Chapter 1: The Web of Life

What are 2 general scientific approaches ecologists use to answer ecological questions?

2 general scientific approaches that ecologists use to answer ecological questions are: -Descriptive science and -Hypothesis-based science

Define "scale." What are two broad categories of scale?

"Scale" refers to the dimensions, both in space and time, that ecologists use to answer a particular question. It refers to *levels of organization*, such as organisms, populations, communities, etc. It also refers to spatial scales, from local to regional to global. Two broad categories of scale are *biosphere* and *population* - Ecology does not study narrower spatial scales such as cells, tissues, organs, or body systems.

Why is scale important? How does it affect how different ecologists study the nat. world?

Scales of time and space are important because *ecosystems change over time* are are affected by our actions in both the past and the present, and *environmental conditions can change dramatically from one place to another*. Scale affects how different ecologists study the natural world because all ecological studies address issues at one scale while ignoring events at other scales.

One goal of ecology is to study interactions. Describe what this means and give examples

Studying interactions means looking at interactions among organisms *(biotic interactions)* and between organisms and their environments *(abiotic interactions* - such as interacting with resources or natural disasters).

One goal of ecology is to study the mechanisms that underlie the patterns and processes we see. Describe what this means and give examples. State the two viewpoints for studying mechanisms that underlie patterns/processes (Mechanisms may be either...).

Studying the *mechanisms* that underlie the patterns and processes we see means *understanding the processes why which something takes place*. Mechanisms can be considered from two viewpoints. Mechanisms may be either -Functional (proximate - describe *how* something operates) -Evolutionary (ultimate - explaining *why* a system operates in a particular way)

Name 3 things ecologists can accomplish using theoretical models and provide an example of each.

Ecologists can accomplish 3 things using theoretical models: 1) Models allow us to *understand complex phenomena*, such as how populations change over time 2) Models allow us to *predict or simulate* ecological processes, such as making projections of change in suitable polar bear habitat 3) Models allow us to *design conservation strategies*

What type of biological and non-biological disciplines are incorporated into various ecological studies?

Ecologists integrate disciplines from the biological sciences, natural sciences, and mathematics. Directly related are genetics, physiology, evolution, and behavior. Also included are geology, physics, chemistry, and mathematics.

What is one critique often espoused regarding hypothesis-based scientific studies?

One critique of hypothesis-based scientific studies is that *correlation does not equal causation*. Simply because two conditions occur together does not mean that one is caused by the other or vice versa.

Give an example of a hypothesis-based observational field study related to understanding amphibian declines (Describe the observations, hypothesis, test, results, and conclusion)

One observational field study of amphibian declines suggested that parasites caused amphibian deformities. 1) Observation: Ribeiroia parasites were found in many frogs that had deformities 2) Hypothesis: Deformed frogs will only occur in ponds that contain the Ribeiroia parasite 3) Test: Sample the water in ponds where deformed frogs have and have not been found and test for the presence of Ribeiroia 4) Results: Deformed frogs only occurred in ponds containing the Ribeiroia parasite 5) Conclusion: Ribeiroia infection leads to deformities in amphibians

What are the general goals of descriptive science/natural history studies? Give examples of types of studies that would be considered descriptive.

The goals of descriptive science are to: -Make descriptions of natural patterns/processes based on *verifiable observations and measurements* -Find new patterns or correlations Examples of descriptive science are: -observing high incidence of amphibian deformities and declining amphibian populations worldwide, and hypothesizing about the causes.

What is the main purpose of the scientific method?

The main purpose of the scientific method is to ensure that you are not made to believe that something is true that is not, or that something is not true when it is.

Describe/name the 2 types of mechanistic questions that ecologists study. Give an example of each.

The two types of mechanistic questions that ecologists study are: -Functional (proximate) questions. They ask *how* a system operates. For example, How is barn owls' hearing so sensitive as to be able to detect prey in total darkness? (disc-shaped face reflects sound to ears) -Second are Evolutionary (ultimate) questions. They ask *why* a system operates in a particular way - *what led to the current system* and how might it change in the future? For example, Why do barn owls hunt at night? Why does a squirrel risk its life by calling when it sees a hawk? (kin altruism and favoring the reproductive success of relatives)

One goal of ecology is to characterize the patterns seen in nature. Describe what this means and give examples.

To characterize patterns in nature is to look for repeated occurrences; similarities in morphology, physiology, behavior, and genetics; life history patterns, including how often a species reproduces, the number of offspring produced, and lifespan; population structure.

