Red-backed salamander: Difference between revisions

Red-backed salamander
	"Redback" phase
	"Leadback" phase
Conservation status
	; Least Concern (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Order:	Urodela
Family:	Plethodontidae
Subfamily:	Plethodontinae
Genus:	Plethodon
Species:	P. cinereus
Binomial name
	Plethodon cinereus; (Green, 1818)
	Range of P. cinereus
Synonyms
	Salamandra cinerea Green, 1818; Plethodon cinereus — Tschudi, 1838;

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The red-backed salamander (Plethodon cinereus) is a small, hardy woodland salamander species in the family Plethodontidae. The species inhabits wooded slopes in eastern North America, west to Missouri, south to North Carolina, and north from southern Quebec and the Maritime provinces in Canada to Minnesota.^[3] It is also known as the redback salamander,^[4] eastern red-backed salamander,^[4] or the northern red-backed salamander to distinguish it from the southern red-backed salamander (Plethodon serratus). It is one of 56 species in the genus Plethodon. Red-backed salamanders are notable for their color polymorphism and primarily display two color morph varieties ("red-backed" and "lead-backed"), which differ in physiology and anti-predator behavior.^[5]^[6]^[7]

Description and ecology

The red-backed salamander is a small terrestrial salamander, 5.7–10.0 cm (2.2–3.9 in) in total length (including tail), which usually lives in forested areas under rocks, logs, bark, and other debris.^[3] It is one of the most numerous salamanders throughout its range.^[3] Red-backed salamanders are mostly insectivorous, but prey on a wide assortment of other small invertebrates including isopods, millipedes, centipedes, pseudoscorpions, harvestmen, spiders, and gastropods.^[8] On one occasion an individual was found to have cannibalized a P. cinereus embryo.^[8] Predators of the red-backed salamander are many and varied, and include small mammals, snakes, ground-foraging birds, and larger salamanders.^[9]

As with all amphibians, the red-backed salamander has permeable skin. They also lack lungs, a condition which is an ancestral trait of the Plethodontidae.^[10] Red-backed salamanders are thus entirely reliant on cutaneous respiration for gas exchange. Permeable skin is susceptible to desiccation and must be kept moist in order to facilitate cutaneous respiration; as a result much of the ecology and behavior of the red-backed salamander is restricted by climatic and microclimatic variables, particularly dryness and temperature.^[11] Individuals confine themselves to moist microhabitats (beneath rocks, woody debris, etc. as well as beneath the soil) for long periods of time in order to maintain hydration when surface conditions are inhospitably dry or hot, and are only active on the surface to travel, forage, or reproduce for short periods.^[11] The duration of surface activity is directly limited by the rate of cutaneous water loss to the environment, which is influenced by environmental variables such as altitude, forest canopy cover, and the amount of recent precipitation.^[11]^[12] Hydric limitations are thus a major constraint on red-backed salamander growth and reproductive success as well as the genetic interconnectedness of red-backed salamander populations.^[11]^[12]^[13]

The skin of red-backed salamanders was found to contain Lysobacter gummosus, an epibiotic bacterium that produces the chemical 2,4-diacetylphloroglucinol and inhibits the growth of certain pathogenic fungi.^[14]

Polymorphism

Plethodon cinereus has color diversity, the common ones are the red-striped morph and the lead-phase, two color forms. The "red-backed" or "red-stripe" variety has a red dorsal stripe that tapers towards the tail, and the darker variety, known as the "lead-backed" (or simply "lead") phase, lacks most or all of the red pigmentation.^[3] The red-backed phase is not always red, but may actually be various other colors (e.g., yellow-backed, orange-backed, white-backed, or a rare erythristic morph in which the body is completely red).^[3] Both morphs have speckled black and white bellies.^[3] Additional color anomalies of this species also exist, including iridistic, albino, leucistic, amelanistic, and melanistic anomalies.^[15] These color morphs are rarer than the red-backed, lead-backed, and erythristic morphs, but still have been reported with consistency among varying populations of this species.^[15] polymorphism

Color polymorphism is thought to be an adaptive strategy in a heterogeneous environment, so the maintenance of polymorphism is derived from behavioral and physiological choices. The color polymorphism of The red-striped morph Plethodon cinereus and the lead-phase Plethodon cinereus show different anti-predator responses in behavior, and predator attacks differently based on the color form. Compared to red-striped morph P. cinereus which prefers an "all trunk raised" posture and tends to stay still, the lead-phase P. cinereus is significantly more mobile. More lead-phase P. cinereus has the ability to automatically cut off the tail, indicating that the two forms also differ in the frequency of being attacked^[7].

As an evidence that polymorphism is to adapt the environment, P. cinereus color morph frequencies are correlated with climatic variables, suggesting habitat temperature and more broadly climate to be potential sources of selective pressure on P. cinereus polymorphism.^[5]^[6] The red-backed form is found with greater frequency in colder regions at more northerly latitudes and easterly longitudes throughout its range, whereas the opposite is true of the lead-backed form.^[5]^[6] Additionally, lead-backed morphs withdraw from surface activity earlier in the autumn than red-backed morphs, presumably to avoid cooling temperatures.^[5]^[16]^[17] Standard metabolic rate has also been found to differ between the morphs at certain temperatures, with significantly lower metabolic rates being displayed by the lead-backed form at 15 °C;^[16] in the same study, lead-backed individuals were also more active on the ground surface at this temperature.^[16] These findings suggest that the lead-backed color variant is less tolerant of cool temperatures than the red-backed color variant, and that the two color forms differ physiologically and behaviorally at certain temperatures.^[5]^[6]^[16]^[17]

An alternate explanation for the uneven geographic distribution of the red-backed and lead-backed P. cinereus color morphs involves phenotypic plasticity responding to developmental temperature. Although the genetic origins of the P. cinereus polymorphic condition are not fully understood, initial studies indicate that color morph dominance is likely subject to epistasis, and that multiple loci may interact to determine an individual's morph condition.^[18]^[19] However, more recent research indicates that a plastic response to thermal conditions during development also contributes to color morph determination; in one study, P. cinereus eggs incubated at a higher temperature hatched a greater proportion of lead-backed morphs than eggs incubated at a lower temperature.^[20] Temperature-dependent color morph determination may therefore also potentially influence the spatial distribution of P. cinereus color morphs.^[20]

The two primary P. cinereus color morphs also differ in diet.^[17]^[21] The prevalence of certain prey taxa and the overall diversity and quality of prey items have been observed to differ seasonally between the two morphs in the spring and autumn when surface activity is greatest.^[17]^[21] In one study, the autumn diet of red-backed morphs was more diverse and of higher quality, and found to be dominated by mites, springtails, and ants, whereas the most important prey for lead-backed morphs were ants, mites, and isopods.^[17]

Moreover, the two morphologies have different standard metabolic rates, while lead-phase P. cinereus favor warm habitats or microclimates. So the strong argument is that the geographic distribution of color form is caused by the selection of physiological traits^[7].

Distribution

Distribution and reproduction of P. cinereus are in close contact with the soil on the forest floor. As deciduous forests mature, acid deposition can accelerate the acidification of soils. Acidic conditions can limit the distribution of amphibians and the numbers of sibling species, while the pH value of soil has a strong effect on the density and distribution of P. cinereus. When choosing between acidic and neutral soils, P. cinerea prefers to occupy more neutral soils. P. cinereus is rarely found in soils with a pH value of 3.7, and relatively more to be found in soils with a pH value of about 3.8 or higher. Juvenile P. cinereus have never been found in soils with a pH vlaue lower than 3.7. At the same, similar conclusions have also been supported in the laboratory. P. cinereus prefers to occupy substrates near neutral pH. A pH value between 2.5 and 3 results in acute mortality, while a pH value between 3 and 4 results in chronic mortality. Low pH will reduce their growth and respiration. Slowed growth and delayed metamorphosis make juvenile P. cinereus more vulnerable to predators and has serious consequences for population survival. In addition, as upper-level consumers in the system, the effect of soil pH value on P. cinereus's distribution can alter forest tree decomposition food webs^[22].

