Jordan's Salamander, Red-Cheecked Salamander, Jordan's Redcheeck Salamander
© 2019 Alexander Murray (1 of 38)
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
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
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
Possible reasons for amphibian decline
Habitat modification from deforestation, or logging related activities
This species was featured as News of the Week on 16 November 2020:
To improve predictions for how species will respond to our changing climate, we should not neglect the behavioral consequences of climate change. Gade et al. (2020) set out to address this shortcoming: they wanted to project how the changing conditions of the next century will influence salamander surface activity. They conducted surveys of three species of the Plethodon jordani complex in the Appalachians of the US, identified predictors of salamander surface activity and abundance (temperature and water vapor pressure), then used this relationship to explore how the surface activity of P. jordani complex species will respond to stabilization and high emissions climate scenarios. They found that the probability of salamander surface activity during peak active season increased over time, though gladly temperatures were not predicted to surpass the species' thermal maxima. Surface activity is important to salamanders because it their opportunity to forage and mate, so this outcome may sound like good news. However, the authors qualify that there are physiological trade-offs at play, so modified behavioral patterns can have unpredictable consequences. For example, higher temperatures increase metabolism and may decrease the energy assimilation of salamanders, which can result in smaller body sizes and lower growth rates, and in turn, result in delayed sexual maturity and lower fecundity. The authors show how the examination of behavior like surface activity, critical to their fitness, can reshape our understanding of how species will fare with a changing climate (Written by Emma Steigerwald).
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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.
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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.
Originally submitted by: Christopher Searcy (first posted 2002-11-26)
Edited by: Meredith Mahoney and Christopher Searcy, Kevin Gin (12/03), Ann T. Chang (2020-11-16)
Species Account Citation: AmphibiaWeb 2020 Plethodon jordani: Jordan's Salamander <https://amphibiaweb.org/species/4137> University of California, Berkeley, CA, USA. Accessed Jan 22, 2022.
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Citation: AmphibiaWeb. 2022. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Jan 2022.
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