Camas pocket gopher
Camas pocket gopher | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Rodentia |
Family: | Geomyidae |
Genus: | Thomomys |
Subgenus: | Megascapheus
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Species: | T. bulbivorus
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Binomial name | |
Thomomys bulbivorus (Richardson, 1829)
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Distribution of the camas pocket gopher in the Willamette Valley of northwest Oregon | |
Synonyms[2] | |
List
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The camas pocket gopher (Thomomys bulbivorus), also known as the camas rat or Willamette Valley gopher, is a
Although the camas pocket gopher is fiercely defensive when cornered, it may become tame in captivity. While population trends are generally stable, threats to the species' survival include urbanization, habitat conversion for agricultural use and active
Taxonomy
There are six
Early history
The taxonomy of the camas pocket gopher and its genus, Thomomys, have a convoluted history.[12] According to a review article published by the American Society of Mammalogists in 1987, Johann Friedrich von Brandt was the first to refer to the camas pocket gopher as Thomomys bulbivorus in an 1855 article published by the Imperial Academy of Sciences.[6] In the 1855 article, Brandt refers to Tomomys bulbivora without the "h" and ending with an "a".[13] He writes parenthetically "(man schreibe nicht Thomomys)".[14] The authors of the 1987 review note that they did not see Brandt's actual article, but source the textbook The mammals of North America published in 1981.[6]
Early confusion arose from writings by
In Fauna boreali-americana, Richardson assigns the mammal to the now-defunct genus Diplostoma described by Rafinesque in 1817.[9] He named it Diplostoma ? bulbivorum.[12] Illustration-labeling errors in Richardson's book further confounded subsequent taxonomists; the plate was labeled Diplostoma douglasii.[12]
There is a specimen of a quadruped in the Hudson's Bay Museum, which Mr David Douglas informs me is the animal known on the banks of the Columbia by the name of the camas-rat, because the bulbous root of the Quamash or Camas plant (Scilla esculenta) forms its favourite food. The scull is wanting, and the animal, therefore, cannot be with certainty referred to a genus, but the form of its exterior cheek-pouches leads me to think that it may belong to the diplostoma of M Rafinesque-Schmaltz.
— John Richardson, Fauna boreali-americana, 1829[9]
The confusion around the species' taxonomy and identification amplified when naturalist
Clarifications
Although Baird and
The distribution of Elliot's "great pocket gopher" (as it was known) extended along the California coast "north of San Francisco."[23] James Audubon and John Bachman reassessed the taxonomy on the camas pocket gopher in the late 1800s. They referred it as the "camas rat". They reclassified the gopher as Pseudostoma borealis.[24] They rejected Diplostoma as a genus, and assigned Diplostoma bulbivorum as synonymous with P. borealis. They attributed any differences described by Richardson to artifact, from a specimen that was "twisted and disfigured" in preparation.[25] Based on observations of taxidermy specimens in Europe, they suggested that Townsend's pocket gopher (Geomys (Thomomys) townsendii) belonged to the same species.[26] In 1875, the camas pocket gopher was reported as a sub-species of the northern pocket gopher (Thomomys talpoides),.[27] During the 1920s H. M. Wight referred to it colloquially as the "Willamette Valley gopher".[28]
Current phylogeny
In 2008, a team of biologists from the University of California, Berkeley and Harvard University published multilocus phylogenetic analysis results of the genus Thomomys. The camas pocket gopher was found to be well separated from other taxa in the subgenus Megascapheus. These findings suggested that the camas pocket gopher was a sister to the other taxa in the subgenus, but the relationships between those other animals was less clear.[29] Only one camas pocket gopher was included in this study, which limited the ability to distinguish features such as monophyly.[30] The following cladogram was presented showing the placement of the camas pocket gopher among its closest relatives:[30]
Thomomys
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Patterns of genetic variation in the camas pocket gopher have been studied.[31] Although there are no subspecies, there is substantial genetic diversity within the species. Its genetic patterns are consistent with limited inbreeding within specific populations.[32] This is similar to patterns described in Botta's pocket gopher and the southern pocket gopher, both of which are members of the same genus. However, it contrasts with patterns noted in Baird's pocket gopher and the plains pocket gopher, members of a separate genus, Geomys, which showed a higher degree of inbreeding.[32]
The species' genetic diversity is similar to that of other pocket gophers occupying a larger geographic range and diversity of habitat.[33] Compared to Townsend's pocket gopher, which is distributed across a much larger area, but less diverse habitat, it is more genetically heterogeneous.[33] Although there is considerable differentiation between separate populations of camas pocket gophers, their genetic variability does not affect the mammal's appearance.[34] Study of the effects of genetic change over time revealed a pattern affected by a cataclysmic event across the species' entire geographic area about 13,000 years ago.[34] Such an event would cause a population bottleneck, leading to scattered, isolated populations.[34]
Description
The camas pocket gopher is, by a small margin, the largest member of its genus (Thomomys).
