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Charles W. Walker - One of the best experts on this subject based on the ideXlab platform.
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exposure to ultraviolet radiation 290 400 nm causes oxidative stress dna damage and expression of p53 p73 in laboratory experiments on embryos of the Spotted Salamander ambystoma maculatum
Physiological and Biochemical Zoology, 2001Co-Authors: Michael P. Lesser, Sarah L. Turtle, Julianne H. Farrell, Charles W. WalkerAbstract:Abstract Developing embryos of the Spotted Salamander, Ambystoma maculatum, exposed to ultraviolet radiation (UVR; 290–400 nm) in the laboratory show a significant sensitivity to UVB (290–320 nm) radiation. Embryos in laboratory experiments exhibited significant DNA damage during exposures to UVR despite a significant increase in the production of the protective pigment melanin in response to UVR exposure. DNA damage occurs as a result of both the direct effects of exposure to UVR, and the indirect effects are mediated by the production of reduced oxygen intermediates. The production of reactive oxygen species initiates the expression of p53/p73 that leads to either DNA repair or apoptosis. When similar experiments are conducted on Salamander embryos exposed to solar UVR in vernal pools, the embryos show significantly less sensitivity and higher survivorship. The differences between laboratory and field experiments are a result of the attenuation of UVR caused by the accumulation of dissolved organic carb...
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Exposure to ultraviolet radiation (290-400 nm) causes oxidative stress, DNA damage, and expression of p53/p73 in laboratory experiments on embryos of the Spotted Salamander, Ambystoma maculatum.
Physiological and biochemical zoology : PBZ, 2001Co-Authors: Michael P. Lesser, Sarah L. Turtle, Julianne H. Farrell, Charles W. WalkerAbstract:Abstract Developing embryos of the Spotted Salamander, Ambystoma maculatum, exposed to ultraviolet radiation (UVR; 290–400 nm) in the laboratory show a significant sensitivity to UVB (290–320 nm) radiation. Embryos in laboratory experiments exhibited significant DNA damage during exposures to UVR despite a significant increase in the production of the protective pigment melanin in response to UVR exposure. DNA damage occurs as a result of both the direct effects of exposure to UVR, and the indirect effects are mediated by the production of reduced oxygen intermediates. The production of reactive oxygen species initiates the expression of p53/p73 that leads to either DNA repair or apoptosis. When similar experiments are conducted on Salamander embryos exposed to solar UVR in vernal pools, the embryos show significantly less sensitivity and higher survivorship. The differences between laboratory and field experiments are a result of the attenuation of UVR caused by the accumulation of dissolved organic carb...
Michael P. Lesser - One of the best experts on this subject based on the ideXlab platform.
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exposure to ultraviolet radiation 290 400 nm causes oxidative stress dna damage and expression of p53 p73 in laboratory experiments on embryos of the Spotted Salamander ambystoma maculatum
Physiological and Biochemical Zoology, 2001Co-Authors: Michael P. Lesser, Sarah L. Turtle, Julianne H. Farrell, Charles W. WalkerAbstract:Abstract Developing embryos of the Spotted Salamander, Ambystoma maculatum, exposed to ultraviolet radiation (UVR; 290–400 nm) in the laboratory show a significant sensitivity to UVB (290–320 nm) radiation. Embryos in laboratory experiments exhibited significant DNA damage during exposures to UVR despite a significant increase in the production of the protective pigment melanin in response to UVR exposure. DNA damage occurs as a result of both the direct effects of exposure to UVR, and the indirect effects are mediated by the production of reduced oxygen intermediates. The production of reactive oxygen species initiates the expression of p53/p73 that leads to either DNA repair or apoptosis. When similar experiments are conducted on Salamander embryos exposed to solar UVR in vernal pools, the embryos show significantly less sensitivity and higher survivorship. The differences between laboratory and field experiments are a result of the attenuation of UVR caused by the accumulation of dissolved organic carb...
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Exposure to ultraviolet radiation (290-400 nm) causes oxidative stress, DNA damage, and expression of p53/p73 in laboratory experiments on embryos of the Spotted Salamander, Ambystoma maculatum.