Several other factors, such as moisture and temperature, can affect the population density or dispersion of Botrytis as well. During prolonged dry periods, individuals move down into the soil, while during short dry periods they retreat under logs or rocks. They will avoid very warm areas, and when the temperature drops to 4-5 celsius degrees, they will retreat to the ground as well. The optimum temperature is 10 to 15-celsius degrees. Moreover, intraspecific and interspecific competition also affected the distribution of P. cinerea^[22].

Spatial distributions of Salamander Plethodon cinereus is observed to seasonal. This supports that competition exists in the population of this species, which plays a role in population dynamics that interfere. In spring, Plethodon cinereus are more likely to exist in groups of around 2 to 7 individuals under some object covers such as rocks and wood, than in the other seasons, while the density on the forest floor stays constant. This is because that spatial dispute starts in spring. A study in Blackrock Mountian, Virginia indicatss that the mean number of salamanders in each quadrat of 100*100 m varies from 1.6 to 3 in spring compared to that 0.8 to 1.8 in summer. A significant increase in the spatial distribution of P. cinereus from spring to summer thinks to be due to the intraspecific interference competition. The cover objects on the ground can be a good choice of moisture refuge for P. cinereus during the rainy season. The failure of P. cinereus to forage underground causes them to restict down to areas under and around the cover objects. Aggression and territoriality under resources, food and shelter limitation are the reasons for the observed spacing^[22].

Behavior

Antipredator behavior of P. cinereus was found to differ between the two color phases; the lead-backed phase has a tendency to run away from predators, whereas the red-backed phase often stays immobile and possibly exhibits aposematic coloration.^[7] Stress levels of each color phase were estimated by determining the ratio of neutrophil to lymphocyte cells in the blood, and the results suggest stress levels are higher in the lead-backed phase than in the red-backed phase.^[23] This may be a consequence of a higher predation risk experienced in the wild by the lead-backed phase, and may also mean lead-phase salamanders could be more vulnerable in captivity settings.^[23]

Plethodon cinereus, like many plethodon species, exhibit homing behavior, with homing of females to their nests, as well as non-attending females and males to a home range.^[24] This allows for essential contact between a female and her eggs in order to ensure their survival, as well as for non-attending females and males to explore beyond the home range when under predation pressures, or searching for food or cover, and return to their home range if a more favorable microhabitat is not found.^[24]

Defense Mechanism toward bacterial pathogen

Plethodon cinereus coexists with some bacteria. These bacteria help salamanders defend against fungal pathogens. For example, Batrachochytrium dendrobatidis, a fungal pathogen that causes a disease called Chytridiomycosis, has led to a rapid decline in amphibian populations worldwide. Around one-third of amphibians are endangered because of the disease, but some species persist from the infection, and some even clear the pathogen. And Plethodon cinereus has such chemical defenses against these threats. As evidence, Plethodon cinereus has bacterial symbionts called Microsymbiont Janthinobacterium lividum on the skin of Plethodon cinereus. These substances can be detected by a range of methods including reversed-phase HPLC, high-resolution mass spectroscopy, NMR, and UV-Vis spectroscopy. Janthinobacterium lividum produces antifungal metabolites, which are indole-3-carboxaldehyde and violacein. These metabolites can inhibit the growth of pathogens. This finding suggests an idea for providing long-term protection to individuals who are infected with chytridiomycosis. It also provides a research pathway for future drug development which is to use novel antifungal compounds for the treatment of human pathogens^[25].

Reproduction and biomass

Males and females of P. cinereus typically establish separate feeding and/or mating territories underneath rocks and logs. However, some red-backed salamanders are thought to engage in social monogamy, and may maintain co-defended territories throughout their active periods. Breeding occurs in June and July. Females produce from four to 17 eggs in a year. The eggs hatch in 6 to 8 weeks. Not much is known about the dispersal of neonates, although neonates and juveniles are thought to be philopatric. The species largely consumes invertebrates and other detritus dwellers. In some areas with good habitat, these salamanders are so numerous, their population densities may surpass 1,000 individuals per acre (2,471 individuals per hectare). Pokagon State Park in Indiana is one such place.^[26]

As in many Plethodon species, female red-backed salamanders have the ability to store sperm as spermatophore, and have been evidenced in doing so up to eight months prior to the oviposition period in June and July.^[27] Sperm or spermatophores are not retained following the oviposition period.^[27]

Mutualism

Male Plethodon cinereus actively defends its territory from intrusion by other males and is less aggressive towards invading females and juveniles. Plethodin cinereus usually directs aggressive behavior towards conspecific as well as heterospecific, as long as it's thought to be potential competitor. Plethodon cinereus positively interacts not only with conspecifics, but also with other potential competitors such as centipedes^[28].

It is necessary to have a visual display in order to elicit the threat posture of P. Cinereus, and there will be no obvious aggressive behavior toward conspecifics and heterospecifics if only chemical cues exist. However, P. cinereus will increase time spent in aggressive postures when paired with centipedes but did not show increased aggression when paired with conspecifics. The specific test method was to expose male Botrytis cinerea to four substrate chemical cue treatments separately: control, self, conspecific, or centipede (Scolopocryptops sexspinosus) to determine its behavior in the presence or absence of conspecifics and heterospecific cues reaction^[28].

Their residence status affects the attack level as well. Even if in different residency statuses, they do attack centipedes^[28].

Mimicry

The lead-backed are absent in northeastern United States and southeastern Canada. Instead, another phase called erythristic is observed and exclusive in these areas. This phase shows macroand microgeographic variation in frequency. Regardless the wide geographic variation, the highest frequency is always under 25%. This phase of P. cinereus mimic Notophthalmus viridescens to protect themselves. Birds selectively avoid to predate all-red or reytheristic color P. cinereus because they think that red color is a signal of noxiouness and toxicness. Even if people trained the birds to enhance the avoidance by increasing exposure to red efts (juvenile Notophtajalmus viridescens), the frequencies of ertherism is never above 25%^[29].

Interactions with humans

Roads have various negative effects on animal populations. For example, a major source of direct mortality for many species is accidental collisions with moving vehicles. Due to the slow movement of amphibians, it is estimated that the mortality rate of these animals on roads is as high as 10% of the total population each year. From a genetic point of view, roads also reduce gene flow and thus divide animal populations, causing drift and loss of genetic diversity. Eventually, populations separated by roads may become more and more distinct from each other, thus losing the original population. Amongst different sizes of roads, it is known that the interstate highway leads to increased genetic differentiation of Plethodon cinereus by microsatellite examination. Genetic distances between regions on either side of an interstate highway were significantly larger than those between equally spaced quadrants on the same side of the highway. However, plots on smaller roads were not genetically different compared to that in the case of interstate highways. Narrow paved roads reduce the movement of redback salamanders by approximately 25-75% but do not completely eliminate the dynamic of the population. And the detection of genetic differences across the interstate means that the spread on this road is reduced by well over 25-75%. So there is little gene flow on very large roads, and the P. cinereus population diverges from each other. The indirect effect of smaller roads on genetic population structure is also not a big issue for terrestrial salamanders and is not a direct effect of mortality and habitat change^[30].

