February 16, 2010

Darwin Days: Biodiversity on Land

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On Tuesday, panelists discussed the topic, “Evolution and Biodiversity on Land.” The goal, as moderator Prof. Warren D. Allmon, earth and atmospheric science, said, was to make Cornell expertise available to a wider audience, to go beyond the “buzz word” connotations of biodiversity and to examine what biodiversity really means.

Prof. Rick Harrison, ecology and evolutionary biology, who specializes in speciation, pointed out the problem with determining biodiversity by tabulating species.

According to Harrison, biodiversity must both account for great and subtle morphological variations between species.

“About one-quarter of described species are beetles,” Harrison said. He attributed beetle diversity to co-evolution with plants.

Plants interact with insects, like flowering plants and pollinators. Each group has exacted selective pressures on the other, and overtime, changes in beetle diversity has accompanied changes in plant diversity.

Prof. Cole Gilbert, entomology, focused on Darwin’s Galapagos Island finches. Gilbert acknowledged that to the untrained eye, differences between finches may not seem significant.

Darwin himself initially ignored the significance of his discovery, thinking the birds were entirely different types. He was wrong.

Now, the importance of the finches is widely known — finches are model examples of adaptive radiation and evolution.

It may seem out of place for panelist Prof. Amy McCune, ecology and evolutionary biology, to make a land presentation. After all, McCune studies fishes. As she explained, freshwater fish are land animals.

McCune said that biodiversity is more than a species count. “You’d think that we would know all the species,” McCune said. Scientists have identified about two million out of an estimated 50 million species.

Even through identified species, scientist can learn more. McCune showed a computer-generated model of a gar. A gar is common fish that had been abundant in the Ithaca area. McCune showed how new research techniques allowed her to learn about the swim bladder of multiple species.

Last to speak, Kelly Zamudio, ecology and evolutionary biology, described her own experiences with Darwinian biodiversity.

Instead of studying finches, she focuses on salamanders in the Mexican trans-volcanic belt. By looking at them and observing factors that affect gene flow, Zamudio and others determined how the salamanders may have originally spread through the area. This provides continued evidence for evolution.

Original Author: Tim Gahr