Dr. Thomas Sawicki, American Public University - New Stygobitic Species
In today’s Academic Minute, Dr. Thomas Sawicki of American Public University describes the discovery of a number of new species in the subterranean caves of Florida.
Thomas Sawicki is an adjunct professor at American Public University. His research examines the rate of gene flow between populations that live in separate water filled caves of the Florida aquifer. He has 16 years of experience diving in and making scientific collections from water filled caves, and his collections have resulted in the discovery and subsequent description of numerous new species and genera. He earned his Ph.D. at Old Dominion University.
Dr. Thomas Sawicki - New Stygobitic Species
The water filled caves of the Floridan aquifer form a complex, interconnected habitat within which numerous species have invaded and evolved. At least 27 invertebrate and one vertebrate species have been described from Florida’s caves. To date, out of this rich biodiversity only two species of stygobitic amphipods have been formally described. These are Crangonyx hobbsi and C. grandimanus.
The two Crangonyx species endemic to the Floridan aquifer are widely distributed, and often found sympatrically (living at the same location at the same time) in cave systems from Tallahassee to Miami. Amphipods brood their young which hatch from eggs as an immature form, eventually reaching the adult form through a series of molts—thus they do not have a planktonic larval stage that can result in the distribution of their larvae over a wide area. The two Crangonyx species found in the Floridan aquifer reach an adult size of approximately 10-17 mm and thus have a very limited ability to disperse widely from their home range.
Because of their broad distribution and sympatry, Crangonyx hobbsi and C. grandimanus should act as good proxies to the understanding of gene flow between cave populations—in other words, to help us determine how genes flow through rock. To answer this question, a detailed morphological and molecular analysis of C. hobbsi and C. grandimanus populations from various systems across their range is currently being conducted.
To date, through this research, I have discovered at least three new species of amphipods and one new species of isopod—the description of one of the species of amphipods is currently underway, and should be in press later this spring. In addition to the basic scientific knowledge that this research is producing, it also has the potential to significantly influence the conservation of at least some elements of these habitats. This is due to the fact that populations of stygobitic organisms that are genetically isolated, or which represent new and endemic species, are extremely vulnerable because of their isolation within and dependence upon specific cave systems. Destruction of such systems means destruction of the habitat and, by definition, extirpation of the population or species living within that habitat.