ATHENS, Ga. - In centuries past, natural historians like William Bartram collected and identified the world's plants and animals, making clear the rich diversity of the planet. The new pioneers, however, are molecular natural historians, and they stand at the brink of an entirely new discipline - one that is beginning to expand our understanding of nature.

One area in which scientists are using the techniques of molecular biology with great success is in examining animal mating systems. Studies of these genetic systems in mammals and birds are now extensive, but until recently, almost no such research had been done on fishes or other cold-blooded vertebrates.

A team of geneticists at the University of Georgia is helping change all that and has published a series of research papers that is altering how science views the diverse reproductive strategies of these creatures.

"When it comes to the oft-secret world of mating strategies, field observations alone often provide poor or even misleading descriptions of the full panoply of reproductive tactics," said Dr. John Avise. "This is where molecular genetic techniques can help."

Avise describes the advances from his lab in an essay, "Natural History, Early 21st Century Style," which was just published in Intecol, the newsletter of the International Association of Ecology.

While Avise has done path-breaking work on birds for many years, his laboratory since the mid-90s has been deeply involved in studying reproductive behavior in fishes and turtles. Among the discoveries from his lab:

• Some fish get divorces. Seahorses, he writes, are quite unusual in the fish world for being socially monogamous. His lab's studies on the Western Australian seahorse showed that while the study population was genetically monogamous within a breeding period, more than 40 percent of the couples get "divorces" and "remarry" between successive reproductive bouts.
• Gender roles are sometimes reversed. In t
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