Like other gophers, it has small eyes and ears and a nearly hairless tail. Its shoulders are broader than its hips. It is pentadactyl, with five claws on each foot. The claws on its forefeet are longer than those on its hind feet, and its middle claws are longest.[6] The front claws of the camas pocket gopher are short and weak relative to its size.[38] It employs plantigrade locomotion. The male is larger than the female, measuring an average 300 mm (12 in) in length. A large male weighs about 500 g (18 oz).[6] One male specimen was 321 mm (12.6 in) long and weighed 633.8 g (22.36 oz).[35] Females are about 271 mm (10.7 in) long. The tail measures 90 mm (3.5 in) in the male and 81 mm (3.2 in) in the female. An adult male's hind feet measure 40–43 mm (1.6–1.7 in), and an average female's hind feet measure 39 mm (1.5 in).[6] There are four mammary glands: two in the inguinal region and two in the pectoral region, each supplying a pair of nipples.[2] Morphologically, it most closely resembles Botta's pocket gopher;[37] differentiation can be made based on the concavity of the inner surface of the pterygoids, small claws, more uniform fur coloring and exoccipital groove of the camas pocket gopher.[39][40]
Skull and dentition
The skull of the camas pocket gopher is sturdily proportioned.
The dentition of the camas pocket gopher is symmetric, with one set of incisors, one set of premolars, and three sets of molars above and below. This gives a dental formula of 1.0.1.31.0.1.3, for a total of 20 teeth.[6] The slender incisors are prominent and distinctive, smooth with yellow surface enamel and white tips due to soil abrasion.[37] These distinctive, large, protuberant upper incisors give the gopher a buck-toothed appearance.[6][36] The lips do not cover the incisors, but close behind them. There are faintly visible grooves on the inner aspect of the upper incisors, which are more pronounced in other members of the genus (such as the Mazama pocket gopher, T. mazama). The upper molars have an alveolar length of 10 mm (0.39 in).[6]
Cheek pouches
Gophers are burrowing rodents of the family Geomyidae, characterized by fur-lined, external cheek pouches used to gather and transport food.
Male genitalia
Like many mammals, the penis of the camas pocket gopher contains a bone, the baculum. Although its baculum was initially reported as smaller than that of other gophers—1.5 mm (0.059 in) high, 1.8 mm (0.071 in) wide at the base and 8.5 mm (0.33 in) long—the examiner did not know if the specimen had reached full maturity.[43] Subsequent reports averaged about 2.1 mm (0.083 in) high, 2.2 mm (0.087 in) wide at the base and 10.1 mm (0.40 in) long.[44] The phallus' total length averaged 13.5 mm (0.53 in), with the glans covering more than half its length.[6]
Distribution and habitat
The camas pocket gopher is found in the Willamette Valley and the drainage areas of the Yamhill River and other tributaries of the Willamette River.[6] Its range extends north from Eugene to Portland and Forest Grove and west to Grand Ronde.[2] A 1920 report of a Pleistocene fossil in Fort Rock, Oregon has been questioned, since it is far outside the species' current geographic range; as of 1987, the specimen could not be located for further evaluation.[6]
The clay-rich Willamette Valley soils are hard in the dry season, and the gopher's protuberant incisors are well adapted to these conditions.[37] Adequate soil drainage and suitable plant food are essential components of the gopher's ideal habitat. Not typically found in wetland areas (where its tunnels would flood), the species is found in seral communities of grasses and shrubs. They are also established in agricultural fields in the Willamette Valley, including fields of alfalfa, wheat and oats. The species has also been found in areas of ecological disturbance with similar terrain features.[45]
On a geologic timescale, the Willamette Valley has been the site of massive floods.
