Download K and r selection activity

AP* Environmental Science
Daily Lesson Plans
Population Dynamics Unit
Day 3
I. Topic: Selection Strategies
II. Warm-up:
5 minutes
Prior to class, draw two columns on the board and title the one on
the left “K-selected” and the one on the right “r-selected.” Write the
following on the board: Under one of the columns, list one of the
characteristics of organisms in that category. (K-selected: long life
span, late sexual maturity, few offspring, etc.; r-selected: short
gestation period, precocious young, broad niche, etc.)
III. Activity One: Evolutionary Survival Strategies
20 minutes
Objectives:
a) TLW identify the different evolutionary survival strategies of r- and
K-selected species.
b) TLW come up with examples of r- and K-selected species to
complement the information given on each description (“Survival
Strategies”) card.
Materials:
For each student: one “Survival Strategies Card Game” handout
and one set of 8 “Survival Strategies” cards. For the class:
computers with Internet access, or a variety of field identification
books (for insects, plants, amphibians, reptiles, mammals, birds,
etc.) to be used by the lab groups as reference materials.
Procedure:
1. Prior to class, photocopy the “Survival Strategies” page that follows this
lesson plan onto cardstock paper so that each student will have a set of 8
cards. Cut out the sets of cards or, if there is time, give the students
scissors to cut the cards out themselves before they begin the activity. (To
prolong the life of the cards, you may want to laminate them.)
2. Discuss the warm-up, guiding the students to think of any characteristics
not listed.
3. Ask the students to imagine that the right side of their desks represents rselected characteristics and the left side of their desks represents Kselected characteristics. Tell the students to read the cards and place the
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 19
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4.
5.
6.
7.
8.
described organisms in order along an imagined continuum from left to
right based on whether they have more r- or K-selected characteristics.
There is no order that will be absolutely correct since each organism
possesses various r- and K-selected characteristics but must be
considered as a whole. However, the students should be able to identify
definitively that the red-tailed hawk is more K-selected than the
roadrunner, the Western rattlesnake is more K-selected than the Whiptail
lizard and that the coyote is more K-selected than the Kangaroo mouse.
Ask the students to discuss their continuum order with a neighbor/lab
partner. As an opportunity to create discussion, ask the students if there
are any disagreements they would like to offer up or defend.
When the students are satisfied with the arrangement of their cards, ask
them to complete the reflection questions (in the handout provided) with
their neighbor/lab partner.
When they finish the reflection questions, ask them to use the Internet or
field guides to create two additional “Survival Strategies” cards—one for
an r-selected species and one for a K-selected species.
Allow time to discuss the reflection questions if you think these concepts
will be difficult for your students, or use the questions to decide whether or
not the students need more reinforcement on the links between selection
strategies and evolution.
Remind the students of the fruit fly data they have been collecting for the
past few weeks. Ask the following questions to help them make the
connections between this experience and the activity they have just
completed:
a. Are the fruit flies growing in an r- or K-selected pattern? (rselected)
b. What type of population growth graph would correspond to an rselected species? (Exponential or logarithmic growth.)
c. What type of population growth graph would correspond to a Kselected species? (Sigmoid or logistical growth.)
d. What do you predict happens to populations of r-selected species
that continue to reproduce with unlimited resources? (They will
eventually be overpopulated and be overcome with waste or
bodies.)
Special note: Maintain the growing population of fruit flies, using additional fresh
food tubes as needed to keep the population healthy and prosperous. These
flies will be used in a few weeks for a toxicity study on Day 3 of the Toxicity,
Agriculture and Pesticides Unit.
IV. Activity Two: Survivorship Curves
20 minutes
Objectives:
a) TLW relate r- and K-selected characteristics to survivorship curves.
b) TLW practice good scientific graphing techniques.
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 20
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Materials:
For each student: map pencils/colored pens; a ruler; one sheet of
graph paper; one copy of the “Live for Today Life Table” handout.
Procedure:
1. Ask the students to take out their copy of the handout “Guidelines for
Creating Scientific Graphs” as well as their notes on graphing.
2. Distribute the graph paper and the “Live for Today Life Table” handout and
ask the students to create a high quality scientific graph of the handout
data, using different colors to represent the various species.
3. Once they’ve completed their graphs, ask the students to compare theirs
with those created by their lab group. Have the students correct their
graphs, adding anything they left out or addressing anything that needs
improvement.
