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Description

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Rana pipiens is a slim green or brownish frog, varying in length between about 5 and 11 cm. On its back it has dark rounds spots with pale borders. Its underside is white or cream colored. Spotting may be reduced or absent on young. The species has well-defined, continuous dorsolateral folds, which are not angled inward. The upper jaw has a white stripe. The male has a swollen, darkened thumb base and loose skin between jaw and shoulder during breeding season. Tadpoles are dark brown or olive to gray on top, often with gold spots. Their undersides are cream to whitish, light enough that intestines often show through (Stebbins 2003).See another account at californiaherps.com (http://www.californiaherps.com/frogs/pages/r.pipiens.html).This species was featured as News of the Week on 12 August 2019:Understanding the ways climate change may impact species survival is critical for conservation planning. Many amphibian species rely on ephemeral or semi-permanent water bodies for the egg and tadpole stage of their lifecycle. But what happens to amphibians when these ponds dry up faster than ever before? A group of researchers led by Laura Brannelly and Michel Ohmer (2019) recently published a study testing this question using the Northern Leopard Frog (Rana pipiens) grown in controlled, outdoor pools called mesocosms. They found that metamorphosed individuals reared in pools that dried faster were significantly smaller and had a reduced immune response, indicating a multidimensional negative impact of faster pond drying. It will be important to factor these findings into future predictions and planning for amphibians that rely on these vulnerable ephemeral habitats (Written by Allison Byrne).

References

  • Brodkin, M., Vatcnick, I., Simon, M., Hollyann, H., Butler-Holston, K., and Leonard, M. (2003). ''Effects of acid stress in adult Rana pipiens.'' Journal of Experimental Zoology, 298A(1), 16-22.
  • Gibbs, J. P. (2000). ''Wetland loss and biodiversity conservation.'' Conservation Biology, 14(1), 314-317.
  • Glennemeier, K. A. and Denver, R. J. (2001). ''Sublethal effects of chronic exposure to an organochlorine compound on northern leopard frog (Rana pipiens) tadpoles.'' Environmental Toxicology, 16(4), 287-297.
  • Hayes, T., Haston, K., Tsui, M., Hoang, A., Haeffele, C., and Vonk, A. (2002). ''The feminization of male frogs in the wild.'' Nature, 419, 895-896.
  • Hecnar, S. J. (1995). "Acute and chronic toxicity of ammonium nitrate fertilizer to amphibians from southern Ontario." Environmental Toxicology and Chemistry, 14(12), 2131-2137.
  • Lannoo, M. J., Lang, K., Waltz, T., and Phillips, G. S. (1994). "An altered amphibian assemblage: Dickinson County, Iowa, 70 years after Frank Blanchard's survey." American Midland Naturalist, 131(2), 311-319.
  • Linck, M. (2000). ''Reduction in road mortality in a northern leopard frog population.'' Journal of the Iowa Academy of Science, 107(3-4), 209-211.
  • Peterson, G., Johnson, L. B., Axler, R. P., and Diamond, S. A. (2002). ''Assessment of the risk of solar ultraviolet radiation to amphibians. II. In situ characterization of exposure in amphibian habitats.'' Environmental Science and Technology, 36(13), 2859-2865.
  • Schothoeffer, A. M., and Koehler, A. V., Meteyer, C. U., Cole, R. A. (2003). ''Influence of Ribeiroia ondatrae (Trematoda: Digenea) infection on limb development and survival of northern leopard frogs (Rana pipiens): Effects of host stage and parasite-exposure level.'' Canadian Journal of Zoology, 81(7), 1144-1153.

