Postfreeze locomotion performance in wood frogs (Rana sylvatica) and spring peepers (Pseudacris crucifer)

2003 ◽  
Vol 81 (12) ◽  
pp. 2061-2065 ◽  
Author(s):  
Jack R Layne, Jr., ◽  
Matt E Rice
Keyword(s):  
Treatment Group ◽  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Early Spring ◽  
Wood Frogs ◽  
Impaired Performance ◽  
Pseudacris Crucifer ◽  
Jump Distance ◽  
Frog Species ◽  
Recovery Dynamics

Freeze tolerance exists among a few species of terrestrially hibernating North American frogs such as the wood frog (Rana sylvatica) and the spring peeper (Pseudacris crucifer). We investigated jump distance and swimming speed of these two frog species during postfreeze recovery because impaired performance, even if reversible, could have adverse ecological consequences for these frogs. Following a nonlethal freeze at –1.5 °C, R. sylvatica returned to the prefreeze level of both modes of locomotion sooner than P. crucifer (54 h vs. 11 d or longer). Wood frogs recovered slowly following more intense freezes: a –4.0 °C treatment group failed to reach the prefreeze level after 11 d, and a –3.0 °C treatment group took 54 h to reach 50% of the prefreeze level. As a result of their diminished locomotive performance, frogs recovering from natural freezes may be temporarily less able to exploit environmental resources and less able to escape predators active in winter. Nevertheless, given the massive biochemical and physiological disturbances accompanying tissue freezing, the recovery dynamics in these frogs seem sufficiently rapid to minimize most ecological risks and to permit early spring breeding. The faster recovery of locomotion in R. sylvatica compared with P. crucifer is consistent, however, with its greater northward distribution.

The ability of wood frog eggs to withstand prolonged terrestrial stranding: an empirical study

1988 ◽  
Vol 66 (8) ◽  
pp. 1733-1735 ◽  
Author(s):  
Don C. Forester ◽  
David V. Lykens
Keyword(s):  
Thermal Stress ◽  
Rana Sylvatica ◽  
Thermal Exposure ◽  
Early Spring ◽  
Egg Laying ◽  
Wood Frog ◽  
Seasonal Precipitation ◽  
Wood Frogs ◽  
Egg Masses ◽  
Ephemeral Ponds

In Maryland, the wood frog, Rana sylvatica, oviposits in ephemeral ponds and pools during early spring. Seasonal precipitation is often unpredictable and egg masses may become exposed as ponds recede. The ability of wood frog eggs to withstand prolonged terrestrial exposure was tested in the laboratory. Egg mortality rate was exponential. Compared with a submerged control, 49% of the eggs died within 2 days, but 11% of the eggs were alive after 10 days and a few survived as long as 14 days. Wood frogs are thought to have evolved communal egg laying as a mechanism to minimize thermal stress during development. We suggest that this behavior also enabled egg masses to withstand terrestrial stranding. Today, advantages accrued through reduced thermal exposure and resistance to desiccation likely act in concert to stabilize communal egg-laying behavior.

Glucose concentration regulates freeze tolerance in the wood frog Rana sylvatica

1993 ◽  
Vol 181 (1) ◽  
pp. 245-255 ◽  
Author(s):  
J. P. Costanzo ◽  
R. E. Lee ◽  
P. H. Lortz
Keyword(s):  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Conclusive Evidence ◽  
Freezing Injury ◽  
Critical Determinant ◽  
Wood Frogs ◽  
Glucose Levels ◽  
Elevated Glucose ◽  
Ice Content

In spring, the lowest temperature during freezing that can be survived by wood frogs (Rana sylvatica) from southern Ohio is approximately −3 degrees C. We investigated whether the thermal limit of freeze tolerance in these frogs is regulated by tissue levels of glucose, a putative cryoprotectant that is distributed to tissues during freezing. Frogs receiving exogenous glucose injections prior to freezing showed dose-dependent increases in glucose within the heart, liver, skeletal muscle and blood. Tissue glucose concentrations were further elevated during freezing by the production of endogenous glucose. Most glucose-loaded frogs survived freezing to −5 degrees C, whereas all control (saline-injected) frogs succumbed. Further, we investigated some mechanisms by which glucose might function as a cryoprotectant in R. sylvatica. Organ dehydration, a normal, beneficial response that reduces freezing injury to tissues, occurred independently of tissue glucose concentrations. However, elevated glucose levels reduced both body ice content and in vivo erythrocyte injury. These results not only provided conclusive evidence for glucose's cryoprotective role in R. sylvatica, but also revealed that tissue glucose level is a critical determinant of freeze tolerance capacity in this species.

