Rana sylvatica (LeConte, 1825)
Taxonomic Notes: This species was placed in the genus Lithobates by Frost et al. (2006). However, Yuan et al. (2016, Systematic Biology, doi: 10.1093/sysbio/syw055) showed that this action created problems of paraphyly in other genera. Yuan et al. (2016) recognized subgenera within Rana for the major traditional species groups, with Lithobates used as the subgenus for the Rana palmipes group. AmphibiaWeb recommends the optional use of these subgenera to refer to these major species groups, with names written as Rana (Aquarana) catesbeiana, for example. However, Rana sylvatica has proven difficult to resolve phylogenetically and it remains the only member of the genus not assigned to a subgenus.
© 2003 John White (1 of 91)
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Canada, United States
U.S. state distribution from AmphibiaWeb's database: Alaska, Alabama, Arkansas, Colorado, Connecticut, District of Columbia, Delaware, Georgia, Idaho, Illinois, Indiana, Kentucky, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Montana, North Carolina, North Dakota, New Hampshire, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Virginia, Vermont, Wisconsin, West Virginia, Wyoming
Canadian province distribution from AmphibiaWeb's database: Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland and Labrador, Nova Scotia, Northwest Territories, Nunavut, Ontario, Prince Edward Island, Quebec, Saskatchewan, Yukon
It is a terrestrial species, often found in or near moist wooded areas, sometimes considerable distances from open water.
Life History, Abundance, Activity, and Special Behaviors
This species was featured as News of the Week on 14 January 2019:
Human activities ranging from vehicle traffic to industry are making the world an increasingly noisy place to live in; two recent studies show frogs have found ways to cope with the human soundscape. Tennessen et al. (2018) studied wood frogs (Rana sylvatica) in northeastern United States where noise from vehicle traffic is physiologically stressful to recently metamorphosed tadpoles, negatively impacting frog health. However, these researchers found that wood frogs from populations living near human noise have rapidly evolved to no longer be stressed by noisy human environments. In Panama, predators like bats and midges avoid noisy urban areas because they rely on sounds to hunt. Halfwerk and colleagues (2018) found that male túngara frogs (Engystomops pustulosus) from urban habitats can flexibly adjust their calls. Urban dwelling male túngara create more conspicuous calls, which are more attractive to females. When these urban males are placed in the forest, they adjust their calls to be less conspicuous and therefore less obvious to predators. Male túngara frogs from forests are unable to flexibly adjust their calls if they are placed in the city. Together, these studies show that some frogs species can rapidly evolve to deal with noisy human environments whereas others can adjust their behaviors accordingly (Written by Max Lambert)
This species was featured as News of the Week on 25 October 2021:
Amphibian larval development is highly temperature sensitive; larvae develop faster at warmer temperatures and slower at cooler ones. Countergradient variation is a form of local adaptation where – for example, in the Wood frog (Rana sylvatica)- tadpoles living in colder ponds (due to more enclosed, shaded forest canopies) are adapted to develop at faster rates than tadpoles from populations living in warmer ponds (with more open, sunnier forest canopies). This allows tadpoles in cold ponds to developmentally catch up to tadpoles in warmer habitats. The original study (Skelly 2004) found that this countergradient variation occurs at very small 'microgeographic' spatial scales, i.e., Wood frog populations are adapting to local environmental conditions well within the distance that the frogs can disperse and interbreed within a metapopulation. Arietta and Skelly (2021) performed the identical experiment with the same Wood frog populations 17 years later (~ 6-9 frog generations) and found persistent microgeographic countergradient evolution as before with overall Wood frog embryonic developmental rates accelerated by 14-19%. During this period, the forest canopy over these ponds generally became more shaded, but pond temperatures still increased across the metapopulation. With warmer ponds, it would be expected that the Wood frog populations would evolve slower tadpole development rates, not faster. Critically, ponds experiencing more change (i.e., canopy cover and temperature change) also had declining populations and several disappeared altogether. Overall, their experiment illustrates how amphibians might be able to adapt to environmental change relatively quickly and at relatively small spatial scales, but, even so, there are limits on rescuing populations from rapid environmental change through evolutionary adaptation. (Written by Max Lambert)
This species was featured as News of the Week on 14 March 2022:
One of the silverlinings of the COVID-19 pandemic has been reduced human activities on the landscape (sometimes called the "anthropause"), notably a decrease in motor vehicle traffic during lockdown. This provided a unique opportunity while monitoring amphibians in northeastern United States. Using a community citizen science project, The Maine Big Night: Amphibian Migration Monitoring, Leclair et al. (2021) collected data on migrating amphibians crossing roads at sites throughout Maine during amphibian mating seasons, from March to May in 2018 through 2021. Almost 8,000 amphibians representing 16 species were recorded at 199 sites surveyed during these four years. They found a 50% decrease in frog mortality in 2020 compared to the other survey years, mainly due to decreased frog deaths in March and April. Wildlife collision data for other species in Maine (e.g., deer, turkeys, moose) were consistent with this trend of lower wildlife mortality in spring 2020. Thus, there was a significant reduction in frog deaths in Maine because of the traffic reductions during the COVID-19 lockdown. In the same time period, increasing precipitation correlated with increasing frog deaths, but not in salamanders, suggesting that environmental factors influence frog and salamander movements differently. Roads can be significant barriers to amphibian migrations; thus, even small changes can have large effects for these populations, especially for frogs. (Written by Carol Spencer)
This species was featured as News of the Week on 26 December 2022:
The evolution of chemical alarm cues has been puzzling to evolutionary biologists. At first glance, the cues appear to only help other individuals, not the preyed-upon individual that produced and released the cues (the 'sender'). However, according to theory, the evolution of communication systems requires benefits to senders. Releasing alarm cues can benefit the sender’s genes by warning their nearby kin, but prey often do not associate based on kinship. There is some evidence that alarm cues can protect against certain parasites and pathogens. However, an alternative hypothesis is that alarm cues attract additional predators to an attack, thereby interfering with it, and allows the prey to escape. This is known as the 'Predator Attraction Hypothesis'. Previous studies on fishes have provided support for this hypothesis, but amphibians had not been tested before. Crane et al. (2022) used Tiger salamander (Ambystoma mavortium) larvae (predators) and Wood Frog (Rana sylvatica) tadpoles (prey) to test this hypothesis and found the predators were attracted to alarm cues. This was even more apparent when the salamanders had prior experience with tadpole prey. When two salamanders were present, they rushed their attacks and were less accurate than when alone. This increased the chances of escape for tadpoles. We also found that the mere presence of visual and chemical cues from a second salamander caused enough of a distraction to increase tadpole survival. All together, their results support the Predator Attraction Hypothesis for the evolution of chemical alarm cues in tadpoles. (Written by Adam Crane)
Martof, B. S. (1963). ''Rana sylvatica (Le Conte). Wood Frog.'' Catalogue of American Amphibians and Reptiles. American Society of Ichthyologists and Herpetologists, 86.1-86.4.
Wiebler JM, Kohl KD, Lee Jr RE, Costanzo JP. (2018). ''Urea hydrolysis by gut bacteria in a hibernating frog: evidence for urea-nitrogen recycling in Amphibia.'' Proceedings of the Royal Society B, 285, 20180241.
Originally submitted by: Franziska Sandmeier (first posted 2001-02-21)
Edited by: Arie van der Meijden (2/28/2001), Michelle S. Koo (2023-01-01)
Species Account Citation: AmphibiaWeb 2023 Rana sylvatica: Wood Frog <https://amphibiaweb.org/species/5162> University of California, Berkeley, CA, USA. Accessed Sep 24, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Sep 2023.
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