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Distribution and Habitat

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Rana pipiens is a wide-ranging species. It can be found across a broad swath of territory from the Hudson Bay south to northern Virginia, and to the west as far as southern British Columbia and eastern Washington and Oregon. In the west its range extends south through Utah, Colorado, New Mexico, and Arizona. It exists in scattered populations in some areas of California and Nevada, and has been introduced in other areas of California. In the western U.S. its range is now greatly fragmented and lacks confirmation in recent years. (Stebbins 2003). R. pipiens lives in a wide variety of habitats: grassland, brushland, and forest. It is the most cold-adapted of all the leopard frogs, and can be found up to an elevation of about 11,000 feet (Stebbins 2003). It can also be found in agricultural lands and in developed areas such as golf courses (Hayes et al. 2002). It prefers to live where there is a permanent body of standing or slowly flowing water, and among the aquatic vegetation of such places (Stebbins 2003).
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Life History, Abundance, Activity, and Special Behaviors

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R. pipiens faces a number of threats. One identified threat is chemical contamination, particularly from agricultural enterprises. One of the most extensively cited contaminants is the herbicide atrazine, the most commonly used herbicide in the United States and one of the most widely used throughout the world. The breeding season for R. pipiens follows the annual peak period for the application of atrazine in the U.S., and thus coincides with the annual peak of atrazine contamination of water sources (Hayes et al. 2002). In a laboratory study of the effects of water-borne atrazine on R. pipiens, Hayes et al. found that 10-92% of exposed males developed gonadal abnormalities such as retarded development and hermaphroditism. Hermaphroditism was also found in wild R. pipiens specimens collected in a transect from Utah to Iowa. The Hayes study found males with testicular oocytes in all areas where local atrazine sales exceeded .4 kilograms per square kilometer, and water-borne atrazine exceeded 2 parts per billion. It is believed that atrazine may induce the production of an enzyme that converts androgens into estrogens, and can cause males to produce estrogens at the expense of androgens. This would explain both the presence of oocytes and the inhibition of spermatogenesis. At one site in the Hayes study, a wild population exposed continuously to atrazine exhibited fewer abnormalities than a population exposed intermittently, leading to the suggestion that adaptive resistance may be occurring in the more frequently exposed populations. Atrazine is a significant threat to R. pipiens, and possibly to amphibians in general, because most water sources in the U.S., including rain, contain atrazine at higher levels than those needed to induce abnormalities in laboratory specimens (Hayes et al 2002). Another agriculture-related threat to R. pipiens is nitrate contamination of water sources. In a laboratory study, tadpoles of four amphibian species were exposed to levels of nitrate commonly exceeded in agricultural areas around the world. Effects varied across the species, but included reduced activity, lower rates of metamorphosis, and physical abnormalities (Hecnar 1995). Some environmental conditions do not directly cause death, but may induce behavior that increases the likelihood of predation by other species. Exposure to organochlorines, the remnants of such pollutants as DDT, has been suggested as a possible cause of population declines. While organochlorines do not appear to have the same dramatic effects on amphibians as they do on large animals such as predatory birds, exposure to these compounds does appear to induce behavior that might cause a population to decline. In a laboratory study, R. pipiens tadpoles exposed to organochlorines tended to spend more time resting and less time feeding, behavior that could reduce the ability of tadpoles’ to consume scarce resources. Organochlorines may also affect the production of certain hormones that help R. pipiens respond to local environmental changes such as pond drying. Most products that contain organochlorines are now banned, but their derivatives are common and persistent pollutants even today (Glennemeier et al. 2001). The decline of R. pipiens in areas where it used to thrive has also been attributed in recent years to infectious diseases, whose prevalence may be exacerbated by environmental stresses such as acidification (Brodkin et al. 2003). Acidification is a problem for this species because the breeding season, during which the frogs spend a great deal of time in the water, coincides with the highest levels of acidity