Desmognathus Ochrophaeus Research Articles

Noxious Skin Secretions of an Eastern Small Plethodon, P. nettingi hubrichti

Plethodon nettingi hubrichti were distasteful and avoided by avian predators. This supports the hypothesis that several species of Plethodon may serve as models for Desmognathus ochrophaeus which is a polymorphic Batesian mimic.

Experimental Study of Batesian Mimicry in the Salamanders Plethodon jordani and Desmognathus ochrophaeus

Feeding trials demonstrated that red-cheeked Plethodon jordani were noxious and were avoided by wild-caught potential avian predators. Red-cheeked individuals of Desmognathus ochrophaeus were also avoided by birds conditioned to avoid red-cheeked P. jordani. In addition to noxious skin secretions and aposematic coloration, defensive behavior and tail autotomy are probably important antipredation devices employed by P. jordani against avian predators.

Energy Allocation in the Allegheny Mountain Salamander, Desmognathus Ochrophaeus

The reproductive cycle, energy budget, and relationships between rates and energetics of vitellogenesis, lipid deposition and depletion, and changes in lean carcass tissue were examined in Desmognathus ochrophaeus salamanders from northeastern Ohio. Oviposition begins prior to emergence in mid—April, reaches a peak in mid—May, and continues in greatly reduced frequency into September. Lipids in the carcass and ovarian fat bodies apparently are used for maintenance and vitellogenesis during winter dormancy (mid—October to mid—April) and after emergence in the spring when food reserves are scarce. Carcass lipids, lean carcass tissue, and perhaps fat body lipids are used for maintenance during brooding. A typical female oviposits in mid—May, replaces depleted lipids and lean carcass tissue by late August, and produces intermediate—sized follicles before winter and full—sized follicles during April and early May. Energy ingested, egested, assimilated, and lost through respiration was examined in gravid females, spent females, and males acclimated to four temperature—photoperiod regimes: (1) 5°C, LD 10:14; (2) 5°C, LD 14:10; (3) 15°C, LD 10:14; and (4) 15°C, LD 14:10. Size, sex, reproductive condition, and temperature significantly influence energetics in D. ochrophaeus. Photoperiod does not affect metabolism significantly at either temperature. There is an inverse exponential relationship between body weight and weight—specific rates of ingestion, egestion, assimilation, and respiration. Gravid females, actively depositing yolk in follicles, show higher O2 consumption rates than recently spent females and males at 15°C, but not at 5°C when yolking rates apparently are reduced. Rates of O2 consumption are significantly higher at 15°C than 5°C. At 15°C gravid females, spent females, and males lost 43.2, 3.60, and 3.84 cal g—1 day—1 metabolic heat; at 5°C they lost 1.92, 1.92, and 1.68 cal g—1 day—1, respectively. Salamanders cease to feed at 5°C. At 15°C gravid females, spent females, and males ingested 21.0, 37.8, and 23.8 cal g—1 day—1 and egested 2.7, 5.1, and 2.9 cal g—1 day—1, with assimilation efficiencies of 87.2%, 86.3%, and 88.2%, respectively. The estimated annual energetics of a typical female are: ingestion = 2,940 cal; egestion = 378; assimilation = 2,562; respiration = 1,104.4; and secondary production = 1,457.6. Reproductive activities (vitellogenesis = 807.5 and brooding maintenance = 430 cal) cost 48.3% of a female's annual energy flow (A = 2,562 cal).

Rock‐Face Populations of the Mountain Salamander, Desmognathus Ochrophaeus, In North Carolina

The ecology and life history of Desmognathus ochrophaeus inhabiting wet rock faces at high elevations near Highlands, North Carolina, were studied. Comparisons were made with rock—face populations in Great Smoky Mountains National Park and with woodland populations at Rabun Bald, Scaly Mountain, and Blue Valley in the Blue Ridge Mountains. The reproductive cycle in rock—face populations is annual; spawning occurs mostly in July and August, and females begin to emerge from brooding as early as late August. The new spermatogenic cycle begins in May and June. Animals on rock faces average 40—45 cm in movements between successive captures and appear to have a limited range. Animals displaced to the base of the rock face and higher on the rock face can return to their home range. Population density is high (up to 25 individuals/m2), diurnal activity is nearly as high as nocturnal activity (correlated with subdued body colors), and at least a moderate level of activity occurs during warm winter periods. Animals mature at 2 years of age as in woodland populations, but at a smaller size, and grow more slowly thereafter. Small body size is not due to paucity of food on the rock faces. The high population densities on the wet rock faces indicate that they are highly favorable habitats for D. ochrophaeus. Differences between rock—face and forest—floor populations are attributable to modified selective pressures in the two different ecological settings. Variation among rock—face populations is attributed to the intensity of selection for small body size and cryptic coloration, the size of the rock face, and variation among forest—floor populations from which they were derived. Since rock—face populations are linked genetically to surrounding forest—floor populations of D. ochrophaeus, they cannot be considered examples of taxonomic variation, but rather of ecotypic variation.

