Painted turtle
| Painted turtle Temporal range: 15–0 Ma Neogene–recent[1] |
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| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Testudines |
| Family: | Emydidae |
| Subfamily: | Deirochelyinae |
| Genus: | Chrysemys Gray, 1844 |
| Species: | C. picta |
| Binomial name | |
| Chrysemys picta (Schneider, 1783) |
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| Subspecies | |
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C. p. bellii[2] |
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| Synonyms[5] | |
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Species synonymy[3]
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The painted turtle (Chrysemys picta) is the most widespread native turtle of North America. It lives in slow-moving fresh waters, from southern Canada to Louisiana and northern Mexico, and from the Atlantic to the Pacific. The turtle is the only species of the genus Chrysemys, which is part of the pond turtle family Emydidae. Fossils show that the painted turtle existed 15 million years ago. Four regionally based subspecies (the eastern, midland, southern, and western) evolved during the last ice age.
The adult painted turtle female is 10–25 cm (4–10 in) long; the male is smaller. The turtle's top shell is smooth and oval without a keel (ridge). Its skin is olive to black with red, orange, or yellow stripes on its extremities. The subspecies can be distinguished by their shells: the eastern has straight-aligned top shell segments; the midland has a large gray mark on the bottom shell; the southern has a red line on the top shell; the western has a red pattern on the bottom shell.
The turtle eats aquatic vegetation, algae, and small water creatures including insects, crustaceans, and fish. Although they are frequently consumed as eggs or hatchlings by rodents, canines, and snakes, the adult turtles' hard shells protect them from most predators. Reliant on warmth from its surroundings, the painted turtle is active only during the day when it basks for hours on logs or rocks. During winter, the turtle hibernates, usually in the muddy bottoms of waterways. The turtles mate in spring and autumn. Females dig nests on land and lay eggs between late spring and mid-summer. Hatched turtles grow until sexual maturity: 2–9 years for males, 6–16 for females.
In the traditional tales of Algonquian tribes, the colorful turtle played the part of a trickster. In modern times, four U.S. states have named the painted turtle their official reptile. Habitat loss and road killings have reduced the turtle's population, but its ability to live in human-disturbed settings has helped it remain the most abundant turtle in North America. Adults in the wild can live for more than 55 years.
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Taxonomy and evolution
The painted turtle (C. picta) is the only species in the genus Chrysemys.[4] The parent family for Chrysemys is Emydidae: the pond turtles. Emydidae is split into two sub families; Chrysemys is part of the Deirochelyinae (Western Hemisphere) branch.[6] The four subspecies of the painted turtle are the eastern (C. p. picta), midland (C. p. marginata), southern (C. p. dorsalis), and western (C. p. bellii).[7]
The painted turtle's generic name is derived from the Ancient Greek words for "gold" (chryso) and "freshwater tortoise" (emys); the species name originates from the Latin for "colored" (pictus).[8] The subspecies name, marginata, derives from the Latin for "border" and refers to the red markings on the outer (marginal) part of the upper shell; dorsalis is from the Latin for "back", referring to the prominent dorsal stripe; and bellii honors zoologist Thomas Bell, a collaborator of Charles Darwin.[9] An alternate East Coast common name for the painted turtle is "skilpot", from the Dutch for turtle, schildpad.[10]
Classification
Originally described in 1783 by Johann Gottlob Schneider as Testudo picta,[4][11] the painted turtle was called Chrysemys picta first by John Edward Gray in 1855. The four subspecies were then recognized: the eastern by Schneider in 1783,[11][12] the western by Gray in 1831,[12][13] and the midland and southern by Louis Agassiz in 1857.[14][15]
Until the 1930s many of the subspecies of the painted turtle were labeled by biologists as full species within Chrysemys, but this varied by the researcher. The painted turtles in the border region between the western and midland subspecies were sometimes considered a full species, treleasei. In 1931, Bishop and Schmidt defined the current "four in one" taxonomy of species and subspecies. Based on comparative measurements of turtles from throughout the range, they subordinated species to subspecies and eliminated treleasei.[16]
Since at least 1958,[17][nb 2] the subspecies were thought to have evolved in response to geographic isolation during the last ice age, 100,000 to 11,000 years ago.[18] At that time painted turtles were divided into three different populations: eastern painted turtles along the southeastern Atlantic coast; southern painted turtles around the southern Mississippi River; and western painted turtles in the southwestern United States.[19] The populations were not completely isolated for sufficiently long, hence wholly different species never evolved. When the glaciers retreated, about 11,000 years ago, all three subspecies moved north. The western and southern subspecies met in Missouri and hybridized to produce the midland painted turtle, which then moved east and north through the Ohio and Tennessee river basins.[17][19]
