Answers to Review Questions
1. The phrase “connections in nature” is meant to evoke the fact that interactions among organisms and between organisms and their environment cause events in nature to be interconnected.
As a result of such connections, an action that directly affects one part of an ecological community may cause unanticipated effects in another part of the community. Various examples related to amphibian deformities and population declines illustrate such connections and their indirect effects. For example, it appears that the addition of fertilizers to ponds has led to the following chain of events: the fertilizer stimulates increased algal growth, which then leads to increased snail abundance, increased Ribeiroia abundance, and hence more frequent amphibian deformities.2. Ecology is the scientific study of interactions between organisms and their environment. The scope of ecology is broad, and it may address virtually any level of biological organization (from molecules to the biosphere). Most ecological studies, however, emphasize on one or more of the following levels: individuals, populations, communities, or ecosystems. Thus, if ecologists studied the effects of a particular gene, they probably would emphasize how the gene affected interactions in nature—they might, for example, study how a gene affected the ability of an organism to cope with its environment, or how a gene affected interactions among species. Compared with a geneticist or cell biologist, an ecologist would be less likely to emphasize either the gene itself or its effects on the workings of a cell, and more likely to study how the gene affected interactions in nature that occur at the individual, population, community, or ecosystem levels.
3. The scientific method summarizes the process of scientific inquiry. The four key steps in this inquiry process are: (1) observe nature and ask a question about those observations; (2) use previous knowledge or intuition to develop hypotheses (possible answers) to those questions; (3) evaluate different hypotheses by performing experiments, collecting new observations, or analyzing results from quantitative models; and (4) use the results from the approaches taken in (3) to modify the hypotheses, pose new questions, or draw conclusions about the natural world. An essential feature of many scientific investigations is a controlled experiment in which results from an experimental group (that has the factor being tested) are compared with results from a control group (that lacks the factor being tested).