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Comparative Genomics: What Is It? - 2001-05-30


Recently, the American Museum of Natural History established the Institute for Comparative Genomics. It is dedicated to comparing the difference in genetic makeup between various animal species and human beings and finding out how those differences evolved.

A full fifth of the Museum's 200 research scientists are now hard at work on projects relating to genetics and the mechanisms that determine the characteristics of all organisms through their DNA the molecule of life. Ellen Futter, the president of the museum, says, "Genetic variation is an essential element of that research and it is also critical to other areas that we pursue, including understanding the evolution of life and understanding our relationship to other species… and very important, now, learning about genetic variation across species and across time…"

One powerful way to discover the exact variations and similarities between species is to analyze the sequence pattern of amino acids that make up an organism's DNA and then to compare it with the genetic sequence in other species. Those sequences are many billions of combinations long, and super-computers are needed for the task.

But genetic comparison and analysis also depends on intact DNA. Now, thanks to a new state-of-the-art frozen tissue collection at the museum, up to one million tissue samples can be stored at temperatures cold enough to arrest all biological decay. Darrell R. Frost, the scientist who oversees the facility, explains: "You start getting at questions like 'Why does this organism look the way it does?' 'What is the genetic diversity within a population?' and 'what is the evolutionary relationship among populations?' Comparative genomics allows us to get at those kinds of questions."

Mr. Frost adds that modern DNA sequencing uses the same logic museum scientists have used for the past 130 years to answer those questions but with far better tools. "Why do we feel that goats are more closely related to cows than one of them is to foxes? Well, they both have cloven hooves," he says. "And we have reason to believe that cloven hooves happened once in the history of mammals. So we presume that all of them had a single origin. Why do we think that all things that have jaws are more closely related to each other than anything else? It's a rather complex mechanism and seems to have happened only once."

Well, with sequencing, you can use the same logic. This part was removed. This part was put in. And using that same logic you can actually analyze gene differences and morphological differences with the same logical tools. If we have commonality, if, over and over and over again, we see the same pattern in different groups of organisms, we presume that there is likelihood that there will be a common cause."

Comparative genomics may be complex, but it is far from dry, at least according to Jeff Rogers, the education director at the Museum's Genome Learning Lab. "I think what we're really looking at is trying to figure out where we fit into the big picture," he says. "Chemistry and hard science say that you and I and the ribbon worm and the milkweed are all related intimately, that we are built of the same stuff... Take it where you will. You might not want to compare yourself with a platypus but you might want to think about the interconnectedness of life on earth. To me, that's very profound."

The American Museum of Natural History has just opened a blockbuster new exhibit "The Genomic Revolution" that explores these and related issues. It will be on display until January 2002.