Physiological and biochemical zoology : PBZ, 2001Co-Authors: Michael P. Lesser, Sarah L. Turtle, Julianne H. Farrell, Charles W. WalkerAbstract:Abstract Developing embryos of the Spotted Salamander, Ambystoma maculatum, exposed to ultraviolet radiation (UVR; 290–400 nm) in the laboratory show a significant sensitivity to UVB (290–320 nm) radiation. Embryos in laboratory experiments exhibited significant DNA damage during exposures to UVR despite a significant increase in the production of the protective pigment melanin in response to UVR exposure. DNA damage occurs as a result of both the direct effects of exposure to UVR, and the indirect effects are mediated by the production of reduced oxygen intermediates. The production of reactive oxygen species initiates the expression of p53/p73 that leads to either DNA repair or apoptosis. When similar experiments are conducted on Salamander embryos exposed to solar UVR in vernal pools, the embryos show significantly less sensitivity and higher survivorship. The differences between laboratory and field experiments are a result of the attenuation of UVR caused by the accumulation of dissolved organic carb...
Sarah L. Turtle - One of the best experts on this subject based on the ideXlab platform.
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exposure to ultraviolet radiation 290 400 nm causes oxidative stress dna damage and expression of p53 p73 in laboratory experiments on embryos of the Spotted Salamander ambystoma maculatum
Physiological and Biochemical Zoology, 2001Co-Authors: Michael P. Lesser, Sarah L. Turtle, Julianne H. Farrell, Charles W. WalkerAbstract:Abstract Developing embryos of the Spotted Salamander, Ambystoma maculatum, exposed to ultraviolet radiation (UVR; 290–400 nm) in the laboratory show a significant sensitivity to UVB (290–320 nm) radiation. Embryos in laboratory experiments exhibited significant DNA damage during exposures to UVR despite a significant increase in the production of the protective pigment melanin in response to UVR exposure. DNA damage occurs as a result of both the direct effects of exposure to UVR, and the indirect effects are mediated by the production of reduced oxygen intermediates. The production of reactive oxygen species initiates the expression of p53/p73 that leads to either DNA repair or apoptosis. When similar experiments are conducted on Salamander embryos exposed to solar UVR in vernal pools, the embryos show significantly less sensitivity and higher survivorship. The differences between laboratory and field experiments are a result of the attenuation of UVR caused by the accumulation of dissolved organic carb...
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Exposure to ultraviolet radiation (290-400 nm) causes oxidative stress, DNA damage, and expression of p53/p73 in laboratory experiments on embryos of the Spotted Salamander, Ambystoma maculatum.
Physiological and biochemical zoology : PBZ, 2001Co-Authors: Michael P. Lesser, Sarah L. Turtle, Julianne H. Farrell, Charles W. WalkerAbstract:Abstract Developing embryos of the Spotted Salamander, Ambystoma maculatum, exposed to ultraviolet radiation (UVR; 290–400 nm) in the laboratory show a significant sensitivity to UVB (290–320 nm) radiation. Embryos in laboratory experiments exhibited significant DNA damage during exposures to UVR despite a significant increase in the production of the protective pigment melanin in response to UVR exposure. DNA damage occurs as a result of both the direct effects of exposure to UVR, and the indirect effects are mediated by the production of reduced oxygen intermediates. The production of reactive oxygen species initiates the expression of p53/p73 that leads to either DNA repair or apoptosis. When similar experiments are conducted on Salamander embryos exposed to solar UVR in vernal pools, the embryos show significantly less sensitivity and higher survivorship. The differences between laboratory and field experiments are a result of the attenuation of UVR caused by the accumulation of dissolved organic carb...