in the lakes and streams of the northeastern United States. The breeding season also directly follows the period of winter hibernation, during which cold-exposure weakens the immune system of frogs. In a laboratory study by Brodkin et al., both the degree of cold exposure and the level of acidity to which frogs were exposed correlated to the health of the frogs’ immune systems. Frogs exposed to acid, and frogs exposed to acid after being exposed to cold, demonstrated higher levels of bacterial colonization of the spleen and higher rates of mortality. Brodkin et al. conclude that acidic conditions of pH 5.5 and below contribute to this contamination by: 1) damaging the intestinal epithelium, thereby allowing bacteria to pass from the intestinal tract to the bloodstream and spleen, and 2) reducing the number and viability of white blood cells. Cold exposure alone did not damage frogs’ immune systems, and pH levels of 6.0 or above, while damaging to the intestinal epithelium, were not sufficient to induce high levels of mortality. While it is fairly certain that acid exposure is a threat to R. pipiens, it is not clear why it has become a problem in the last twenty years or so (Brodkin et al. 2003). There has been a flurry of reports in recent years on the widespread prevalence of limb deformities among many species of frogs, even those in seemingly pristine environments. R. pipiens is one of the species most commonly reported to exhibit such deformities. A number of hypotheses have emerged to explain this trend. One suggestion is that increased exposure to ultraviolet light may be responsible, because ultraviolet light is known to cause damage to cellular DNA. The validity of the hypothesis when applied to conditions in the wild requires further study. Preliminary work has been done to assess how UVB light penetrates aquatic environments, and to determine what other environmental factors affect amphibians’ exposure to that light (Peterson et al. 2002). Another hypothesis suggests that environmental stresses have increased the vulnerability of amphibians to parasites such as trematodes (Schothoeffer et al. 2003). In a laboratory study of the interaction between R. pipiens tadpoles and the larvae of the trematode Ribeiroia ondatrae, infection of the frog tadpoles by R. ondatrae led to a number of different types of malformations. Depending on the stage of development at which the tadpole is infected and the intensity of the infection, the developing R. pipiens may develop extra limbs, digits, or phalanges; its limbs or digits may be smaller than normal; bones may bridge, skin may web, and the ilium may be reduced or misshapen. The timing of infection appeared to be crucial, as R. pipiens exhibits different levels of vulnerability as it develops. It appears to be most vulnerable at the larval stage, pre-limb bud stage, and limb bud stage. Infections at the paddle stage appear to have no effect on limb development. In addition to mortality due to limb malformations, infected tadpoles may also die as a result of the infections themselves. It is not yet known what environmental factors relate to the timing of infections, or what factors affect the length of amphibian larval periods and tadpole vulnerability (Schothoeffer et al. 2003). It is also possible that R. pipiens is suffering decline due to the type of fungal infections that have been found responsible for the decline of other species. The chytrid fungus Batrachochytrium dendrobatidis, for example, was found to cause oral abnormalities in the species Rana muscosa, a species in the Sierra Nevada that has drastically declined recently (Fellers et al. 2001). Introduced species may also be contributing to the decline of this species (Lannoo et al. 1994). A 1994 study investigated amphibian populations in Dickinson County, Iowa, and found that since a study of the same area in 1923, several populations had declined and two had disappeared. In Dickinson County around the year 1900, R. pipiens was collected and exported at a rate of about 20 million specimens per year. In their 1994 report, Lannoo et al. reported an estimated population of about 50,000 for Dickinson County. They cite the introduction of the common carp and predatory bullfrogs as a partial reason for the decline, in addition to disturbance and loss of habitat (Lannoo et al.). On the subject of habitat loss, James P. Gibbs reports that by the late 1980s, the lower 48 states had lost 53% of the wetlands that existed in the 1780s. Naturally, water-dependent species such as R. pipiens are negatively affected (Gibbs 2000). In a related matter, R. pipiens’ decline has been attributed to vehicular traffic, particularly in areas where wintering areas are separated from breeding areas by roads. The full extent of this risk has not been established (Linck 2000).
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Life History, Abundance, Activity, and Special Behaviors