The observed rate of dispersion in P. cinereus is far less than in most of the animals previously studied. Because P. cinereus have very high population densities, this should reduce the effects of genetic drift in isolated populations. From a conservation standpoint, red-backed salamanders are an important research organism because of their behavioral and physiological similarities to many threatened and endangered salamanders ^[30].

References

^ IUCN SSC Amphibian Specialist Group (2015). "Plethodon cinereus". IUCN Red List of Threatened Species. 2015: e.T59334A78907687. doi:10.2305/IUCN.UK.2015-4.RLTS.T59334A78907687.en. Retrieved 19 November 2021.
^ Stejneger L, Barbour T (1917). A Check List of North American Amphibians and Reptiles. Cambridge, Massachusetts: Harvard University Press. 125 pp. (Plethodon cinereus, p. 15).
^ ^a ^b ^c ^d ^e ^f Conant R, Collins JT (1998). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Third Edition. Boston: Houghton Mifflin. 616 pp. ISBN 0-395-90452-8.
^ ^a ^b Integrated Taxonomic Information System [Internet] 2012. [updated 2012 Sept; cited 2012 Nov 26] Available from: www.itis.gov
^ ^a ^b ^c ^d ^e Lotter, Fred; Scott, Norman J. (1977). "Correlation between Climate and Distribution of the Color Morphs of the Salamander Plethodon cinereus". Copeia. 1977 (4): 681–690. doi:10.2307/1443166. ISSN 0045-8511. JSTOR 1443166.
^ ^a ^b ^c ^d Gibbs, James P.; Karraker, Nancy E. (2006). "Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology". Conservation Biology. 20 (3): 913–917. doi:10.1111/j.1523-1739.2006.00375.x. ISSN 1523-1739. PMID 16909583.
^ ^a ^b ^c ^d Venesky, Matthew D.; Anthony, Carl D. (2007). "Antipredator adaptations and predator avoidance by two color morphs of the eastern red-backed salamander, Plethodon cinereus". Herpetologica. 63 (4): 450–458. doi:10.1655/0018-0831(2007)63[450:AAAPAB]2.0.CO;2.
^ ^a ^b Burton, Thomas M. (1976). "An Analysis of the Feeding Ecology of the Salamanders (Amphibia, Urodela) of the Hubbard Brook Experimental Forest, New Hampshire". Journal of Herpetology. 10 (3): 187–204. doi:10.2307/1562980. ISSN 0022-1511. JSTOR 1562980.
^ Grant, Alexa H.; Ransom, Tami S.; Liebgold, Eric B. (April 2018). "Differential Survival and the Effects of Predation on a Color Polymorphic Species, the Red-Backed Salamander (Plethodon cinereus)". Journal of Herpetology. 52 (2): 127–135. doi:10.1670/16-185. ISSN 0022-1511. S2CID 90207320.
^ Noble, G. Kingsley (1931). The biology of the amphibia (1st ed.). New York: McGraw-Hill. doi:10.5962/bhl.title.82448.
^ ^a ^b ^c ^d Feder, Martin E. (1983). "Integrating the Ecology and Physiology of Plethodontid Salamanders". Herpetologica. 39 (3): 291–310. ISSN 0018-0831. JSTOR 3892572.
^ ^a ^b Peterman, W. E.; Semlitsch, R. D. (2014-10-01). "Spatial variation in water loss predicts terrestrial salamander distribution and population dynamics". Oecologia. 176 (2): 357–369. Bibcode:2014Oecol.176..357P. doi:10.1007/s00442-014-3041-4. ISSN 1432-1939. PMID 25154754. S2CID 11041103.
^ Peterman, William E.; Semlitsch, Raymond D. (2013-05-06). "Fine-Scale Habitat Associations of a Terrestrial Salamander: The Role of Environmental Gradients and Implications for Population Dynamics". PLOS ONE. 8 (5): e62184. Bibcode:2013PLoSO...862184P. doi:10.1371/journal.pone.0062184. ISSN 1932-6203. PMC 3646024. PMID 23671586.
^ Brucker, Robert M.; Baylor, Cambria M.; Walters, Robert L.; Lauer, Antje; Harris, Reid N.; Minbiole, Kevin P. C. (2008). "The identification of 2,4-diacetylphloroglucinol as an antifungal metabolite produced by cutaneous bacteria of the salamander Plethodon cinereus". Journal of Chemical Ecology. 34 (1): 39–43. doi:10.1007/s10886-007-9352-8. PMID 18058176. S2CID 27149357.
^ ^a ^b Moore, Jean-David; Ouellet, Martin (2014-10-16). "A review of colour phenotypes of the Eastern Red-backed Salamander, Plethodon cinereus, in North America". The Canadian Field-Naturalist. 128 (3): 250–259. doi:10.22621/cfn.v128i3.1603. ISSN 0008-3550.
^ ^a ^b ^c ^d Moreno, Gabriel (1989). "Behavioral and Physiological Differentiation between the Color Morphs of the Salamander, Plethodon cinereus". Journal of Herpetology. 23 (4): 335–341. doi:10.2307/1564043. ISSN 0022-1511. JSTOR 1564043.
^ ^a ^b ^c ^d ^e Anthony, Carl D.; Venesky, Matthew D.; Hickerson, Cari-Ann M. (2008). "Ecological separation in a polymorphic terrestrial salamander". Journal of Animal Ecology. 77 (4): 646–653. doi:10.1111/j.1365-2656.2008.01398.x. ISSN 1365-2656. PMID 18479343.
^ Highton, Richard (1959). "The Inheritance of the Color Phases of Plethodon cinereus". Copeia. 1959 (1): 33–37. doi:10.2307/1440097. ISSN 0045-8511. JSTOR 1440097.
^ Highton, Richard (1975-06-25). "Geographic Variation in Genetic Dominance of the Color Morphs of the Red-Backed Salamander, Plethodon Cinereus". Genetics. 80 (2): 363–374. doi:10.1093/genetics/80.2.363. ISSN 1943-2631. PMC 1213333. PMID 17248684.
^ ^a ^b Evans, Annette E.; Urban, Mark C.; Jockusch, Elizabeth L. (2020-04-01). "Developmental temperature influences color polymorphism but not hatchling size in a woodland salamander". Oecologia. 192 (4): 909–918. Bibcode:2020Oecol.192..909E. doi:10.1007/s00442-020-04630-y. ISSN 1432-1939. PMID 32162072. S2CID 212669210.
^ ^a ^b Stuczka, Angela; Hickerson, Cari-Ann; Anthony, Carl (2016-01-01). "Niche partitioning along the diet axis in a colour polymorphic population of Eastern Red-backed Salamanders, Plethodon cinereus". Amphibia-Reptilia. 37 (3): 283–290. doi:10.1163/15685381-00003055. ISSN 1568-5381.
^ ^a ^b ^c Wyman, Richard L.; Hawksley-Lescault, Dianne S. (1987-12). "Soil Acidity Affects Distribution, Behavior, and Physiology of the Salamader Plethodon Cinereus". Ecology. 68 (6): 1819–1827. doi:10.2307/1939873. ISSN 0012-9658. {{cite journal}}: Check date values in: |date= (help)
^ ^a ^b Davis AK, Milanovich JR (2010). "Lead-phase and red-stripe color morphs of red-backed salamanders Plethodon cinereus differ in hematological stress indices: A consequence of differential predation pressure?" Current Zoology 56 (2): 238–243.
^ ^a ^b Kleeberger, Steven R.; Werner, J. Kirwin (1982). "Home range and homing behavior of Plethodon cinereus in northern Michigan". Copeia. 1982 (2): 409–415. doi:10.2307/1444622. ISSN 0045-8511. JSTOR 1444622.
^ Brucker, Robert M.; Harris, Reid N.; Schwantes, Christian R.; Gallaher, Thomas N.; Flaherty, Devon C.; Lam, Brianna A.; Minbiole, Kevin P. C. (2008-11-01). "Amphibian Chemical Defense: Antifungal Metabolites of the Microsymbiont Janthinobacterium lividum on the Salamander Plethodon cinereus". Journal of Chemical Ecology. 34 (11): 1422–1429. doi:10.1007/s10886-008-9555-7. ISSN 1573-1561.
^ APPALACHIAN NATURE: An Entrée of Salamanders
^ ^a ^b Sayler, Anne (1966). "The reproductive ecology of the red-backed salamander, Plethodon cinereus, in Maryland". Copeia. 1966 (2): 183–193. doi:10.2307/1441125. ISSN 0045-8511. JSTOR 1441125.
^ ^a ^b ^c Burgett, Amber A.; Smith, Geoffrey R. (2012-11). "Differential Responses of Eastern Red-Backed Salamanders (Plethodon cinereus) to Conspecifics and Centipedes". Current Herpetology. 31 (2): 78–86. doi:10.5358/hsj.31.78. ISSN 1345-5834. {{cite journal}}: Check date values in: |date= (help)
^ Tilley, Stephen G.; Lundrigan, Barbara L.; Brower, Lincoln P. (1982). "Erythrism and Mimicry in the Salamander Plethodon cinereus". Herpetologica. 38 (3): 409–417. ISSN 0018-0831.
^ ^a ^b Marsh, David M.; Page, Robert B.; Hanlon, Teresa J.; Corritone, Rachael; Little, Elizabeth C.; Seifert, David E.; Cabe, Paul R. (2008-06-01). "Effects of roads on patterns of genetic differentiation in red-backed salamanders, Plethodon cinereus". Conservation Genetics. 9 (3): 603–613. doi:10.1007/s10592-007-9377-0. ISSN 1572-9737.

