Gray treefrog | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Amphibia |
Order: | Anura |
Family: | Hylidae |
Genus: | Dryophytes |
Species: | D. versicolor |
Binomial name | |
Dryophytes versicolor (LeConte, 1825) | |
Range of D. versicolor | |
Synonyms | |
Hyla versicolorLeConte, 1825 |
The gray treefrog (Dryophytes versicolor) is a species of small arboreal holarctic tree frog native to much of the eastern United States and southeastern Canada. [2]
It is sometimes referred to as the eastern gray treefrog, northern gray treefrog, [3] common gray treefrog, or tetraploid gray treefrog to distinguish it from its more southern, genetically distinct relative, Cope's gray treefrog.
As the scientific name implies, gray treefrogs are variable in color. This ability to vary their color provides them with the ability to camouflage themselves from gray to green or brown, depending on the environment around them. D. versicolor can change from nearly black to nearly white. They change color at a slower rate than a chameleon. A unique aspect of the appearance of gray treefrogs is that its legs feature a dark band-like pattern which then contrast sharply with the black-marked bright yellow or orange under the sides of its legs and arms. Dead gray treefrogs and ones in unnatural surroundings are predominantly gray. The female does not call; however, the male does call. Female gray treefrogs are usually larger than their male counterparts. They are relatively small compared to other North American frog species, typically attaining no more than 1.5 to 2 in (3.8 to 5.1 cm) in length. Their skin has a lumpy texture to it, giving them a warty appearance.
This species is virtually indistinguishable from Cope's gray treefrog, the only readily noticeable difference being that Cope's Gray treefrog has a shorter, faster call. This varies depending on the temperature, however, as the call rates of both gray treefrogs are temperature dependent. At lower temperatures, Cope's gray treefrog can have a call rate approximating that of the gray treefrog. [4] This difference in calling can be heard, but it is best quantified by counting the number of pulses per second in their whistled trills. At usual temperatures, the gray treefrog has a pulse rate of 16 to 34 pulses per second, while Cope's gray treefrog has a pulse rate of 34 to 60 pulses per second. Even though there is potential for overlap, because of the temperature dependence of the pulse frequency the two species are easily distinguished where they occur together. At a given temperature, the pulse frequency for the gray treefrog is approximately one-half that of Cope's gray treefrog. [5]
The gray treefrog also has 48 chromosomes (4n), and is sometimes referred to as the tetraploid gray treefrog in scientific literature. Cope's gray treefrog, or diploid gray treefrog, retained its 2n (24) original chromosome count. Hybridization between these species results in early mortality of many larvae, some individuals survive to adulthood, but these individuals suffer from reduced fertility. [6]
Both of these similar species have bright-yellow patches on their hind legs, which distinguishes them from other treefrogs, such as the bird-voiced tree frog. [7] The bright patches are normally only visible while the frog is jumping. Both species of gray treefrogs are slightly sexually dimorphic. Males have black or gray throats, while the throats of the females are lighter. [8]
Tadpoles have rounded bodies (as opposed to the more elongated bodies of stream species) with high, wide tails that can be colored red if predators are in the system. [9] Metamorphosis can occur as quickly as two months with optimal conditions. During metamorphosis, the new froglets will almost always turn green for a day or two before changing to the more common gray. Young frogs will also sometimes maintain a light green color, only turning gray or darker green once adulthood is reached.
Gray treefrogs inhabit a wide geographic range, and can be found in most of the eastern half of the United States and as far west as central Texas and Oklahoma. They also range into Canada in the provinces of Quebec, [10] Ontario, and Manitoba, with an isolated population in New Brunswick.