4. Ask the students to discuss the reflection questions with their lab groups
and record their own responses on their handouts.
5. After they have completed their reflection questions and discussions, ask
the following to ensure their depth of understanding:
a. What type of survivorship curve best describes an r-selected
species? (An early-loss curve.)
b. What type of survivorship curve best describes a K-selected
species? (A late-loss curve.)
c. Using a new color, draw a curve that represents Leatherback sea
turtles, which emerge from nests of about 100 eggs. The babies
hatch and then crawl quickly towards the ocean with the threat of
being eaten by waiting flocks of birds. Once in the ocean, they
attempt to avoid sharks and large-mouthed fish until they can get to
the safety of the Sargasso grass beds, where it is thought that they
spend the next 10-20 years of their lives eating and growing until
their carapace is 30cm in diameter. When a Leatherback sea turtle
leaves the sea grass, it ventures out into the coastal ocean to feed
and becomes sexually mature around 20-30 years of age. It mates
seasonally and grows into a full adult with a carapace of about 100200cm in diameter. Label the graph you have just made “Male Sea
Turtle Data.” If the data included only female sea turtles that lay
eggs on the beach about 8 times a season every other year, what
would its survivorship curve look like? Graph the expected curve
and label this line “Female Sea Turtle Data.” When you have
finished, turn in your work to be graded. (This last graph would
look very similar to the first line they drew, but with a slight
decrease in the curve at sexual maturity since some turtles are
captured by humans when they come on shore to mate. Also, the
curve should be smooth and not include any “bumps” for the
number of nesting attempts or the “every other year” nesting cycle,
since these data are averages for all the females of the entire
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 21
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species.)
HW: Ask the students to complete their Fruit Fly Population Study and write a
lab report with their conclusions.
HW: Ask the students to read the excerpts from Dr. Tatiana’s Sex Advice for All
Creation by Olivia Judson, which describes the evolutionary significance of
reproductive strategies from all different parts of the animal kingdom. The letters
and responses from chapters 11 and 12, pp.169-211, provide for a good
discussion of the evolutionary advantages of sexual recombination.
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 22
This product is licensed to a single user.
Survival Strategies Cards
Lifespan: 7 years
Lifespan: 4 years
Lifespan: 15 years
Lifespan:
Offspring per litter: 6
Offspring per litter: 15
Offspring per litter: 6
Offspring per litter:
Gestation: 19 days
Gestation: 1 month
Gestation: 62 days
Gestation:
Duration of parenting:
2-3 months
Duration of parenting:
none
Duration of parenting:
minimum 1 year
Duration of parenting:
Sexual maturity: 2.5
yrs.
Sexual maturity: 1
month
Sexual maturity: 1.5
yrs.
Sexual reproduction
only
Sexual reproduction
only
Asex./sexual
reproduct.
Sexual reproduction
only
Generalist
Specialist
Generalist
Generalist
Stable population
Irruptive population
Irruptive population
Lifespan: 15 years
Lifespan: 30 years
Lifespan: 2 years
Lifespan:
Offspring per litter: 2
Offspring per litter: 15
Offspring per litter: 3
Offspring per litter:
Gestation: 30 days
Gestation: 90 days
Gestation: 32 days
Gestation:
Duration of parenting:
3-4 months
Duration of parenting:
none
Duration of parenting:
1 month
Duration of parenting:
Sexual maturity: 3
years
Sexual maturity: 2
years
Sexual maturity: 3
mos.
Sexual reproduction
only
Sexual reproduction
only
Only sexual reproduct.
Sexual reproduction
only
Generalist
Specialist
Generalist
Stable population
Stable population
change curve
Lifespan: 7 years
Lifespan: 4 years
Lifespan: 15 years
Lifespan:
Offspring per litter: 6
Offspring per litter: 15
Offspring per litter: 6
Offspring per litter:
Gestation: 19 days
Gestation: 1 month
Gestation: 62 days
Gestation:
Duration of parenting:
2-3 months
Duration of parenting:
none
Duration of parenting:
minimum 1 year
Duration of parenting:
Sexual maturity: 2.5
yrs.
Sexual maturity: 1 mo.
Sexual maturity: 1.5
yrs.
Asex./sexual
reproduct.
Sexual reproduction
only
Generalist
Sexual reproduction
only
Specialist
Specialist
Sexual maturity:
Irruptive population
change curve
Sexual maturity:
Irruptive population
change curve
Irruptive population
Asex./sexual
reproduct.
