| 词条 | Gray tree frog |
| 释义 |
|name = Gray treefrog |image = Hyla versicolor.jpg |image_caption = |status = LC |status_system = IUCN3.1 |status_ref = [1] |genus = Hyla |species = versicolor |authority = LeConte, 1825 }} The gray treefrog (Hyla versicolor) is a species of small arboreal frog native to much of the eastern United States and southeastern Canada.[2] It is sometimes referred to as the eastern gray treefrog, common gray treefrog, or tetraploid gray treefrog to distinguish it from its more southern, genetically disparate relative, the Cope's gray treefrog (Hyla chrysoscelis). It may sometimes be referred to as the North American treefrog by Europeans to distinguish it from their European treefrog (Hyla arborea). DescriptionAs the scientific name implies, gray treefrogs are variable in color owing to their ability to camouflage themselves from gray to green, depending on the substrate where they are sitting. The degree of mottling varies.[3] They can change from nearly black to nearly white. They change color at a slower rate than a chameleon. Dead gray treefrogs and ones in unnatural surroundings are predominantly gray. The female does not call and has a white throat; however, the male does call and can show a black/gray/brown throat during the breeding season. The female is usually larger than the male. They are relatively small compared to other North American frog species, typically attaining no more than {{convert|1.5|to|2|in|cm|abbr=on}}. Their skin has a lumpy texture to it, giving them a warty appearance. This species is virtually indistinguishable from the Cope's gray treefrog, H. chrysoscelis, the only readily noticeable difference being that Cope's Gray Treefrog has a shorter, faster call. However, the call rates of both gray treefrogs are temperature dependent and at lower temperatures Hyla chrysoscelis can have a call rate approximating that of Hyla versicolor.[4] The difference in call can be heard, but it is best quantified by counting the number of pulses per second in their whistled trills. Hyla versicolor has a pulse rate of 16-34 pulses per second while Hyla chrysoscelis has a pulse rate of 34-60 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 Hyla versicolor is approximately 1/2 that of Hyla chrysoscelis.[5] The gray treefrog also has 48 chromosomes (4n), and is called tetraploid gray treefrog in scientific circles. The 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, but some individuals survive to adulthood though they have reduced fertility.[6] Both H. chrysoscelis and H. versicolor have bright-yellow patches on their hind legs, which distinguishes them from other treefrogs, such as H. avivoca.[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. At 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 and turn gray or darker green after reaching adulthood. Distribution and habitatGray treefrogs inhabit a wide range, and can be found in most of the eastern half of the United States, 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 their internal body fluids to temperatures as low as -8 °C.[11] The gray treefrog is most common in forested areas, as it is highly arboreal. Their calls are often heard in rural residential areas of the East Coast and the Midwest. They prefer to breed in semipermanent woodland ponds without fish, but also lay eggs in swamps, vernal pools, man- made fountains and water gardens, and even in rainwater filled swimming pool covers.{{citation needed|date=August 2014}} BehaviorThese frogs rarely ever descend from high treetops except for breeding. They are strictly nocturnal. Male gray tree frogs rarely have large choruses, as they are mostly solitary animals, but might vocalize competitively at the height of breeding periods. Gray treefrogs may congregate around windows and porch lights to eat insects that are attracted to the light. During the day they often rest on horizontal tree branches or leaves out in the open, even in the sun. Evidently they are less prone to overheating and desiccation than other amphibians and rely on their superb camouflage to hide them from predators.{{citation needed|date=August 2014}} BreedingMating calls and chorusing are most frequent at night, but individuals often call during daytime in response to thunder or other loud noises. In captivitySee American green treefrog References1. ^{{IUCN2014.3|assessor= IUCN SSC Amphibian Specialist Group|year=2014|id=55687|title=Hyla versicolor|downloaded=2015-01-17}} 2. ^NatureServe 'Hyla versicolor' 3. ^{{cite journal|author=Mary Hoff|title=Chirp, Croak, Snore|publisher=Minnesota Conservation Volunteer|work=DNR|date=March–April 2014|page=32}} 4. ^{{cite journal|author1=Carl Gerhardt |author2=John A. Doherty |date=1988|title=Acoustic communication in the gray treefrog, 'Hyla versicolor': evolutionary and neurobiological implications|journal=J. Comp. Physiol. A|volume=162|issue=2|pages=261–278|doi= 10.1007/BF00606090|url=http://www.springerlink.com/content/n7216jh0285155w2/}} 5. ^http://frogcalls.blogspot.com/2016/03/gray-treefrogs-hyla-versicolor-vs-hyla_29.html 6. ^{{cite journal|author1=H. Carl Gerhardt |author2=Margaret B. Ptacek |author3=Louise Barnett |author4=Kenneth G. Torke |date=1994|title=Hybridization in the Diploid-Tetraploid Treefrogs Hyla chrysoscelis and Hyla versicolor|journal=Copeia|volume=1994|issue=1|pages=51–59|jstor=1446670|doi=10.2307/1446670}} 7. ^Bernard S. Martof et al. (1980). "Amphibians and Reptiles of the Carolinas and Virginia". Chapel Hill: University of North Carolina Press. {{ISBN|0-8078-4252-4}}. 8. ^Thomas F. Tyning (1990). A Guide to Amphibians and Reptiles. Boston: Little, Brown and Company. {{ISBN|0-316-81719-8}}. 9. ^{{Cite journal|last=McCollum|first=S.|date=12 May 2017|title=Costs and benefits of a predator-induced polyphenism in the gray treefrog Hyla chrysoscelis.|jstor=2410833|journal=Evolution|volume=50|pages=583–593|doi=10.2307/2410833}} 10. ^Quebec range map, Quebec Biodiversity website 11. ^Adaptations of Frogs to Survive Freezing
External links{{Commons category|Hyla versicolor}}{{Wikispecies|Hyla versicolor}}
11 : Hyla|Cryozoa|Amphibians of Canada|Amphibians of the United States|Fauna of the Eastern United States|Fauna of the Northeastern United States|Fauna of the Plains-Midwest (United States)|Animals that can change color|Articles containing video clips|Extant Pleistocene first appearances|Amphibians described in 1825 |
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