ecology

Why is a statistical analysis important when interpreting results?

It is important when interpreting results because accurate readings of data lead to accurate conclusions.

Explain how the natural world is connected. Describe what might happen if a primary consumer suddenly dies off in a system. (A) What might happen to the predator population in the system? (B) What might happen to the primary producers? (C) How might this affect adjacent systems?

The natural world is connected because a change in one part of an ecological system can alter other parts of that system. If the primary consumers became extinct, there would be nothing to eat the producers, therefore they would become over populated and there would be no food for the secondary consumers, therefore they would die. The primary producer population would drastically increase. This could affect other systems because with an increase in population, there is a direct correlation with food/space needed.

What characteristics of amphibians make them good "biological indicators?" What does it indicate about the environment when they begin to have deformities and/or die off?

Amphibians are both land and aquatic inhabitants. They also have a thin permeable membrane for skin that lets pollutants and other biological indicators to be shown; their eggs have no protective shell. This would indicate that the environment they are living in is detrimentally affecting them. This could be caused by parasites, pollutants, etc.

Define descriptive science. How does this play a role in hypothesis-based science?

Descriptive science, which is usually inductive, aims to observe, explore, and discover, while hypothesis-based science, which is usually deductive, begins with a specific question or problem and a potential answer or solution that can be tested.

What kinds of questions do ecologists try to answer?

Ecologist answer questions regarding patterns, interactions, & mechanisms of nature. They are asked to predic the consequences of broad-scale, complex problems.

Describe the idea that there is a "balance of nature?" Why is this not correct? What role do disturbances play in a system?

Ecologists now recognize that natural systems do not necessarily return to their original state after a disturbance, and seemingly random perturbations can play an important role. Evidence suggests that different species often respond in different ways to changing conditions.

Define ecology. How is this different from environmental science? Which is described as a sub-discipline, and which is interdisciplinary?

Ecology is the scientific study of interactions between organisms and their environment, and between one another. Environmental Science incorporates concepts from the natural sciences (including ecology) and the social sciences; focuses on how people affect the environment and how to address environmental problems. Ecology is a subdiscipline of Biology. Environmental Science is interdisciplinary.

What types of studies do ecologists use (4)? What would be the benefit of a controlled lab experiment versus an observational field study? What are the benefits of using a model?

Hypothesis-based science • Observational field studies • Controlled lab experiments • Controlled field experiments • Theoretical models

What is a spatial scale? Why might an ecologist choose one over another? For example, given that an ecologist wants to study the interactions between different species, which spatial scale might they use? What about when the ecologist then includes interactions between the organisms and their environment?

In spatial ecology, scale refers to the spatial extent of ecological processes and the spatial interpretation of the data. They would use the Community scale. They would use the Ecosystem scale.

Describe the observational field study that was conducted to investigate if the Ribeiroia parasite causes frog deformities. Describe the hypothesis, methods, results, and conclusion(s). Did this study confirm that Ribeiroia infections lead to frog deformities? Why or why not? (Think about correlation versus causation.)

Observation of Pacific tree frogs suggested that a parasite Ribeiroia ondatrae, a parasitic trematode flatworm, can cause deformities. Yes, all frogs with deformed limbs had Ribeiroia cysts.

In the controlled field experiment, what possible contributing factor of frog deformation did Joseph Kiesecker and his colleagues examine? What were the hypotheses, methods, results, and conclusions? What was the control?

Q: Do multiple factors influence frog deformities? Do the effects of a parasite and pesticides interact in nature? Method: Six ponds, all with Ribeiroia, three with pesticide contamination. Wood frog tadpoles were placed in 6 cages in each pond; 3 had mesh size that allowed parasites to enter. Conclusion: All deformed frogs had parasitic infection. Parasitic exposure was necessary for deformities to occur. A greater % of deformed frogs were in ponds with pesticides. When exposed to parasites, deformities were more common when also exposed to pesticides (i.e. interaction of parasites and pesticides)

Why is it important to replicate each treatment in an experiment multiple times? How does randomization play into this concept?

Replication in scientific experiments is important because they reinforce the findings of predecessors. By using randomization the experiment lacks potential bias.

How is this different from a temporal scale? When might temporal scales be important?

Temporal scale relates to time. This could be used when looking for long/short term data.

What is a theoretical model? What do they allow ecologists to do?

Theoretical models allow ecologist to predict how the data will be spread.

Describe the controlled lab experiment that Pieter Johnson and his colleagues conducted to determine the link between exposure to Ribeiroia and frog deformities. (A) Describe the hypothesis, methods, results and conclusion. (B) What was the control for this experiment? Why is it important? (C) What are some pros of this experiment? What are the shortcomings?

Tree frog tadpoles were exposed to Ribeiroia parasites in the lab. The control was the frogs were lacking the factor being tested (Ribeiroia). The pros of this experiment are excluding the factors thought to be the cause to confirm what causes deformities.