In evolutionary theory, it's natural selection that results in
adaptations to the environment--adaptations that mimic design. So, what are the factors
that allow natural selection to work in real life, rather than just in theory? There
are four basic principles involved, all based on abundant evidence. First, all kinds of
organisms on earth produce many more offspring than can possibly survive over the long
term, thanks to limited resources. Secondly, many of the physical traits of the parents
are genetically set and potentially inherited by their offspring. Thirdly, all
individuals vary in those genetically-set physical characteristics and abilities. And
lastly, this variability produces differences in fitness for the specific environment
that they find themselves in. This means that some individuals will be better at
adapting to change, or finding food, or any number of other things that affect the
chance of survival. What a biologist sees as a successful organism is the one that
lives to produce offspring that, in their turn, can survive to reproduce again.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
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.