Doctoral student tracks
changing cavefish
The cavefish (Cottus carolinae) are widespread throughout the southeastern United States. Some have been found in cave environments, but not with the morphological changes that the southeast Missouri population has shown. With a wide jawline and delicate bands of pigment, these specimens are works in progress for evolutionary changes. Reduction in eye size, in pigmentation and in numbers of pelvic fin rays - - all these have been found in varying degrees in the cave-dwelling fish. Perry County is unique because it has more then 630 known caves, most located on private land. "People have been exploring them for years, mapping them, but few biologists have done work in that area," Adams said. She continued, "In the early '90s one of the cavers recognized that these sculpin are unique. Even the surface species there are different from other surface populations." Adams believes the fish have entered the caves independently and are changing differently. She is tackling four areas of research regarding the cave-dwelling sculpin: reproductive life history, morphology, physiology and population genetics. For instance, she hopes to find out why cave specimens reproduce in December but external ones wait until March. And although she has found gravid females, she is still hoping to find actual eggs in the caves. She also wants to describe the morphology to a greater extent, particularly the brain. "We can see eyes getting smaller, so is the optic lobe getting smaller? If so, is the olfactory lobe or some other lobe getting bigger to compensate?" she asked. Adams also wants to examine the population genetics to see how closely related or distinct the cave population is compared with the surface. Gathering this information from the field is labor intensive, though. Caves are "innately cool," but logistically they are difficult to work in, she said. Some of the caves are very easy to get into, where Adams and her assistants might just drop down into the caverns. Others, however, are more difficult. In one, she has to walk through neck-high water - - very cold neck-high water - - with a limited air space to reach a cave that has a water temperature of 14 degrees Celsius. Another takes a 100-foot belly crawl to reach the destination. Adams did her master's research on Ozark cavefish and cave crayfish at the University of Arkansas. There, she worked on fully adapted cave specimens, whereas the sculpin in southeast Missouri seem to be in the transitory phases. Comments: siucnews@siu.edu This page is Bobby approved |
