Davidson College Department of Biology Statement on Plagiarism

Plagiarism is representing another's ideas or words as one's own.
Plagiarism, as a form of cheating, is a violation of Davidson's Honor Code.

The statements above may seem straightforward, but plagiarism can take many forms, some of which constitute a gray area in people's understanding of the issue. Furthermore, there are variations among different academic fields concerning citation styles and expectations. The purpose of this document is to clarify WHEN and HOW to cite your sources when writing for a biology class. Note that self-plagiarism, or the use of your own previous work in another class, is also an Honor Code violation unless re-use of your work is expressly allowed by the professor. Your biology professors expect original work to be submitted in their classes.

WHEN to cite your sources (Click here for HOW..)

Direct quotations
Let's start with the obvious. If you repeat someone else's words verbatim, you must enclose those words in quotation marks and provide a citation. For the citation to be complete, there MUST be a properly formatted in-text citation at the end of the sentence and a corresponding entry in your list of references (see section below on how to cite sources). It is not sufficient simply to name the source within the sentence. Omitting quotation marks and/or a complete citation is considered plagiarism. Keep in mind that direct quotations are not commonly used in scientific writings such as lab reports or grant proposals but can be appropriate in biology essays and term papers. Make sure that any direct quotations flow smoothly within your own thought progression in the assignment; your task is to synthesize the relevant literature, not just copy and paste direct quotes from each source or provide a summary sentence for each.

Paraphrasing is restating someone else's ideas while not copying verbatim. There are acceptable and unacceptable ways to paraphrase, and it is crucial that you understand the difference. Unacceptable paraphrasing includes any of the following: 1) using phrases from the original source without enclosing them in quotation marks; 2) emulating sentence structure even when using different wording; 3) emulating paragraph organization even when using different wording or sentence structure. See examples below. Unacceptable paraphrasing--even with correct citation--is considered plagiarism. When you do paraphrase in an acceptable manner, a proper citation is always required. Omitting a citation is considered plagiarism.

Original text
Unacceptable paraphrasing: copying phrases without using quotation marks
Unacceptable paraphrasing: emulating sentence structure (here, paragraph structure is also emulated)
Unacceptable paraphrasing: emulating paragraph structure (even though sentence structure is original)
Acceptable paraphrasing

Few laboratory creatures have had such a spectacularly successful and productive history as Drosophila. It first entered laboratories about 1900, revealed its talent for experimental genetics to Thomas Hunt Morgan and his students at Columbia University in the early 1910s, and after some ups and downs in status is still going strong almost a century later.

(from Kohler, R.E. 1994. The Lords of the Fly. The University of Chicago Press, 321 pages.)

Despite some ups and downs in status, nearly a century after the fly revealed its talent to Thomas Hunt Morgan and his students, Drosophila genetics research continues its spectacularly successful history (Kohler, 1994).

(Can you spot the copied phrases? The author of the paraphrasing could avoid trouble by using quotation marks, though it would be much better to write in more original language.)

No model organism has been so amazingly useful and effective as the fruit fly. The fly came on the scene as an experimental tool at the beginning of the 20th century, was adopted by Thomas Hunt Morgan and his Columbia pupils at Columbia University around 1910, and (despite some fluctuations in attention paid to it) is still a widely used experimental system (Kohler 1994).

(Within each sentence, can you trace the structural similarities?)

Drosophila is model organism with a rich and useful legacy. Upon arriving on the scene at the turn of the century, the fruit fly soon became the organism of choice for Thomas Hunt Morgan and his Columbia University pupils. Despite fluctuations in status, fly research is still central to the progress of genetics (Kohler, 1994).

(Trace how the ideas flow in a manner identical to the original.)

Thomas Hunt Morgan and colleagues at Columbia University were among the first to use the fruit fly Drosophila as a model organism, adopting it as an experimental system around 1910. Since then, the popularity of the fly has waxed and waned somewhat, but the breadth and depth of current research indicates that Drosophilacontinues its legacy as an incredibly important research tool (Kohler, 1994).

