Download Biol 106 Ecology Modeling Lab

Biol 106 Ecology Modeling Lab – Fender's Blue Butterflies
Introduction
Global biological diversity (the variety of organisms living in the biosphere, the global
ecosystem) is vast, with over 1.8 million described species and estimates of more than
10 million species not yet discovered. Some ecosystems, like tropical rain forests,
support large concentrations of species. Many of these species may go extinct before
they are ever discovered, due to a variety of factors affecting the distribution of species
within populations, communities and ecosystems. The study of the interactions
between these organisms and their environment is called ecology. Ecology integrates
multiple disciplines of biological research, where scientists study the interactions of
organisms in the environment from a variety of hierarchical levels, including organismal
ecology (study of individuals), population ecology (study of groups of individuals of the
same species) and community ecology (study of groups of populations of different
species in an area) to name a few. Identifying factors affecting species distributions
allows biologists to work to preserve our current biological diversity.
Conservation biology integrates ecology, physiology, molecular biology, genetics, and
evolutionary biology to preserve biological diversity at all levels. Each species has an
ecological niche, that is, the combination of biotic and abiotic factors required for the
species to exist. Over evolutionary time ecological niches change and species either
respond to change (e.g., via natural selection) or go extinct. This pattern is a natural
phenomenon occurring since life first evolved; however, the current rate of species
extinction has increased due to human activities. Species require specific habitats
(areas that support a specific group of species) for survival and reproduction, but human
activity has directly or indirectly altered or even eliminated the habitats of many species.
For example, farms, cities and roads have reduced the size of species’ habitats, limiting
populations to small isolated habitats called fragments.
The fragmentation of existing habitat into smaller patches does more than simply
reduce the available habitat area available for populations. Edges of habitat fragments
are often of lower quality than the interiors of habitat fragments, because the edges of a
habitat are influenced by its surrounding landscape. For example, pesticides and other
agricultural products are more likely to drift into the edge of the habitat than into the
interior, and weeds are more likely to immigrate to the edge of the habitat from
surrounding fields or road cuts. Therefore, what factor should an ecologist minimize
when conserving habitats?
In an effort to preserve species severely affected by human activity, such as
endangered species (a species in danger of extinction throughout all or a significant
portion of its range), biologists have developed the field of restoration ecology. In this
field, ecological principles are used to return disturbed ecosystems to conditions as
similar as possible to their natural state.
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In today’s lab we will discuss the biology of an endangered butterfly species call the
Fender’s blue butterfly (Icaricia icarioides fenderi), a species native to the prairies of
western Oregon and southwestern Washington. Specifically we will use a computer
simulation to examine possible strategies to save the Fender’s blue butterfly through
restoration of its fragmented prairie habitat.
Fender’s blue butterfly
In the last century, farms, cities, and roads have replaced most of the native prairie
habitat in western Oregon and southwestern Washington. Today, less than 1% of the
indigenous prairie remains, distributed in isolated patches that are often separated by
several kilometers. Among the species that live in the prairie habitat is the Fender’s blue
butterfly. This is a small butterfly, with a wingspan of about two centimeters (about one
inch). Females have rusty brown wings and males have iridescent blue wings, which
gives the butterfly its name. The Fender's blue butterfly requires native prairie species
for nectar and larval food sources. Because of the reduction in prairie habitat, the
Fender’s blue butterfly is in danger of extinction (and up until 1989 it was believed to be
extinct). Less than 4000 of these butterflies are left in western Oregon and
southwestern Washington.
The government and other private agencies are willing to attempt to save the Fender's
blue butterfly by restoring old farmlands and other abandoned areas to butterfly habitat.
Habitat restoration is quite costly (estimated cost for restoring populations of Fender’s
blue butterfly by 2033 is around 16 million dollars) and requires hours of manual labor
(removing unwanted non-native species and adding native species). Because the
restoration process is time consuming and expensive, ecologists must first identify
which areas of land would have the highest impact in restoring the population of
Fender’s blue butterflies. Ecological models allow ecologists to compare a variety of
possible restoration plans to determine the best possible strategy for the time and
money allotted to a project.
Exercise:
Funds are available to restore 200 acres of native prairie habitat necessary to
allow populations of Fender’s blue butterflies to recover to stable levels. Your
job is to use a modeling program to determine the best way to distribute the
200 acres of restored prairie in order to maximize the number of populations
of Fender’s blue butterflies.