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R. pipiens breeds from mid-March to early June (Stebbins 1985). Egg clusters are typically firm and globular, and 2-6 inches in diameter. They are usually attached to vegetation in the calm water of lakes, ponds, canals, and streams. A cluster can contain up to about 6,500 eggs (Stebbins 2003). The species has a snore-like call, interspersed with grunting and chuckling and lasting from 1 to 5 seconds. Choruses are a mixture of moaning, grunting, and chuckling. Individuals sometimes squawk when jumping into the water, and may scream if caught. (Stebbins 1985). R. pipiens may forage far from water in damp meadows. If frightened on land, it rushes toward water in a zigzag pattern of jumps. Specimens are most easily found at night by their eyeshine (Stebbins 1985).
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Relation to Humans

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Many of the threats to R. pipiens are human-induced. Human activity can directly damage the species, as in the case of declines due to vehicular traffic, and can also interfere with its life processes indirectly, as is likely the case where pollutants travel to seemingly pristine environments.
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Lifespan, longevity, and ageing

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Maximum longevity: 9 years (wild) Observations: In the wild, these animals may live up to 5 years (Smirina 1994).
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Habitat

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Leopard frogs are found in a wide variety of habitats, including marshlands, brushlands, and forests. They prefer the presence of permanent, slow-moving water, including aquatic vegetation, but can be found in agricultural areas and on golf courses. Leopard frogs are well-adapted to cold and can be found at elevations up to 3,350 meters. They are commonly known as meadow frogs or grass frogs because they tend to stray far from the water when it is not breeding season. They prefer open areas to woods.

Range elevation: 3350 (high) m.

Habitat Regions: temperate ; terrestrial ; freshwater

Terrestrial Biomes: savanna or grassland ; forest ; scrub forest

Aquatic Biomes: lakes and ponds

Wetlands: marsh

Other Habitat Features: agricultural ; riparian

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Associations

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Many predators take advantage of leopard frog prey. Adults are taken by fish (bass and pike), herons, green frogs, bullfrogs, garter snakes, water snakes, hawks, gulls, raccoons, foxes, mink, and otters, as well as other predators. Eggs are eaten by leeches, newts, and turtles. Tadpoles are preyed on by diving beetles, giant water bugs, dragongfly larvae, and most of the vertebrates that prey on adults.

Leopard frogs do not have distasteful skin secretions, they rely on their quick responses to leap into the water or make erratic hops to escape capture. Their coloration makes them blend into their surroundings when in vegetation. In areas where they co-occur with pickerel frogs (Lithobates palustris), leopard frogs have spots that are squarish, like those of pickerel frogs. Because pickerel frogs have distasteful skin secretions, it is thought that perhaps leopard frogs in those areas are mimicing pickerel frogs to avoid predation.

Known Predators:

  • bass (Micropterus)
  • pike (Esox)
  • herons (Ardeidae)
  • green frogs (Lithobates clamitans clamitans)
  • bullfrogs (Lithobates catesbeianus)
  • garter snakes (Thamnophis)
  • water snakes (Nerodia)
  • hawks (Accipitridae)
  • gulls Laridae
  • raccoons (Procyon lotor)
  • foxes (Vulpes vulpes)
  • mink (Neovison vison)
  • otters (Lontra canadensis)
  • leeches (Hirudinea)
  • newts (Salamandridae)
  • turtles (Testudines)
  • diving beetles (Dysticidae)
  • giant water bugs (Belostomatidae)
  • dragonfly larvae (Odonata)

Anti-predator Adaptations: mimic; cryptic

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Morphology

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Leopard frogs are from 5 to 11.1 cm long. They are green or greenish-brown dorsally, with round, brown spots arranged on their back, sides, and legs. These spots usually have a whitish or yellow border. There is a distinct, white dorso-lateral fold along the length of the back extending from each eye. A white line runs on either side of the mouth, from the nose to the shoulder. The underside is white or greenish white.

As with most frogs, males are smaller than females. Males have thickened thumb pads and paired vocal sacs that inflate over their shoulders as they call.

Tadpoles are greenish or brown, with yellow or black speckles frequently visible. The belly is white and somewhat transparent, with the intestinal coils visible through the skin. Tadpoles reach a maximum size of 8.4 cm.

Range length: 5 to 11.1 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger

Average mass: 29.0222 g.

Average basal metabolic rate: 0.00576 W.

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Life Expectancy

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Leopard frogs may live up to 9 years in the wild, although very few leopard frogs will live for this long. Most mortality occurs as a tadpole or newly transformed froglet, when as many as 95% will die.

Range lifespan
Status: wild:
9 (high) years.