External links

Data related to Plethodon cinereus at Wikispecies

Plethodon cinereus at Animal Diversity Web
Parental Care in Plethodon cinereus
Plethodon cinereus, Caudata Culture

[iucn_status_19_November_2021-1] IUCN SSC Amphibian Specialist Group (2015). "Plethodon cinereus". IUCN Red List of Threatened Species. 2015: e.T59334A78907687. doi:10.2305/IUCN.UK.2015-4.RLTS.T59334A78907687.en. Retrieved 19 November 2021.

[2] Stejneger L, Barbour T (1917). A Check List of North American Amphibians and Reptiles. Cambridge, Massachusetts: Harvard University Press. 125 pp. (Plethodon cinereus, p. 15).

[ConantCollins1998-3] ^ ^a ^b ^c ^d ^e ^f Conant R, Collins JT (1998). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Third Edition. Boston: Houghton Mifflin. 616 pp. ISBN 0-395-90452-8.

[ITIS-4] Integrated Taxonomic Information System [Internet] 2012. [updated 2012 Sept; cited 2012 Nov 26] Available from: www.itis.gov

[:4-5] Lotter, Fred; Scott, Norman J. (1977). "Correlation between Climate and Distribution of the Color Morphs of the Salamander Plethodon cinereus". Copeia. 1977 (4): 681–690. doi:10.2307/1443166. ISSN 0045-8511. JSTOR 1443166.

[:5-6] Gibbs, James P.; Karraker, Nancy E. (2006). "Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology". Conservation Biology. 20 (3): 913–917. doi:10.1111/j.1523-1739.2006.00375.x. ISSN 1523-1739. PMID 16909583.

[Venesky_and_Anthony_2007-7] Venesky, Matthew D.; Anthony, Carl D. (2007). "Antipredator adaptations and predator avoidance by two color morphs of the eastern red-backed salamander, Plethodon cinereus". Herpetologica. 63 (4): 450–458. doi:10.1655/0018-0831(2007)63[450:AAAPAB]2.0.CO;2.

[:3-8] Burton, Thomas M. (1976). "An Analysis of the Feeding Ecology of the Salamanders (Amphibia, Urodela) of the Hubbard Brook Experimental Forest, New Hampshire". Journal of Herpetology. 10 (3): 187–204. doi:10.2307/1562980. ISSN 0022-1511. JSTOR 1562980.

[9] Grant, Alexa H.; Ransom, Tami S.; Liebgold, Eric B. (April 2018). "Differential Survival and the Effects of Predation on a Color Polymorphic Species, the Red-Backed Salamander (Plethodon cinereus)". Journal of Herpetology. 52 (2): 127–135. doi:10.1670/16-185. ISSN 0022-1511. S2CID 90207320.

[10] Noble, G. Kingsley (1931). The biology of the amphibia (1st ed.). New York: McGraw-Hill. doi:10.5962/bhl.title.82448.

[:02-11] Feder, Martin E. (1983). "Integrating the Ecology and Physiology of Plethodontid Salamanders". Herpetologica. 39 (3): 291–310. ISSN 0018-0831. JSTOR 3892572.

[:12-12] Peterman, W. E.; Semlitsch, R. D. (2014-10-01). "Spatial variation in water loss predicts terrestrial salamander distribution and population dynamics". Oecologia. 176 (2): 357–369. Bibcode:2014Oecol.176..357P. doi:10.1007/s00442-014-3041-4. ISSN 1432-1939. PMID 25154754. S2CID 11041103.

[:22-13] Peterman, William E.; Semlitsch, Raymond D. (2013-05-06). "Fine-Scale Habitat Associations of a Terrestrial Salamander: The Role of Environmental Gradients and Implications for Population Dynamics". PLOS ONE. 8 (5): e62184. Bibcode:2013PLoSO...862184P. doi:10.1371/journal.pone.0062184. ISSN 1932-6203. PMC 3646024. PMID 23671586.

[Brucker_et_al._2008-14] Brucker, Robert M.; Baylor, Cambria M.; Walters, Robert L.; Lauer, Antje; Harris, Reid N.; Minbiole, Kevin P. C. (2008). "The identification of 2,4-diacetylphloroglucinol as an antifungal metabolite produced by cutaneous bacteria of the salamander Plethodon cinereus". Journal of Chemical Ecology. 34 (1): 39–43. doi:10.1007/s10886-007-9352-8. PMID 18058176. S2CID 27149357.

[:1-15] Moore, Jean-David; Ouellet, Martin (2014-10-16). "A review of colour phenotypes of the Eastern Red-backed Salamander, Plethodon cinereus, in North America". The Canadian Field-Naturalist. 128 (3): 250–259. doi:10.22621/cfn.v128i3.1603. ISSN 0008-3550.

[:6-16] Moreno, Gabriel (1989). "Behavioral and Physiological Differentiation between the Color Morphs of the Salamander, Plethodon cinereus". Journal of Herpetology. 23 (4): 335–341. doi:10.2307/1564043. ISSN 0022-1511. JSTOR 1564043.

[:72-17] Anthony, Carl D.; Venesky, Matthew D.; Hickerson, Cari-Ann M. (2008). "Ecological separation in a polymorphic terrestrial salamander". Journal of Animal Ecology. 77 (4): 646–653. doi:10.1111/j.1365-2656.2008.01398.x. ISSN 1365-2656. PMID 18479343.

