Download BIL 161 Research Project: Biodiversity in Local Ecosystems and

BIL 161 Research Project:
Biodiversity in Local Ecosystems and Microhabitats
The responsibility and rush of every day life sometimes distracts us from the natural world.
The diversity of non-human species is immense and all around us, and yet most people rarely
notice it. Today, we hope you will gain a naturalist’s perspective.
The species you will encounter this semester--small and large, simple and complex--are
the working cogs of that living machine we call the biosphere. Each species is important to the
workings of its ecosystem. Even though we may not yet fully understand the ecological roles
of every species, it is important to be able to identify them for further study. Biodiversity is
defined as the degree of variation of living organisms within a particular ecosystem (or the
entire planet). In the first research project of this semester, you will explore the biodiversity in
microhabitats of local ecosystems.
I. Biodiversity
The biological definition of a species is a group of organisms able to interbreed in nature to
produce fertile, viable offspring. A population is defined as all the members of a single
species living in a defined area. All the populations in a given area comprise that area’s
community. And the communities interacting with the non-living components of the
environment make up the ecosystem. Ecosystems are as varied as the surface of the earth,
and within each ecosystem there are microhabitats—smaller areas within the ecosystem that
are characterized by specific physical factors that determine what lives there. For example, a
pond ecosystem might have microhabitats including (1) the interstitial space of pond plants, (2)
the bottoms of stones, (3) the water column, (4) the sediment at various depths, and (5) the
pond’s surface, to name a few.
All living organisms have evolved tolerance limits for various environmental factors,
including temperature, light, humidity, nutrients, etc. Because different ecosystems and
microhabitats have different levels and combinations of each of these factors, the species in
each ecosystem differ accordingly. The abiotic (non-living) components of any given habitat
determine the composition and abundance of the biotic (living) components of that habitat,
and the biotic components, in turn, affect each other's abundance and diversity.
A. Measures of Biodiversity
Ecologists use specific terms to describe the number, density, and variety of species living
in a particular ecosystem. When you devise your study, be sure to use this vocabulary
appropriately.
The simplest measure of biodiversity in an ecosystem is species richness (S). This is no
more than a count of the number of different species found in a collected sample, and it does
not take into account species abundances. One index used to represent species richness is
Menhinick’s Index (D): the number of species in the sample divided by the square root of the
number of individuals in the sample.
where s equals the number of different species in your sample and N equals the total number
of individual organisms in the sample.
In ecology, the term abundance is used to describe the relative representation of species
in an ecosystem. If you collect a sample from an ecosystem, the abundance of a particular
species is simply the number of individuals per unit area or volume of your sample. The
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relative abundance of a particular species refers to how common or rare that species is in
comparison to other species in the same locality or ecosystem. The relative abundance of any
given species can be calculated as the number of individuals of that species divided by the
total number of individuals of all species combined. For example, if you collected a one
milliliter (mL) sample of pond water and found the following numbers of each of three species:
100 diatoms (Neidium pseudodensestriatum)
50 nematodes (Psilenchus hilarulus)
5 mosquito larvae (Aedes aegypti)
Then the relative density of each species would be:
Neidium pseudodensestriatum:
Psilenchus hilarulus):
Aedes aegypti
100/155 = 0.64
50/155 = 0.32
5/155 = 0.03
Many other measures of biodiversity are important in studies of community ecology, and
you might encounter them during the literature search you will perform in preparation to
designing your research project. For now, review the indices above and be ready to use them
as appropriate for your project. Your team may wish to determine whether there is a
significant difference in species richness between two different types of ecosystems, or from
two different microhabitats in the same ecosystem. Or perhaps you would like to determine
whether certain taxonomic groups are more abundant in one ecosystem (or microhabitat) than
another, and examine why. It is up to your team, with your inquiring minds, to decide on an
interesting, relevant project.
B. Environmental Factors and Biodiversity
Aquatic environments harbor many living organisms, and the biodiversity of an aquatic
system depends, in part, on the salinity of the water. Fresh water is defined as having less
than 0.5 grams dissolved salts per liter, or parts per thousand (ppt). It is hypoosmotic with
respect to the cytosol of a typical living cell. Hence, a freshwater environment presents a
challenge to living cells, which must expend energy pumping water out to maintain proper
osmotic balance.
On the flip side, today’s seawater is hyperosmotic with respect to a typical cell’s cytosol.
Marine saline water has between 30-50 grams of dissolved salts per liter (or ppt). Thus, many
(though not all) marine organisms must expend energy to retain water in the cytosol.
Finally, a brackish environment is defined as having water with between 0.5 – 30 grams of
dissolved salts per liter (or ppt). This is a wide range, and the term “brackish” is thus not very
precise. But the biodiversity of brackish environments can depend on the salinity of the water.