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Distribution

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Leopard frogs are found throughout much of North America, from as far north as the Hudson Bay, along the eastern seaboard to northern Virginia and west to British Columbia, eastern Washington, and Oregon. The western part of the range extends as far south as New Mexico, Arizona, Colorado, Utah, and portions of California and Nevada. Populations in the west are fragmented and some are declining.

Biogeographic Regions: nearctic (Native )

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Trophic Strategy

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Leopard frog tadpoles are mainly herbivorous, eating algae, diatoms, and small animal matter filtered from the water or scraped from surfaces. Once they metamorphose into a frog, leopard frogs eat terrestrial invertebrates, including spiders, insects and their larvae, slugs, snails, and earthworms. Large adults may also eat small vertebrates, such as smaller frogs (spring peepers, Pseudacris crucifer, and chorus frogs, Pseudacris triseriata).

Animal Foods: amphibians; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms

Plant Foods: algae

Other Foods: detritus

Primary Diet: carnivore (Insectivore , Molluscivore )

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Associations

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Leopard frogs are important predators of their invertebrate prey and eggs and adults can act as important food sources for small to medium-sized predators.

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Benefits

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Leopard frogs are eaten by humans (frog legs), and are used as test subjects in many biomedical research projects, both as adults and as tadpoles. Leopard frogs are also taken for use in biology classrooms. Leopard frogs are valuable members of the ecosystems in which they live, controlling invertebrate pests and acting as an important food source to larger predators. They may also act as indicator species for environmental health and water quality.

Positive Impacts: food ; research and education; controls pest population

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Benefits

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There are no negative impacts of leopard frogs on humans.

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Life Cycle

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The small, black and white eggs are laid in clusters and attached to submerged vegetation. When Leopard frog eggs are laid they are roughly 1.7 mm in diameter, but swell to 5 mm when they come in contact with water. Clusters of eggs may act to increase heat absorption by the mass or to protect some eggs from predation. Hatching occurs after 1 to 3 weeks, varying with water temperature, and metamorphosis occurs after 70 to 110 days as a tadpole. Froglets are 2 to 3 cm long at metamorphosis.

Development - Life Cycle: metamorphosis

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Conservation Status

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Leopard frogs were once common and widespread throughout much of North America. However, some populations have experienced serious declines. In the Great Lakes area, leopard frogs were abundant through the 1970's, after which they experienced a population decline. They remain uncommon in this area, although they can be locally abundant. In the western states, the status of many leopard frog populations remains unstudied. Leopard frogs, along with many other frog species, are at risk of poisoning by pesticides, including atrazine and organochlorines, herbicides, such as nitrates, and other water contaminants. Atrazine has been demonstrated to induce reproductive abnormalities in frogs at levels lower than are found in most North American water sources. Infectious diseases may also pose a significant threat to leopard frogs. Susceptibility to infectious diseases may be exacerbated by water acidification, lowering leopard frog immune responses. Introduced species, including bullfrogs (Lithobates catesbeianus) and common carp (Cyprinus carpio carpio), may be contributing to declining numbers of leopard frogs as well, as they prey extensively on young and adults. Leopard frogs are extensively collected in some areas for use in classrooms, laboratories, and as bait, devastating local populations. Finally, leopard frogs, and other freshwater aquatic species, are at risk because of extensive freshwater habitat loss in North America, estimated at 53% of wetlands lost in the 1980's since 1780.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Behavior

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Leopard frogs use calls to attract mates during breeding season. Male advertisement calls are described as sounding like a low, rumbling snore with occasional clicks and croaks. Males and non-receptive females will give a chuckle-like "release" call when clasped by a male hoping to mate. Outside of breeding season there is little need to communicate with conspecifics. They may scream loudly when they have been seized by a predator or squawk as they jump to avoid a predator. Frogs in general are quite sensitive to movement in detecting prey visually.

Communication Channels: tactile ; acoustic

Perception Channels: visual ; tactile ; acoustic

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Untitled

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"Burnsi" morph leopard frogs are rare color variants that are uniformly brownish green on their back and legs, lacking the spots found on most individuals.