[18] Highton, Richard (1959). "The Inheritance of the Color Phases of Plethodon cinereus". Copeia. 1959 (1): 33–37. doi:10.2307/1440097. ISSN 0045-8511. JSTOR 1440097.

[19] Highton, Richard (1975-06-25). "Geographic Variation in Genetic Dominance of the Color Morphs of the Red-Backed Salamander, Plethodon Cinereus". Genetics. 80 (2): 363–374. doi:10.1093/genetics/80.2.363. ISSN 1943-2631. PMC 1213333. PMID 17248684.

[:8-20] Evans, Annette E.; Urban, Mark C.; Jockusch, Elizabeth L. (2020-04-01). "Developmental temperature influences color polymorphism but not hatchling size in a woodland salamander". Oecologia. 192 (4): 909–918. Bibcode:2020Oecol.192..909E. doi:10.1007/s00442-020-04630-y. ISSN 1432-1939. PMID 32162072. S2CID 212669210.

[:9-21] Stuczka, Angela; Hickerson, Cari-Ann; Anthony, Carl (2016-01-01). "Niche partitioning along the diet axis in a colour polymorphic population of Eastern Red-backed Salamanders, Plethodon cinereus". Amphibia-Reptilia. 37 (3): 283–290. doi:10.1163/15685381-00003055. ISSN 1568-5381.

[:7-22] Wyman, Richard L.; Hawksley-Lescault, Dianne S. (1987-12). "Soil Acidity Affects Distribution, Behavior, and Physiology of the Salamader Plethodon Cinereus". Ecology. 68 (6): 1819–1827. doi:10.2307/1939873. ISSN 0012-9658. {{cite journal}}: Check date values in: |date= (help)

[DavisMilanovich2010-23] Davis AK, Milanovich JR (2010). "Lead-phase and red-stripe color morphs of red-backed salamanders Plethodon cinereus differ in hematological stress indices: A consequence of differential predation pressure?" Current Zoology 56 (2): 238–243.

[:0-24] Kleeberger, Steven R.; Werner, J. Kirwin (1982). "Home range and homing behavior of Plethodon cinereus in northern Michigan". Copeia. 1982 (2): 409–415. doi:10.2307/1444622. ISSN 0045-8511. JSTOR 1444622.

[25] Brucker, Robert M.; Harris, Reid N.; Schwantes, Christian R.; Gallaher, Thomas N.; Flaherty, Devon C.; Lam, Brianna A.; Minbiole, Kevin P. C. (2008-11-01). "Amphibian Chemical Defense: Antifungal Metabolites of the Microsymbiont Janthinobacterium lividum on the Salamander Plethodon cinereus". Journal of Chemical Ecology. 34 (11): 1422–1429. doi:10.1007/s10886-008-9555-7. ISSN 1573-1561.

[26] APPALACHIAN NATURE: An Entrée of Salamanders

[:2-27] Sayler, Anne (1966). "The reproductive ecology of the red-backed salamander, Plethodon cinereus, in Maryland". Copeia. 1966 (2): 183–193. doi:10.2307/1441125. ISSN 0045-8511. JSTOR 1441125.

[:10-28] Burgett, Amber A.; Smith, Geoffrey R. (2012-11). "Differential Responses of Eastern Red-Backed Salamanders (Plethodon cinereus) to Conspecifics and Centipedes". Current Herpetology. 31 (2): 78–86. doi:10.5358/hsj.31.78. ISSN 1345-5834. {{cite journal}}: Check date values in: |date= (help)

[29] Tilley, Stephen G.; Lundrigan, Barbara L.; Brower, Lincoln P. (1982). "Erythrism and Mimicry in the Salamander Plethodon cinereus". Herpetologica. 38 (3): 409–417. ISSN 0018-0831.

[:11-30] Marsh, David M.; Page, Robert B.; Hanlon, Teresa J.; Corritone, Rachael; Little, Elizabeth C.; Seifert, David E.; Cabe, Paul R. (2008-06-01). "Effects of roads on patterns of genetic differentiation in red-backed salamanders, Plethodon cinereus". Conservation Genetics. 9 (3): 603–613. doi:10.1007/s10592-007-9377-0. ISSN 1572-9737.

