AMPHIBIAWEB
Plethodon jordani
Jordan's Salamander , Red-Cheecked Salamander, Jordan's Redcheeck Salamander
Subgenus: Plethodon
family: Plethodontidae
subfamily: Plethodontinae

© 2013 John P. Clare (1 of 26)

View distribution map using BerkeleyMapper.


Conservation Status (definitions)
IUCN (Red List) Status Near Threatened (NT)
See IUCN account.
NatureServe Status Use NatureServe Explorer to see status.
CITES No CITES Listing
Other International Status None
National Status None
Regional Status None

   

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Description
This species is characterized by a dull bluish-grey belly and by red cheeks with a pale background color that contrasts markedly with the top of the head, which is deep brown (Hairston and Pope 1948, Hairston 1950, and Bishop 1943). The ventral surface of the head is a dull flesh color that blends with the belly. The ventral surface of the tail is darker than the belly, but lighter than the dorsal surface, which is blue-black. The legs and feet are also a slightly lighter grayish-brown. The color of the cheeks can range from dull pink to bright red, and the area is limited behind by the lateral extensions of the gular fold, above by the impressed line running from the eye to the gular fold, in front by the eye, and below, anteriorly, by the lower margin of the upper jaw (Bishop 1943). Juveniles have pale bellies and all individuals less than 29 mm have red spots on dorsum, but not on cheeks (Hairston and Pope 1948).

The head is widest immediately behind the eyes, where it appears slightly swollen. Behind this, the sides converge very slightly to the lateral extensions of the gular fold. In front of the eyes, the sides taper abruptly to a pointed snout. The eyes are large and protuberant and the gular fold is well developed. A deep sinuous groove stretches from the posterior angle of the eye to the lateral extension of the gular fold, and from here a short vertical groove runs to the angle of the jaw. The trunk is moderately stout, well rounded above and on the sides, and slightly flattened beneath. The tail is nearly circular in cross section at the base and evenly tapers to a slender tip. There are 15-16 costal grooves, including 1 in the axilla, which is usually poorly developed, and 1 in the groin, where 2 frequently run together. There are 2-3 intercostal spaces between the toes of appressed limbs. The limbs are stout and larger than in most species of Plethodon. There are four fingers, which in order from longest to shortest are either 3-4-2-1 or 3-2-4-1, and which have no webbing between them. There are 5 toes, which in order from longest to shortest are 3-4-2-5-1, with the innermost toe being rudimentary (Bishop 1943). Number of vomerine teeth ranges from 5 to 11, with an average of 8 (Hairston and Pope 1948). The series of teeth arises behind or just outside the outer edge of the nares and curves gently inward and backward toward the mid-line, where they are separated by about twice the diameter of an inner naris. The parasphenoid teeth are in a large patch narrower in front than in back. The patch is rounded in the back and a narrow, elongate area free of teeth runs through the center. The tongue is fairly large, and the margins are thick and smooth (Bishop 1943).

Average length of 10 adults of both sexes was 112.5 mm. The largest specimen, a female, had a total length of 135 mm with a tail length of 65 mm, head length of 18 mm, and head width of 10 mm. Proportions of a male were total length of 119 mm with tail length of 60.5 mm, head length of 14 mm, and head width of 9 mm. The tail always comprises about half of the body length (Bishop 1943). Individuals are larger at lower elevations. Males can be identified year-round by conspicuous cloacal lips and a slightly more pointed lower jaw, and during breeding season by distinct mental glands (Hairston 1983 and Bishop 1943).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: North Carolina, Tennessee