The gray treefrog is capable of surviving freezing of its internal body fluids to temperatures as low as −8 °C (18 °F). [11]
The gray treefrog is most common in forested areas, as it is highly arboreal. Its calls are often heard in rural residential areas of the East Coast and the Midwest. It prefers to breed in semipermanent woodland ponds without fish, but it also lays eggs in swamps, vernal pools, man-made fountains and water gardens, and even in rainwater-filled swimming pool covers.[ citation needed ]
Male gray treefrogs rarely have large choruses, as they are mostly solitary animals, but might vocalize competitively at the height of breeding periods. Gray treefrogs have been observed to congregate around windows and porch lights to eat insects that are attracted to the light. Insect larvae, mites, spiders, plant lice, harvestmen, and snails also contribute towards the diet of the gray treefrog. [12] Some populations have a diet high in ants and beetles. [13] However, like most frogs, D. versicolor is opportunistic and may also eat smaller frogs, including other treefrogs. [12] During the day, they often rest on horizontal tree branches or leaves out in the open. Gray treefrogs have also been observed to lay out in the direct sun. Gray tree frogs are less prone to overheating and desiccation than other amphibians and rely on their superb camouflage to hide them from predators.[ citation needed ]
Research on anuran communication reveals that groups of male frog chorus attract female frogs to mate. The relative success of these male frogs, including D. versicolor males, at attracting females depends on how their advertisement call is able to lead females to their calling space. As male density increases, a male's advertisement call is confused with the other calls. This confusion leads to the inability of females to accurately locate the origin of the call. The lowest intensity of a neighbor's call that a male frog is tolerant of is known as the aggressive threshold. When this threshold is reached, a male frog will use a different call known as an aggressive call to initiate male-male conflict or intolerance. [14]
Aggressive calls are usually much shorter in length and have lower frequencies than advertisement calls. Aggressive calls specifically in D. versicolor males also do not show much variation in amplitude throughout the call, unlike advertisement calls which contain many pulses. This is very unique to the D. versicolor species since most species with graded aggressive calls have advertisement and aggressive calls with very similar structures. They are similar in that they both have two peak frequencies, but the aggressive call peak frequencies are usually lower. [15] [16]
Since females do not prefer call overlap between males in a close range of each other, this can cause a change in call-timing as well as a change in the characteristics of the calls these males produce. [17] [18] When there are other male frogs calling, H. versicolor males will adjust the timing of their calls; however, this is done in a much less strict fashion than most frog species. Compared to other species, H. versicolor does not exhibit selective attention. Selective attention is the phenomenon observed in many chorusing male frog species to change the timing of their calls to reduce overlap based on their loudest one or two neighboring male competitors, while ignoring the timing of other calls farther away. [19] Instead, H. versicolor males will avoid call overlap when paired with only one other male, but will not actively avoid overlap with adjacent frogs in a group nearly as much as other frog species do. [19] In response to increased competition, males can change the timing of their calls, but also change the characteristics of their calls. As surrounding competition increases, males will increase the length of their advertisement calls, but produce those calls less often since each call requires more energy to produce. But call amplitude and call frequency do not change as the amount of surrounding competition changes. [18]
When males get closer and there is infiltration of each others territories, there are increased chances of aggressive encounters. This results in males engaging in conflict with one another through aggressive calls. The timing of these aggressive calls changes as distance from the intended recipient varies. [17]
Conflict between two D. versicolor males will begin with trading advertisement calls between each other. Even though advertisement calls are primarily used to attract females, they still play a role in male-male interactions. Rarely the conflict escalates from this point and transitions into the exchange of aggressive calls and only in few cases will conflict result in physical contact. [15] [16]
Unlike most species, D. versicolor females do not prefer leading calls, but do prefer leading pulses if there is call overlap between male calls. Overall, females prefer the lack of call overlap. However, increasing the distance between males producing overlapping calls may reduce the cost that usually causes females to not choose those potential mates. The distance between the males allows the female to distinguish calls opposed to overlapping calls produced from very close points that make two individual males harder to distinguish by sound. This means that H. versicolor males are not as forced to make specific timed-call responses and initiations to increase mate attractiveness compared to other chorus anurans and insects. Instead, H. versicolor males can allow call-timing to be more dependent on other things, like the social environment and male competition. [17]