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@@ Line 28: / Line 28: @@
 === Polymorphism ===
-The red-backed salamander exhibits color [[Polymorphism (biology)|polymorphism]] and two color variations are common: the "red-backed" or "red-stripe" variety has a red dorsal stripe that tapers towards the tail, and the darker variety, known as the "lead-backed" (or simply "lead") phase, lacks most or all of the red pigmentation.<ref name="ConantCollins1998" /> The red-backed phase is not always red, but may actually be various other colors (e.g., yellow-backed, orange-backed, white-backed, or a rare [[Erythrism|erythristic]] morph in which the body is completely red).<ref name="ConantCollins1998" /> Both morphs have speckled black and white bellies.<ref name="ConantCollins1998" /> Additional color anomalies of this species also exist, including iridistic, [[Albinism|albino]], [[Leucism|leucistic]], [[Amelanism|amelanistic]], and [[Melanism|melanistic]] anomalies.<ref name=":1">{{Cite journal|last1=Moore|first1=Jean-David|last2=Ouellet|first2=Martin|date=2014-10-16|title=A review of colour phenotypes of the Eastern Red-backed Salamander, ''Plethodon cinereus'', in North America|url=https://www.canadianfieldnaturalist.ca/index.php/cfn/article/view/1603|journal=The Canadian Field-Naturalist|language=en|volume=128|issue=3|pages=250–259|doi=10.22621/cfn.v128i3.1603|issn=0008-3550|doi-access=free}}</ref> These color morphs are rarer than the red-backed, lead-backed, and erythristic morphs, but still have been reported with consistency among varying populations of this species.<ref name=":1" />
+Plethodon cinereus has color diversity, the common ones are the red-striped morph and the lead-phase, two color forms. The "red-backed" or "red-stripe" variety has a red dorsal stripe that tapers towards the tail, and the darker variety, known as the "lead-backed" (or simply "lead") phase, lacks most or all of the red pigmentation.<ref name="ConantCollins1998" /> The red-backed phase is not always red, but may actually be various other colors (e.g., yellow-backed, orange-backed, white-backed, or a rare [[Erythrism|erythristic]] morph in which the body is completely red).<ref name="ConantCollins1998" /> Both morphs have speckled black and white bellies.<ref name="ConantCollins1998" /> Additional color anomalies of this species also exist, including iridistic, [[Albinism|albino]], [[Leucism|leucistic]], [[Amelanism|amelanistic]], and [[Melanism|melanistic]] anomalies.<ref name=":1">{{Cite journal|last1=Moore|first1=Jean-David|last2=Ouellet|first2=Martin|date=2014-10-16|title=A review of colour phenotypes of the Eastern Red-backed Salamander, ''Plethodon cinereus'', in North America|url=https://www.canadianfieldnaturalist.ca/index.php/cfn/article/view/1603|journal=The Canadian Field-Naturalist|language=en|volume=128|issue=3|pages=250–259|doi=10.22621/cfn.v128i3.1603|issn=0008-3550|doi-access=free}}</ref> These color morphs are rarer than the red-backed, lead-backed, and erythristic morphs, but still have been reported with consistency among varying populations of this species.<ref name=":1" /> [[Polymorphism (biology)|polymorphism]]
 [[File:Lead-backed phase Redback Salamander - Plethodon cinereus.jpg|alt=Lead-backed phase Redback Salamander - Plethodon cinereus|thumb|Lead-backed phase Redback Salamander - Plethodon cinereus]]
+Color polymorphism is thought to be an adaptive strategy in a heterogeneous environment, so the maintenance of polymorphism is derived from behavioral and physiological choices. The color polymorphism of The red-striped morph Plethodon cinereus and the lead-phase Plethodon cinereus show different anti-predator responses in behavior, and predator attacks differently based on the color form. Compared to red-striped morph P. cinereus which prefers an "all trunk raised" posture and tends to stay still, the lead-phase P. cinereus is significantly more mobile. More lead-phase P. cinereus has the ability to automatically cut off the tail, indicating that the two forms also differ in the frequency of being attacked<ref name="Venesky and Anthony 2007" />.
-''P. cinereus'' color morph frequencies are correlated with climatic variables, suggesting habitat temperature and more broadly climate to be potential sources of [[Evolutionary pressure|selective pressure]] on ''P. cinereus'' polymorphism.<ref name=":4">{{Cite journal|last1=Lotter|first1=Fred|last2=Scott|first2=Norman J.|date=1977|title=Correlation between Climate and Distribution of the Color Morphs of the Salamander Plethodon cinereus|url=https://www.jstor.org/stable/1443166|journal=Copeia|volume=1977|issue=4|pages=681–690|doi=10.2307/1443166|jstor=1443166|issn=0045-8511}}</ref><ref name=":5">{{Cite journal|last1=Gibbs|first1=James P.|last2=Karraker|first2=Nancy E.|date=2006|title=Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology|url=https://conbio.onlinelibrary.wiley.com/doi/abs/10.1111/j.1523-1739.2006.00375.x|journal=Conservation Biology|language=en|volume=20|issue=3|pages=913–917|doi=10.1111/j.1523-1739.2006.00375.x|pmid=16909583|issn=1523-1739}}</ref> The red-backed form is found with greater frequency in colder regions at more northerly latitudes and easterly longitudes throughout its range, whereas the opposite is true of the lead-backed form.<ref name=":4" /><ref name=":5" /> Additionally, lead-backed morphs withdraw from surface activity earlier in the autumn than red-backed morphs, presumably to avoid cooling temperatures.<ref name=":4" /><ref name=":6">{{Cite journal|last=Moreno|first=Gabriel|date=1989|title=Behavioral and Physiological Differentiation between the Color Morphs of the Salamander, Plethodon cinereus|url=https://www.jstor.org/stable/1564043|journal=Journal of Herpetology|volume=23|issue=4|pages=335–341|doi=10.2307/1564043|jstor=1564043|issn=0022-1511}}</ref><ref name=":72">{{Cite journal|last1=Anthony|first1=Carl D.|last2=Venesky|first2=Matthew D.|last3=Hickerson|first3=Cari-Ann M.|date=2008|title=Ecological separation in a polymorphic terrestrial salamander|journal=Journal of Animal Ecology|language=en|volume=77|issue=4|pages=646–653|doi=10.1111/j.1365-2656.2008.01398.x|pmid=18479343|issn=1365-2656|doi-access=free}}</ref> [[Basal metabolic rate|Standard metabolic rate]] has also been found to differ between the morphs at certain temperatures, with significantly lower metabolic rates being displayed by the lead-backed form at 15&nbsp;°C;<ref name=":6" /> in the same study, lead-backed individuals were also more active on the ground surface at this temperature.<ref name=":6" /> These findings suggest that the lead-backed color variant is less tolerant of cool temperatures than the red-backed color variant, and that the two color forms differ physiologically and behaviorally at certain temperatures.<ref name=":4" /><ref name=":5" /><ref name=":6" /><ref name=":72"/>
+As an evidence that polymorphism is to adapt the environment, ''P. cinereus'' color morph frequencies are correlated with climatic variables, suggesting habitat temperature and more broadly climate to be potential sources of [[Evolutionary pressure|selective pressure]] on ''P. cinereus'' polymorphism.<ref name=":4">{{Cite journal|last1=Lotter|first1=Fred|last2=Scott|first2=Norman J.|date=1977|title=Correlation between Climate and Distribution of the Color Morphs of the Salamander Plethodon cinereus|url=https://www.jstor.org/stable/1443166|journal=Copeia|volume=1977|issue=4|pages=681–690|doi=10.2307/1443166|jstor=1443166|issn=0045-8511}}</ref><ref name=":5">{{Cite journal|last1=Gibbs|first1=James P.|last2=Karraker|first2=Nancy E.|date=2006|title=Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology|url=https://conbio.onlinelibrary.wiley.com/doi/abs/10.1111/j.1523-1739.2006.00375.x|journal=Conservation Biology|language=en|volume=20|issue=3|pages=913–917|doi=10.1111/j.1523-1739.2006.00375.x|pmid=16909583|issn=1523-1739}}</ref> The red-backed form is found with greater frequency in colder regions at more northerly latitudes and easterly longitudes throughout its range, whereas the opposite is true of the lead-backed form.<ref name=":4" /><ref name=":5" /> Additionally, lead-backed morphs withdraw from surface activity earlier in the autumn than red-backed morphs, presumably to avoid cooling temperatures.<ref name=":4" /><ref name=":6">{{Cite journal|last=Moreno|first=Gabriel|date=1989|title=Behavioral and Physiological Differentiation between the Color Morphs of the Salamander, Plethodon cinereus|url=https://www.jstor.org/stable/1564043|journal=Journal of Herpetology|volume=23|issue=4|pages=335–341|doi=10.2307/1564043|jstor=1564043|issn=0022-1511}}</ref><ref name=":72">{{Cite journal|last1=Anthony|first1=Carl D.|last2=Venesky|first2=Matthew D.|last3=Hickerson|first3=Cari-Ann M.|date=2008|title=Ecological separation in a polymorphic terrestrial salamander|journal=Journal of Animal Ecology|language=en|volume=77|issue=4|pages=646–653|doi=10.1111/j.1365-2656.2008.01398.x|pmid=18479343|issn=1365-2656|doi-access=free}}</ref> [[Basal metabolic rate|Standard metabolic rate]] has also been found to differ between the morphs at certain temperatures, with significantly lower metabolic rates being displayed by the lead-backed form at 15&nbsp;°C;<ref name=":6" /> in the same study, lead-backed individuals were also more active on the ground surface at this temperature.<ref name=":6" /> These findings suggest that the lead-backed color variant is less tolerant of cool temperatures than the red-backed color variant, and that the two color forms differ physiologically and behaviorally at certain temperatures.<ref name=":4" /><ref name=":5" /><ref name=":6" /><ref name=":72" />