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Reproduction

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Leopard frogs gather at communal breeding ponds in the spring, where males call to attract females. If successful, a male will hold a female in "amplexus", using his specialized thumbs, and fertilize her eggs as they leave her body. Mating pairs may move to an area of the pond where other pairs have laid their eggs before they add their own.

Mating System: polygynandrous (promiscuous)

Mating occurs from March to June, but peaks in April. Females lay from 300 to 6500 eggs in globular clusters in breeding ponds. After metamorphosis, sexual maturity is reached in 1 to 3 years, depending on conditions.

Breeding interval: Leopard frogs breed once yearly.

Breeding season: Leopard frogs breed from March to June.

Range number of offspring: 300 to 6500.

Range age at sexual or reproductive maturity (female): 1 to 3 years.

Range age at sexual or reproductive maturity (male): 1 to 3 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Most parental investment occurs prior to fertilization. Females will provide the eggs with nourishment to grow and will attempt to attach them to underwater vegetation in a tight cluster, after which the eggs are left to develop on their own.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female)

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Dewey, T. 1999. "Lithobates pipiens" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lithobates_pipiens.html
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Brief Summary

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Slim green or brownish, with well-defined, pale-bordered, oval or round dark spots on back, white to cream below. White stripe on upper jaw. Well-defined, pale dorsolateral folds that are continuous and not angled inward. Voice is a low 'motorboat' or snore-like sound interspersed with grunting and chuckling, lasting about 1-5 seconds. Choruses are a medley of moaning, grunting, and chuckling that suggests the sounds made by rubbing a well-inflated rubber balloon. Paired vocal sacs expand over the forelimbs" (Stebbins 1985). There is usually one spot on the head anterior to the eyes. Few or no tubercules on the dorsal and lateral body surface. Mean SVL in males is 68.3 mm (2.7 in) and in females 74.2 mm (2.92 in). The eardrum is without a light center. During breeding season the males have a swollen, darkened thumb base and loose skin between the jaw and the shoulder. Males are usually smaller in size. The tadpole has coarse indistinct mottling on the tail. The distal half of the tail tends to darken approaching metamorphosis. Color variations include the Burnsi variant, which may be found in either brown or green and does not have any dorsal spots. It has spots or bars on the limbs and may have black stippling on the back and sides. The second variant Kandiyohi, is brown with dashes of white and brown or black. The spots on the back and legs are still discernable, as well as the dorsolateral fold (LeClere). Found in a variety of habitats, most cold-adapted of all leopard frogs. May forage far from water, when frightened seeks water in a zigzag pattern of jumps. Like most frogs, leopard frogs are sluggish animals, often staying immobile for long periods of time. Sometimes the males call while underwater. They produce a low-pitched snore often followed by a chuckling noise, or a deep urr, urr, urr. They have internal vocal sacs, so their throats do not appear to move when they call. When they move far from a body of water they may absorb dew to keep moist. Hibernates in deep water. Juvenile leopard frogs often cluster together. Consumes small invertebrates; rarely eats small vertebrates. Larvae eat algae, plant tissue, organic debris, and probably small invertebrates (TNC 1988).

Northern leopard frog

provided by wikipedia EN

Lithobates pipiens[1][2][3][4] or Rana pipiens,[5][6] commonly known as the northern leopard frog, is a species of leopard frog from the true frog family, native to parts of Canada and the United States. It is the state amphibian of Minnesota and Vermont.

Description

Young northern leopard frog

The northern leopard frog is a fairly large species of frog, reaching about 11 cm (4.3 in) in snout-to-vent length. It varies from green to brown in dorsal color, with large, dark, circular spots on its back, sides, and legs.[7] Each spot is normally bordered by a lighter ring. A pair of dorsolateral folds starting from the back of the eye runs parallel to each other down the back. These dorsolateral folds are often lighter or occasionally pinkish in colour. Also, a pale stripe runs from the nostril, under the eye and tympanum, terminating at the shoulder. The ventral surface is white or pale green. The iris is golden and toes are webbed.

Tadpoles are dark brown or grey, with light blotches on the underside. The tail is pale tan.