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Embryonic Survivorship of the Spotted Salamander (Ambystoma maculatum) in Roadside and Woodland Vernal Pools in Southeastern New Hampshire
Journal of Herpetology, 2000Co-Authors: Sarah L. TurtleAbstract:-Roadside wetlands are often contaminated by highway runoff; however, little is known about the impact of pollution on the organisms that use these wetlands. Most amphibians use wetlands as breeding habitats and are therefore vulnerable to aquatic pollutants. In 1995 and 1996, I conducted transplant experiments to compare the embryonic survivorship of Ambystoma maculatum in temporary woodland pools to that in roadside pools. Chemical parameters were monitored to identify differences between roadside and woodland pool environments. Failure time analysis was used to compare embryonic survival probabilities for transplant experiments in both years. The results indicate that deicing salts heavily contaminate roadside vernal pools. Ambystoma maculatum survivorship was significantly lower in roadside pools for four of five transplants in 1995 and all transplants in 1996. Deicing salts used for highway maintenance contaminated roadside vernal pools, and are a possible factor in the reduced embryonic survival observed in these pools. al of Herpetol gy, Vol. 34, No. 1, pp. 607, 2000 right 20 Society for the Study of Amphibians d Reptil s ryonic Survivorship of the Spotted Salamander stoma maculatum) in Roadsi e and Woodland Vernal Pools in eastern New Hampshire Approximately one-half of the frog species and one-third of the Salamander species in North America rely on ephemeral wetlands for embryonic and larval development (Pierce, 1985). Ephemeral (seasonal) wetlands include vernal pools, which dry annually, as well as semi-permanent ponds that dry more infrequently. In New Hampshire, Rana sylvatica (wood frog), Ambystoma maculatum (Spotted Salamander), Ambystoma laterale (blue Spotted Salamander), Ambystoma jeffersonianum (Jefferson's Salamander) and hybrids of the latter two species depend on these unique wetlands for reproduction. Suitable breeding sites for these amphibians must dry often enough to exclude fish and must retain water long enough to allow amphibian larvae to complete development and metamorphose into terrestrial adults. The impact of pollution on the chemical, physical, and biological properties of vernal pools is not well understood. The chemical composition of the water in vernal pools reflects the chemical content of upper soil horizons, leaf litter, runoff from surrounding areas, and even atmospheric conditions (Rowe and Dunson, 1993). The watersheds of these pools tend to be small; thus, precipitation and runoff entering these pools have little contact with soil buffering systems. There is often little water volume in the pool to dilute polluted inflow (Pough, 1976; Gascon and Planas, 1986), resulting in a greater effect of pollutants on the water in these wetlands than in lakes and streams. In addition, evaporation during late spring and summer may increase the concentration of ions in the water causing chemical and physical stress for 60 This content downloaded from 157.55.39.203 on Sat, 27 Aug 2016 06:25:30 UTC All use subject to http://about.jstor.org/terms SURVIVORSHIP OF AMBYSTOMA MACULATUM EMBRYOS TABLE 1. Description of maximum length and depth of pools and transplant pairs. Transplant Pair (maximum length/maximum depth) Transplant A95 WI (41.3 m/1.4 m) vs. R1 (45 m/1.5 m) Reciprocal Transplant A95 R1 (45 m/1.5 m) vs. W1 (41.3 m/1.4 m) Transplant A96 W1 (41.3 m/1.4 m) vs. R1 (45 m/1.5 m) Transplant B95 W2 (39 m/1.7 m) vs. R2 (34.6 m/1.3 m) Transplant B96 W2 (39 m/1.7 m) vs. R2 (34.6 m/1.3 m) Transplant C95 W3 (29 m/0.87 m) vs. R3 (25 m/0.93) Transplant D95 W5 (15 m/2.1 m) vs. R5 (17.9 m/1.1) Transplant E96 W6 (26.7/1.2 m) vs. R3 (25 m/0.93 m) Transplant F96 W4 (21 m/1.6 m) vs. R5 (17.9/1.1) organisms living in these pools (Albers and Prouty, 1987). The semi-permeability of skin and eggs makes amphibians especially vulnerable to habitat contamination, particularly during embryonic and larval stages (Zug, 1993). Ambystoma Salamanders may be at greater risk than other amphibians because they return to natal pools to breed (Shoop, 1968; Stenhouse, 1985). Few studies have investigated the impact of contaminated highway runoff on the animals that depend on these wetlands. Scientists have found elevated levels of lead, cadmium, nickel, zinc, and salts in adjacent highway habitat (Lagerwerrf and Specht, 1970). In New Hampshire a likely source of highway contamination is deicing salt. The New Hampshire Department of Transportation (NHDOT) relies heavily on deicing salt as a safety precaution for motorists in winter. For the past 25 years NHDOT has used an average of 16.75 tons*lanemile-~ of salt on the state's highways. In 1995, NHDOT used 13.90 tons*lanemile-1 and in 1996 they used 18.08 