June 16, 2007
Cope's Giant Salamander
Up it the high reaches of (relatively) undisturbed rocky streams here in Clatsop County lives a curious salamander. It is what we in the ecology business call an obligate species with requirements so specialized and so narrow that it is particularly suseptible to environmental impacts. The Cope's Giant Salamander (Dicamptodon copei) requires cold, clear, running streams with rocky bottoms. They prefer their streams to be in dark, closed canopy forests. They are so stream dependent that adults rarely metamorphos into terrestrial adults, instead the adults retain their gills in a condition called neoteny. There are only one or two sites in Clatsop County where Cope's Giant Salamander can be found.
The Cope's often shares its streams with it's larger, more mobile cousin, the Pacific Giant Salamander (D. tenebrosus) and identification can be complicated. The Cope's has a narrower, rectangular head, less frilly gills, a longer body relative to the length of the limbs and distinctive tannish spotting.
In 2005, I took Craig Steele, a molecular biologist, up to Fox Creek to look for Cope's Salamanders so he could obtain tissue samples for genetics work he was doing on the Dicamptodon complex. His findings are soon to be published in the Journal of Molecular Phylogenetics and Evolution. I was given an advanced copy and can share some of the findings. First, and most importantly, the critters we've been calling Cope's Giant Salamanders are, in fact, Cope's Giant Salamander. The Fox Creek population represents a genetically distinct subpopulation from its nearest Cope's relatives across the river in the Willapa Hills. Cope's apparently broke off from other Dicamptodon's in the Cascades of northern Oregon and expanded west to the Coast Range during the Pleistocene. Post-iceage warming isolated Oregon populations south of the Columbia River from those to the north. Fox Creek populations have been isolated long enough to form their own distictive branch on the cladistic family tree (Baysian topology for all you purists).