Scientists are convinced that there is a real universe out there, and their job is to determine its character. Doing science is a lot of fun—but it's seldom simple. And it's complex in spades when you're working outside the laboratory, where you don't have the experimental control that the simple sciences like chemistry and physics can bring to bear. Not only are data often hard to come by, but Nature is complex by its own—well, nature.
For example, we define a biological species on the basis of who its
members are able to breed with. If one population can't breed with another, then
they belong to different species. The trouble is, as species evolutionarily split into
different species, we have all sorts of in-between situations. Where do we draw the
line? Working with incomplete data, we often have to make an educated guess. Thus, a
while back, our Chihuahuan Desert Apache Pocket Mouse was judged to actually be the
same species as the Plains Pocket Mouse. Good call? Time and more data will tell.
Hopefully!
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.
Despite the difference in looks, these two specimens of Plains Pocket Mice from southern New Mexico are assigned to the same species because they are not believed to be reproductively isolated from each other. The bottom specimen is from the White Sands' population that has been evolutionarily selected to better blend in with the white, gypsum background. Scanned specimens from the Laboratory for Environmental Biology research collections.
Findley, J. S. 1987. The natural history of New Mexican mammals. University of New Mexico Press, Albuquerque. 164 pp.
Strickberger, M. W. 2000. Evolution. 3rd ed., Jones and Bartlett Publishers, Sudbury, MA. 722 pp.