tons*lanemile-1 (R. Hogan, NHDOT, pers. comm.). Stormwater runoff transports the deicing salt to adjacent wetlands and the resulting high salt concentrations affect water chemistry and plant species diversity (Burbeck et al., 1971; Isabelle et al., 1987). The goal of this project was to quantify the impact of highway contamination on vernal pool water chemistry and on A. maculatum embryos. I tested the null hypothesis that A. maculatum embryonic survivorship in roadside pools was not significantly different than woodland pools. Transplant experiments were conducted in two years to detect possible effects of pool type on embryonic survivorship. Water chemistry variables were measured and compared between pool types to determine if they correlated with the outcomes of the transplant experiments. MATERIALS AND METHODS Site Description.-The study areas were located in southeastern New Hampshire in the towns of Durham, Lee, Epping, and Nottingham (Lat. 47?, Long. 71?). A total of six woodland and five roadside pools were use during the two year study (Table 1). Bre ding sites were identified in early spring by the presence of R. sylvatica egg masses, Am ystoma spermatophores, or other signs of amphibian breeding activity in the pools. All pools were less than 0.25 ha in early spring and all dried completely by August both years of this study. A pool was designated as 'woodland' if it was more than 50 m from a paved road and any human development and 'roadside' if it was within 2 m of a paved state highway. Pools were labeled "W" for woodland and "R" for roadside and then numbered in the order in which they were used. W1, W2, W3, Rl, R2, R3, and R5, were located in Nottingham, New Hampshire. W4 was located in Durham, New Hampshire and R4 was located in Epping, New Hampshire. W5 and W6 were located in Lee, New Hampshire. In all cases the surrounding forest was dominated by Quercus rubra, Acer rubrum, Acer saccharinum, Pinus strobus, and Tsuga canadensis. Vaccinium corymbosum and Ilex verticillata were the most common shrubs found in the pools. Transplant Experi ents.-Each roadside pool was paired wi h woodland pool based on similar lengths and water depths (Table 1). In both 1995 and 1996 ransplan experiments were conducted in four pairs of pools. One pair of pools in 1995 involved reciprocal transplants in which eggs were transplanted from woodland to roadside pools and also from roa side to woodland pools; all other experiments involved transplants from a woodland pool to a roadside pool, only. Transplants could only be conducted if pools contained more then 300 embryos. In 1995, pool Rl was the only roadside pool that contained enough A. maculatum egg masses to conduct a roadside to woodland transplant. In 1996 no roadside pool contained enough egg masses to conduct reciprocal transplant experiments. For each woodland to roadside transplant, A. maculatum egg masses were collected from the woodland pool and divided into sections, each 61 This content downloaded from 157.55.39.203 on Sat, 27 Aug 2016 06:25:30 UTC All use subject to http://about.jstor.org/terms
James R. Vonesh - One of the best experts on this subject based on the ideXlab platform.
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Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander
Diversity, 2018Co-Authors: Julie F. Charbonnier, Jacquelyn Pearlmutter, James R. Vonesh, Caitlin R. Gabor, Zachery R. Forsburg, Kristine L. GraysonAbstract:For organisms with complex life cycles, conditions experienced during early life stages may constrain later growth and survival. Conversely, compensatory mechanisms may attenuate negative effects from early life stages. We used the Spotted Salamander, Ambystoma maculatum, to test how aquatic larval density and terrestrial moisture influence juvenile growth, food intake, evaporative water loss and water reuptake rates, and corticosterone levels. We conducted an outdoor mesocosm experiment to manipulate larval density and transferred metamorphosed Salamanders into low and high terrestrial moisture treatments in laboratory terrariums. After the larval stage, high-density Salamanders were significantly smaller and had higher corticosterone release rates than those from low-density treatments. Salamanders in the low terrestrial moisture treatment consumed fewer roaches, had lower mass-specific growth rates, higher water reuptake, and higher corticosterone release rates than Salamanders in high terrestrial moisture treatments. Across moisture treatments, smaller Salamanders had higher mass-specific growth rates than larger Salamanders. Our results suggest that Salamanders can partially compensate for competition in the larval aquatic habitat with increased growth as juveniles, but this response is dependent on terrestrial habitat quality. Thus, the persistence of early life stage effects can be an important, yet context-dependent, component of amphibian life cycles.
