Diversity of Appalachian Salamanders
Old forests like
those along the Cliff Trail are a perfect place to witness one of
central Appalachia’s specialties --- salamanders. These little
critters are amphibians,
related to frogs and toads, but are often overlooked since most of them
spend their days hidden under leaves, logs, or rocks where they can
stay moist. Only at night do they come out to hunt insects, mate,
and defend their territories, each activity being facilitated by the
salamanders’ keen sense of smell.
Although
salamanders can be found throughout Europe, Asia, and North America
(and here and there in South America), they reach a peak of diversity
here in the the southern Appalachian mountains. Like our cove hardwood forests,
our current Appalachian salamanders can be traced back a few million
years to the Pliocene, when dry temperatures turned most of the eastern
United States into grassland. The ancestors of our modern
salamanders were trapped on “islands” of mountain forest separated by
grassy plains in the valleys. Since the salamanders were unable
to survive in the dry grasslands, each group of salamanders mated only
with other salamanders in its immediate area. Over thousands of
years, these populations became inbred and developed traits different
from those shown by salamanders on the next mountain over.
When the
grasslands receded and the forests crept down off the mountaintops to
coat the entire eastern United States, the salamanders came with the
trees. But so much time had elapsed that salamander groups which
had begun as the same species were no longer able to successfully
reproduce with related salamanders from a different island. On
one mountain island, for example, the salamanders had evolved to
survive in talus heaps at the bases of cliffs while on another mountain
island the salamanders had evolved to live on the forest floor.
These two populations of salamanders had transformed from one species
into two.
Until recently,
scientists did not realize how far the Appalachian salamander evolution
had progressed. Our region’s largest genus of salamanders --- the
Plethodon salamanders --- was thought to contain only 16 species as
recently as 1962. Now that number has nearly tripled. Where
did all of these new species come from? They certainly did not
evolve in the last fifty years. Instead, advances in technology
have allowed us to untangle the DNA of salamanders and discover that
many salamanders that look alike to the human eye are unable to breed
with each other and are in fact distinct species. The Northern
Slimy Salamander you find on Sugar Hill, for example, could be any one
of 16 species. Like a human child searching for his real father,
a DNA test would be necessary to distinguish between the types of
Northern Slimies.
Although I am
not equipped to tease apart the exact identities of salamanders on
Sugar Hill, I am always ready to spend an afternoon hunting down these
secretive members of the animal kingdom. Salamanders are sparse
in young woods, but it never takes long to find a salamander in a
mature forest like that found on the side of Sugar Hill. In fact,
salamanders are near the top of the forest floor food chain and are
often so numerous in mature forests that they outweigh all of the birds
and mammals from that same area combined. Just imagine how many
salamanders it would take to outweigh a single deer.
With such great
numbers, salamanders are not hard to find. Creeks and their banks
are often home to the Northern Dusky Salamander and the Southern
Two-lined Salamander, one of the Northern Slimy Salamanders can be
found in nearly every moist forest, and dry forests are often full of
Red-backed Salamanders. All told, the southern Appalachian
mountains are home to 101 salamander species, about a quarter of which
can be discerned using the naked eye in our part of southwest
Virginia. As long as you do not get too caught up in figuring out
the exact species, turning over logs in search of salamanders can
consume many a pleasant afternoon.
The
Most Common Central Appalachian Salamanders (Not Pictured)
Northern
Dusky Salamander
Scientific
Name: Desmognathus fuscus fuscus
Family:
Plethodontidae (Lungless Salamander Family)
Habitat:
In and near creeks, springs, and seeps
Southern
Two-lined Salamander
Scientific
Name: Eurycea cirrigera
Family:
Plethodontidae (Lungless Salamander Family)
Habitat:
In or near creeks
Red-backed
Salamander
Scientific
Name: Plethodon cinereus complex
Family:
Plethodontidae (Lungless Salamander Family)
Habitat:
Woods
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