D. versicolor females are not usually attracted to aggressive calls no matter the range of aggressive frequency it is produced in, but may occasionally still be attracted to aggressive calls. Females also exhibit no preference within the range of advertisement call frequencies, they generally prefer advertisement calls over aggressive ones. There is a range in the advertisement and aggressive call frequencies because H. versicolor males are capable of producing certain frequencies based on their size and properties of their vocal structures. [15] [16]
Females are more attracted to longer male calls, which is also supported by their preference for advertisement calls over any aggressive call. [18] Aggressive calls from nearby males do not reduce the attractiveness of advertisement calls from a given other male. [20]
Male frogs will change their vocalizations when female frogs move closer to them. They do this in order to increase the likelihood that their advertisement call is received by a female over the other noise and vocalizations that could obscure it. D. versicolor males specifically do this by increasing the length of their calls to several lengths of a normal advertisement call. [19] Males will also lengthen the duration of their calls when they see a female or sense them through touch. Females will initiate the mating position by touching the male frog resulting in the male frog vocalizing one or two especially long calls, known as courting calls. [18]
D. versicolor males are known to follow a similar pattern that is seen in other species termed graded aggressive calling. Compared to aggressive calls, H. versicolor male aggressive calls are a lower frequency than advertisement calls. However, they decrease the frequency of their aggressive calls as the aggressiveness with another male rises. This gradient in frequencies allows their calls to efficiently balance energy costs of calling and when intense calling is necessary during male-male conflict. The energetic cost of producing vocalizations increases if there is any shift from a male's individual natural frequency. That being said, there is more of an energetic cost for low frequency and frequency decreasing calls than higher frequency ones, so this could be an explanation for why these types of calls are usually reserved for the most intense conflict. [15] [16]
Graded aggressive calling and a lower need to avoid call overlap allows D. versicolor males to have more freedom in the types of calls they produce. More freedom in call-timing also allows D. versicolor males to use advertisement call-overlap to signal the beginning of rising levels of aggressiveness between two males. Increasing overlapping calls can also be a response to an increase in the level of male competition or might simply be because call overlap increases as males communicate with each other for a longer period of time. For the same reason why males respond with call overlap in areas with the most acoustic competition, males in high density call choruses also produce the highest levels of overlapping calls with male frogs closest to them. [17]
Male aggressive calling not only is affected by mating and their need to defend their calling space but is also affected by social communication with other aggressive males. [21] The social environment can change as male callers move around and as females arrive to assess their potential mates producing different levels of perceived male competition heard by D. versicolor males. [17] In particular, the social environment surrounding a male responding to an intruder will affect the intensity of the responding aggressive calls produced. This idea of a social environment affecting aggressive call output arose in this frog species from research that examined the relationship between aggressive call intensity in environments with an intruder versus and environment with other surrounding male competitors. With that being said, the effect of the social environment is more complex and requires further research. [21] There are effects of other male competition on a male's advertisement call timing in the gray tree frog. As males get closer to another males calling space, they become more aggravated by another male infiltrating their calling space. This results in males engaging in conflict with one another through aggressive calls and the timing of these calls changes when the intended recipient is within close range. [17]
Dryophytes versicolor is known to be largely intersterile with D. chrysoscelis but there may be a limited amount of interfertility in sympatry. When D. versicolor is sympatric with D. chrysoscelis, females more strongly weight a species-specific cue (call rate) than a more general cue (call duration) when choosing mates. [22] This appears to be an example of reproductive character displacement to keep the species separate. In addition, to enforce speciation there may be unknown mechanisms of reinforcement deployed between these species and further research may be fruitful. [23]
Dryophytes versicolor and Dryophytes chrysoscelis call next to each other ponds resulting in interference of their vocalizations because their calls are so similar acoustically. In response to male advertisement calls, D. versicolor male answers with the same level of aggressiveness to males of the same species and to D. chrysoscelis males producing the initial call. D. versicolor male interactions with D. chrysoscelis males increase in aggressive intensity more quickly than with male interactions with their own species. Once the aggression levels intensified between these species, the weaker frog was more likely to retreat from the winner. In general, D. versicolor males initiate physical attacks during intense vocal conflict between the two species more often than D. chrysoscelis.
