D2 Writing in the biological sciences

D2-d: Kinds of evidence

D2-dUnderstand the kinds of evidence biologists use.

Biologists use many kinds of evidence:

data from site studies or site surveys
observations of specimens with the aid of special equipment, such as a microscope
observations and measurements made in experimental settings
data taken from reports that other biologists have published

Data in biology, which are either quantitative (that which can be counted) or qualitative (that which can be described without numbers), can take various forms, depending on the nature of the site, the type of experiment, or the specialized field in which the research is performed. Following are some examples.

For a study of the mating choices of female swordfish, biologists might record and analyze responses from females placed in tanks with males.
In forensic biology, researchers might interpret the data they collect from tests on criminal suspects’ DNA samples.
Plant biologists might analyze the rates of survival of native tree seedlings affected by chemicals released by invasive plant species.

Because evidence can have more than one plausible interpretation, biologists offer alternative explanations for the results obtained in experiments. For example, the authors of one article suggested that differences in the type and availability of prey could account for why Atlantic blue marlin larvae grew faster in one body of water than in another, but they also recognized that other possible causes related to differences in spawning populations.