Download Types of Natural selection

Types of Natural selection
Wednesday 1/22/14
 Grab a book and a new bellringer so you
are not TARDY
 LT: I can identify types of selection
 BR: What is natural selection?
 ** if you finish bellringer begin & finish
vocab for day 2. We will begin class 10
min after bell rings. Day 2 is due on
Tuesday
2
Friday 1/24/14
 Study day 2 vocab for quiz on Monday
 Continue day 3 vocab
 Finish worksheet for lab yesterday
 natural selection is the process by which individuals
that are better adapted to their environment survive
and reproduce
 What have we been studying in class so far how does it
connect
4
Evolution by Natural
Selection
Steps:
1.
Individuals vary in some traits.
2. Some of the differences in traits are passed along to offspring.

This requires a genetic basis to the trait

The trait is thus heritable
(more…)
5
Evolution by Natural
Selection
3. Different individuals produce different numbers of surviving
offspring.
 Produce different numbers, or
 Different numbers survive.
4. The particular value of a trait is connected to the number of
offspring produced.
 Traits that allow for more offspring to be produced are said to be
“naturally selected.”
6
evolution
 Evidence of evolution
 Natural selection
 Genes
7
Types of Natural Selection
 Directional – The most extreme form of a
trait is favored and becomes more
common
 Disruptive- 2 extreme forms of a trait are
selected for
 Stabilizing-The average form of a trait is
favored and becomes more common
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Example 1
 The tall man virus has taken over the country. It only
infects men over the height of 6 feet. Scientists are
scrambling to find a cure. This is an example of what
type of selection. Draw the appropriate graph that goes
with it.
 Directional because it selects for one extreme of the
population. Thus the allele for short men will continue
on while the allele for tall men are being selected
against
Example 2
 Clutch Size in Birds: Females that lay intermediate
numbers of eggs have the highest reproductive success.
Too many eggs, and the offspring all starve. Too few
eggs, and the mother could have laid more. Called the
Lack optimum, it applies to many birds.
 Stabilizing because individuals with the average trait
have the highest fitness.
Example 3
 A population of rabbits consist of black, white and gray
fur color.
 If this population of rabbits were put into an area that
had very dark black rocks as well as very white colored
stone, the rabbits with black fur would be able to hide
from predators amongst the black rocks and the white
furred rabbits would be able to hide in the white rocks,
but the gray furred rabbits would stand out in both of
the habitats and thus would not survive. What type of
selection is this? Draw the appropriate graph that goes
with it.
 Disruptive because it is selecting for the individuals with
either extreme of the trait.
Example 4
 Infants with average birth weight are more likely to
survive than a baby that is too small or too large. The
bell curve peaks at a birth weight that has the minimum
death rate. What type of selection is this? Draw the
appropriate graph that goes with it.
 Stabilizing because individuals with the average trait
have the highest fitness.
Example 5
 Salmon migrate to the rivers they were reproduce at
approximately the same time every year. Fisherman
know this and fish for salmon at this time. However a
population of fish arrive earlier than the other salmon.
This earlier population has been growing larger every
year while the later population has been growing
smaller. What type of selection is this? Draw the
appropriate graph that goes with it.
 Directional because it selects for one extreme of the
population. Thus salmon that mate at an earlier time of
the year are being selected for.
Example 6
 The giraffe population at one time was made up of
giraffes with different neck sizes, short, medium, long.
However, tree heights only got taller and taller until
there were no short trees to eat from. Over time the
short neck giraffes died and only long neck giraffes
survived. What type of selection is this? Draw the
appropriate graph that goes with it.
 Directional because it selects for one extreme of the
population. Thus the allele for short necks will not
continue on while the allele for tall necks are being
selected for
Example 7
 imagine a plant of extremely variable height that is
pollinated by three different pollinators, one that was
attracted to short plants, another that preferred plants
of medium height and a third that visited only the tallest
plants. If the pollinator that preferred plants of medium
height disappeared from an area, medium height plants
would be selected against and the population would tend
toward both short and tall, but not medium height
plants. What type of selection is this? Draw the
appropriate graph that goes with it.
 Disruptive because it is selecting for the individuals with
either extreme of the trait.
Example 8
 The desert population of spiny cacti are under attack.
Peccaries are eating those plants with low-spine-number.
A second predator, a parasitic insect, arrives in the study
area. Preferring densely spined cacti, these egg-laying
parasites more often destroy varieties of plants with
larger numbers of spines. The only cacti left are those
with a moderate amount of spines. What type of
selection is this? Draw the appropriate graph that goes
with it.

Stabilizing because individuals with the average trait
have the highest fitness.
Example 9
 A population of birds with small medium and large beaks
exists. The birds with small beaks can only eat small
seeds, the medium beak birds can only eat medium
seeds and the large beak birds can only eat large seeds.
The plants that provide medium seeds dies out and thus
the medium beak bird population dies off. What type of
selection is this and draw the graph that goes with it.
 Disruptive because it is selecting for the individuals with
either extreme of the trait.
anatomy
 study of structure of body: the branch of science that
studies the physical structure of animals, plants, and
other organisms
embryology
 The scientific study of embryos and their development
BIOGEOGRAPHY
 The study of geographical distribution of living things
Wednesday 1/22/14
 LT: I can Analyze data from an activity
and explain how it supports the theory of
natural selection citing evidence from
the data.
 BR: List the three types of selection and
give examples of each.
 ** Quiz Thursday
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Thursday 1/23/14
LT: I can Analyze data from an
activity and explain how it supports
the theory of natural selection
citing evidence from the data.
BR: Does natural selection create
the perfect organism? Explain your
choice
Day 2 vocab quiz tomorrow
Peppered moth simulation
 A few changes to the lab
 Number of moths will be 15 for the
starting population
 Time to pick up moths will be 20 seconds
 Don’t sigh or your moths will fly away!!
 Watch your sleeves because the moths will
escape with your clothing!!!
 This will be graded! Do your best as you
always do!
Monday January 27, 2014
 LT: I can design a species and relate it’s adaptations to
it’s overall FITNESS
 BR: what does FITNESS mean?
 ** vocab quiz get a chrome book and study!!
Tuesday 1/28/14
 LT: I can research a species and relate it’s adaptations to
it’s overall FITNESS
 BR: what is the weirdest animal you have ever seen or
heard of?