Heterogeomys

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Heterogeomys
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Geomyidae
Genus: Heterogeomys
Merriam, 1895
Type species
Geomys hispidus
Species

7 recognized species, see article.

Heterogeomys is a genus of rodent in the family Geomyidae, found in Mexico, Central America and Colombia. Heterogeomys are a small genus of rodents commonly known as pocket gophers, though the term applies to all genera within the family Geomyidae. [1] The name pocket gopher was earned for this family because of their fur lined cheek pouches that can be used for carrying food. These pouches can also be turned inside out. Species of Heterogeomys are regarded as pests, one of less than 5% of rodent species classified as pests, and the history of man's attempts to control their populations reaches back into Mayan times. [2] [3] Despite some efforts to the contrary, populations of Heterogeomys seem to be on a general upwards trend. Furthermore, all of the species of Heterogeomys are considered to be of Least Concern in the World Status Key. [4]

Contents

Taxonomy

In 1895, C. H Meriam described 3 genera of pocket gophers: Heterogeomys, Macrogeomys, and Orthogeomys . [5] In the 1968 taxonomic revision, R. J. Russell recognized Heterogeomys and Macrogeomys as subgenera of Orthogeomys. [6] However, recent studies suggests that Orthogeomys s. l. may be paraphyletic to Cratogeomys and Pappogeomys , which is why Spradling et al. (2016) proposed to divide this genus into Orthogeomys s. s. (only O. grandis) and Heterogeomys (rest species; includes Macrogeomys). [7] This classification was accepted by the American Society of Mammalogists. [8]

Species

This genus contains the following seven species: [8]

Morphology

Pocket Gophers range in size from about 170 mm (for example, H. cherriei and H. underwoodi) to around 280 mm (such as H. heterodus and H. cavator). [9] Tails can range in length from 80 to 160 mm depending on the species. Sources have reported that a key factor in determining the size of the animal is the soil composition in the animal's native habitat. Looser, sandy soil types are associated with increased cranial size, while more densely packed soil seems to correlate with a relatively smaller body size. [10] Animals of this genus are typically colored as to blend in with their backgrounds, presenting mostly black or brown or gray coloring on their dorsal sides. The ventral side tends to be more variable in coloration, though in species such as H. underwoodi, the dorsal coat can have patterns such as white bands extending across the hind quarters. Ventral coat coloration is often some combination of white, gray, or brown. [10] [11] Hair on these animals ranges from short to relatively long, and the hairs are generally fine and soft. It is thought that these characteristics are advantageous for the animal to remove dirt from its coat during the grooming process. [10] A very distinctive feature of the Heterogeomys genus is the large incisors that protrude from the mouth, even when the mouth is closed. This is a characteristic that is shared across all rodents, but is particularly prominent in gophers. These enlarged incisors serve two purposes. The first, as is the general trend in animals, tooth shape is adapted to the individual's diet. Secondly, since the teeth protrude out of the mouth, the Heterogeomys can use its teeth to dig, while preventing dirt from entering its oral cavity. [10] Pocket gophers also possess valvular ears, which can be closed to prevent the entry of soil into the auditory canal while digging. [12]

Behavior

Burrowing

Heterogeomys are solitary creatures except during their breeding seasons. [13] In the breeding seasons though, multiple individuals can occupy the same burrow. During the non-breeding times of year, only one Heterogeomys occupies a tunnel system at a given time. These tunnels are subdivided into areas for their nest, the food store, and a separate tunnel for excrement. [14] In the H. cherriei, tunnels have an average height of 12.8 cm, and can be up to almost 200 m in length. Heterogeomys are primarily active during the morning and afternoon, and are mainly found inside their burrows. [14]

Feeding Habits

On the whole, pocket Gophers tend to have a higher daily caloric intake than most rodent species. [10] This is due to the added energy expenditures necessary to move around underground, and is a contributing factor to how destructive these animals can be towards crops that are cultivated by humans. Heterogeomys are herbivores, who feed on corn, grass roots, cassava, rice, and sugar cane. [13] [14] [15] [16]