Color variations

Two burnsi morphs, a green morph, and a brown morph of the northern leopard frog
Brown morph northern leopard frog in a wood chip pile in Iowa

The northern leopard frog has several different color variations, with the most common two being the green and the brown morphs, with another morph known as the burnsi morph. Individuals with the burnsi morph coloration lack spots on their backs, but may or may not retain them on their legs. They can be bright green or brown and have yellow dorsal folds.[8] Albinism also appears in this species, but is very rare.

Ecology and behavior

Northern leopard frogs have a wide range of habitats. They are found in permanent ponds, swamps, marshes, and slow-moving streams throughout forest, open, and urban areas.[9] They normally inhabit water bodies with abundant aquatic vegetation. In the summer, they often abandon ponds and move to grassy areas and lawns. They are well adapted to cold and can be found above 3,000 m (9,800 ft) above mean sea level. Males make a short, snore-like call from water during spring and summer. The northern leopard frog breeds in the spring (March–June). Up to 6500 eggs are laid in water, and tadpoles complete development within the breeding pond. Tadpoles are light brown with black spots, and development takes 70–110 days, depending on conditions. Metamorph frogs are 2–3 cm (0.79–1.18 in) long and resemble the adult.

This species was once quite common through parts of western Canada and the United States until declines started occurring during the 1970s. Although the definitive cause of this decline is unknown, habitat loss and fragmentation, environmental contaminants, introduced fish, drought, and disease have been proposed as mechanisms of decline and are likely preventing species' recovery in many areas.[7] Many populations of northern leopard frogs have not yet recovered from these declines.

Northern leopard frogs are preyed upon by many different animals, such as snakes, raccoons, other frogs, and even humans. They do not produce distasteful skin secretions and rely on speed to evade predation.

They eat a wide variety of animals, including crickets, flies, worms, and smaller frogs. Using their large mouths, they can even swallow birds and garter snakes. In one case, a bat was recorded as prey of this frog.[10] This species is similar to the pickerel frog (Lithobates palustris) and the southern leopard frog (Lithobates sphenocephalus).

Research

Medical

The northern leopard frog produces specific ribonucleases to its oocytes. Those enzymes are potential drugs for cancer. One such molecule, called ranpirnase (onconase), is in clinical trials as a treatment for pleural mesothelioma and lung tumors. Another, amphinase, has been described as a potential treatment for brain tumors.[11]

Neuroscience

The northern leopard frog has been a preferred species for making discoveries about basic properties of neurons since the 1950s. The neuromuscular junction of the sciatic nerve fibers of the sartorius muscle of this frog has been the source of initial data about the nervous system.[12][13][14][15][16][17][18]

Muscle physiology and biomechanics

The northern leopard frog is a popular species for in vitro experiments in muscle physiology and biomechanics due to the ease of accessibility for investigators in its native range and the ability of the sartorius muscle to stay alive in vitro for several hours. Furthermore, the reliance of the frog on two major modes of locomotion (jumping and swimming) allows for understanding how muscle properties contribute to organismal performance in each of these modes.

Range

Northern leopard frogs occur from Great Slave Lake and Hudson Bay, Canada, south to Kentucky and New Mexico, USA.[19][20] It is also found in Panama, where it is endemic to the central cordillera and western Pacific lowlands, although this is most likely an undescribed species.[1] They occupy grasslands, lakeshores, and marshes.