Biologists have long debated the genera of closely related subfamily-mates Chrysemys, Pseudemys (cooters), and Trachemys (sliders). After 1952, some combined Pseudemys and Chrysemys because of similar appearance.[20] In 1964, based on measurements of the skull and feet, Samuel B. McDowell proposed all three genera be merged into one. However, further measurements, in 1967, contradicted this taxonomic arrangement. Also in 1967, J. Alan Holman,[21] a paleontologist and herpetologist, pointed out that, although the three turtles were often found together in nature and had similar mating patterns, they did not crossbreed. In the 1980s, studies of turtles' cell structures, biochemistries, and parasites further indicated that Chrysemys, Pseudemys, and Trachemys should remain in separate genera.[22]
David E. Starkey and collaborators advanced a new view of the subspecies in 2003. Based on a study of the mitochondrial DNA, they rejected the glacial development theory and argued that the southern painted turtle should be elevated to a separate species, C. dorsalis, while the other subspecies should be collapsed into one and not differentiated.[24] However, this proposition was largely unrecognized because successful breeding between all subspecies was documented wherever they overlapped.[12][25] Nevertheless, in 2010, the IUCN recognized both C. dorsalis and C. p. dorsalis as valid names for the southern painted turtle.[2]
DNA
The turtle's karyotype (nuclear DNA, rather than mitochondrial DNA) consists of 50 chromosomes, the same number as the rest of its subfamily-mates and the most common number for Emydidae turtles in general.[26][27][28] Less well-related turtles have from 26 to 66 chromosomes.[29] Little systematic study of variations of the painted turtle's karotype among populations has been done.[30] (However, in 1967, research on protein structure of offshore island populations in New England, showed differences from mainland turtles.[31])
Comparison of subspecies chromosomal DNA has been discussed, to help address the debate over Starkey's proposed taxonomy, but as of 2009 had not been reported.[30][32] Interestingly, the complete sequencing of the genetic code for the painted turtle was at a "draft assembed" state in 2010. The turtle was one of two reptiles chosen to be first sequenced.[33]
Fossils
Although its evolutionary history—what the forerunner to the species was and how the close relatives branched off—is not well understood, the painted turtle is common in the fossil record.[34] The oldest samples, found in Nebraska, date to about 15 million years ago. Fossils from 15 million to about 5 million years ago are restricted to the Nebraska-Kansas area, but more recent fossils are gradually more widely distributed. Fossils newer than 300,000 years old are found in almost all the United States and southern Canada.[1]
Description
The painted turtle's shell is 10–25 cm (4–10 in) long, oval, smooth, and flat-bottomed.[35][nb 3][36][26] The color of the top shell (carapace) varies from olive to black, allowing the turtle to blend in with its surroundings. The bottom shell (plastron) is yellow, sometimes red, sometimes with dark markings in the center. Similar to the top shell, the turtle's skin is olive to black, but with red and yellow stripes on its neck, legs, and tail.[37][38] As with other pond turtles, such as the bog turtle, the painted turtle's feet are webbed to aid swimming.[39][40][41]
The head of the turtle is distinctive. The face has only yellow stripes, with a large yellow spot and streak behind each eye, and on the chin two wide yellow stripes that meet at the tip of the jaw.[35][26][37] The turtle's upper jaw is shaped into an inverted "V" (philtrum), with a downward-facing, tooth-like projection on each side.[42]
The hatchling has a proportionally larger head, eyes, and tail, and a more circular shell than the adult.[43][44] The adult female is generally longer than the male, 10–25 cm (4–10 in) versus 7–15 cm (3–6 in).[37][45] For a given length, the female has a higher (more rounded, less flat) top shell.[46] The female weighs around 500 g (18 oz) on average, against the males' average adult weight of roughly 300 g (11 oz).[47] The female's greater body volume supports her egg-production.[48] The male has longer foreclaws and a longer, thicker tail, with the anus (cloaca) located further out on the tail.[35][36][26][49]
Subspecies
Although the subspecies may hybridize (intergrade), especially at range boundaries,[50] they are distinct within the hearts of their ranges.[51]
- The male eastern painted turtle (C. p. picta) is 13–17 cm (5–7 in) long, while the female is 14–17 cm (6–7 in). The upper shell is olive green to black and may possess a pale stripe down the middle and red markings on the periphery. The segments (scutes) of the top shell have pale leading edges and occur in straight rows across the back, unlike all other North American turtles, including the other three subspecies of painted turtle, which have alternating segments.[51] The bottom shell is plain yellow or lightly spotted.[52]