Interspecies Interactions

Trapping

Documents from before the Spanish settlement of Mexico report different methods on the catching and preparing of pocket gophers for food. [3] Due to the extended length of time that trapping has been a part of the community, it should come as no surprise that the practice of trapping has gained cultural significance in southeastern Mexico. Unfortunately, the nature of the traps used in the past by the Mayan's is a mystery now, but present methods of gopher trapping can be observed. Two popular snares used in the modern day both make use of a spring, a snare, and a tension line. One trap is set off by a gopher running into a tension line, and another by a gopher chewing through a baited line. [3]

Pest Control

Heterogeomys often feed off of bananas and other crops that are being cultivated by humans. These pocket gophers are capable of being quite destructive towards these crops as well, capable of causing up to a 50% loss in crops. [17] Because of the significant losses, people have poured much effort into trying to control Pocket Gopher populations. In Costa Rica, several methods of pest control have been pursued, but many have been abandoned in searching for the ideal solution. Mongooses have been introduced into the Heterogeomys habitats in hopes of culling their numbers, food has been poisoned and left out for the Heterogeomys to find, or the spreading of toxic chemicals. [17] Unfortunately, the latter two options pose not only are harmful to the Heterogeomys, but to humans as well. Since there is no antidote available in Costa Rica for some of the chemicals used in pest control, so the use of these chemicals must be carefully managed. [17]

Cophylogeny

Evidence suggests that a close relationship has existed between pocket gophers and chewing lice for significant periods of time. [18] It has been posited that this relationship is due to the fact that both of these creatures habits make them quite well suited for parallel evolution. [12] [18] By tunneling underground, these gophers are creating a slightly more palatable environment than had existed before, and this environment would become populated with organisms. These organisms would become gradually adapted, not only to the tunnel environment, but likely also to the gophers who created the tunnels. In the case of chewing lice, this would mean attaching onto, and becoming well suited to overcoming the hosts defense systems, but without causing so much harm as to kill the host. Since pocket gophers are so solitary, any contact that they have with other animals is likely to be with other pocket gophers of their same species. In this way, a certain initial type of lice could be passed on almost exclusively in one species of pocket gopher for generations and generations, producing a new species of louse, specific to one species of pocket gopher. [12] [19]

Related Research Articles

<span class="mw-page-title-main">Heteromyidae</span> Family of rodents

Heteromyidae is a family of rodents consisting of kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within the genus Heteromys are also found in forests and their range extends down as far as northern South America. They feed mostly on seeds and other plant parts, which they carry in their fur-lined cheek pouches to their burrows.

<span class="mw-page-title-main">Gopher</span> Family of burrowing rodents

Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 species are all endemic to North and Central America. They are commonly known for their extensive tunneling activities and their ability to destroy farms and gardens.

<span class="mw-page-title-main">Smooth-toothed pocket gopher</span> Genus of mammals

The smooth-toothed pocket gophers, genus Thomomys, are so called because they are among the only pocket gophers without grooves on their incisors. They are also called the western pocket gophers because they are distributed in western North America. They are considered distinct enough from other pocket gophers to be recognized as a separate subfamily or tribe.

<span class="mw-page-title-main">Yellow-faced pocket gopher</span> Species of rodent

The yellow-faced pocket gopher is a species of pocket gopher that is native to shortgrass prairies in the south-western United States and northern Mexico. It is the species that lives north of the Southern Coahuila Filter-Barrier (SCFB). Among the different species, the yellow-faced pocket gopher has a small to medium-sized skull. The fossil of this genus was recorded from the pre-Pleistocene Benson Beds of Arizona.

<span class="mw-page-title-main">Desert pocket gopher</span> Species of rodent

The desert pocket gopher is a species of rodent in the family Geomyidae. It is found in the state of Chihuahua in Mexico and in Texas and New Mexico in the United States.

The Chiriqui pocket gopher is a species of rodent in the family Geomyidae. It is found in Costa Rica and Panama. Some authors classify it in the genus Orthogeomys, but recent research has allowed this and its related species to be classified in the genus Heterogeomys.

