Heterogeomys

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Heterogeomys
Scientific classification Edit this classification
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

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]

Taxonomy

In 1895,

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).

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]

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. ^ a b c 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. doi:10.2305/IUCN.UK.2016-2.RLTS.T15544A22214782.en
    . Retrieved 14 November 2021.
  5. 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. doi:10.1093/jmammal/gyv185
    .
  8. ^ a b 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. ^ a b c d e Baker, Robert (2003). Wild Mammals of North America: Biology, Management and Conservation. Baltimore: Johns Hopkins University Press. pp. 276–287.
  11. JSTOR 1381975
    .
  12. ^ a b c Hafner, Mark. "Cophylogeny between Pocket Gophers and Chewing Lice". Retrieved 26 November 2012.
  13. ^ a b Zeledon, Fernando. "Orthogeomys heterodus". INBio, Costa Rica. Archived from the original on 9 June 2007. Retrieved 26 November 2012.
  14. ^ a b c 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. ^
    doi:10.15517/am.v22i1.8680
    .
  18. ^
    PMID 11406147
    .
  19. PMID 8066445
    .
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