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The Making of the Fittest Video Lecture
In this 66-minute video talk, replete with slides and photographs, HHMI Investigator Sean Carroll, Ph.D., describes the progress that has been made in understanding the process of evolution. Expanding upon his 2006 book, The Making of the Fittest, he emphasizes the lessons drawn from the DNA record of three billion years of evolution. Dr. Carroll offers numerous examples of the precise changes in DNA that have enabled Earth’s creatures—from the ice fish of the Southern Ocean to the rock pocket mouse of Arizona to the kestrel of Northern Europe—to adapt to changing and often harsh environments. The DNA record underscores three themes: Earth and the life on it evolve together; shifts in lifestyle are reflected in the DNA of pertinent genes; and Darwin’s principles of natural selection are in operation. Dr. Carroll also discusses the concept of “fossil” genes, using the Antarctic ice fish as one example. Today, that fish has no red blood cells. However, a fossilized hemoglobin gene remaining in its DNA shows that the fish has adapted over 55 million years to very cold water by losing its red blood cells but developing an “antifreeze” gene containing proteins that prevent ice crystal growth. “Fossil” genes reveal the genetic history and lifestyle of an organism, although they no longer matter to the organism’s survival. Dr. Carroll says that the existence of fossil genes demonstrates a cardinal rule of genetic evolution: use it or lose it. Using numerous other examples, he shows that variations arise by random mutations, and that selective conditions (such as habitat and predators) determine which variants are favored. Dr. Carroll concludes his talk by noting that similar selective conditions favor similar genetic variations in different species at different times and in different parts of the world. Evolution, he says, is more reproducible and more predictable than scientists had ever realized.
The Violet Opsin Gene
In this video lecture, Dr. Sean Carroll discusses color vision in several organisms. While shallow-water fish often have full color vision, the coelacanth, which lives in very deep waters, has a violet opsin gene that is no longer functional. Because the gene is not functional, it will continue to accumulate additional mutations and deletions that will erode it further, until eventually they erase it from the coelacanth's DNA forever.
Media: Flash Multimedia