An Intruder Among Rare Relicts

For the first time, seal salamanders were discovered in 2003 on the Ozark Plateau in northwest Arkansas. Their closest kin live in the Appalachian Mountains, 700 kilometres (435 miles) to the east. Despite the separation, distributions of some aquatic species suggest that, historically, animals in the two locations were once linked.

Since then, populations became severed by geography and proceeded to evolved independently. The newly-noticed salamanders could be another of these rare relicts.

Isolated populations of plants or animals can carry a unique mix of genes that are critically important to the conservation of a species. But a comparison of the Ozark seal salamander's genes to those of other salamanders finds an identical match with Desmognathus monticola living 1000 km (620 miles) away in northeast Georgia.

If the Ozark population had been isolated for millennia, one would expect some genetic divergence from distant salamanders. The genetic sleuthing indicates itís in fact a much more recent arrival. Ozark seal salamanders are intruders that scientists say may need eliminating rather than protecting because they threaten local species.

Since salamanders don't travel far on their own, the seal salamanders undoubtedly arrived in the Ozarks with help from humans. The most plausible explanation is that an angler left their bait behind. In northern Georgia, thousands of seal salamanders are collected wild and sold as "spring lizards" to fishermen aiming to hook largemouth bass.

The transplanted salamanders are now found at two springs in the Ozarks and are reproducing, indicating the species is prepared to stay. Unfortunately, the newcomer could be disastrous for the four species of Eurycea salamanders already resident there, two of which only live in and around the Ozarks. The burly seal salamanders are known to aggressively oust other kinds of salamanders from prime habitat. This prompts the study's authors to conclude that Ozark amphibians will be much better off without seal salamanders around.

Reference

Ronald M. Bonett, Kenneth H. Kozak, David R. Vieites, Alison Bare, Jessica A. Wooten and Stanley E. Trauth. 2007. The importance of comparative phylogeography in diagnosing introduced species: A lesson from the seal salamander, Desmognathus monticola. BMC Ecology. 7:7.

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