View distribution map using BerkeleyMapper.
Plethodon jordani is found in the Great Smoky Mountains from Mt. Sterling to the mountains north of Bryson City, NC (Hairston and Pope 1948). Hybridization occurs with congener P. metcalfi at Hyatt Ridge, which connects the Great Smoky Mountains with the Balsams in the southeast corner of Great Smoky Mountains National Park (Hairston 1950). The zone of hybridization is 4230 m wide and stretches from Spruce Mountain to Heintooga Overlook (Hairston et. al. 1992). Hybrids show differing amounts of red on the cheek and differing darkness of the belly (Hairston 1950). Transplantation of both species between the two mountain ranges yielded a much lower frequency of hybrids then would be expected from random mating, thus suggesting that either strong selection against hybrids or positive assortative mating occurs. This may be due to the large genetic divergence between the two species, which have a Nei genetic distance of 0.27 (Highton 1998). Another zone of hybridization occurs with congener P. shermani and stretches along a line from Franklin, NC to Andrews, NC. These hybrids are characterized by both red cheeks and red legs (Hairston 1950). A final hybrid exists with congener P. teyahalee in the narrow altitudinal zone where the two species overlap. These hybrids occur throughout the range of P. jordani, but only account for 0.05% of the population (Hairston 1980). This hybrid is characterized by a mixture of red on the cheeks and white spots on other parts of the body.

The lowest elevation at which an individual has been found is 2850 ft and from there they range up to the top of Clingman's Dome, the highest point in the Great Smoky Mountains at 6643 ft (Hairston 1948). The lowest elevation at which P. jordani occurs on any particular slope is mediated by local climate and changes with the direction of the slope face (Hairston 1951). Individuals normally occur down to 900 m on north-facing slopes and down to 1500 m on south-facing slopes (Hairston, Nishikawa, and Stenhouse 1987).

Plethodon jordani is favored by a wet and cool climate, which is normally found in the upper elevations (Hairston 1973). It occurs on heavily forested slopes and can be found among the leaf litter or under old rotten logs or bark. P. jordani is sympatric with 10 other species of salamanders and comprises 73.6% of the individuals (Hairston 1980). Its abundance is about 0.7 individuals/m2 (Hairston 1996).

Life History, Abundance, Activity, and Special Behaviors
Seasonality of P. jordani varies with elevation, but individuals are mainly active from mid-May to early October, reaching their greatest abundance from July to September (Hairston 1981). They emerge from their burrows at the beginning of the night and forage until about 0100 h, when activity begins to die off (Hairston 1987). On any particular night about one-quarter of the individuals are active (Hairston 1984). They are generalist predators that feed on any moving organism of appropriate size (Hairston, Nishikawa, and Stenhouse 1987). They rely mostly on the visual cues of size and velocity to identify prey (Schuelert and Ursula 2002). Pulmonata, Myriapoda, and Coleoptera each compose over 10% of the diet. Foraging usually takes place on the forest floor, but on humid, foggy nights many individuals can be observed climbing on low herbaceous plants (Hairston, Nishikawa, and Stenhouse 1987).

Mating occurs in August and September. P. jordani are territorial and territories are 11.5 m2 for males, 2.8 m2 for females, and 1.7 m2 for juveniles (Merchant 1972). Pheromones are used to communicate and are applied to the substrate and sensed by touch (Hairston 1985). Males can differentiate between the sexes based on odor and prefer the odor of the female (Dawley 1984). Once air temperatures fall as low as 0° in the fall, no surface activity is seen until the following year as the salamanders winter in their burrows deep underground. Eggs are laid underground in May and take two months to hatch. Clutch size is directly related to snout-vent length, which is directly related to age. This allows average clutch size to vary from 3-10 eggs based on the age of the female. The female guards the eggs from predation and parasitism, and survival of the clutch has never been observed without survival of the mother (Hairston 1983). Metamorphosis takes place before hatching, so offspring emerge as miniature adults and there is no aquatic larval stage (Hairston, Nishikawa, and Stenhouse 1987).

