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The gray tree frog or gray treefrog (''Hyla versicolor'') is a species of small arboreal frog native to much of the eastern United States and southeastern Canada.〔(NatureServe 'Hyla versicolor' )〕 It is sometimes referred to as the eastern gray tree frog, common gray tree frog, or tetraploid gray tree frog to distinguish it from its more southern, genetically disparate relative, the Cope's gray tree frog (''Hyla chrysoscelis''). It may sometimes be referred to as the North American tree frog by Europeans to distinguish it from their European tree frog (''Hyla arborea''). ==Description== As the scientific name implies, gray tree frogs 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. They can change from nearly black to nearly white. They change color at a slower rate than a chameleon. Dead gray tree frogs and ones in unnatural surroundings are predominantly gray. The female does not croak and has a white throat; however, the male does croak and has a black/gray throat. The female is usually larger than the male. They are relatively small compared to other North American frog species, typically attaining no more than . Their skin has a lumpy texture to it, giving them a warty appearance. They are virtually indistinguishable from the Cope's gray tree frog, ''H. chrysoscelis'', the only readily noticeable difference being that Cope's gray tree frog has a shorter, faster call. The gray tree frog also has 48 chromosomes (4n), and is called tetraploid gray tree frog in scientific circles. The Cope's gray tree frog, or diploid gray tree frog, 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. Both ''H. chrysoscelis'' and ''H. versicolor'' have bright-yellow patches on their hind legs, which distinguishes them from other tree frogs, such as ''H. avivoca''.〔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.〕 The bright patches are normally only visible while the frog is jumping. Both species of gray tree frogs are slightly sexually dimorphic. Males have black or gray throats, while the throats of the females are lighter.〔Thomas F. Tyning (1990). ''A Guide to Amphibians and Reptiles.'' Boston: Little, Brown and Company. ISBN 0-316-81719-8.〕 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. 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「gray tree frog」の詳細全文を読む スポンサード リンク
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