Describing scientific findings that are not your own
In many forms of scientific writing, you are expected to compile and summarize experimental results from other researchers. Using in-text citations, you must give credit for every mentioned scientific fact that you did not discover yourself, with the exception of facts that are common knowledge, such as "all cells come from pre-existing cells." (If you are not sure what is common knowledge, play it safe and provide a citation; however, if a fact is treated as common knowledge in your source, then you can generally do the same.) Technically, you should provide a citation for each distinct idea, and that sometimes means including one citation in the middle of a sentence and then another citation at the end. However, if a series of sentences clearly go together, with all of them describing findings from a single source, it is acceptable to cite the source only once (instead of after every sentence).

Proposing an idea that is not your own
If you propose a bit of analysis or interpretation that originated in someone else's brain, you must provide a citation.

Using images from the WWW or print sources
In your papers and web page assignments, the use of an image (whether photocopied, scanned, or downloaded) that you did not create is the equivalent of a direct quotation. You must include both an in-text citation next to the image and a corresponding entry in your list of references. If you are designing a web page that will be available publically, you must seek permission to use any borrowed images.


HOW to cite your sources (Click here for WHEN..)

Biologists expect in-text citations and then a list of references at the end of the work. There are two main approaches: AUTHOR-DATE and NUMERICAL. The author-date method is most common. Here is a quick overview of these two formats.

General approach
Examples of in-text citations

Sometimes, depending on the particular mutation, the same gene can be involved in dominant or recessive deafness (Kelsell et al., 1997). Several genes involved in syndromic and nonsyndromic deafness have already been identified and are reviewed in Kalatzis and Petit (1998).

(adapted from Kubisch et al., Cell 96: 437-446)

Kuru was the first human prion disease shown to be transmissible, by inoculation of chimpanzees with autopsy-derived brain tissue (1). It is hypothesized that kuru originated from consumption of an individual with sporadic CJD (2), a disease with a remarkably uniform worldwide incidence of around 1 per million and a lifetime risk of around 1 in 50,000.

(adapted from Mead et al., Science 300: 640-643)

Examples of reference lists

Alphabetize the references by the last name of the first author.

Kalatzis, V., and C. Petit. 1998. The fundamental and medical impacts of recent progress in research on hereditary hearing loss. Hum. Mol. Genet. 7: 15891597.

Kelsell, D.P., Dunlop, J., Stevens, H.P., Lench, N.J., Liang, J.N., Parry, G., Mueller, R.F., and Leigh, I.M. 1997. Connexin 26 mutations in hereditary non-syndromic sensorineural deafness. Nature 387: 8083.

Number the entries in the order in which they were cited in the text:

1. Gajdusek, D. C., C. J. Gibbs, and M. Alpers. 1966. Experimental transmission of a Kuru-like syndrome to chimpanzees. Nature 209: 794-796.

2. Alpers, M., and L. Rail. 1971. Kuru and Creutzfeldt-Jakob disease: clinical and aetiological aspects. Proc. Aust. Assoc. Neurol. 8: 7-15.

Rules and variations for in-text citations:

A. For the author-date type of in-text citation, if the source has two authors, list both last names, as in (Roberts and Gonzalez, 1998); if the source has three or more authors, use the format with et al.as in (Jackson et al., 1998). The abbreviation et al. should be italicized, with a period after the al.

B. If you have already mentioned the authors' names in the sentence, your in-text citation can consist of just a date: Jones and Smith (1992) demonstrated that the D1S80 marker is not linked to chocolophilia.

C. The in-text citation can be placed in the middle of a sentence to indicate that only part of the information in the sentence is taken from the source. Example: The cho gene product metabolizes aromatic amino acids (Tobler et al., 1994) and physically associates with the vangene product (Breyer et al., 1997).

D. If you cite multiple papers for a single idea, include all in-text citations within one set of parentheses and separate each citation with semi-colon, as in (Tong et al., 1997; Gallagher et al., 1998).

