Body Part Loss in Fish Yields Surprise

When two species of stickleback fish evolved and lost their pelvises and body armor, the changes were caused by different genes in each species, scientists have learned.

The researchers expected the same genes would control the same changes in both related fish.

Biologists knew that in many cases of evolution, "the same gene has been used over and over again — even in different species — to result in the same anatomy," said Mike Shapiro, a biologist at the University of Utah who worked on the study. "What we are finding now is that different genes can have similar effects."

The findings shed new light on how evolution produces diversity in nature, and on the evolution of limb loss — and not just the loss of the pelvis and leg-like pelvic spines in certain sticklebacks.

"Limb loss is something we see in many other groups — snakes, whales, manatees and some amphibians," Shapiro says. "We can't do genetic studies on those animals. Sticklebacks give us insight into what may be going on in many other animal groups."

Results of the study, funded by the National Science Foundation, are published online today in the journal Current Biology.