Taxonomy
''Lithobates clamitans'' is a member of the true frog family Ranidae and genus Lithobates. Litho- meaning stone, a rock climber. Originally from genusSubspecies
The two recognizedDescription
This species is a mid-sizedHabitat and Distribution
Green frogs are associated with bodies of water and have been found in a variety of habitats, living at the margins of shallow freshwater ponds, road-side ditches, lakes, swamps, and streams, and ofHabitat Loss
Due to increasing destruction of their habitat, deforestation, climate change, diseases, and chemical contaminants, amphibian population decline and extinctions may be as high as 211 times the background extinction rate. Both water and air temperatures play a major role in timing and rates of breeding, larval development, time-to-time metamorphosis, size-at-metamorphosis, growth, and physiological parameters. There is experimental data present that details how organisms are more sensitive to contaminants when there is variation in temperature, which explains how chemical contamination can greatly impact the development of these frogs.Diet
Green frogs will attempt to eat any mouth-sized animal they can capture, including insects, spiders, fish, crayfish, shrimp, other frogs, tadpoles, small snakes, slugs, and snails. Green frogs practice "sit and wait" hunting and therefore eat whatever comes within reach. Tadpoles will eat nearly anything organic, including diatoms, algae, and tiny amounts of small animals such as zooplankton (copepods and cladocerans).Reproduction
Males become sexually mature at one year, females may mature in either two or three years. Males will establish breeding territories and maintain them throughout the entirety of the breeding period, with the season occurring from spring through summer, with variations depending on location and temperature. During this breeding period, an egg clutch consisting of 1000 to 7000 eggs is laid in surface films about 15–30 cm in diameter and are attached to vegetation in shallow water in order to protect the eggs from predators. Females may sometimes lay two clutches of eggs in a single season, with their size reaching a maximum of 98–105 mm. Females who were ready to mate typically came into male territories and assumed a low posture to demonstrate the clear power difference between the two (the lower posture emphasizes their subordination as does the fact that they come to the males once ready to mate). However, females did still exhibit selection when choosing a male as the process of choosing a mate typically took 2 to 3 days. In this case, females tend to favor males who exhibit territoriality and have strong mating calls (the basis for this is selfish as it lies in the female’s desire for the greatest reproductive success and the best traits to be passed down to their children). Once a female was a few centimeters in front of the male, she would back her body into his and once physical contact was reached, the males would clasp the females and fertilization would begin. There are several instances where females will not be clasped due to the stimuli which initiateHome Range and Territoriality
Regarding territoriality, males will often physically wrestle with one another in order to defend their territory.Wells, K. D. (2004, December 16). Territoriality in the green frog (Rana clamitans): Vocalizations and agonistic behaviour. Animal Behaviour. Retrieved October 14, 2022 Resident male frogs would also create loud splashing noises by jumping up and down in the water or by sitting in one place and rapidly kicking his hind legs. This act of both jumping up and down and creating a distinct noise serves many different purposes. Firstly, males would leap high out of the water to patrol their territory borders in order to locate intruders, and would then proceed to make a loud splashing noise to both mark their territory and scare off intruders. These splashing displays were also performed in response to intruders entering their territories and by victorious males pursuing their opponents once again emphasizing another form in which these frogs maintain their dominance.Meshaka Jr, W. E., & Hughes, D. F. (n.d.). Collinsorum 3 1 - ksherp.com. Retrieved October 14, 2022 If both the advertisement calls and acts of splashing did not deter the intruder, then more aggressive acts were performed by the resident male. The resident male would retaliate by jumping at the frog and chasing him away or attacking the intruder and immediately clasping him around the head, waist, or one leg. While most attacks were directed towards males in an act of defending territory, some attacks were directed towards females. This is due to the fact that resident males cannot visually see the difference between females and males and therefore might mistake a female going through his territory as an intruder male. This results in females adopting a similar position to the satellite males when traversing through a resident male’s territory. Most interactions among the males of this species involve splashing and vocalizations to scare off intruders or satellite males. However, once there were two males who would present equal competition to one another thereby creating real contests for possession of lands, wrestling bouts ensued. In the beginning, two males would approach one another in high posture demonstrating the equal status between the two. Once these frogs were only a few centimeters apart, they would tip their heads at an angle which would expose their bright yellow throat to the opponent. Soon after, the wrestling would begin and each frog would jump, swim, or splash at each other to attempt to secure a strong hold on the opponent. Eventually, once each frog clasped the other around the pectoral region, they would engage in a pushing contest until the other fell on its back. Once the frog fell, the dominant frog would hold his opponent under water and squeeze him until they admit defeat and free themselves from the hold.Behavior
Vocalizations