In previous studies, D. versicolor mate attractiveness decreases when there is call overlap with D. chrysoscelis. The D. versicolor mate attractiveness decreases even more so than D. chrysoscelis when there is call overlap, which can explain why the D. versicolor male tends to initiate aggressive physical contact more often: the D. versicolor has more to lose from the call overlap continuing to take place. While the advertisement calls of D. versicolor and D. chrysoscelis are distinguishable, the aggressive calls between these two species are similar. [24]
The spring peeper is a small chorus frog widespread throughout the eastern United States and Canada. It prefers permanent ponds due to its advantage in avoiding predation; however, it is very adaptable with respect to the habitat it can live in. In northern regions, the frog is able to endure below freezing temperatures due to the capacity of its liver to exude and flush the bloodstream with a glucose cryoprotectant which acts both as an anti-freeze in its blood, and allows organs like the heart to enter into a state of protected dormancy. The peeper earned its name from its chirping call, which marks the beginning of spring. Crucifer is derived from the Latin root meaning "cross-bearing", a reference to the cross-like pattern on the spring peeper's dorsal side.
Hylidae is a wide-ranging family of frogs commonly referred to as "tree frogs and their allies". However, the hylids include a diversity of frog species, many of which do not live in trees, but are terrestrial or semiaquatic.
Hyla is a genus of frogs in the tree frog family Hylidae. As traditionally defined, it was a wastebasket genus with more than 300 species found in Europe, Asia, Africa, and across the Americas. After a major revision of the family, most of these have been moved to other genera so that Hyla now only contains 17 extant (living) species from Europe, northern Africa and Asia. The earliest known fossil member of this genus is †Hyla swanstoni from the Eocene of Saskatchewan, Canada, but its designation to Hyla happened before the major revision, meaning that its position needs confirmation.
The American green tree frog is a common arboreal species of New World tree frog belonging to the family Hylidae. This nocturnal insectivore is moderately sized and has a bright green to reddish-brown coloration. Commonly found in the central and southeastern United States, the frog lives in open canopy forests with permanent water sources and abundant vegetation. The American green tree frog is strictly aquatic during the hibernating and mating seasons. When defending its territory, the frog either emits aggressive call signals or resolves to grapple with intruders, seldom leading to injury or death. To avoid predation, the frog will leap into the water or jump into the treetops.
Hyla japonica, commonly known as the Japanese tree frog, is a species of anuran native to Japan, China, and Korea. H. japonica is unique in its ability to withstand extreme cold, with some individuals showing cold resistance at temperatures as low as −30 °C for up to 120 days. H. japonica are not currently facing any notable risk of extinction and are classified by the IUCN as a species of "least concern". Notably, H. japonica have been sent to space in a study that explored the effect of microgravity on H. japonica. Hyla japonica is synonymous with Dryophytes japonicus.
Cope's gray treefrog is a species of treefrog found in the United States and Canada. It is almost indistinguishable from the gray treefrog, and shares much of its geographic range. Both species are variable in color, mottled gray to gray-green, resembling the bark of trees. These are treefrogs of woodland habitats, though they will sometimes travel into more open areas to reach a breeding pond. The only readily noticeable difference between the two species is the mating call — Cope's has a faster-paced and slightly higher-pitched call than D. versicolor. In addition, D. chrysoscelis is reported to be slightly smaller, more arboreal, and more tolerant of dry conditions than D. versicolor.
Dryophytes gratiosus, commonly known as the barking tree frog, is a species of tree frog endemic to the south-eastern United States. Formerly known as Hyla gratiosa.
Anomaloglossus beebei is a species of frog in the family Aromobatidae. This frog is endemic to Guyana, specifically in the Kaieteur National Park. It mainly survives on the giant bromeliad called Brocchinia micrantha. The phytotelmata of this bromeliad is the site of oviposition and tadpole rearing and are defended over time by the males. The females of this species are more brightly golden coloured whereas males are more of a dull tan with brown pigmentation. Males take care of offspring and are preferred due to the elongation of their calls.
Dendropsophus ebraccatus, also known as the hourglass treefrog, referring to the golden-brown hourglass shape seen surrounded by skin yellow on its back. Their underbellies are yellow. Their arms and lower legs usually display bold patterns while their upper legs or thighs are light yellow giving them the appearance of wearing no pants. The species name "ebraccata" translates to "without trousers" in Latin.
The pine woods tree frog is a species of frog in the family Hylidae, endemic to the southeastern United States.