Define ecology - traditional definition and more comprehensive definition

Traditionally, ecology is defined as the study of interactions between organisms and their environment. But, a more comprehensive outlook suggests that ecology is: -Recognizing *patterns*, *studying interactions*, and *understanding mechanisms* that lead to patterns and processes.

Give an example of a hypothesis-based controlled *field* experiment related to amphibian declines

Field experiment: To test whether the effects of pesticides and Ribeiroia interact in nature 1) Hypothesis: Ribeiroia causes frog deformities, pesticides do not. Ribeiroia and pesticides interacting causes more deformities than Ribeiroia acting alone. 2) Testing: screened cages were placed in 6 ponds, 3 containing pesticides and 3 without pesticides; 3 of the cages also had mesh that allowed the parasite to enter and 3 had mesh that prevented the parasite from entering. 3) Results: Tadpoles in cages that protected them from Ribeiroia did not develop deformities. Tadpoles in unprotected cages developed deformities, and the *highest percentage of deformities occurred in tadpoles exposed to both the parasite and pesticides*. 4) Conclusion: Pesticide exposure can affect the frequency with which parasites cause deformities in amphibians

Describe the steps of the scientific method

1. Observation 2. Formulate questions 3) Hypothesize about the cause of the phenomenon being observed, using previous knowledge or intuition to develop possible answers. 4) Testing - Evaluate your hypothesis by performing experiments. Should involve an experimental/treatment group and a control group, to which the factor being tested is not applied/that is not subjected to alterations 5) Results 6) Drawing conclusion(s) 7) Conclusion may raise more questions and lead to forming more hypotheses

What is meant by a "control" in hypothesis-based scientific studies?

A control is the group to which treatment/factor being tested is not applied. It is the "baseline" and it is compared to the treatment groups.

Define and describe "hypothesis"

A hypothesis is a possible explanation *of the cause* of an observed phenomenon that can be *tested via experimentation or observation*

Define model and theoretical model.

A model is a conceptual, graphical, or mathematical representation of empirical objects, phenomena, and physical processes. A theoretical model is a representation of a phenomena or physical process.

Describe 2 examples of a hypothesis-based controlled lab experiment related to amphibian declines.

A. (from class): Controlled lab experiment to test whether more Ribeiroia parasites causes more frog deformities 1) Observation: Ribeiroia parasites were found in many deformed frogs 2) Hypothesis: More Ribeiroia parasites will cause higher incidence of frog deformities 3) Test: Tadpoles are put in enclosures with *varying amounts* of the parasite 4) Results: In enclosures with more parasites, fewer tadpoles survived, and more of the survivors had deformities 5) Conclusion: Ribeiroia can lead to frog deformities and the *density* of the parasite can affect how prevalent deformities are. B. (from text): Controlled lab experiment to test how pesticides may weaken tadpole immune systems 1) Observation: Increased fertilizer use ends with increased numbers of Ribeiroia 2) Hypothesis: Pesticides weaken tadpole immune systems 3) Test: Tadpoles were exposed to high or low concentrations of pesticide and then exposed to Ribeiroia parasite, and then examines for cysts and numbers of white blood cells. 4) Results: Tadpoles exposed to the pesticide had fewer white blood cells and more cysts than the controls, which were only exposed to Ribeiroia.

What are the two types of biotic interactions?

Biotic interactions are either *interspecific*, occurring between animals of two different species, or *intraspecific*, occurring between members of the same species (such as competition for a mate).

Name the four different approaches ecologists use for hypothesis-based scientific studies and describe each.

Hypothesis-based science follows the steps of the scientific method. The four methods of hypothesis-based studies are: 1) Observational field studies (in which the researcher does not attempt to manipulate the test 2) Controlled laboratory experiments 3) Controlled field experiment (Controlled experiments have an experimental group that is compared w/ a control group that lacks the factor being tested) 4) Theoretical models - representations of phenomena or physical processes that may be complex or occur on a huge scale

How does a scientific journal differ from other science related publications?

In the hierarchy of journal publications, peer-reviewed journals are at the top. They have been screened by the author's peers (experts in the same field). The contents of scientific/refereed journals undergo the most scrutiny before they can be published.

What is meant by "peer review?" What role does peer review play in science?

Peer review is *evaluation of work by others in the same field*. In science, peer review is used to maintain quality standards, improve performance, and provide credibility.

Describe the process of peer review

Peer review is a multi-step process: 1) First, public presentation and feedback 2) Second, publication in scientific journals 3) Third, public scrutiny and retesting