See also

References

  1. ^ a b c IUCN SSC Amphibian Specialist Group (2022). "Lithobates pipiens". IUCN Red List of Threatened Species. 2022: e.T79079800A3072377. Retrieved 14 December 2022.
  2. ^ Frost, Darrel (2011). "American Museum of Natural History: Amphibian Species of the World 5.5, an Online Reference". Herpetology. The American Museum of Natural History. Retrieved 2013-02-17.
  3. ^ Frost, D.-R.; et al. (2009). "Response to the Point Of View of Gregory B. Pauly, David M. Hillis, and David C. Cannatella, by the Anuran Subcommittee of the SSRA/HL/ASIH Scientific and Standard English Names List". Herpetologica. 65 (2): 136–153. doi:10.1655/09-009R1.1. S2CID 55147982.
  4. ^ Integrated Taxonomic Information System [Internet] 2012. Lithobates pipiens [updated 2012 Sept; cited 2012 Dec 26] Available from: www.itis.gov/
  5. ^ Hillis & Wilcox (2005), Hillis (2007), Stuart (2008), Pauly et al. (2009), AmphibiaWeb (2016)
  6. ^ Yuan, Z.-Y.; et al. (2016). "Spatiotemporal diversification of the true frogs (genus Rana): A historical framework for a widely studied group of model organisms". Systematic Biology. 65 (5): 824–42. doi:10.1093/sysbio/syw055. PMID 27288482.
  7. ^ a b Northern Leopard Frog Rana pipiens, National Geographic. Retrieved 2015-03-28
  8. ^ "Northern Leopard Frog Rana pipens". HerpNet. Retrieved 2013-10-30.
  9. ^ Northern Leopard Frog (Lithobates pipiens), Nevada Fish and Wildlife Office. Retrieved 2015-03-28.
  10. ^ Mikula, P (2015). "Fish and amphibians as bat predators". European Journal of Ecology. 1 (1): 71–80. doi:10.1515/eje-2015-0010.
  11. ^ Frog molecule could provide drug treatment for brain tumors
  12. ^ Fatt, P; Katz, B (1952). "Spontaneous subthreshold activity at motor nerve endings". The Journal of Physiology. 117 (1): 109–28. doi:10.1113/jphysiol.1952.sp004735. PMC 1392564. PMID 14946732.
  13. ^ Del Castillo, J; Katz, B (1954). "Quantal components of the end-plate potential". The Journal of Physiology. 124 (3): 560–73. doi:10.1113/jphysiol.1954.sp005129. PMC 1366292. PMID 13175199.
  14. ^ Lettvin, J.Y.; Maturana, H.R.; McCulloch, W.S.; Pitts, W.H. (1959). "What the Frog's Eye Tells the Frog's Brain". Proceedings of the IRE. 47 (11): 1940–51. doi:10.1109/JRPROC.1959.287207. S2CID 8739509.
  15. ^ Katz, B; Miledi, R (1965). "The Measurement of Synaptic Delay, and the Time Course of Acetylcholine Release at the Neuromuscular Junction". Proceedings of the Royal Society of London. Series B. 161 (985): 483–95. Bibcode:1965RSPSB.161..483K. doi:10.1098/rspb.1965.0016. PMID 14278409. S2CID 8663912.
  16. ^ Kuffler, SW; Yoshikami, D (1975). "The number of transmitter molecules in a quantum: An estimate from iontophoretic application of acetylcholine at the neuromuscular synapse". The Journal of Physiology. 251 (2): 465–82. doi:10.1113/jphysiol.1975.sp011103. PMC 1348438. PMID 171380.
  17. ^ Hille, B (1967). "The selective inhibition of delayed potassium currents in nerve by tetraethylammonium ion". The Journal of General Physiology. 50 (5): 1287–302. doi:10.1085/jgp.50.5.1287. PMC 2225709. PMID 6033586.
  18. ^ Anderson, CR; Stevens, CF (1973). "Voltage clamp analysis of acetylcholine produced end-plate current fluctuations at frog neuromuscular junction". The Journal of Physiology. 235 (3): 655–91. doi:10.1113/jphysiol.1973.sp010410. PMC 1350786. PMID 4543940.
  19. ^ Stebbins, R.C. (1985). A Field Guide to Western Reptiles and Amphibians. Second Edition. Houghton Mifflin Company, Boston, Massachusetts.
  20. ^ Conant, R. and Collins, J.T. (1991). A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Third Edition. Houghton Mifflin Company, Boston, Massachusetts.
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Northern leopard frog: Brief Summary

provided by wikipedia EN

Lithobates pipiens or Rana pipiens, commonly known as the northern leopard frog, is a species of leopard frog from the true frog family, native to parts of Canada and the United States. It is the state amphibian of Minnesota and Vermont.

license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN