jimtrue.com : school : BSC2011L : Lab 01: Taxonomy Handout
Posted by Jim True on August 30, 2004 7:39 AM. Last Updated October 22, 2006 9:23 PM
Disclaimer for all material noted here is at the bottom of this web page.
When we look at nature, it is apparent that we are surrounded by an enormous number of living things, especially if we use a microscope to view organisms not readily visible to the naked eye. If we look more closely at the many living things surrounding us, we would observe two things: A) There are many different types of living things (diversity), and; B) some types of living things are more numerous than others (abundance).
Throughout this presentation, we'll use animals as examples, because that is the group of living organisms most students recognize.
The first of these observations, the number of different types of living things is referred to as diversity. With regard to diversity, I'd like to draw your attention to three things:
If you were to carefully search your backyard for living organisms, you would probably find a large number of different types of organisms. If you kept note of the total numbers of each type of organism you found, you would discover that some types of organisms occur in much greater numbers than others. For example, you might note several hundred ants, while at the same time you only observe two blue jays.
This is your second major observation, that not all types of things occur in equal numbers. The total number of any one type of organism is referred to as its abundance.
Abundance of organisms can vary enormously in both time and space, that is, how long you look for organisms and over how large an area or volume. For example, if you had searched your backyard for 2 hours, or your entire yard, your counts for those types of animals might have increased.
Diversity and abundance are not synonymous terms: Scientists use diversity measures to determine how rich or poor a sampling site is in terms of living organisms, whereas abundance measurements calculate how well or poorly a particular type of organism is represented.
As mentioned previously, we are aware of many different types of living organisms. How do we know they are types which differ from one another? How do we separate types? How do we recognize or indicate that some types are more similar to one another or are quite different (for example, a blue jay is more similar to a pigeon than it is to an ant)?
Scientists attempt to answer these questions by classifying or categorizing living (and extinct) organisms. Part of human nature is to place things in categories, that is, to organize things by what we observe about them. Such behavior is not limited to scientists. You do this yourself! Think of sitting on a bench in the mall and observing people walking by. You will mentally categorize them according to a variety of things you observe about them. Such categories may be rather general or very subjective, for example, young or old, tall or short, fat or skinny, ugly or pretty, etc. Other categories may be much more specific, such as whether they are male or female, or to which race the individual belongs.
Disclaimer: These are MY notes taken from classroom lectures while I'm in the classroom. While I'm perfectly happy to share my notes with my classmates and I know I take very good notes, you should still make every effort to attend the class and TAKE YOUR OWN NOTES. I will not transcribe everything the instructor says in the classroom, and I will NEVER post pre-exam reviews. My notes will not replace the value of actually attending class and taking your own class notes.I also cannot attest to their accuracy, other than they are what was provided in the lecture; you should not reference my notes as "expert opionion" by any means, and if you notice an error or omission, please do me the favor of e-mailing me with the correction and I will re-post my notes. End of Disclaimer.