Behavior
The gopher has been credited with being one of the most vicious animals known for its size. It has a great deal of courage and fights a man savagely until an opportunity for escape is offered, then it turns and runs as rapidly as possible, attempting to hide from its pursuer.
— H. M. Wight, Economic Entomology: Pamphlets, 1918[47]
The camas pocket gopher is a mostly solitary herbivore which is active throughout the year and does not hibernate.[48] The gopher spends most of its time excavating tunnels in search of food,[49] and the hard clay soils of the Willamette Valley pose a challenge.[10] Although the gopher's front claws are too weak to dig through the clay (particularly during dry seasons), its large incisors and strongly protuberant orientation are well-adapted for this purpose. Tunnel systems constructed by the camas pocket gopher can be complex, with some tunnels exceeding 240 m (260 yd) in length. About 90 mm (3.5 in) in diameter, the tunnels are up to 0.91 m (3.0 ft) deep.[10] When soils are damp the gopher constructs ventilation ducts or chimney mounds (possibly unique to the species),[49] to increase ventilation.[10] The chimney mounds rise vertically 15–25 cm (6–10 in), are open at the top and are thought to ventilate the burrows in accordance with Bernoulli's principle.[49] It is not known if adjacent gopher burrowing systems interconnect.[49] Reports differ about whether or not the ranges of the camas pocket gopher and the Mazama pocket gopher overlap; if so, this refutes the previous belief that Oregon gopher ranges do not overlap.[10]
Although the species is primarily
The camas pocket gopher may behave aggressively when on the defensive, with mammalogist Vernon Orlando Bailey describing the species as "morose and savage."
Ecology
Age (weeks) | Weight | Length | Description |
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Birth | 6.1 g (0.22 oz) | 50 mm (2.0 in) | No hair, no teeth, no cheek pouches |
2 | 23 g (0.81 oz) | 90 mm (3.5 in) | Developing hair |
3 | 35.5 g (1.25 oz) | 108 mm (4.3 in) | Crawling, eat solid food |
4 | 53.6 g (1.89 oz) | 123.5 mm (4.86 in) | Pockets developed |
5 | 70.5 g (2.49 oz) | 153 mm (6.0 in) | Eyes open |
6 | 86 g (3.0 oz) | 164 mm (6.5 in) | Weaned |
Varying onset times and duration of the camas pocket gopher breeding season have been reported. Early reports suggested an early-April onset, with the season extending through June. Other reports cited "evidently pregnant" females seen in late March.
There was little data as of 1998 on the longevity and mortality of the camas pocket gopher.
Two parasitic worms first discovered in the gastrointestinal tract of camas pocket gophers are the nematode Heligmosomoides thomomyos and the cestode Hymenolepis tualatinensis. Other worms include two nematodes and the cestode Hymenolepis horrida.[10]
Human interactions
Camas pocket gophers cause significant economic losses, so may be treated as an agricultural
Proposed methods for controlling gopher populations in agricultural areas include poisoning dandelions,[50] clover, carrots, sweet potatoes and parsnips.[10] Camas pocket gophers are larger than other gophers, so conventional gopher traps may fail to capture them.[10] Toxic baits and fumigants may also fail, since the gophers will sometimes wall off a segment of the burrow.[10] Gophers may also cause local flooding if their tunneling activities damage levees.[55]
In an effort to mitigate damage by camas pocket gophers to sensitive habitat, the
Conservation status
Citing concerns of
The IUCN and others express concern about degradation of the species' habitat due to urbanization and
References
Footnotes
- ^ a b c d e f g Cassola 2016.