- The midland painted turtle (C. p. marginata) is 10–25 cm (4–10 in) long.[53] The centrally located midland is the hardest to distinguish from the other three subspecies.[51] Its bottom shell has a characteristic symmetrical dark shadow in the center which varies in size and prominence.[19]
- The southern painted turtle (C. p. dorsalis), the smallest subspecies, is 10–14 cm (4–6 in) long.[54] Its top stripe is a prominent red,[51] and its bottom shell is tan and spotless or nearly so.[55]
- The largest subspecies is the western painted turtle (C. p. bellii), which grows up to 25 cm (10 in) long.[56] Its top shell has a mesh-like pattern of light lines,[18] and the top stripe present in other subspecies is missing or faint. Its bottom shell has a large colored splotch that spreads to the edges (further than the midland) and often has red hues.[18]
| Eastern painted turtle C. p. picta |
Midland painted turtle C. p. marginata |
Southern painted turtle C. p. dorsalis |
Western painted turtle C. p. bellii |
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Distribution
Range
The most widespread North American turtle,[57] the painted turtle is the only turtle whose native range extends from the Atlantic to the Pacific.[nb 4] It is native to eight of Canada's ten provinces, forty-five of the fifty United States, and one of Mexico's thirty-one states. On the East Coast, it lives from the Canadian Maritimes to the U.S. state of Georgia. On the West Coast, it lives in British Columbia, Washington, and Oregon and offshore on southeast Vancouver Island.[nb 5] The northernmost American turtle,[59] its range includes much of southern Canada. To the south, its range reaches the U.S. Gulf Coast in Louisiana and Alabama. In the southwestern United States there are only dispersed populations. It is found in one river in extreme northern Mexico. It is absent in a part of southwestern Virginia and the adjacent states as well as in north-central Alabama.[18][58][60]
| Native range of the painted turtle (C. picta) Dark grey for national borders White for state and province borders Dark blue for rivers, only showing those in article |
Eastern (C. p. picta)
Midland (C. p. marginata)
Southern (C. p. dorsalis)
Western (C. p. bellii)
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Intergrade mixtures (large areas only) Mix of eastern and midland
Mix of eastern and southern
Mix of midland and western
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The borders between the four subspecies are not sharp, because the subspecies interbreed. Many studies have been performed in the border regions to assess the intermediate turtles, usually by comparing the anatomical features of hybrids that result from intergradation of the classical subspecies.[nb 6] Despite the imprecision, the subspecies are assigned nominal ranges.
Eastern painted turtle
The eastern painted turtle ranges from southeastern Canada to Georgia with a western boundary at approximately the Appalachians. At its northern extremes, the turtle tends to be restricted to the warmer areas closer to the Atlantic Ocean. It is uncommon in far north New Hampshire and in Maine is common only in a strip about 50 miles from the coast.[65][66] In Canada, it lives in New Brunswick and Nova Scotia but not in Quebec or Prince Edward Island. To the south it is not found in the coastal lowlands of southern North Carolina, South Carolina, or Georgia, or in southern Georgia in general or at all in Florida. [18][58][67][68]
The eastern subspecies's range extends slightly into east central Alabama, where it intergrades with the southern subspecies.[58] In the northeast, there is extensive mixing with the midland subspecies, and some writers have called these turtles a "hybrid swarm".[17][69][70] In the southeast, the border between the eastern and midland is more sharp as mountain chains separate the subspecies to different drainage basins.[58][71]
Midland painted turtle
The midland painted turtle lives from southern Ontario and Quebec, through the eastern U.S. Midwest states, to Kentucky, Tennessee and northwestern Alabama, where it intergrades with the southern painted turtle.[72] It also is found eastward through West Virginia, western Maryland and Pennsylvania. The midland painted turtle appears to be moving east, especially in Pennsylvania.[73] To the northeast it is found in western New York and much of Vermont, and it intergrades extensively with the eastern subspecies.[55][58]
Southern painted turtle
The southern painted turtle ranges from extreme southern Illinois and Missouri, roughly along the Mississippi River valley, to the south. In Arkansas, it branches out to the west towards Texas, where it is found in the far northeast part of that state (Caddo Lake region)[74] as well as extreme southeastern Oklahoma (McCurtain County).[75] It is found in much of Louisiana, where it reaches the Gulf of Mexico (in fresh water). Eastward it is found in western Tennessee, northern Mississippi and much of Alabama, including the Gulf Coast city of Mobile[18][58][68] An isolated population in central Texas has been reported but is now believed to be non-native.[76]
Western painted turtle