Cherrie's pocket gopher is a species of rodent in the family Geomyidae. It is found in Honduras, Nicaragua, and Costa Rica. It is threatened by habitat loss. Some authors classify it in the genus Orthogeomys, but recent research has allowed this and its related species to be classified in the genus Heterogeomys.

The Darien pocket gopher is a species of rodent in the family Geomyidae. It is occurs in Panama and Colombia. Some authors classify it in the genus Orthogeomys, but recent research has allowed this and its related species to be classified in the genus Heterogeomys.

The giant pocket gopher, also known as the Oaxacan pocket gopher, is a species of rodent in the family Geomyidae. It is found in Mexico, Guatemala, El Salvador and Honduras. It is the type species of the genus Orthogeomys; some zoologists also include in this genus species that have recently been placed in Heterogeomys.

The variable pocket gopher is a species of rodent in the family Geomyidae. It is endemic to Costa Rica, usually being found in grasslands and tropical forests at higher altitudes, up to 8,000 feet. It is threatened by habitat loss, but are sometimes kept as pets in the United States and elsewhere.

The hispid pocket gopher is a species of rodent in the family Geomyidae. It is found in Mexico, Belize, Guatemala, and Honduras. Some authors classify it in the genus Orthogeomys, but recent research has allowed this and its related species to be classified in the genus Heterogeomys.

The big pocket gopher is a species of rodent in the family Geomyidae. It is endemic to Veracruz state in eastern Mexico. It has only been found on the southeastern slopes of Pico de Orizaba, at elevations of 1,300 metres (4,300 ft).

Underwood's pocket gopher is a species of rodent in the family Geomyidae. It is endemic to Costa Rica. Some authors classify it in the genus Orthogeomys, but recent research has allowed this and its related species to be classified in the genus Heterogeomys.

Buller's pocket gopher is a species of gopher that is endemic to Mexico.

<span class="mw-page-title-main">Merriam's pocket gopher</span> Species of rodent

Merriam's pocket gopher is a species of rodent in the family Geomyidae. It is endemic to Mexico, where it is found in the area of the Valley of Mexico and the Valley of Toluca at elevations from 1800 to 4000 m. Its favored habitats are the Zacatonal grassland and temperate pine-oak woodlands, as well as farmland and rangeland. Its karyotype has 2n = 36 and FN = 68.

<span class="mw-page-title-main">Camas pocket gopher</span> Small species of burrowing rodent from Oregon

The camas pocket gopher, also known as the camas rat or Willamette Valley gopher, is a rodent, the largest member in the genus Thomomys, of the family Geomyidae. First described in 1829, it is endemic to the Willamette Valley of northwestern Oregon in the United States. The herbivorous gopher forages for vegetable and plant matter, which it collects in large, fur-lined, external cheek pouches. Surplus food is hoarded in an extensive system of tunnels. The dull-brown-to-lead-gray coat changes color and texture over the year. The mammal's characteristically large, protuberant incisors are well adapted for use in tunnel construction, particularly in the hard clay soils of the Willamette Valley. The gophers make chattering sounds with their teeth; males and females make purring sounds when they are together, and the young make twittering sounds. Born toothless, blind and hairless, the young grow rapidly before being weaned at about six weeks of age.

The Michoacan pocket gopher is a species of rodent in the family Geomyidae. It is monotypic within the genus Zygogeomys. It is endemic to Mexico where its natural habitat is temperate, high-altitude forests. Its numbers are declining and it is listed by the IUCN as "endangered".

<span class="mw-page-title-main">Oriental Basin pocket gopher</span> Species of rodent

The Oriental Basin pocket gopher is a species of pocket gopher which is endemic to Mexico. It was first described in 1895 by Clinton Hart Merriam. It was considered to be a subspecies of Merriam's pocket gopher in the late 20th and early 21st century but has been reinstated as its own species. The IUCN Red List has evaluated it to be of least concern.

The Perote pocket gopher, or Cofre de Perote pocket gopher, is a species of pocket gopher in the family Geomyidae.