Freeze tolerance and ice formation in wood frogs (Rana sylvatica)

Cryobiology ◽  
1986 ◽  
Vol 23 (6) ◽  
pp. 552 ◽  
Author(s):  
Jack R. Layne ◽  
Richard E. Lee
Keyword(s):  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Ice Formation ◽  
Wood Frogs

Dehydration tolerance in wood frogs: a new perspective on development of amphibian freeze tolerance

1993 ◽  
Vol 265 (6) ◽  
pp. R1324-R1332 ◽  
Author(s):  
T. A. Churchill ◽  
K. B. Storey
Keyword(s):  
Total Body Water ◽  
Protective Layer ◽  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Body Water ◽  
Wood Frogs ◽  
Glucose Levels ◽  
High Concentrations ◽  
Total Body ◽  
New Perspective

Wood frogs, Rana sylvatica, tolerate the loss of 50-60% of total body water during experimental dehydration. The rate of water loss for unprotected frogs is the same whether animals are frozen (at -2 degrees C) or unfrozen (at 1 degrees C) but is greatly reduced when frogs are frozen under a protective layer of moss. Dehydrational death could occur in as little as 7-9 days for unprotected animals; this indicates the importance for winter survival of selecting well-protected and damp hibernation sites. Prior dehydration affected the cooling and freezing properties of frogs, reducing supercooling point and the amount of ice formed after 24 h at -2 degrees C and acting synergistically with freezing exposure in stimulating cryoprotectant synthesis. Analysis of the effects of controlled dehydration at 5 degrees C showed that changes in body water content alone (without freezing) stimulated liver glycogenolysis and the export of high concentrations of glucose into blood and other organs. Autumn-collected frogs dehydrated to 50% of total body water lost showed glucose levels of 165-1,409 nmol/mg protein in different organs, increases of 9- to 313-fold compared with control values and reaching final levels very similar to those induced by freezing exposure. The data support the proposal that various adaptations for natural freeze tolerance may have been derived from preexisting mechanisms for dealing with water stress in amphibians and that cell volume change may be one of the signals involved in triggering and sustaining molecular adaptations (e.g., cryoprotectant output) that support freezing survival.

Freeze tolerance and the dynamics of ice formation in wood frogs (Rana sylvatica) from southern Ohio

1987 ◽  
Vol 65 (8) ◽  
pp. 2062-2065 ◽  
Author(s):  
Jack R. Layne Jr. ◽  
Richard E. Lee Jr.
Keyword(s):  
Time Course ◽  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Ice Formation ◽  
Total Water Content ◽  
Total Water ◽  
Wood Frogs ◽  
Ice Accumulation ◽  
Seasonal Factors ◽  
Ice Content

Freeze tolerance and ice formation were examined in a population of Rana sylvatica from southern Ohio following their emergence in February. Frogs were tolerant of freezing at −2.5 °C but did not survive freezing at −5.5 °C. The level of glucose in the blood of frogs frozen for 48 h at −2.5 °C was fivefold higher than in unfrozen frogs. Both interpopulational and seasonal factors appeared to modify freeze tolerance and ice accumulation in Rana sylvatica when compared with previous studies. The directly determined time course of ice formation roughly paralleled the duration of the exotherm in this species. Ice content of frogs was determined using calorimetry and integrated to the specific heat of wet and dry masses. The equilibrium ice content represented nearly two-thirds of the total water content of these frogs. Freezing beyond this level proved lethal to frogs.

Cryoprotectant production capacity of the freeze-tolerant wood frog, Rana sylvatica

1993 ◽  
Vol 71 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Jon P. Costanzo ◽  
Richard E. Lee Jr.
Keyword(s):  
Production Capacity ◽  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Liver Glycogen ◽  
Wood Frog ◽  
Freezing Injury ◽  
Wood Frogs ◽  
Cryoprotectant Synthesis ◽  
Freeze Tolerant ◽  
The Relationship

Freezing survival of the wood frog (Rana sylvatica) is enhanced by the synthesis of the cryoprotectant glucose, via liver glycogenolysis. Because the quantity of glucose mobilized during freezing bears significantly on the limit of freeze tolerance, we investigated the relationship between the quantity of liver glycogen and the capacity for cryoprotectant synthesis. We successfully augmented natural levels of liver glycogen by injecting cold-conditioned wood frogs with glucose. Groups of 8 frogs having mean liver glycogen concentrations of 554 ± 57 (SE), 940 ± 57, and 1264 ± 66 μmol/g catabolized 98.7, 83.4, and 52.8%, respectively, of their glycogen reserves during 24 h of freezing to −2.5 °C. Glucose concentrations concomitantly increased, reaching 21 ± 3, 102 ± 23, and 119 ± 14 μmol/g, respectively, in the liver, and 15 ± 3, 42 ± 5, and 61 ± 5 μmol/mL, respectively, in the blood. Because the capacity for cryoprotectant synthesis depends on the amount of liver glycogen, the greatest risk of freezing injury likely occurs during spring, when glycogen reserves are minimal. Non-glucose osmolites were important in the wood frog's cryoprotectant system, especially in frogs having low glycogen levels. Presumably the natural variation in cryoprotectant synthesis capacity among individuals and populations of R. sylvatica chiefly reflects differences in glycogen reserves; however, environmental, physiological, and genetic factors likely are also involved.