Life Histories and Natural Selection in Populations of the Salamander Desmognathus Ochrophaeus

Populations of Desmognathus ochrophaeus Cope in the vicinity of Mt. Mitchell, Yancey County, North Carolina, differ from one another with respect to age at first reproduction, a trait in which variation can strongly affect individual fitness. Maturity is delayed in high elevation populations relative to low elevation populations, and in low elevation woodland populations relative to low elevation rockface populations. Juvenile growth rate appears to vary but slightly between populations, so that delay maturity results in individuals being larger at maturity. This may be responsible for the altitudinal size clines noted in D. ochrophaeus by other authors. Body size is positively correlated with clutch size, so that delay reproduction enhances subsequent age—specific fecundity. When populations are compared, indications of delayed maturity are usually accompanied by adult male age structures indicative of higher survivorship. In woodland populations such indications occur in samples from habitats where higher survivorship would be expected. High elevation woodland populations also exhibit higher adult growth rates, which in turn enhance female age—specific fecundities. The degree to which interpopulational differences in life history patterns are genetically based is unknown. The differences which occur are however, compatible with predictions drawn from current theory on the adaptive nature of life history patterns. Specifically, theory predicts that delayed maturity should be adaptive in relative stable environments and where it is accompanied by increased survivorship and fertility. The evolutionary ecology of Desmognathus ochrophaeus is such that these conditions may be met in high elevation woodland environments in southern Appalachians. Evidence for earlier maturity on low elevation rockfaces created by man's activities during 1938—39 suggest that, if these differences are genetically based, natural selection affects are at maturity with great effectiveness. Whether interpopulational differences in age at maturity prove to be genetic or not, interdemic variation in a trait to which fitness is potentially so sensitive is of theoretical interest.

Aspects of Parental Care and Embryonic Development in Desmognathus ochrophaeus

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Influence of sex and reproductive condition on metabolic rates in the allegheny mountain salamander Desmognathus ochrophaeus

1. 1. Oxygen consumption rates were determined, at acclimation temperatures, for three experimental groups of Desmognathus ochrophaeus (gravid females, non-gravid females and males) acclimated at four photoperiod -temperature régimes: 5°C LD 10 : 14; 5°C LD 14 : 10 ; 15°C LD 10 : 14; and 15°C LD 14 : 10. 2. 2. Differences in standard metabolic rates among gravid females, nongravid females and males within and between photoperiods were not significant at 5°C. Metabolic differences within each experimental group between photoperiods were not significant at 15°C. 3. 3. At 15°C, within both photoperiods, gravid females had significantly higher metabolic rates than those of non-gravid females and males. 4. 4. Metabolic differences between non-gravid females and males were not significant at 15°C.

Thermal acclimation and metabolism in the allegheny mountain salamander Desmognathus ochrophaeus

1. 1. Oxygen consumption measurements were made at 5, 10, 15 and 20°C on Desmognathus ochrophaeus salamanders acclimated at these temperatures. 2. 2. Partial acclimation, observed in groups acclimated at 10, 15 and 20°C, correlates with the ability of D. ochrophaeus to maintain relatively constant activity levels in the field during seasonal temperature variations from 10 to 20°C. 3. 3. Undercompensation, observed in the group acclimated at 5°C, suggests there is a metabolic “shut-down” associated with the winter torpor observed in D. ochrophaeus. 4. 4. Groups acclimated at 10, 15 and 20°C displayed thermal homeostasis between 5 and 10°C. This would enable D. ochrophaeus to remain active during early spring and fall when temperatures temporarily fall below 10°C.