The western painted turtle's northern range includes southern parts of western Canada from Ontario to Manitoba, Saskatchewan, Alberta and British Columbia. In Ontario, the western subspecies is found north of Minnesota and directly north of Lake Superior, but there is a 130 km (80 mi) gap to the east of Lake Superior (in the area of harshest winter climate) where no painted turtles of any subspecies occur. Thus Ontario's western subspecies does not intergrade with the midland painted turtle of southeastern Ontario.[62] In Manitoba, the turtle is numerous and ranges north to Lake Manitoba and the lower part of Lake Winnipeg. The turtle is also common in south Saskatchewan, but in Alberta, there may only be 100 individuals, all found very near the U.S. border, mostly in the southeast. In British Columbia, populations exist in the interior in the vicinity of the Kootenai, Columbia, Okanagan, and Thompson river valleys. At the British Columbia coast, turtles occur near the mouth of the Fraser and a bit further north, as well as the bottom of Vancouver Island, and some other nearby islands. Within British Columbia, the turtle's range is not continuous and can better be understood as northward extensions of the range from the United States; high mountains present barriers to east-west movement of the turtles within the province or from Alberta. Some literature has shown isolated populations much further north in Alberta and British Columbia, but these were probably pet-releases.[18][58][77][78]
In the United States, the western subspecies forms a wide intergrade area with the midland subspecies covering much of Illinois as well as a strip of Wisconsin along Lake Michigan and part of the Upper Peninsula of Michigan (UP). Further west, the rest of Illinois, Wisconsin and the UP are part of the range proper, as are all of Minnesota and Iowa, as well as all of Missouri except a narrow strip in the south. All of North Dakota is within range, all of South Dakota except a very small area in the west, and all of Nebraska. Almost all of Kansas is in range; the border of that state with Oklahoma is roughly the species range border, but the turtle is found in three counties of north central Oklahoma.[18][58][75][77]
To the northwest, almost all of Montana is in range. Only a narrow strip in the west, along most of the Idaho border (which is at the Continental Divide) lacks turtles.[79] Wyoming is almost entirely out of range; only the lower elevation areas near the eastern and northern borders have painted turtles.[80] In Idaho, the turtles are found in the far north (upper half of the Idaho Panhandle), as well as separate populations in S.W. Idaho in the Payette River, and S.E. Idaho near St. Anthony. .[81] In Washington state, turtles are common throughout the state within lower elevation river valleys.[82][83] In Oregon, the turtle is native to the northern part of the state throughout the Columbia River valley as well as the Willamette River valley north of Salem.[18][77][84]
To the southwest, the painted turtle's range is fragmented. In Colorado, while range is continuous in the eastern, prairie, half of the state, it is absent in most of the western, mountainous, part of the state. However, the turtle is confirmed present in the lower elevation southwest part of the state (Archuleta and La Plata counties), where a population ranges into northern New Mexico in the San Juan River basin. There are also some unconfirmed sightings in parts of the far west of the state (e.g. Mesa County).[85] In New Mexico, the main distribution follows the Rio Grande and the Pecos River, two waterways that run in a north-south direction through the state.[86] Within the aforementioned rivers, it is also found in the northern part of Far West Texas.[74] In Utah, the painted turtle lives in an area to the south (Kane County) in streams draining into the Colorado River, although it is disputed if they are native.[77][87][88] In Arizona, the painted turtle is native to an area in the east, Lyman Lake.[89][90] The painted turtle is not native to Nevada or California.[18][77]
In Mexico,[86] painted turtles have been found about 50 miles south of New Mexico near Galeana in the state of Chihuahua. There, two expeditions[91][92] found the turtles in the Rio Santa Maria which is in a closed basin.[18][77]
Human-introduced range
Pet releases are starting to establish the painted turtle outside its native range. In California, it is an invasive species that endangers the local western pond turtle, although competition from similarly released red-eared sliders is a greater threat.[93] It has also been introduced into waterways near Phoenix, Arizona,[89] and Miami, Florida,[94] and to Germany, Indonesia, the Philippines, and Spain.[2]
Habitat
To thrive, painted turtles need fresh waters with soft bottoms, basking sites, and aquatic vegetation. They find their homes in shallow waters with slow-moving currents, such as creeks, marshes, ponds, and the shores of lakes. The subspecies have evolved different habitat preferences.[95]
- The eastern painted turtle is very aquatic, leaving the immediate vicinity of its water body only when forced by drought to migrate.[96] Along the Atlantic, painted turtles have appeared in brackish waters.[95]
- The midland and southern painted turtles seek especially quiet waters, usually shores and coves. They favor shallows that contain dense vegetation and have an unusual toleration of pollution.[54][97]
- The western painted turtle lives in streams and lakes, similar to the other painted turtles, but also inhabits pasture ponds and roadside pools. It is found as high as 1,800 m (5,900 ft).