The Italian tree frog is a species of frog in the family Hylidae, found in Italy, Slovenia, Switzerland, and possibly San Marino. Its natural habitats are temperate forests, rivers, intermittent rivers, freshwater marshes, intermittent freshwater marshes, arable land, and urban areas. It is threatened by habitat loss.
Rosenberg's treefrog, also known as Rosenberg's gladiator frog or Rosenberg's gladiator treefrog, is a species of frog in the family of tree frogs (Hylidae) and genus of gladiator frogs (Boana) found in Costa Rica, Panama, Colombia, Trinidad and Tobago and north-western Ecuador. Its scientific name is a testimony to Mr. W. F. H. Rosenberg who collected the type series, and its common name refers to the aggressiveness of males of the species.
The Panama cross-banded tree frog or pug-nosed tree frog is a species of frog in the family Hylidae found in the humid Pacific lowlands of southwestern Costa Rica to eastern Panama and in the Caribbean lowlands of Panama and northern Colombia. Males of the species utilize synchronous calling to hide their position from predators. Females create basins during amplexus and deposit fertilized eggs onto the surface of the water.
Frogs and toads produce a rich variety of sounds, calls, and songs during their courtship and mating rituals. The callers, usually males, make stereotyped sounds in order to advertise their location, their mating readiness and their willingness to defend their territory; listeners respond to the calls by return calling, by approach, and by going silent. These responses have been shown to be important for species recognition, mate assessment, and localization. Beginning with the pioneering experiments of Robert Capranica in the 1930s using playback techniques with normal and synthetic calls, behavioral biologists and neurobiologists have teamed up to use frogs and toads as a model system for understanding the auditory function and evolution. It is now considered an important example of the neural basis of animal behavior, because of the simplicity of the sounds, the relative ease with which neurophysiological recordings can be made from the auditory nerve, and the reliability of localization behavior. Acoustic communication is essential for the frog's survival in both territorial defense and in localization and attraction of mates. Sounds from frogs travel through the air, through water, and through the substrate. Frogs and toads largely ignore sounds that are not conspecific calls or those of predators, with only louder noises startling the animals. Even then, unless major vibration is included, they usually do not take any action unless the source has been visually identified. The neural basis of communication and audition gives insights into the science of sound applied to human communication.
A tree frog is any species of frog that spends a major portion of its lifespan in trees, known as an arboreal state. Several lineages of frogs among the Neobatrachia suborder have given rise to treefrogs, although they are not closely related to each other.
A mating call is the auditory signal used by animals to attract mates. It can occur in males or females, but literature is abundantly favored toward researching mating calls in females. In addition, mating calls are often the subject of mate choice, in which the preferences of one gender for a certain type of mating call can drive sexual selection in a species. This can result in sympatric speciation of some animals, where two species diverge from each other while living in the same environment.
Sexual selection in amphibians involves sexual selection processes in amphibians, including frogs, salamanders and newts. Prolonged breeders, the majority of frog species, have breeding seasons at regular intervals where male-male competition occurs with males arriving at the waters edge first in large number and producing a wide range of vocalizations, with variations in depth of calls the speed of calls and other complex behaviours to attract mates. The fittest males will have the deepest croaks and the best territories, with females making their mate choices at least partly based on the males depth of croaking. This has led to sexual dimorphism, with females being larger than males in 90% of species, males in 10% and males fighting for groups of females.
Dryophytes is a genus of Ameroasian tree frogs in the family Hylidae. They are found mostly in North America, but the genus also includes three species found in eastern Asia.
Reproductive interference is the interaction between individuals of different species during mate acquisition that leads to a reduction of fitness in one or more of the individuals involved. The interactions occur when individuals make mistakes or are unable to recognise their own species, labelled as ‘incomplete species recognition'. Reproductive interference has been found within a variety of taxa, including insects, mammals, birds, amphibians, marine organisms, and plants.
Dryophytes suweonensis, the Suweon treefrog or Suwon treefrog, is a species of frog in the family Hylidae endemic to the Korean Peninsula probably from the Imjin River to the Mangyeong River, south of Iksan. Its distribution and population have been assessed to be below 800 individuals and the status of the species has been updated as Endangered by the IUCN. The natural habitat of the species has been generally transformed into rice fields and it is threatened by habitat loss.