Juveniles begin to emerge in May the year after they hatched. At this time their snout-vent length averages 16.64 mm (Hairston 1983). More one-year olds continue to emerge as the summer progresses, and it is not until September that they reach a number proportional to that of the older age classes. Average growth in snout-vent length during May-October of the second year is 12.02 mm. This is followed by an average growth of 1.90 mm during the winter and then another 9.26 mm of growth from May-October of the third year (Hairston 1983). In May, four age classes can be identified: 1 year-olds, 2 year-olds, 3-year olds, and those 4 years or older. By October, however, the 3 year-olds have merged with the adults. About one-quarter of the salamanders become mature during the third year, and another quarter during the fourth year. By the time they reach their fifth year, all P. jordani are mature, but females still alternate years in which they oviposit. This is due to the fact that it is difficult to capture enough food after laying eggs in May in order to produce enough energy to have a new batch of eggs by the time cold weather halts mating (Hairston 1983). Survival is highest during the first year at 0.837 when the juveniles remain underground. It is lowest during the second year at 0.364, rises during the third year to 0.484, and is 0.81 for each subsequent year. This creates a relatively long mean generation time for such a small creature of 9.8 years (Hairston 1983).

Plethodon jordani is in intense competition with its congener P. teyahalee where they overlap in a narrow altitudinal zone that ranges from 70-120 m in height (Hairston 1980). Below this narrow altitudinal zone the climate is warmer and drier, giving P. teyahalee an advantage, while above this narrow altitudinal zone the climate is cooler and drier, giving P. jordani an advantage. If P. teyahalee is removed from the area of overlap, the proportion of 1 year-old and 2 year-old P. jordani increases. If P. jordani is removed from the area of overlap, the population of P. teyahalee increases by roughly 350% (Hairston 1980). This competition is due to alpha-selection, evolution of interference mechanisms against competing species, in both P. jordani and P. teyahalee (Hairston 1983). This alpha-selection can be seen in the greater aggressiveness of P. teyahalee in the Great Smoky Mountains, where it overlaps with P. jordani, as compared to its aggressiveness in the Balsams, where there is no P. jordani to compete with. P. jordani has also evolved to be much more aggressive than its close relative P. metcalfi, which also overlaps with P. teyahalee. This aggressive interference determines the extent to which the two species can exclude each other from the intermediate elevations (Hairston, Nishikawa, and Stenhouse 1987).

Plethodon jordani responds to snake predation by writhing, trashing, tail wrapping, tail autonomy, and biting. These actions are effective roughly one-third of the time (Feder and Arnold 1982). Like all other large species of Plethodon in the eastern United States, P. jordani possesses a tail that exudes a great deal of slime when it is disturbed. This slime may stick to the feathers around the eyes of bird predators and interfere with vision by gluing the eyelids shut (Highton 1995). P. jordani does not undertake any migrations and average variance in movement is only 1 m every 7.85 days (Nishikawa 1990). The maximum aerobic speed of P. jordani is 0.16 km/h, which increases O2 consumption to 6-9 times standard rate. Lower levels of exercise, however, can be maintained for over 2 hours (Full 1986).

Trends and Threats
There is no consistent trend in the number of individuals of P. jordani based on observations made at Heintooga Overlook since 1972 (Hairston 1993). The only major threat is clearcutting, which has reduced salamander populations in the southern Appalachians by almost 9%, or more than one-quarter of a billion salamanders (Alford and Richards 1999). Logging exposes terrestrial salamanders to altered microclimates, increased soil compaction and desiccation, and reduced habitat complexity.

Possible reasons for amphibian decline

Habitat modification from deforestation, or logging related activities

References
 

Alford, R.A., and Richards, S.J. (1999). ''Global amphibian declines: a problem in applied ecology.'' Annual Review of Ecology and Systematics, 30, 133-165.  

Bishop, S.C. (1943). Handbook of Salamanders. Comstock Publishing Company, Inc., Ithaca, New York.  

Dawley, E.M. (1984). ''Recognition of individual sex and species odors by salamanders Plethodon glutinosis and Plethodon jordani complex.'' Animal Behavior, 32, 353-361.  

