________
Those that survive have favorable traits.
____________________________________________________
A population will change over time.
________________________________________________________
1.Artificial selection– humans “select”
traits
Evolution &
Predator/Prey
Relationships
http://ragamuffinsalt.files.wordpress.com/2008/06/scary-bear.jpg
I. Evolution & Predator/Prey
Relationships
A. Adaptation-An inherited trait
that gives an organism a favorable
advantage to reproduce in a
certain environment.
Example
1. What would be an example of an
adaptation that allows predators to
capture prey?
2. What would be an example of an
adaptation that allows prey to avoid being
captured?
Acute Senses
Snails and Crabs
II. Camouflage, Mimicry and
Warning Coloration
Camouflage, Mimicry and
Warning Coloration
Did you see…
a Cheetah?
an Owl?
an Octopus?
A. Mimicry - the ability of some creatures to imitate
others, either by sound or appearance for protective
purposes
B. Camouflage - Protective coloring or another feature that
conceals an animal and enables it to blend into its
surroundings.
Camouflage
Stick Bug
Chameleon
Chameleon
C. Warning Coloration
Conspicuously recognizable markings of an animal that serve to
warn potential predators of the nuisance or harm that would come
from attacking or eating it. The bold patterns of skunks and the
bright colors of poison arrow frogs are examples of warning
coloration.
III. Natural Selection, Predators,
and Prey
A. Prey that can survive attacks from prey
will reproduce and pass those traits down
to their offspring.
B. Predator that can beat the competition
for food will survive and pass on their
dominant traits to their offspring
C. Carrying Capacity – the
number of individuals that an
environment can support
–Affected by predator prey
relationships and the
environment
Bear and Salmon
A = lag phase (very few organisms to begin with – reproduction is slow
B = acceleration phase
C = exponential phase
F = population crash due to limited resources
You can see an obvious cycle, prey numbers go
up followed by predator numbers going up, then
prey drops, predators drop
Name: ___________
As you watch the video – place each animal shown from the rainforest in
the correct category below.
Camouflage:
Mimicry:
1.
1.
2.
2._____________
3.
3._____________
4.________________
5.________________
6.________________
7.________________
8.________________
9.________________
10.________________
Warning Coloration:
1.________________
2.________________
Write a one to two sentence summary of this video, explaining the
significance of these three terms – hint: use “adaptation” in your
explanation.
Video/United Streaming -
World of Nature: Insect Disguises