Systematics has to do with relationships between organisms. Generally, individuals making up closely related populations tend to form a cluster of similarity. Thus jaguars and tigers share a number of characters that we identify with "catness". Now, this might sound like an easy job just see how similar, or the obverse, how different, two groups are, and you know their relationship.
Unfortunately, there are a lot of things other than genetic makeup that
affect how organisms look. A lot of this we know, if we stop to think. Males differ
from females, and young individuals from old. These are pretty easy to sort out. But
what about a population of rabbits living under extreme drought conditions compared to
a population favored by the rains this generation? Availability of food during youth
has a lot to do with adult size. Or what about a group heavily parasitized? There are
so many environmental factors affecting the morphology—the shape—of individuals that
systematics is far from an easy science. Illusionists may make you believe what
isn't—and possibly nature is the greatest illusionist of all!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.