Feder, M.E., and Arnold, S.J. (1982). ''Anaerobic metabolism and behavior during predatory encounters between snakes Thamnophis elegans and salamanders Plethodon jordani.'' Oecologia, 53, 93-97.  

Full, R.J. (1986). ''Locomotion without lungs: energetics and performance of a lungless salamander Plethodon jordani.'' American Journal of Physiology, 251, 775-780.  

Hairston, N. G., Sr., and Wiley, R. H. (1993). ''No decline in salamander (Amphibia: Caudata) populations: a twenty-year study in the Southern Appalachians.'' Brimleyana, (18), 59-64.  

Hairston, N.G. (1950). ''Intergradation in appalachian salamander of genus Plethodon.'' Copeia, 1950(4), 262-273.  

Hairston, N.G. (1951). ''Interspecies competition and its probable influence upon the vertical distribution of Appalachian salamanders of the genus Plethodon.'' Ecology, 32, 266-274.  

Hairston, N.G. (1973). ''Ecology, selection and systematics.'' Breviora, 414, 1-21.  

Hairston, N.G. (1980). ''Evolution under interspecific competition: field experiments of terrestrial salamanders.'' Evolution, 34, 409-420.  

Hairston, N.G. (1981). ''An experimental test of a guild: salamander competition.'' Ecology, 62, 65-72.  

Hairston, N.G. (1983). ''Alpha selection in competing salamanders: experimental verification of an a priori hypothesis.'' American Naturalist, 122, 105-113.  

Hairston, N.G. (1983). ''Growth, survival and reproduction of Plethodon jordani: trade-offs between selective pressures.'' Copeia, 1983(4), 1024-1035.  

Hairston, N.G. (1984). ''Inferences and experimental results in guild structure.'' Ecological Communities: Conceptual Issues and the Evidence. D. R. Strong, D. Simberloff, L.G. Abele, and A.B.Thistle, eds., Princeton University Press, Princeton, New Jersey.  

Hairston, N.G. (1996). Long-term studies of vertebrate communities. Academic Press, New York, NY.  

Hairston, N.G., Nishikawa, K.C., and Stenhouse, S.L. (1987). ''The evolution of competing species of terrestrial salamanders: niche partitioning or interference?'' Evolutionary Ecology, 1, 247-262.  

Hairston, N.G., Wiley, R.H., and Smith, C.K. (1992). ''The dynamics of two hybrid zones in Appalachian salamanders of the genus Plethodon.'' Evolution, 46(4), 930-938.  

Hairston, N.G., and Pope, C.H. (1948). ''Geographic variation and speciation in Appalachian salamander (Plethodon jordani group).'' Evolution, 2, 266-278.  

Highton, R. (1995). ''Speciation in eastern North American salamanders of the genus Plethodon.'' Annual Review of Ecology and Systematics, 26, 579-600.  

Highton, R. (1998). ''Frequency of hybrids between introduced and native population of the salamander Plethodon jordani in their first generation of sympatry.'' Herpetologica, 54(2), 143-153.  

Merchant, H. (1972). ''Estimated population size and home range of the salamanders Plethodon jordani and Plethodon glutinosus.'' Journal of the Washington Academy of Science, 62, 248-257.  

Nishikawa, K.C. (1990). ''Intraspecific spatial relationships of two species of terrestrial salamanders.'' Copeia, 1990(2), 418-426.  

Schuelert, N., and Ursula, D. (2002). ''The effect of stimulus features on the visual orienting behaviour of the salamander Plethodon jordani.'' Journal of Experimental Biology, 205, 241-251.



Written by Chirstopher Searcy (searcy AT fas.harvard.edu), Harvard University
First submitted 2002-11-26
Edited by Meredith Mahoney and Christopher Searcy , Kevin Gin (12/03) (2003-12-04)



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Citation: AmphibiaWeb: Information on amphibian biology and conservation. [web application]. 2014. Berkeley, California: AmphibiaWeb. Available: http://amphibiaweb.org/. (Accessed: Oct 24, 2014).

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