Different habitats not only have variable abiotic factors, and in our suburban area they also
are subjected to human disturbance such as pesticide and fertilizer runoff, physical disruption,
sanitation/clearing efforts, etc. How might these factors affect species diversity and species
composition of an ecosystem?
Consider various factors that might affect biodiversity, and use these as keywords in your
literature search to find background information about this area.
C. Local Environments and Their Biodiversity
Close to the center of campus lies brackish Lake Osceola, which contains more species
than you might imagine if you merely glance while you walk by. It is connected to the ocean by
a long network of canals, so species from both fresh water and marine environments have
access to the lake.
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Until recently, there was a small, isolated freshwater pond, the Gifford Arboretum Pond
just behind the Cox Science Building. Before the demolition of the area commenced to make
way for the new Cox Annex, we were able to sample the pond and save some of the
microscopic biota for your examination. It can be found in the small aquarium on the window
ledge of each lab. Note that the species living in the water column itself, those in the algae,
and those living in the sludge at the bottom might not be the same.
Coral Gables and surrounding communities are dotted with many man-made ponds and
canals. Some are connected to each other, and some are closed systems. Some are
freshwater, and some are brackish. Some of our faculty have ponds on their properties, and
those are of various sizes and condition.
Your research project is limited only by your imagination. You can choose what to ask
about biodiversity. Does it differ between two different ecosystems? Two different types of
water? Nighttime and daytime? Polluted or unpolluted? Consider interesting, relevant
possibilities, and use these as keywords in the literature search assignment you will be given
during the first lab session.
II. Assignment: Literature Search and Review
An essential part of undertaking a research project is to find out what is already known
about your area of interest, why it is important, relevant. Previous research might give you
ideas about what questions still need to be addressed in this area.
For example, you might be interested in finding out if a particular environmental factor (e.g.,
pH) affects biodiversity, but it’s quite possible that research in this area has already been done.
In order to conduct a study that is not simply a repeat of someone else’s work, it is important to
conduct a literature search and review before embarking on your experimental project.
A literature search is an organized search for published material on a selected topic. For
our purpose, you will be required to use databases that retrieve academic sources of high
quality and reliability. Literature databases allow you to search a wide array of journals and
other sources, and enable you to collect scholarly references. Some of these may be in the
form of an abstract, whereas others might be the full text of a journal article. You can usually
save these to your own computer for future reference.
An effective literature search takes an organized approach:
1. Decide on a search topic
With your team, formulate a question to narrow and define the topic. For example, if you wish
to determine the effect of pH on biodiversity, you might ask “Does lower pH change the
biodiversity in a freshwater ecosystem?”
2. Use appropriate keywords to use in your search
Identify important keywords. In the example above, you might include “biodiversity, pH,
ecosystem, acid, alkaline,” or any number of terms related to this area. Also consider:
 When to use broad terms, and when to use narrower terms to refine your search
 Use synonyms for your keywords to find every possible variant of the vocabulary used in the
research on this topic.
 Use dictionaries to check spelling and find keyword synonyms
 Using online encyclopedias (e.g., Wikipedia) to find initial background information that might
help you refine your search or choose an area for your research topic.
3. Choose a Database
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GoogleScholar is an excellent place to start, but there are other databases available through
the UM library system that you may wish to use, as well.
4. Perform your Search
 Use Boolean operators (always use them un upper case) to combine search
keywords.
 Truncate (shorten) your keywords to make your search broader.
 If you are not sure how to spell a keyword, use wildcards.
 To narrow your search, use phrases enclosed on quotation marks. For example, “pH
effect on species richness”.
 Use the database to search for keywords in different places, such as “title” or “abstract”.
 If you find a useful article by a particular author, search that author’s name to find
papers on the same topic.
 If you find a useful article, search its Literature Cited section to find additional, related
sources.
 Make sure the literature you are citing is recent and current.
 Make sure the literature you use is from a peer-reviewed, scientific journal.
 Make sure to identify whether your source is a journal article, a book, a thesis, etc.
5. Determine the availability of the material you wish to reference.
If the paper you wish to read is not available online, you may be able to get a copy by
contacting the people at the Richter Library Help Desk. If our library does not have the paper
you need, they may be able to get it via interlibrary loan. Since this requires turnaround time,
this is one very good reason to start this assignment immediately, and not find yourself
hamstrung by time constraints.
Each student will be assigned the task of finding at least one relevant paper from a
refereed scientific journal on the topic of biodiversity, and preferably narrowed to an area
discussed in advance by your team. Once you find a paper of interest, read it completely and
analytically. Your assignment is to turn in (1) the journal paper and (2) a one-page summary
and review of the paper to your instructor. At the end of your summary, include at least three
questions that the research paper inspires. One or more of these could lead your team to an
interesting and unique research project of your own design.
Your laboratory instructor will give you additional details about this assignment.
Your literature search paper and summary are due at your laboratory session, whether or not
there is a class meeting. Your Laboratory Instructor will give you the information you need to
turn this in on time. And so it begins!
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