Biology Now, 2e

12 ■ CHAPTER 01 The Nature of Science

SCIENCE

knowledge is tentative and therefore open to

challenge at any time by anyone. An absolute

requirement of the scientific method is that

evidence be based on observations or experi-

ments, or both. Furthermore, the observations

and experiments that furnish the evidence

must be subject to testing by others; indepen-

dent researchers should be able to make the

same observations, or obtain the same results,

if they use the same conditions. In addition,

the evidence must be collected in as objective a

fashion as possible—that is, as free of personal

or group bias as possible. Blehert’s experiment

fit all these conditions.

The main mechanism for policing personal

or group bias and even outright fraud in science

is peer-reviewed publication. Peer-reviewed

publications are found in scientific journals that

publish original research after it has passed

the scrutiny of experts who have no direct

involvement in the research under review.

Before Blehert’s research was published, it was

reviewed by numerous scientists who had not

participated in the experiment. If reviewers

have concerns during the peer-review process,

such as whether the evidence is strong enough

to support a hypothesis, they can ask the paper’s

authors to address those concerns (for exam-

ple, by gathering additional evidence) and to

resubmit the paper. Blehert’s paper passed the

peer-review process and was published in the

scientific journal Nature in 2011. At that point,

says Blehert, the evidence that G. destructans

causes WNS was strong enough that “I think

we’d convinced most people.” (In 2013, scien-

tists renamed G. destructans as Pseudogymno-

ascus destructans when the fungus’s genus was

reclassified.)

But identifying the cause of W NS did not

stop the disease from spreading. By March

2008, just a year after Hicks’s team found the

thousands of dead bats near Albany, more bats

were found dead and dying in caves across

Vermont, Massachusetts, and Connecticut.

Within a year, the disease had spread as far as

Te n ne s s e e a nd M i s s ou r i. T he s pr e a d o f W N S

is a fact: bats around the United States are

dying. In casual conversation, we typically use

the term “fact” to mean a thing that is known

to be true. A scientific fact is a direct and

repeatable observation of any aspect of the

natural world.

caused white-nose syndrome, but exposure

through the air did not. Healthy bats that had

fungus applied directly to their wings or were

caged with naturally infected bats had high

rates of WNS by the experiment’s end. It was

the first direct evidence that the fungus was the

primary cause of white-nose syndrome.

When a prediction is not upheld, the

hypothesis is reexamined and changed, or it

is discarded. Over the years, other hypotheses

about the cause of white-nose syndrome have

not been upheld. For example, scientists were

not able to identify a single environmental

contaminant at elevated levels in infected bats.

A follow-up study by Blehert and others showed

that the fungus not only leads to symptoms of

WNS in bats, but is sufficient to cause death

(Figure 1.7).

The story of the bats with white noses is just

a single example of the scientific process. One of

the greatest strengths of science is that scientific

0 20 40 60 80 100 120

Day of study

2

4

6

8

10

12

14

16

18

20

Number of individuals

18 bats were injected with

a closely related European

fungus; most died before

the end of the study.

18 bats were injected with

the North American

fungus; most died before

the end of the study.

18 bats were “sham

injected” and received

no fungus; none died.

The closed circle marks the end of the

experiment for each group of bats.

Figure 1.7

Experiments support the hypothesis that the fungus causes

WNS in bats

The experiment whose results are plotted here was conducted by some of

the same researchers interviewed for this story.

Q1: What is the control group in this experiment, and what are the

two treatment groups?

Q2: At day 40, approximately how many individuals were alive in each

treatment group? At day 80? At day 100?

Q3: In one or two sentences, state the conclusions you can draw

from the experiment. Was the hypothesis supported? Why or why not?