- ^ a b c d e f Bailey 1915, p. 40.
- ^ Patton 2005, pp. 859–870.
- ^ a b Patton 2005, p. 868.
- ^ Elbroch 2006, p. 296.
- ^ a b c d e f g h i j k l m n o p Verts & Carraway 1987, p. 1.
- ^ "Thomomys (Megascapheus)". Integrated Taxonomic Information System. Retrieved 14 November 2014.
- ^ a b Verts & Carraway 1987, p. 4.
- ^ a b c d Richardson 1829, p. 206.
- ^ a b c d e f g h i j k l m n o p Verts & Carraway 1987, p. 3.
- ^ Wight 1918, p. 12.
- ^ a b c d e f Allen 1893, p. 53.
- ^ Brandt 1855, p. 188.
- ^ Brandt 1855, p. 189.
- ^ Allen 1893, pp. 53–64.
- ^ Allen 1893, p. 55.
- ^ a b c d e f g Allen 1893, p. 56.
- ^ Richardson 1829, pp. 206–207.
- ^ Allen 1893, pp. 53–56.
- ^ Ripley & Dana 1879.
- ^ DePuy 1895, p. 703.
- ^ a b c d e Allen 1893, p. 57.
- ^ Elliot 1905, p. 272.
- ^ Audubon, Audubon & Bachman 1851, p. 198.
- ^ Audubon, Audubon & Bachman 1851, pp. 200–201.
- ^ Audubon, Audubon & Bachman 1851, p. 200.
- ^ Coues 1875, pp. 136–137.
- ^ a b Wight 1922.
- ^ Belfiore, Liu & Moritz 2008, p. 300.
- ^ a b Belfiore, Liu & Moritz 2008, p. 304.
- ^ Carraway & Kennedy 1993, p. 952.
- ^ a b c d Carraway & Kennedy 1993, p. 958.
- ^ a b Carraway & Kennedy 1993, p. 957.
- ^ a b c d Carraway & Kennedy 1993, p. 960.
- ^ a b c Verts & Carraway 1998, p. 229.
- ^ a b Kays & Wilson2010, p. 82.
- ^ a b c d e f g Bailey 1915, p. 41.
- ^ Bailey 1915, p. 42.
- ^ a b Bailey 1915, p. 32.
- ^ Bailey 1915, p. 36.
- ^ Vaughan, Ryan & Czaplewski 2011, p. 207.
- ^ a b c Merriam 1895, p. 101.
- ^ a b Verts & Carraway 1987, pp. 1–2.
- ^ a b c d e f g h Verts & Carraway 1987, p. 2.
- ^ a b c d e f g h Verts & Carraway 1998, pp. 229–231.
- ^ a b c Carraway & Kennedy 1993, p. 959.
- ^ Wight 1918, p. 16.
- ^ a b Comprehensive Report Species – Thomomys bulbivorus 2014.
- ^ a b c d e Verts & Carraway 1998, p. 230.
- ^ a b c d e Experiment Station Record 1920.
- ^ a b Verts & Carraway 1987, pp. 3–4.
- ^ Wight 1918, p. 3.
- ^ Whitaker et al. 2007, pp. 86.
- ^ Whitaker et al. 2007, pp. 13–14.
- ^ a b Nowak 1999.
- ^ a b c The Camas pocket gopher – Small but fierce!.
- ^ Kincaid's lupine.
- ^ Plebejus icarioides fenderi. NatureServe. 2012.
- ^ a b Ricketts 1999, p. 155.
- ^ Jewell & McRae 2011, p. 9.
