Geography Reference
In-Depth Information
Medicine, agriculture, natural resource extraction, and urban living are
strong, contemporary selective forces that together with the ancient actions of
island formation, glacial advancement and retreat, and continental drift are
shaping today's species, including our own. How we recognize, embrace, and
foster contemporary evolution will af ect the diversity of subirdia. Confront-
ing the loss of species such as the passenger pigeon, great auk, and ivory-billed
woodpecker makes me hungry for new ones. Perhaps I am overly optimistic at
our ability to enhance rather than only curtail evolution. When one holds
what could be the last individual of a species, or looks into the eyes of a young
person stunned at what is being lost from our world, as I do, you grip tightly
onto good, albeit faint, news. The life we create does not replace what we have
destroyed, but it is important to recognize the positive along with the nega-
tive. All destructive forces in nature have a creative side; i res create unique
ecosystems and diversify forest structure, earthquakes create lakes, volcanic
eruptions enrich the soil. Urbanization too has the ability to create biological
diversity.
The partially albino towhee at my bird feeder sports a distinctive coat of
black and white. I've nicknamed him the palomino, and I wonder whether his
of spring will be similarly plumed when they molt their dusky juvenile feath-
ers. The extra brilliance he wears seems to contradict the role natural selec-
tion has played in muting the junco's tail. Yet the expression, and the eventual
sorting among random mutations, is also part of the creative evolutionary pro-
cess. The palomino reminds me of the changes seen in foxes that Russian
scientists have bred to be tame during the past century. With a change in fox
personality came barking, prick ears, a raised tail, play, and a diversity of coat
colors. Could albinism in urban birds also be an unintended consequence of
adaptation to yard life? Aberrant coloration is common in backyard birds.
Considering such possibilities brings us close to the evolutionary process.
Time will show me whether predators weed out the palomino's genes or