To emphasize their territory during breeding season, males advertise their positions with vocalizations and exhibit aggressive behavior including chases and jump attacks. Males have four main vocalizations used to maintain their territories. The first type of call is the advertisement call, which functions to advertise a male’s position to other males and to prospective mates. The distinctive call sounds like a plucked loose banjo string, usually given as a single note, but sometimes repeated. Many studies show that aggressive behavior is evoked from other male frogs in response to this call. The second type of call is similar to the first but is more urgent. This call is used in response to a disturbance in the territory. It is thought to demonstrate dominance because it is often given by the winners of wrestling bouts when chasing the losers out of their territories. The third type of call is often directed towards others in an agonistic encounter. It is usually the first call produced when a frog’s territory has been invaded and while the male approaches the intruder. Consequently, this call antagonizes more aggressive behavior since there were often physical bouts between the intruder and owner of the territory. This is different from the second type of call, because the second call serves as more of a warning call while this call meant that violence would follow. Finally, the fourth type of call is produced during wrestling bouts and given by the male that is winning the fight. Additionally, there is also a fifth call type that both males and females use which serves as a release call when an individual is clasped by another frog. For males, it was released when they were losing wrestling bouts, while for females, it was released both when non-gravid females were being clasped by males and when females were ready to be released after completing oviposition. Both the females and losing males releasing the same call emphasizes the fact that males without territory or males who lost to other males are seen as weaker and subordinate in this species.Movement and Posture
Males often move from territory to territory since they occupy several different territories to increase their mating appeal to females. Males that do not have a territory for the breeding season often move into other males’ territory and become satellite males. Satellite males use these new territories to intercept females who are responding to the call of territory owners, demonstrating a type of sexual coercion. In contrast, females did not exhibit any particularly aggressive interactions since they normally spent the day hiding in vegetation while at night they foraged for resources. Males demonstrating territorial behavior often presented different postures emphasizing different aspects of their physical appearance when compared to satellite males. Territorial males maintain a high posture, with the lungs inflated and only the lower parts of the limbs under water. These frogs tilt their head at a certain angle to allow their bright yellow throat to be exposed which is an act of presenting dominance and marking their own territory. They maintain this posture throughout the entire day (calling time or not). In contrast, satellite males assume a low posture with only the top of the head and eyes above the water’s surface. Since their main focus is to steal the territory from the dominant male when he leaves to go to his other territories, the satellite males assume a more sneaky position since they will often stalk the resident male and move cautiously through the territory. This low position also decreases the chances of the satellite male being attacked by the resident male since they were seen as being subordinate/below the resident male.Predation and Enemies
Due to their environment being so dependent on water, pathogens, predators, and other deadly problems often trouble the Green Frog. The fungal pathogen ''Anti-Predatory Measures
Green Frogs have also developed certain anti-predatory measures in order to survive. One example of an anti-predatory measure developed by several different organisms is the use of chemical cues. Chemicals are released by predators and prey throughout the entire duration of a predation event thereby allowing the prey to detect the presence of predators through chemicals subconsciously released by the predators. Several research studies have demonstrated that aquatic prey tend to avoid chemical cues as their form of an anti-predatory measure. Specifically for the tadpoles of the Green Frog, they reacted with spatial anti-predator behavior (distancing themselves from the chemical cues), when only exposed to both Anax kairomones and conspecific alarm cues together. Experimenters hypothesize that presence of both of these cues are needed because the costs of fleeing their habitat may result in a massive loss of foraging opportunities. If they choose to respond to a certain cue that is not strong or reliable, then they are losing a vast amount of resources. Thus, when they choose to demonstrate spatial avoidance, there must be multiple chemical cues present in order for the benefits to outweigh the risks. Typically, when encountering predators, animals tend to develop anti-predator traits in order to promote reproductive success. Consequently, these traits will be passed down throughout generations until the predator develops a new trait to counteract this measure thereby creating an arms race between the predator and the prey. Another consequence of this type of evolution is subsets of a species developing new traits due to the different exposure of predators due to their different environments (diverging evolution). Regarding the Bronze Frog (which is a subspecies of the Green Frog), when present in ponds inhabited by invertebrate predators, the tadpoles may develop small bodies and large tail muscles in order to increase fast-start locomotor performance to escape from their predators. Consequently, the presence of fish and invertebrate predators plays a large role in size, shape, and swimming performance of the tadpoles of the Green Frog. As a result, this can lead to some morphological differences between the subspecies within the Green Frog, which highlights divergent natural selection and adaptiveExternal links
Footnotes
References
* Database entry includes a range map and justification for why this species is of least concern. * 1801. ''In:'' (1801). ''Histoire naturelle des reptiles, avec figures desinées d'après nature; Tome II. Première partie. Quadrupèdes et bipèdes ovipares'' Natural History of the Reptiles, with Figures Drawn from Nature; Volume 2. First Part. Oviparous Quadrupeds and Bipeds Paris: Deterville. 332 pp. (''Rana clamitans'', new species, pp. 157–158). (in French). {{Taxonbar, from=Q4667968 clamitans Amphibians of North America Amphibians of the United States Fauna of the Eastern United States Taxa named by Pierre André Latreille Amphibians described in 1801