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.

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.

Variation in acid tolerance of Connecticut wood frogs: genetic and maternal effects

1985 ◽  
Vol 63 (7) ◽  
pp. 1647-1651 ◽  
Author(s):  
Benjamin A. Pierce ◽  
Nalin Sikand
Keyword(s):  
Genetic Variation ◽  
Acidic Solution ◽  
Acid Tolerance ◽  
Rana Sylvatica ◽  
Larval Survival ◽  
Wood Frog ◽  
Maternal Factors ◽  
Wood Frogs ◽  
Significant Difference ◽  
Sib Families

Acid tolerance in wood frog (Rana sylvatica) embryos and larvae was examined in full- and half-sib families. Among the embryos, no significant difference in acid tolerance at pH 3.75 was observed among the progeny of males. At pH 4 only slight differences in embryo acid tolerance existed among the progeny of males mated to the same female. Thus, there is relatively little direct genetic variation in embryo acid tolerance. However, progeny from different females differed significantly in their acid tolerance at both pH 4 and pH 3.75, indicating that maternal factors are important in embryo acid tolerance. Whether these maternal factors are genetic is not known. Among larvae, maternal factors did not appear to influence acid tolerance, but significant genetic variation was present. Larval survival in an acidic solution was not correlated with embryo acid tolerance.

scholarly journals Species loss in developed landscapes: an experimental evaluation

2014 ◽  
Author(s):  
Alex Shepack ◽  
Kealoha Freidenburg ◽  
David Skelly
Keyword(s):  
Growth Rate ◽  
Experimental Evaluation ◽  
Rana Sylvatica ◽  
Development Rate ◽  
Wood Frog ◽  
Species Loss ◽  
Landscape Development ◽  
Wood Frogs ◽  
Lithobates Sylvaticus ◽  
Human Use

Conversion of landscapes for human uses is widely associated with loss of biodiversity. Here we focus on limits to distribution defined by intensity of landscape development. Using a translocation experiment, we ask does degradation of wetland habitat contribute to species loss? Wood frog larvae (Rana sylvatica = Lithobates sylvaticus), were reared within enclosures in 7 ponds harboring populations of wood frogs and in 5 ponds where they are absent. Survival, growth rate, and development rate were equivalent between ‘present’ and ‘absent’ ponds. While it is clear that landscapes surrounding ‘absent’ ponds had been heavily influenced by human use, we find no evidence that such wetlands provide inferior habitat for wood frog recruitment. Their absence in human altered landscapes may stem from influences outside of pond basins. The results provide a caution to the typically unexamined presumption that relictual habitats in developed landscapes are degraded in their utility for wildlife.

scholarly journals Species loss in developed landscapes: an experimental evaluation

2014 ◽  
Author(s):  
Alex Shepack ◽  
Kealoha Freidenburg ◽  
David Skelly
Keyword(s):  
Growth Rate ◽  
Experimental Evaluation ◽  
Rana Sylvatica ◽  
Development Rate ◽  
Wood Frog ◽  
Species Loss ◽  
Landscape Development ◽  
Wood Frogs ◽  
Lithobates Sylvaticus ◽  
Human Use

Conversion of landscapes for human uses is widely associated with loss of biodiversity. Here we focus on limits to distribution defined by intensity of landscape development. Using a translocation experiment, we ask does degradation of wetland habitat contribute to species loss? Wood frog larvae (Rana sylvatica = Lithobates sylvaticus), were reared within enclosures in 7 ponds harboring populations of wood frogs and in 5 ponds where they are absent. Survival, growth rate, and development rate were equivalent between ‘present’ and ‘absent’ ponds. While it is clear that landscapes surrounding ‘absent’ ponds had been heavily influenced by human use, we find no evidence that such wetlands provide inferior habitat for wood frog recruitment. Their absence in human altered landscapes may stem from influences outside of pond basins. The results provide a caution to the typically unexamined presumption that relictual habitats in developed landscapes are degraded in their utility for wildlife.

Cold hardiness in two helminth parasites of the freeze-tolerant wood frog, Rana sylvatica

2000 ◽  
Vol 78 (6) ◽  
pp. 1085-1091 ◽  
Author(s):  
Douglas C Woodhams ◽  
Jon P Costanzo ◽  
Jonathan D Kelty ◽  
Richard E Lee, Jr.
Keyword(s):  
Cold Hardiness ◽  
Rana Sylvatica ◽  
Wood Frog ◽  
Digenetic Trematode ◽  
Helminth Parasites ◽  
Wood Frogs ◽  
Freeze Avoidance ◽  
Body Tissues ◽  
Freeze Tolerant

Wood frogs, Rana sylvatica, tolerate the freezing of their body tissues as an overwintering adaptation. Various parasites infect wood frogs of northern populations, but nothing is known about their strategies for surviving within a frozen host. We examined winter-conditioned wood frogs that were experimentally exposed to 0°C (nonfrozen) or –4°C (frozen) to determine whether endoparasites survive the freezing of their host. We found no differences in the prevalence or intensity of adult lungworms Rhabdias ranae (Nematoda) or of larvae of an unidentified species of digenetic trematode between these groups. Live individuals of both species were observed in hosts that recovered from experimental freezing at –4°C. Within the host, R. ranae also tolerated exposure to –5°C, a temperature near the lower limit of survival of the wood frog. Cryostage experiments showed that, like its host, R. ranae was highly susceptible to inoculative freezing and tolerant of the freezing of its tissues. Rhabdias ranae frozen in vitro in the presence or absence of 250 mM glucose, the cryoprotectant used by wood frogs, recovered from a 10-h exposure to –4°C. The mechanism of cold tolerance used by larval trematodes was not investigated; however, we hypothesize that freeze avoidance by supercooling may be important in this species. Freeze-tolerant anurans, such as the wood frog, are useful subjects in the study of coevolution of thermal tolerance in parasites and their host.

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.

Physiological and ecological aspects of low-temperature tolerance in embryos of the wood frog, Rana sylvatica

2000 ◽  
Vol 78 (6) ◽  
pp. 1032-1041 ◽  
Author(s):  
Malcolm Pratt Frisbie ◽  
Jon P Costanzo ◽  
Richard E Lee, Jr.
Keyword(s):  
Water Column ◽  
Rana Sylvatica ◽  
Wood Frog ◽  
Temporary Ponds ◽  
Late Winter ◽  
Daily Maximum ◽  
Similar Degree ◽  
Wood Frogs ◽  
Daily Minimum ◽  
Subzero Temperatures

Wood frogs (Rana sylvatica) breed in late winter in temporary ponds, where eggs are deposited in communal surface rafts. Subsequently, developing embryos may face subzero temperatures. In the laboratory, individual embryos supercooled moderately (to –4.2°C for embryos in their jelly capsules; to –5.0°C for embryos removed from the jelly capsule) when chilled in the absence of external ice nuclei, but did not resist inoculative freezing when chilled in contact with external ice. They survived acute episodes (1–18 h) of supercooling to temperatures between ca. –0.5 and –2.0°C. Stage-12 embryos (six of six) survived freezing for 1 h at –2.0°C, but only one of six survived a 3.5-h freezing episode at the same temperature. Stage-13 and -14 embryos survived freezing episodes of 4.5 h at –1.0°C (six of six survived) and 18 h at –0.5°C (six of six survived), respectively. In the field, temperatures were monitored every 5 min for 21 d in embryo masses of wood frogs and Jefferson salamanders (Ambystoma jeffersonianum) at a breeding pond in central Kentucky. Wood frog embryos experienced higher daily maximum and lower daily minimum temperatures than salamander embryos, which were deeper in the water column. Wood frog embryos spent more time at risk of cryoinjury (i.e., at temperatures [Formula: see text]1°C), but the two species accumulated similar degree-days over the 21-d observation period. Their position in the water column may permit wood frogs to garner a developmental advantage in milder years, when daily minimum temperatures are similar between the two species. Wood frog embryos appear to offset some of the risks associated with this more exposed position by tolerating somatic freezing at high subzero temperatures.

Spring pond water chemistry and the reproduction of the wood frog, Rana sylvatica

1986 ◽  
Vol 64 (2) ◽  
pp. 543-550 ◽  
Author(s):  
Claude Gascon ◽  
Dolors Planas
Keyword(s):  
Hatching Success ◽  
Rana Sylvatica ◽  
Pond Water ◽  
Early Spring ◽  
Low Ph ◽  
Wood Frog ◽  
Egg Mass ◽  
Embryo Survival ◽  
Ph Range ◽  
The Impact

To determine the impact of snowmelt water quality on egg mass abundance and embryo survival of the wood frog (Rana sylvatica) in Québec, 15 breeding ponds, with an early spring pH range between 3.4 and 6.7, were surveyed. Acidity and total organic carbon were correlated with the density of egg masses. Hatching success was reduced (and mould increased) in low pH ponds.

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.

Growth of the Wood Frog, Rana sylvatica

Copeia ◽  
1961 ◽  
Vol 1961 (1) ◽  
pp. 74 ◽  
Author(s):  
Edward D. Bellis
Keyword(s):  
Rana Sylvatica ◽  
Wood Frog
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