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impacts of road deicing salt on the demography of vernal pool breeding amphibians
Ecological Applications, 2008Co-Authors: Nancy E Karraker, James P Gibbs, James R. VoneshAbstract:Deicing agents, primarily road salt, are applied to roads in 26 states in the United States and in a number of European countries, yet the scale of impacts of road salt on aquatic organisms remains largely under-studied. The issue is germane to amphibian conservation because both adult and larval amphibians are known to be particularly sensitive to changes in their osmolar environments. In this study, we combined survey, experimental, and demographic modeling approaches to evaluate the possible effects of road salt on two common vernal-pond-breeding amphibian species, the Spotted Salamander (Ambystoma maculatum) and the wood frog (Rana sylvatica). We found that in the Adirondack Mountain Region of New York (USA), road salt traveled up to 172 m from the highway into wetlands. Surveys showed that egg mass densities of Spotted Salamanders (A. maculatum) and wood frogs (R. sylvatica) were two times higher in forest pools than roadside pools, but this pattern was better explained by road proximity than by incr...
Chris A Phillips - One of the best experts on this subject based on the ideXlab platform.
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Asymmetric Introgression in a Spotted Salamander Hybrid Zone
The Journal of heredity, 2015Co-Authors: Benjamin B. Johnson, Chris A Phillips, Thomas A. White, Kelly R. ZamudioAbstract:Before the establishment of reproductive isolation, deeply diverged intraspecific lineages can experience complex genetic and behavioral interactions as they come into secondary contact. Divergent selective and demographic processes mediate gene flow among lineages, resulting in hybrid zones with complex biogeographic structure. Discordance in the biogeographic patterns of autosomal and maternally inherited loci provides a useful window to infer the processes mediating admixture and introgression across hybrid zones. Here, we sampled 489 genotypes across a hybrid zone between 2 phylogeographic lineages of the Spotted Salamander, Ambystoma maculatum, and characterize discordant patterns of nuclear and mitochondrial introgression across the contact boundary. Our results indicate asymmetric introgression of nuclear DNA beyond the contact boundary from the western to eastern lineage, with introgression of eastern mitochondrial DNA into the western lineage. We discuss alternative mechanisms for this pattern and attribute this result to neutral patterns of population expansion of the western lineage into the east in combination with female mate choice for larger-bodied western males. Our results underscore the complexity of interacting mechanisms that give rise to reproductive asymmetries in the earliest stages of the speciation process.
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Spotted Salamander ambystoma maculatum
1994Co-Authors: Chris A PhillipsAbstract:I analyzed geographic partitioning of mitochondrial DNA (mtDNA) restriction-site variants in the Spotted Salamander, Ambystoma maculatum. Two highly divergent and geograph- ically separate genetic lineages were identified that differed by a minimum of 19 restriction sites (6% sequence divergence). One of the lineages has a disjunct distribution with very closely related haplotypes occurring in Missouri, Arkansas, North Carolina, and Virginia. The other lineage is found in Michigan, Illinois, and Alabama. The geographic separation of highly divergent mtDNA haplotypes, a pattern that was predicted based on the sedentary nature of these Salamanders, is evidence for long-term barriers to gene flow. In contrast, the large-scale disjunction of very similar haplotypes suggests recent, long-distance gene flow and does not match the phylogeographic ex- pectation for a small terrestrial vertebrate. I explain this potential contradiction in the level of importance assigned to gene flow by a scenario in which historical barriers to gene flow account for the two divergent mtDNA assemblages, but stochastic sorting of ancestral polymorphism is responsible for the large-scale geographic disjunction. Ten of 16 populations collected in the Ozark Highlands were fixed for the same haplotype. I attribute this lack of detectable variation to recent colonization of this area, a hypothesis that is supported by paleoecological data and demonstrates the potential benefits of combining data from paleobotany, geology, and other disciplines to re- construct the historical biogeography of a species.