Freeze-thaw injury in erythrocytes of the freeze-tolerant wood frog, Rana sylvatica

1991 ◽  
Vol 261 (6) ◽  
pp. R1346-R1350 ◽  
Author(s):  
J. P. Costanzo ◽  
R. E. Lee
Keyword(s):  
Cell Injury ◽  
Osmotic Fragility ◽  
Rana Sylvatica ◽  
Freeze Tolerance ◽  
Wood Frog ◽  
In Vitro Tests ◽  
Freezing And Thawing ◽  
Freeze Tolerant ◽  
High Concentrations

Erythrocytes from the freeze-tolerant wood frog (Rana sylvatica) were subjected to in vitro tests of freeze tolerance, cryoprotection, and osmotic fragility. The responses of cells from frogs acclimated to 4 or 15 degrees C were similar. Erythrocytes that were frozen in saline hemolyzed at -4 degrees C or lower. The addition of high concentrations (150 and 1,500 mM) of glucose or glycerol, cryoprotectants produced naturally by freeze-tolerant frogs, significantly reduced cell injury at -8 degrees C, but concentrations of 1.5 or 15 mM were ineffective. Hemolysis was reduced by 94% with 1,500 mM glycerol and by 84% with 1,500 mM glucose; thus glycerol was the more effective cryoprotectant. Mean fragility values for frog erythrocytes incubated in hypertonic and hypotonic saline were 1,938 and 49 mosM, respectively. Survival in freeze tolerance and cryoprotection experiments was comparable for erythrocytes from frogs and humans, suggesting that these cells may respond similarly to freezing-related stresses. However, the breadth of osmotic tolerance, standardized for differences in isotonicity, was greater for frog erythrocytes than for human erythrocytes. Our data suggest that erythrocytes from R. sylvatica are adequately protected by glucose under natural conditions of freezing and thawing.

Variation in amount of surrounding forest habitat influences the initial orientation of juvenile amphibians emigrating from breeding ponds

2008 ◽  
Vol 86 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Leroy J. Walston ◽  
Stephen J. Mullin
Keyword(s):  
Positive Relationship ◽  
Rana Sylvatica ◽  
Environmental Cues ◽  
Bufo Americanus ◽  
Forest Habitat ◽  
Amphibian Species ◽  
Wood Frogs ◽  
Juvenile Dispersal ◽  
Woodland Ponds ◽  
Emigration Behavior

Juvenile dispersal is important for the persistence of ​amphibian populations. Previous studies have observed nonrandom orientation in juvenile amphibians emigrating from breeding ponds; however, the environmental cues associated with these movements are not well understood. We examined the emigration behavior of recently metamorphosed juveniles of three pond-breeding amphibian species from three woodland ponds. We found that juvenile small-mouthed salamanders ( Ambystoma texanum (Matthes, 1855)), American toads ( Bufo americanus Holbrook, 1836), and wood frogs ( Rana sylvatica LeConte, 1825) exhibited nonrandom orientation upon exiting the breeding ponds. Furthermore, we found a positive relationship between captures of juvenile small-mouthed salamanders and wood frogs and width of the surrounding forest habitat, indicating that these species are selecting areas with broader forested habitat upon exiting the breeding ponds. Our results indicate that migrating juvenile amphibians may rely on direct environmental cues because the orientation of small-mouthed salamanders and wood frogs was influenced by width of the surrounding forested habitat. These observations support previous studies suggesting that maintaining forest habitat, along at least a portion of breeding ponds, is important for the persistence of amphibian populations.

Kin recognition by larval wood frogs (Rana sylvatica): effects of diet and prior exposure to conspecifics

Oecologia ◽  
1991 ◽  
Vol 86 (3) ◽  
pp. 319-324 ◽  
Author(s):  
George J. Gamboa ◽  
Keith A. Berven ◽  
Randy A. Schemidt ◽  
Thomas G. Fishwild ◽  
Kelli M. Jankens
Keyword(s):  
Kin Recognition ◽  
Rana Sylvatica ◽  
Prior Exposure ◽  
Wood Frogs

Sexual differences in color and color change in wood frogs

1991 ◽  
Vol 69 (7) ◽  
pp. 1963-1968 ◽  
Author(s):  
Richard B. King ◽  
Bethia King
Keyword(s):  
Color Change ◽  
Red Light ◽  
Green Light ◽  
Rana Sylvatica ◽  
Sexual Differences ◽  
Wood Frog ◽  
Color Classification ◽  
Wood Frogs ◽  
Evolutionary Response ◽  
Males And Females

An observer-free method of color classification was used to determine whether wood frogs, Rana sylvatica, exhibit sexual differences in color and color change. Males and females captured from breeding aggregations differed significantly in color: females reflected a greater amount of long-wavelength (yellow–red) light and less short-wavelength (blue–green) light than males. The color difference was not just a result of differences in the state of physiological color change at the time of capture but persisted for a month after capture. Males and females also differed in their color-change responses to black and white backgrounds: both sexes changed in brightness, but only males changed in the relative amount of light reflected at different wavelengths. Wood frog color may function in predator avoidance through crypsis. There was a good match between frogs and some of the leaves from the leaf litter surrounding the breeding ponds. Hypotheses for the development of sexual differences in wood frog color include sexual differences in availability of pigment and pigment precursors, morphological color change, and evolutionary response to different selection pressures.

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