 An alternate explanation for the uneven geographic distribution of the red-backed and lead-backed ''P. cinereus'' color morphs involves [[phenotypic plasticity]] responding to developmental temperature. Although the genetic origins of the ''P. cinereus'' polymorphic condition are not fully understood, initial studies indicate that color morph [[Dominance (genetics)|dominance]] is likely subject to [[epistasis]], and that multiple [[Locus (genetics)|loci]] may interact to determine an individual's morph condition.<ref>{{Cite journal|last=Highton|first=Richard|date=1959|title=The Inheritance of the Color Phases of Plethodon cinereus|url=https://www.jstor.org/stable/1440097|journal=Copeia|volume=1959|issue=1|pages=33–37|doi=10.2307/1440097|jstor=1440097|issn=0045-8511}}</ref><ref>{{Cite journal|last=Highton|first=Richard|title=Geographic Variation in Genetic Dominance of the Color Morphs of the Red-Backed Salamander, Plethodon Cinereus|date=1975-06-25|journal=Genetics|volume=80|issue=2|pages=363–374|doi=10.1093/genetics/80.2.363|pmid=17248684|pmc=1213333|issn=1943-2631|doi-access=free}}</ref> However, more recent research indicates that a [[Phenotypic plasticity|plastic]] response to thermal conditions during development also contributes to color morph determination; in one study, ''P. cinereus'' eggs incubated at a higher temperature hatched a greater proportion of lead-backed morphs than eggs incubated at a lower temperature.<ref name=":8">{{Cite journal|last1=Evans|first1=Annette E.|last2=Urban|first2=Mark C.|last3=Jockusch|first3=Elizabeth L.|date=2020-04-01|title=Developmental temperature influences color polymorphism but not hatchling size in a woodland salamander|url=https://doi.org/10.1007/s00442-020-04630-y|journal=Oecologia|language=en|volume=192|issue=4|pages=909–918|doi=10.1007/s00442-020-04630-y|pmid=32162072|bibcode=2020Oecol.192..909E|s2cid=212669210|issn=1432-1939}}</ref> Temperature-dependent color morph determination may therefore also potentially influence the spatial distribution of ''P. cinereus'' color morphs.<ref name=":8" />
-The two primary ''P. cinereus'' color morphs also differ in diet.<ref name=":72"/><ref name=":9">{{Cite journal|last1=Stuczka|first1=Angela|last2=Hickerson|first2=Cari-Ann|last3=Anthony|first3=Carl|date=2016-01-01|title=Niche partitioning along the diet axis in a colour polymorphic population of Eastern Red-backed Salamanders, Plethodon cinereus|url=https://brill.com/view/journals/amre/37/3/article-p283_4.xml|journal=Amphibia-Reptilia|language=en|volume=37|issue=3|pages=283–290|doi=10.1163/15685381-00003055|issn=1568-5381}}</ref> The prevalence of certain prey taxa and the overall diversity and quality of prey items have been observed to differ seasonally between the two morphs in the spring and autumn when surface activity is greatest.<ref name=":72" /><ref name=":9" /> In one study, the autumn diet of red-backed morphs was more diverse and of higher quality, and found to be dominated by [[mite]]s, [[springtail]]s, and [[ant]]s, whereas the most important prey for lead-backed morphs were [[ant]]s, [[mite]]s, and [[Isopoda|isopods]].<ref name=":72" />[[File:Redback Salamander Plethodon cinereus lead phase LML.jpg|thumb|right|Lead-backed phase]]
+The two primary ''P. cinereus'' color morphs also differ in diet.<ref name=":72"/><ref name=":9">{{Cite journal|last1=Stuczka|first1=Angela|last2=Hickerson|first2=Cari-Ann|last3=Anthony|first3=Carl|date=2016-01-01|title=Niche partitioning along the diet axis in a colour polymorphic population of Eastern Red-backed Salamanders, Plethodon cinereus|url=https://brill.com/view/journals/amre/37/3/article-p283_4.xml|journal=Amphibia-Reptilia|language=en|volume=37|issue=3|pages=283–290|doi=10.1163/15685381-00003055|issn=1568-5381}}</ref> The prevalence of certain prey taxa and the overall diversity and quality of prey items have been observed to differ seasonally between the two morphs in the spring and autumn when surface activity is greatest.<ref name=":72" /><ref name=":9" /> In one study, the autumn diet of red-backed morphs was more diverse and of higher quality, and found to be dominated by [[mite]]s, [[springtail]]s, and [[ant]]s, whereas the most important prey for lead-backed morphs were [[ant]]s, [[mite]]s, and [[Isopoda|isopods]].<ref name=":72" />
+Moreover, the two morphologies have different standard metabolic rates, while lead-phase P. cinereus favor warm habitats or microclimates. So the strong argument is that the geographic distribution of color form is caused by the selection of physiological traits<ref name="Venesky and Anthony 2007" />.[[File:Redback Salamander Plethodon cinereus lead phase LML.jpg|thumb|right|Lead-backed phase]]
+== Distribution ==
+Distribution and reproduction of P. cinereus are in close contact with the soil on the forest floor. As deciduous forests mature, acid deposition can accelerate the acidification of soils. Acidic conditions can limit the distribution of amphibians and the numbers of sibling species, while the pH value of soil has a strong effect on the density and distribution of P. cinereus. When choosing between acidic and neutral soils, P. cinerea prefers to occupy more neutral soils. P. cinereus is rarely found in soils with a pH value of 3.7, and relatively more to be found in soils with a pH value of about 3.8 or higher. Juvenile P. cinereus have never been found in soils with a pH vlaue lower than 3.7. At the same, similar conclusions have also been supported in the laboratory. P. cinereus prefers to occupy substrates near neutral pH. A pH value between 2.5 and 3 results in acute mortality, while a pH value between 3 and 4 results in chronic mortality. Low pH will reduce their growth and respiration. Slowed growth and delayed metamorphosis make juvenile P. cinereus more vulnerable to predators and has serious consequences for population survival. In addition, as upper-level consumers in the system, the effect of soil pH value on P. cinereus's distribution can alter forest tree decomposition food webs<ref name=":7">{{Cite journal |last=Wyman |first=Richard L. |last2=Hawksley-Lescault |first2=Dianne S. |date=1987-12 |title=Soil Acidity Affects Distribution, Behavior, and Physiology of the Salamader Plethodon Cinereus |url=http://dx.doi.org/10.2307/1939873 |journal=Ecology |volume=68 |issue=6 |pages=1819–1827 |doi=10.2307/1939873 |issn=0012-9658}}</ref>.
+Several other factors, such as moisture and temperature, can affect the population density or dispersion of Botrytis as well. During prolonged dry periods, individuals move down into the soil, while during short dry periods they retreat under logs or rocks. They will avoid very warm areas, and when the temperature drops to 4-5 celsius degrees, they will retreat to the ground as well. The optimum temperature is 10 to 15-celsius degrees. Moreover, intraspecific and interspecific competition also affected the distribution of P. cinerea<ref name=":7" />.
+Spatial distributions of Salamander Plethodon cinereus is observed to seasonal. This supports that competition exists in the population of this species, which plays a role in population dynamics that interfere. In spring, Plethodon cinereus are more likely to exist in groups of around 2 to 7 individuals under some object covers such as rocks and wood, than in the other seasons, while the density on the forest floor stays constant. This is because that spatial dispute starts in spring. A study in Blackrock Mountian, Virginia indicatss that the mean number of salamanders in each quadrat of 100*100 m varies from 1.6 to 3 in spring compared to that 0.8 to 1.8 in summer. A significant increase in the spatial distribution of P. cinereus from spring to summer thinks to be due to the intraspecific interference competition. The cover objects on the ground can be a good choice of moisture refuge for P. cinereus during the rainy season. The failure of P. cinereus to forage underground causes them to restict down to areas under and around the cover objects. Aggression and territoriality under resources, food and shelter limitation are the reasons for the observed spacing<ref name=":7" />.
