Learning Outcomes for Unit 1:
Understand the structure of the course.
Understand the concept and importance of biological diversity and how it can be affected by
Define the basic concept of evolution.
Identify the most important information as it relates to a specific biological issue or question.
Identify traits of organisms/species that relate to species survival and/or invasion ability.
As you proceed through this Inquiry Case, write down any technical terms (“jargon”) that you are
unfamiliar with. You will want to make sure you understand these eventually (you can learn them by
having them in context in the Inquiry Case, by looking them up, or by discussing them in the Discussion
Forum with your peers).
Introduction to Inquiry Case 1
Like most residents of southern Ontario, we had heard about the invasion of zebra mussels into the Great
Lakes region. We knew that it had been a relatively recent invasion followed by a rapid spread across the
region, and that it was a major cause for concern for both environmental and economic reasons.
However, also like most residents of this area, the depth of our knowledge did not extend much farther
We decided to investigate the issue much further, not just as concerned citizens, but as trained biologists.
Dr. Ryan Gregory, a professor who teaches BIOL*1070 in alternate semesters, decided to take a closer
look. His expertise is in evolutionary biology, genomics, and biodiversity science, but not in conservation
biology or in malacology (the study of molluscs).
Throughout this Inquiry Case, you will be able to join Dr. Gregory as he explores the topic as a curious
biologist — that is, by formulating questions and using a biologist’s training to seek answers to them
(when they exist!). This included a search of the primary scientific literature, which is usually the first step
for scientists seeking information, as well consultations with experts in the field, and even hands-on
fieldwork to properly understand how one studies mussel biodiversity in freshwater systems.
It has been a fascinating journey of discovery, as biological investigations often are. We have learned a
great deal about a major issue facing our region, and about some truly remarkable animals with which we
share it. Now, we look forward to sharing this experience with you, and in helping you to develop the skills
needed to explore similar topics on your own in the future.
1. Initial Observations
Dr. Gregory grew up in the area around Orillia, Ontario, about 100km north of Toronto. It’s a region known
as a tourist hot spot due to the presence of two popular lakes, Lake Couchiching to the north and Lake
Simcoe to the south, and because it is a gateway to “cottage country”.
In Hawkestone, Ontario — between Orillia and Barrie — he used to spend hot summer days swimming in
Lake Simcoe, either from the beach or, more often, by jumping off the dock. Over the past few years, as
he has returned home to visit family, he has noticed changes in the lake. For one, the water has become
much clearer as the quantity of particulate matter in the water column has been greatly reduced. This is
one of the byproducts of the huge abundance of zebra mussels, whose filter-feeding activities cycle
massive amounts of water every day.
As you saw in the video, the beach, which is sandy, does not show other obvious signs of zebra mussel
infestation, but the dock is simply covered in zebra mussels below the water line.
One can witness the effects of zebra mussels even when it isn't expected, for example while on vacation
camping on Georgian Bay and Lake Huron. On Sauble Beach at the southern part of the Bruce Peninsula
— which represents 11km of some of the most beautiful beachfront in Ontario and is one of the longest
freshwater beaches in the world — the impacts are evident as well. (See Video) 2. Finding More Information
Dr. Gregory saw first-hand how abundant zebra mussels could be, and how this can impact our
enjoyment of lakes. Of course, this is not the only negative consequence of zebra mussel infestations.
The fact that they are able to attach to just about any solid surface has made them real menaces as they
clog pipes and cover industrial equipment, docks, and boats.
In fact, it has been estimated that the economic damage by zebra mussels and the efforts to
control them have already cost billions of dollars (yes, that’sbillions with a b).
For a biologist faced with this situation, several questions immediately come to mind. Take a
moment and think of what you might consider to be important questions that a trained biologist would
want to find answers to.
Not surprisingly, a great deal of research has been aimed at answering these sorts of questions.
In the case of the zebra mussel, much of this information has been made available on the internet in an
effort to inform the public. The issue, however, is to make sure to consult reliable sources of information
— just because someone wrote it doesn’t mean it’s accurate!
You should always ask: Who is making the statement? Where did they get their information?
Have they backed this up with references or data? Are there alternative interpretations that the authors
seem to have missed?
Some good sources of information about zebra mussels include national or provincial/state
government agencies (e.g., Fisheries and Oceans Canada, US Geological Survey), regional,
provincial/state conservation society webpages, and websites authored by scientists. Wikipedia, blogs,
newspaper articles, etc., should always be interpreted with caution.
Of course, the best source of information is, well, the original source. In science, that generally
means peer-reviewed publications in scientific journals. Peer review means that the article reporting new
information was sent to at least two anonymous experts in the field who provided critical comments on the
reliability of the research, the interpretation of data, and the overall quality of the paper. Papers that
survive this review process (usually after being revised to address reviewers’ criticisms) may be accepted
for publication. Peer review provides a significant filter that helps to improve the accuracy of scientific
publications. However, it is not perfect, and in fact it is really just a first step — once published, a paper
can be seen, commented on, or even refuted by anyone in the scientific community.
Peer-reviewed scientific publications, also known as the “primary literature” are the means by which
scientists share their results with other researchers. As members of the University of Guelph, you have
access to an extraordinary number of peer-reviewed journals through the library, most of them with
electronic access. Search engines such as Google Scholar, PubMed, and Web of Science can all be
used to locate papers on any topic.
3. What Do We Know?
Consulting the most reliable sources of information available (especially websites and books by
scientists and the primary literature) provides the following basic details about the zebra mussel
The zebra mussel (Dreissena polymorpha) is native to eastern Eurasia, specifically the Black Sea
and Caspian Sea.
The most likely mode of transport across the Atlantic was in the ballast water of an ocean liner.
(Probably larvae, though some authors suggest that the stowaways were adults attached to
ships). The zebra mussel was first reported in North America in 1988 in Lake St. Clair, in a peer-