Generalist
Sexual maturity:
_________ population
change curve
Generalist
Stable population
Irruptive population
change curve
Lifespan: 15 years
Lifespan: 30 years
Lifespan: 2 years
Lifespan:
Offspring per litter: 2
Offspring per litter: 15
Offspring per litter 3
Offspring per litter:
Gestation: 30 days
Gestation: 90 days
Gestation: 32 days
Gestation:
Duration of parenting:
3-4 months
Duration of parenting:
none
Duration of parenting:
1 month
Duration of parenting:
Sexual maturity: 3 yrs.
Sexual maturity: 2 yrs.
Sexual reproduction
only
Sexual reproduction
only
Sexual maturity: 3
mos.
Asex./sexual
reproduct.
Specialist
Sexual reproduction
only
Generalist
Specialist
Stable population
change curve
Stable population
change curve
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
Irruptive population
Generalist
Sexual maturity:
_________ population
change curve
Irruptive population
AP* Environmental Science Daily Lesson Plans pg. 23
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Survival Strategies Cards
Copy the next two pages back to back so that they become two-sided cards.
Make your own
card:
Coyote
Whiptail lizard
Roadrunner
Make your own
card:
Kangaroo
mouse
Western
rattlesnake
Red-tailed hawk
Make your own
card:
Coyote
Whiptail lizard
Roadrunner
Make your own
card:
Kangaroo
mouse
Western
rattlesnake
Red-tailed hawk
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 24
This product is licensed to a single user.
Survival Strategies Card Game
Reflection Questions
1. Asexual reproduction tends to be found more often in r-selected species.
Give two scientific explanations for this correlation.
a.
b.
2. Long-term parenting is often a trait of K-selected species. What is the
evolutionary purpose of this characteristic?
3. Describe one evolutionary advantage and one disadvantage of precocious
young.
Advantage:
Disadvantage:
4. Most species with stable population curves are K-selected. Give one
scientific reason an r-selected species might have a stable population.
5. What correlations do you see between population change curves and r- or
K-selection?
6. Describe one evolutionary advantage and one disadvantage of being a
specialist.
Advantage:
Disadvantage:
7. Are humans an r- or K-selected species? Provide three supporting details
for your answer.
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 25
This product is licensed to a single user.
Live for Today Life Table
The following figures reflect the projected life expectancy for various species and
the percentage of the birth group that survives to each stage at each listed age.
Graph the following data points on a single graph using a different color line for
each species. Use “Lifespan” as the independent axis and 0.0-1.0 for the range
so that all species can be compared equally, regardless of their life expectancy.
Some information is just for background purposes and does not need to be
graphed. Be sure that your graph contains all of the features of an excellent,
scientifically accurate graph.
Species:
Number in cohort
group at birth:
Life expectancy
Time:
0.0 of lifespan
0.1 of lifespan
0.2 of lifespan
0.3 of lifespan
0.4 of lifespan
0.5 of lifespan
0.6 of lifespan
0.7 of lifespan
0.8 of lifespan
0.9 of lifespan
1.0 of lifespan
Black Phoebe
3-6 eggs
Mountain Gorilla
1 young
Southern Toad
30,000 eggs
10 years
% of survivors:
1.00
0.95
0.85
0.75
0.65
0.55
0.45
0.35
0.25
0.15
0.00
50 years
% of survivors:
1.00
0.999
0.999
0.997
0.985
0.980
0.95
0.93
0.82
0.65
0.00
15 years
% of survivors:
1.00
0.1
0.01
0.001
0.001
0.001
0.001
0.001
0.0006
0.0004
0.00
Reflection Questions:
1. Which species has a late-loss curve? ______________ An early-loss
curve? _______________ A constant-loss curve? _____________
2. K-selected species tend to reach sexual maturity late in life, which might
put them at risk for dying before they get a chance to reproduce.
However, most offspring survive to reproduction age. Explain why this is
so.
3. Consider a species of organisms that molts three times in its lifespan.
Draw a line to represent this species and label it “molting species.”
4. Name a species from your local area that you are familiar with:
_________. Describe the survivorship curve for this species using the
correct terminology.
© Kristen Daniels Dotti 2007
www.catalystlearningcurricula.com
AP* Environmental Science Daily Lesson Plans pg. 27
This product is licensed to a single user.