 ==Behavior==
@@ Line 40: / Line 51: @@
 ''Plethodon cinereus'', like many plethodon species, exhibit homing behavior, with homing of females to their nests, as well as non-attending females and males to a home range.<ref name=":0">{{Cite journal|last1=Kleeberger|first1=Steven R.|last2=Werner|first2=J. Kirwin|date=1982|title=Home range and homing behavior of ''Plethodon cinereus'' in northern Michigan|journal=Copeia|volume=1982|issue=2|pages=409–415|doi=10.2307/1444622|jstor=1444622|issn=0045-8511}}</ref> This allows for essential contact between a female and her eggs in order to ensure their survival, as well as for non-attending females and males to explore beyond the home range when under predation pressures, or searching for food or cover, and return to their home range if a more favorable microhabitat is not found.<ref name=":0" />
+== Defense Mechanism toward bacterial pathogen ==
+Plethodon cinereus coexists with some bacteria. These bacteria help salamanders defend against fungal pathogens. For example, Batrachochytrium dendrobatidis, a fungal pathogen that causes a disease called Chytridiomycosis, has led to a rapid decline in amphibian populations worldwide. Around one-third of amphibians are endangered because of the disease, but some species persist from the infection, and some even clear the pathogen. And Plethodon cinereus has such chemical defenses against these threats. As evidence, Plethodon cinereus has bacterial symbionts called Microsymbiont Janthinobacterium lividum on the skin of Plethodon cinereus. These substances can be detected by a range of methods including reversed-phase HPLC, high-resolution mass spectroscopy, NMR, and UV-Vis spectroscopy. Janthinobacterium lividum produces antifungal metabolites, which are indole-3-carboxaldehyde and violacein. These metabolites can inhibit the growth of pathogens. This finding suggests an idea for providing long-term protection to individuals who are infected with chytridiomycosis. It also provides a research pathway for future drug development which is to use novel antifungal compounds for the treatment of human pathogens<ref>{{Cite journal |last=Brucker |first=Robert M. |last2=Harris |first2=Reid N. |last3=Schwantes |first3=Christian R. |last4=Gallaher |first4=Thomas N. |last5=Flaherty |first5=Devon C. |last6=Lam |first6=Brianna A. |last7=Minbiole |first7=Kevin P. C. |date=2008-11-01 |title=Amphibian Chemical Defense: Antifungal Metabolites of the Microsymbiont Janthinobacterium lividum on the Salamander Plethodon cinereus |url=https://doi.org/10.1007/s10886-008-9555-7 |journal=Journal of Chemical Ecology |language=en |volume=34 |issue=11 |pages=1422–1429 |doi=10.1007/s10886-008-9555-7 |issn=1573-1561}}</ref>.
 ==Reproduction and biomass==
@@ Line 45: / Line 59: @@
 As in many ''Plethodon'' species, female red-backed salamanders have the ability to store sperm as spermatophore, and have been evidenced in doing so up to eight months prior to the oviposition period in June and July.<ref name=":2">{{Cite journal|last=Sayler|first=Anne|date=1966|title=The reproductive ecology of the red-backed salamander, ''Plethodon cinereus'', in Maryland|journal=Copeia|volume=1966|issue=2|pages=183–193|doi=10.2307/1441125|jstor=1441125|issn=0045-8511}}</ref> Sperm or spermatophores are not retained following the oviposition period.<ref name=":2" />
+== Mutualism ==
+Male Plethodon cinereus actively defends its territory from intrusion by other males and is less aggressive towards invading females and juveniles. Plethodin cinereus usually directs aggressive behavior towards conspecific as well as heterospecific, as long as it's thought to be potential competitor. Plethodon cinereus positively interacts not only with conspecifics, but also with other potential competitors such as centipedes<ref name=":10">{{Cite journal |last=Burgett |first=Amber A. |last2=Smith |first2=Geoffrey R. |date=2012-11 |title=Differential Responses of Eastern Red-Backed Salamanders (Plethodon cinereus) to Conspecifics and Centipedes |url=https://bioone.org/journals/current-herpetology/volume-31/issue-2/hsj.31.78/Differential-Responses-of-Eastern-Red-Backed-Salamanders-Plethodon-cinereus-to/10.5358/hsj.31.78.full |journal=Current Herpetology |volume=31 |issue=2 |pages=78–86 |doi=10.5358/hsj.31.78 |issn=1345-5834}}</ref>.
+It is necessary to have a visual display in order to elicit the threat posture of P. Cinereus, and there will be no obvious aggressive behavior toward conspecifics and heterospecifics if only chemical cues exist. However, P. cinereus will increase time spent in aggressive postures when paired with centipedes but did not show increased aggression when paired with conspecifics. The specific test method was to expose male Botrytis cinerea to four substrate chemical cue treatments separately: control, self, conspecific, or centipede (Scolopocryptops sexspinosus) to determine its behavior in the presence or absence of conspecifics and heterospecific cues reaction<ref name=":10" />.
+Their residence status affects the attack level as well. Even if in different residency statuses, they do attack centipedes<ref name=":10" />.
+== Mimicry ==
+The lead-backed are absent in northeastern United States and southeastern Canada. Instead, another phase called erythristic is observed and exclusive in these areas. This phase shows macroand microgeographic variation in frequency. Regardless the wide geographic variation, the highest frequency is always under 25%. This phase of P. cinereus mimic Notophthalmus viridescens to protect themselves. Birds selectively avoid to predate all-red or reytheristic color P. cinereus because they think that red color is a signal of noxiouness and toxicness. Even if people trained the birds to enhance the avoidance by increasing exposure to red efts (juvenile Notophtajalmus viridescens), the frequencies of ertherism is never above 25%<ref>{{Cite journal |last=Tilley |first=Stephen G. |last2=Lundrigan |first2=Barbara L. |last3=Brower |first3=Lincoln P. |date=1982 |title=Erythrism and Mimicry in the Salamander Plethodon cinereus |url=https://www.jstor.org/stable/3892425 |journal=Herpetologica |volume=38 |issue=3 |pages=409–417 |issn=0018-0831}}</ref>.
+== Interactions with humans ==
+Roads have various negative effects on animal populations. For example, a major source of direct mortality for many species is accidental collisions with moving vehicles. Due to the slow movement of amphibians, it is estimated that the mortality rate of these animals on roads is as high as 10% of the total population each year. From a genetic point of view, roads also reduce gene flow and thus divide animal populations, causing drift and loss of genetic diversity. Eventually, populations separated by roads may become more and more distinct from each other, thus losing the original population. Amongst different sizes of roads, it is known that the interstate highway leads to increased genetic differentiation of Plethodon cinereus by microsatellite examination. Genetic distances between regions on either side of an interstate highway were significantly larger than those between equally spaced quadrants on the same side of the highway. However, plots on smaller roads were not genetically different compared to that in the case of interstate highways. Narrow paved roads reduce the movement of redback salamanders by approximately 25-75% but do not completely eliminate the dynamic of the population. And the detection of genetic differences across the interstate means that the spread on this road is reduced by well over 25-75%. So there is little gene flow on very large roads, and the P. cinereus population diverges from each other. The indirect effect of smaller roads on genetic population structure is also not a big issue for terrestrial salamanders and is not a direct effect of mortality and habitat change<ref name=":11">{{Cite journal |last=Marsh |first=David M. |last2=Page |first2=Robert B. |last3=Hanlon |first3=Teresa J. |last4=Corritone |first4=Rachael |last5=Little |first5=Elizabeth C. |last6=Seifert |first6=David E. |last7=Cabe |first7=Paul R. |date=2008-06-01 |title=Effects of roads on patterns of genetic differentiation in red-backed salamanders, Plethodon cinereus |url=https://doi.org/10.1007/s10592-007-9377-0 |journal=Conservation Genetics |language=en |volume=9 |issue=3 |pages=603–613 |doi=10.1007/s10592-007-9377-0 |issn=1572-9737}}</ref>.
+The observed rate of dispersion in P. cinereus is far less than in most of the animals previously studied. Because P. cinereus have very high population densities, this should reduce the effects of genetic drift in isolated populations. From a conservation standpoint, red-backed salamanders are an important research organism because of their behavioral and physiological similarities to many threatened and endangered salamanders <ref name=":11" />.
 ==References==