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Geographic-Distribution of Mitochondrial-DNA Variants and the Historical Biogeography of the Spotted Salamander, Ambystoma-Maculatum
Evolution, 1994Co-Authors: Chris A PhillipsAbstract:I analyzed geographic partitioning of mitochondrial DNA (mtDNA) restriction-site variants in the Spotted Salamander, Ambystoma maculatum. Two highly divergent and geographically separate genetic lineages were identified that differed by a minimum of 19 restriction sites (6% sequence divergence). One of the lineages has a disjunct distribution with very closely related haplotypes occurring in Missouri, Arkansas, North Carolina, and Virginia. The other lineage is found in Michigan, Illinois, and Alabama. The geographic separation of highly divergent mtDNA haplotypes, a pattern that was predicted based on the sedentary nature of these Salamanders, is evidence for long-term barriers to gene flow. In contrast, the large-scale disjunction of very similar haplotypes suggests recent, long-distance gene how and does not match the phylogeographic expectation for a small terrestrial vertebrate. I explain this potential contradiction in the level of importance assigned to gene flow by a scenario in which historical barriers to gene flow account for the two divergent mtDNA assemblages, but stochastic sorting of ancestral polymorphism is responsible for the large-scale geographic disjunction. Ten of 16 populations collected in the Ozark Highlands were fixed for the same haplotype. I attribute this lack of detectable variation to recent colonization of this area, a hypothesis that is supported by paleoecological data and demonstrates the potential benefits of combining data from paleobotany, geology, and other disciplines to reconstruct the historical biogeography of a species.
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The response of naive breeding adults of the Spotted Salamander to fish
Behaviour, 1994Co-Authors: Owen J. Sexton, Chris A Phillips, Eric J. RoutmanAbstract:Several recent investigations have shown that somc species of Salamanders are capable of perceiving the presence of fish in breeding ponds through olfaction. It has been suggested that breeding adult Salamanders may avoid depositing eggs in pools containing fish. We examined the hypothesis that breeding Salamanders avoid fish ponds through olfactory cues in two field tests. In the first, naive Spotted Salamanders (Ambystoma maculatum) restrained within screened enclosures were submerged in either fish or fishless ponds. The number of eggs laid within each enclosure was counted at the conclusion of breeding. There was no difference in the number of eggs within and among four fishless and three fish ponds. In the fourth fish pond the fish harassed the Salamanders and completely inhibited reproduction. We repeated the experiment using double screened enclosures in which the Salamanders were free from direct fish attack but were still exposed to fish scent. There was no difference in egg production. The second test repeated the design of the first but provided the Salamanders with the choice of remaining in the double screened enclosures or exiting the pond. The test animals from both the fish and fishless ponds responded similarly in their breeding activities. We conclude that naive Spotted Salamanders do not avoid fish ponds based solely on olfactory cues.
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Variation in metamorphosis in Spotted Salamanders, Ambystoma maculatum from eastern Missouri
American Midland Naturalist, 1992Co-Authors: Chris A PhillipsAbstract:I examined timing of metamorphosis in the Spotted Salamander Ambystoma maculatum for five years at a pond in east-central Missouri. Timing of metamorphosis was variable both among and within years. In three years most larvae failed to undergo metamorphosis by November and either died or overwintered and metamorphosed from the pond in the following spring. In two other years most larvae apparently metamorphosed by October and did not overwinter. In 1986, 81 newly transformed animals were captured from June to September. Individuals that metamorphosed later exhibited larger body sizes than those that left the pond early in the season. Variation in time and size at metamorphosis may be important in population regulation by affecting adult traits that contribute to fitness.
