Most of our desert animals occasionally produce an albino. Albinism is genetic, with genes that don't turn on the production of the normal pigments. Seemingly appearing out of the blue, you might think it must be a new mutation, a newly arisen change in the genetic material. Most of the time, though, it's not—it's merely revealing some of the hidden variation virtually universal in animals.
Most animals receive one copy of a gene from each parent. If one of the
copies is normal for pigment production, the individual has normal coloration. It's
only when both copies are for albinism that we end up with a colorless individual. Such
genes are said to be recessive, since they are hidden when a dominant gene is present.
The result? Numerous genetic traits can be in a population but show up only when two
parents happen to have the same recessive gene. But next time you see an albino,
treasure the sight—contrasting against the desert background in a world of predators, a
brief life and a sudden death is its usual fate.
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.