References

  1. ↑ Encyclopædia Britannica. "Pocket Gopher" . Retrieved 14 December 2012.
  2. ↑ Witmer, Gary; Richard M. Engeman (15 May 2007). "Subterranean Rodents as Pests: The Case of the Pocket Gopher". USDA National Wildlife Research Center - Staff Publications: 287–299. Retrieved 27 November 2012.
  3. 1 2 3 Hovey, Kevin; Dominique Rissolo (1999). "The Process and Sociocultural Significance of Gopher Trapping in a modern Yucatec Maya Community". Journal of Ethnobiology. 19 (2): 261–276.
  4. ↑ Samudio, R. (2016). "Orthogeomys cavator". IUCN Red List of Threatened Species . 2016: e.T15544A22214782. doi: 10.2305/IUCN.UK.2016-2.RLTS.T15544A22214782.en . Retrieved 14 November 2021.
  5. ↑ Merriam, C. H. (1895). "Monographic revision of the pocket gophers family Geomyidae (exclusive of the species of Thomomys)". North American Fauna. Washington. 262 (8): 1–258. OCLC   1201401641.
  6. ↑ Russell, R. J. (1968). Evolution and classification of the pocket gophers of the subfamily Geomyinae. Museum of Natural History, University of Kansas, Lawrence: University of Kansas Publications.
  7. ↑ Spradling, T. A.; Demastes, J. W.; Hafner, D. J.; Milbach, P. L.; Cervantes, F. A.; Hafner, M. S. (2016). "Systematic revision of the pocket gopher genus". Journal of Mammalogy. 97 (2): 405–423. doi: 10.1093/jmammal/gyv185 .
  8. 1 2 Search results for "Heterogeomys" on the ASM Mammal Diversity Database.
  9. ↑ Suarez, Alina. "Orthogeomys". INBio, Costa Rica. Archived from the original on 9 June 2007. Retrieved 27 November 2012.
  10. 1 2 3 4 5 Baker, Robert (2003). Wild Mammals of North America: Biology, Management and Conservation. Baltimore: Johns Hopkins University Press. pp. 276–287.
  11. ↑ Hafner, Mark (13 February 1991). "Evolutionary Genetics and Zoogeography of Middle American Pocket Gophers, Genus Orthogeomys" (PDF). Journal of Mammalogy. 72 (1): 1–10. doi:10.2307/1381975. JSTOR   1381975.
  12. 1 2 3 Hafner, Mark. "Cophylogeny between Pocket Gophers and Chewing Lice" . Retrieved 26 November 2012.
  13. 1 2 Zeledon, Fernando. "Orthogeomys heterodus". INBio, Costa Rica. Archived from the original on 9 June 2007. Retrieved 26 November 2012.
  14. 1 2 3 Suarez, Alina. "Orthogeomys cherriei". INBio, Costa Rica. Archived from the original on 9 June 2007. Retrieved 26 November 2012.
  15. ↑ Zeledon, Fernando. "Orthogeomys underwoodi". INBio, Costa Rica. Retrieved 26 November 2012.[ permanent dead link ]
  16. ↑ Suarez, Alina. "Orthogeomys cavator". INBio, Costa Rica. Retrieved 26 November 2012.[ permanent dead link ]
  17. 1 2 3 Monge-Meza, Javier (16 May 2011). "El impacto de las taltuzas en el cultivo de banano". Agronomía Mesoamericana. 22 (1): 167–174. doi: 10.15517/am.v22i1.8680 .
  18. 1 2 Paterson, Adrian; Jonathan Banks (2 January 2001). "Analytical approaches to measuring cospeciation of host and parasites: through a glass, darkly" (PDF). International Journal for Parasitology. 31 (9): 1012–1022. doi:10.1016/s0020-7519(01)00199-0. PMID   11406147.
  19. ↑ Hafner, Mark; Philip D. Sudman; Francis X. Villablanca; Theresa A. Spradling; James W. Demastes; Steven A. Nadler (19 August 1994). "Disparate Rates of Molecular Evolution in Cospeciating Hosts and Parasites". Science. 265 (5175): 1087–1090. Bibcode:1994Sci...265.1087H. CiteSeerX   10.1.1.492.9461 . doi:10.1126/science.8066445. PMID   8066445.
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