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- Audubon, John James; Audubon, John Woodhouse; Bachman, John (1851). The Quadrupeds of North America, Volume 3. New York: V.G. Audubon. pp. 198–201. Archived from the original on 29 April 2015. Retrieved 21 November 2014.
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- Belfiore, Natalia; Liu, Liang; Moritz, Craig (April 2008). "Multilocus phylogenetics of a rapid radiation in the genus Thomomys". Systematic Biology. 57 (2): 294–310. PMID 18432550.
- Brandt, Johann Friedrich (1855). Beiträge zur Nähern Kenntniss der Säugethiere Russland's (in German). St. Petersburg: De l'Imprimerie de l'Académie impériale des sciences. Archived from the original on 25 November 2014. Retrieved 25 November 2014.
- Carraway, Leslie N.; Kennedy, Phyllis K. (November 1993). "Genetic variation in Thomomys bulbivorus, an endemic to the Willamette Valley, Oregon". Journal of Mammalogy. 74 (4): 952–962. JSTOR 1382434.
- Cassola, F. (2016). "Thomomys bulbivorus". . Retrieved 17 November 2021.
- "Comprehensive Report Species – Thomomys bulbivorus". NatureServe Explorer: An Online Encyclopedia of Life [web application]. Version 7.1. NatureServe, Arlington, Virginia. 2014. Retrieved 28 November 2014.
- Coues, Elliott (1875). "Synopsis of the Geomyidae". Proceedings of the Academy of Natural Sciences of Philadelphia. 27: 136–137. Retrieved 8 February 2015.
- DePuy, W. H., ed. (1895). "Entry for California "Fauna"". OCLC 2320653.
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- Kays, Roland W.; Wilson, Don E. (2010). Mammals of North America (2nd ed.). Princeton: Princeton University Press. ISBN 978-1-4008-3350-4. Retrieved 12 November 2014.
- "Kincaid's lupine". Oregon Fish & Wildlife Office Home. Retrieved 29 March 2015.
- Merriam, Clinton Hart (January 1895). "Monographic revision of the pocket gophers: Family Geomyidæ". North American Fauna. 8: 1–262. . Retrieved 28 November 2014.
- Nowak, Ronald M. (1999). Walker's Mammals of the World (6th ed.). Baltimore, Md.: Johns Hopkins University Press. ISBN 978-0-8018-5789-8. Retrieved 28 November 2014.
- OCLC 62265494.
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- Vaughan, Terry; Ryan, James; Czaplewski, Nicholas (2011). Mammalogy. Jones & Bartlett Learning. ISBN 978-0-7637-6299-5. Retrieved 27 November 2014.
- Verts, B.J.; Carraway, Leslie N. (27 February 1987). "Thomomys bulbivorus" (PDF). Mammalian Species (273): 1–4. JSTOR 3504014. Archived from the original(PDF) on 12 November 2014. Retrieved 27 November 2014.
- Verts, B.J.; Carraway, Leslie N. (1998). Land Mammals of Oregon. Berkeley: University of California Press. ISBN 978-0-520-21199-5. Retrieved 15 November 2014.
- Whitaker, John O.; Walters, Brianne L.; Castor, Linda K.; Ritzi, Christopher M.; Wilson, Nixon (24 July 2007). "Host and distribution lists of mites (acari), parasitic and phoretic, in the hair or on the skin of North American wild mammals north of Mexico: records since 1974". Faculty Publications from the Harold W. Manter Laboratory of Parasitology.
- Wight, H.M. (October 1922). "The Willamette Valley gopher". The Murrelet. 3 (3): 6–8. JSTOR 3533661.
- Wight, H.M. (1918). Economic Entomology: Pamphlets.
External links
- Media related to Thomomys bulbivorus at Wikimedia Commons
- Data related to Thomomys bulbivorus at Wikispecies
- UniProt. "Thomomys bulbivorus". Retrieved 5 August 2016.