E. Do not indicate the source page number in your in-text citation.

F. If you cite a source, you are implying that the idea in question originated in that source. If your source actually cites someone else for the same idea, you should track down and cite the original. Only sources that you have examined directly should be included in your reference list. If it is not possible to obtain the original source, you can do the following: (Robertson et al., 1992, as cited in Burgess and Leonard, 2001). Sometimes it is useful to cite a review paper, if there is an appropriate one available-- then you don't need to cite as many individual sources. Your in-text citation would read something like (reviewed in Smith and Jones, 2001). If you don't know how to distinguish a review paper from an original research paper, ask your instructor. A good indicator of an original research paper is a section (often called Materials and Methods, or just Methods) describing specific experimental techniques. Some journals, however, include descriptions of methods in odd places (e.g. embedded in the references, as in Science), so the absence of a Methods section per se is not a sure sign that the paper you're looking at is a review paper.

G. If you use the numerical approach, the numbers themselves can be enclosed in either parentheses or brackets, or they can be superscripted. Just be consistent throughout the paper.


Rules and variations for reference lists:

A. Citing journal articles:
Biologists (unlike members of some other fields) have not agreed on a standard way for formatting references. For a given assignment, check the course syllabus and other handouts for guidance on what reference format to use. If you do not find specific instructions, you will be safe if you follow the following common format (which is also illustrated in the examples in the table above):
Primary Author's Last Name, Initials, Other Author's Initials, Last Name. Year. Title of article (only capitalize first word). Journal and volume number: page numbers.

In different journals you will see that each publisher seems to have a different style for formatting entries in reference lists. Aspects that vary among different journals include:
--whether initials come before or after an author's last name
--whether the date comes before or after the paper title
--whether the title is even included (journals like Science and Nature leave it out as a space-saving device)
--whether the date is enclosed in parentheses
--whether the journal name is italicized
--whether the volume number is italicized or in bold face
--whether there is a colon or comma after the journal volume number
--whether the issue number (in addition to the volume number) is included
--whether the whole page range or just the first page number is listed

--whether different components (e.g. authors, title, journal, etc.) are in boldface.

Whatever format you are expected to use, you should be completely consistent in how you format your list of references.

B. Citing books:

Use the following format to cite a whole book
Author Last Name, Initials. Date. Title. Publisher, number of pages.

Use this format for citing book chapters:
Author Last Name, Initials. Date. Title of chapter. In: Title of book (editors). Publisher, number of pages.

C. Citing web sites:

If you obtain from the WWW a journal article originally published in a print journal, cite the article exacly as you would for a print source.

If you obtain an peer-reviewed article from one of the growing number of online-only journals, cite the article as for a print source, but also append <URL>. Accession Date.

Most other web sites are not peer-reviewed, and so their reliability is highly variable. It is rare to use such non-peer-reviewed web sites as sources for scientific writing. For any given assignment, check your course syllabus or assignment handout to see if you are permitted to use such sources. If so, then it is still up to you to evaluate the reliability of a web site; consider the credentials of the author, the purpose of the web page, and the date of the last revision, among other things. For more guidance on evaluating web pages, see the Evaluating Web Sites Tutorial from the Ohio State Libraries.

To cite a web site, use the following reference format :
Author Last Name, Initials. Date page created or revised. Title of page. Title of larger work if applicable. <URL>. Accession date.


See links at bottom right for more information and examples for citing different types of sources in biology assignments.

Davidson sites on plagiarism:

The Honor Code
Dr. Epes's address to the incoming class, 2002
Department of History statement on Plagiarism

Plagiarism views from elsewhere:

Indiana University
Georgetown University
UC Davis
Northwestern University
Princeton University
Dartmouth University
Purdue University

Other sites on citing sources for a biology assignment:

Lewis and Clark Biology Dept Writing Guidelines
Earlham College Biology Dept- How to Cite Sources

ONLINE! Instructions for citing web pages

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Copyright 2003-2012 Department of Biology, Davidson College, Davidson NC 28035
last modified May 29, 2012 by K. Hales