Variation in the Dorsal Pattern of Desmognathus ochrophaeus at Mt. Mitchell, North Carolina, and Elsewhere in the Southern Appalachian Mountains

The dorsal pattern of Desmognathus ochrophaeus is a composite of several components, each of which is influenced by different combinations of sexual, genetic, and ontogenetic variation. Analysis of variation within these components at Mt. Mitchell, North Carolina, has failed to indicate the presence of more than one sympatric species at that locality. Variation in one component, the dorsolateral pattern, indicates that its various configurations have genetic bases, and that a zone of maximum variability exists in the southern Appalachians. This zone may represent an area of secondary contact resulting from the southward dispersal of individuals from the Cumberland and Allegheny mountains carrying genes for straight dorsolateral stripes.

Body Size and Metabolic Rate in Salamanders

Body Size and Metabolic Rate in Salamanders

Feeding Experiments with a Supposed Mimetic Complex in Salamanders

The supposed mimetic complex consisting of the red- cheeked salamander, Plethodon jordani, and the red-cheeked variants of the Allegheny Mountain salamander, Desmognathus ochrophaeus, was tested by subjecting members of this complex to laboratory predation by four natural predator species. Predation by the eastern garter snake, the large short-tailed shrew, the Blue Ridge spring salamander, and the black-bellied salamander failed to reveal discriminatory feeding behavior. The possibility that mimicry has not been involved in the evolution of the red cheek patch in D. ochrophaeus remains. The hypothesis that infrequent but discriminate predation by uncommon predators such as birds could confer slight selective advantage upon the D. ochrophaeus the range of red-cheeked P. jordani the incidence of the red cheek coloration among normally patterned D. ochrophaeus is low. Numerous individuals have suggested that the similarity can be best explained in terms of mimicry. According to the theory of Bate- sian mimicry, the red cheek patch of P. jordani (the model) could be considered warning or aposematic coloration, which would ad- vertise to, predators some distasteful or undesirable quality. Huheey (1960) suggests that this undesirable characteristic is a slimy exuda- tion from the tail, not found in D. ochrophaeus. The red-cheeked variant of D. ochrophaeus (the mimic), which exhibits pseudapose- matic or false warning coloration, would thus gain survival value from its close resemblance to the model, even though it possessed none of the undesirable qualities. In Miillerian mimicry, both P. jordani and the red-cheeked D. ochrophaeus would possess unde- sirable qualities and thus the model and the mimic are both protected by undesirable characteristics. In the study of any suspected mimicry complex, the determina- tion of a natural predator that discriminates between the supposed mimics and nonmimetics is of utmost importance. If one can ascer- tain the natural predators of the models and mimics by field obser- vations or stomach analyses, and then prove the discriminating behavior of at least one such predator, he greatly strengthens the hypothesis 147

Geographic Variation in Southern Populations of Desmognathus ochrophaeus

Geographic Variation in Southern Populations of Desmognathus ochrophaeus

Ecology, Maturation and Reproduction of Thamnophis Sauritus Proximus

Salamanders of several species were heated in experiments designed to reveal differences between species with respect to the critical thermal maximum. Also the effect of acclimation on the upper thermal level tolerated was tested. It was found that salamanders of the species Desmognathus fuscus and D. quadramacula-tus have significantly lower critical thermal maxima after being kept for several days at five degrees Centigrade than when kept at fifteen degrees before being used in experiments. At the five-degree level of acclimation, the widely distributed fuscus has a slightly but statistically significantly higher critical thermal maximum than quadramnaculatus, a species restricted to montane streams. Desmognathus ochrophaeus carolinensis has possibly the lowest CTM among the species tested, while Diemiictylus viridescens proved to have greater resistance to high temperatures than the other species. This greater tolerance of high temperature enables viridescens to utilize warm standingwater habitats unfavorable to other species, and possibly plays an important part in the wide geographic distribution of the species.

The Herpetology of Hardy County, West Virginia

Observations and collections of the reptiles and amphibians occurring in Hardy County, West Virginia, have been carried on for a period of nine years, from March 1938 until March 1947. The total collection assembled during this period consists of 1,916 specimens representing 49 species and subspecies. Eumeces laticeps and Clemmys guttata have been recorded from Jefferson County and should be sought for in this region. Acris crepitans is known from Hampshire County. Natrix semptemvitta has been collected in Rockingham County, and Pituophis melanoleucus melanolecus from nearby Shenandoah County, Virginia. Desmognathus ochrophaeus ochrophaeus and Pseudacris brachyphona are possibilities.