Possible ways to distribute restored land:
.
• Make existing patches of prairie larger.
.
• Make corridors connecting existing patches of prairie.
.
• Make a series of small patches (stepping-stones) between the larger ones.
.
• Use combinations of the above or try something completely different!
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Directions for running the program
1. Click on the Ecobeaker icon in the dock (beaker with tree coming out the top).
2. Go to the Labs pull down menu at the top, choose butterflies
3. Go to the Markers pull down menu. It lists different habitat scenarios. First choose
100 years ago. You will use the Marker pull down menu several times
throughout this lab.
Simulation 1: 100 yrs Ago
To start the simulation click on the green arrow on the bottom left of the screen
or select the Action pull down menu and choose Go. Let the simulation run for a
total of 700 weeks. You can observe the number of weeks the simulation is
running on the bottom of the screen. You can also adjust the speed of the
simulation (Slider bar at the bottom of the screen) by clicking and sliding the
speed bar. In order to stop the simulation at 700 weeks, slow the simulation
down, once it gets close to 700, then stop by clicking on the stop icon or
selecting the Action pull down menu and choose Stop. Note that this is an
annual population so every year (52 weeks) it starts over.
Run this simulation 1 time. After your simulation, RECORD the number of
butterflies in the population after 700 weeks in Table 1 below (The number
of remaining butterflies can be found in the Statistics box). Share your
data with the other lab tables.
Simulation 2: Today (Baseline Data)
Today represents the remaining habitat currently available for the butterflies. Go
to the Markers pull down menu. Choose Today. You will notice the farmland
habitat is the most prevalent and the prairie remnants are quite small. Your
total Area of Prairie is 800 acres (Located in the Statistics box).
Run this simulation 6 times. After each simulation, RECORD the number of
butterflies in the population after 700 weeks in Table 1 below (The number
of remaining butterflies can be found in the Statistics box). Make sure to
RESET for each simulation. To reset: select the Action pull down menu,
choose reset or choose the reset icon at the bottom of the screen (icon to the
right of the stop icon).
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Simulations 3 – 8: Possible Methods of Habitat Restoration
Simulation 3 = Patch Expansion (increase the size of the patches)
Simulation 4 = Corridors (directly connect habitats)
Simulation 5 = Stepping stones (connect patches by small patches rather
than continuous corridors)
Simulations 6, 7, 8 = Create your own models (A, B, & C). Try to create
models that will generate the largest population of Fender’s blue
butterflies!
For above simulations (3 - 8) you will be adding new prairie habitat. You may
only add an additional 200 acres of prairie, making the total prairie habitat
= 1000 acres.
To make a new habitat, first reset the simulation using the reset icon to the right
of the stop icon. Then go to the Action pull down menu, choose Paint, then
choose Prairie in the Habitats box. This converts the mouse into a "paint" tool
so you can "paint" prairie habitat. If you add more than 200 acres, you can
remove the excess by choosing Farmland in the Habitats box and removing
some prairie. After you finish painting each prairie habitat, save your newly
painted habitat before you run a simulation, so you can run the same
simulation 6 times.
Saving new habitats: Go to the Marker pull down menu, choose Add Marker
(name your marker something that corresponds to the simulation you are
running, for example if you just created a Patch expansion name the new
habitat Patch). After the new habitat is saved you can now run the simulation.
Run the simulation 6 times, for 700 weeks each and record the data in
Table 1 below Note: To run multiple simulations for new habitats, you will
reset, go to the Marker pull down menu and select your newly saved habitat
(i.e., Patch). For simulations 3-8 also provide a drawing (map) of each new
habitat you create in the spaces provided at the end of this lab write-up.
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Table 1. Fender’s Blue Butterfly population sizes for various habitat models.
Trial #
Number of Surviving Butterflies in each Model Habitat
100 yrs
ago
Today
Patch
Corridors
(Baseline) Expansion
Stepping
Stones
Model A
Model B
Model C
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2
3
4
5
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Average
of all
trials for
each
model
Conclusions: On average, which of the above habitat models resulted in the most surviving butterflies? Explain
why you think that model worked the best. In your answer, include other factors that should also be considered
before implementing the best model. Be thorough, there’s a lot of time and money associated with your habitat
restoration decision!
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Maps of Prairie Habitat Models
Patch Expansion
Corridors
Stepping Stones
Model A
Model B
Model C
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