Damaraland mole-rat

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Damaraland mole-rat
Damaraland mole-rat.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Bathyergidae
Genus: Fukomys
Species:
F. damarensis
Binomial name
Fukomys damarensis
(Ogilby, 1838)
Synonyms

Cryptomys damarensis

The Damaraland mole-rat (Fukomys damarensis [2] ), Damara mole rat or Damaraland blesmol, is a burrowing rodent found in southern Africa. [3] Along with the smaller, less hairy, naked mole rat, it is a species of eusocial mammal.

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Damaraland mole-rat. Note the white patch of fur on top of the head Fukomys damarensis.jpg
Damaraland mole-rat. Note the white patch of fur on top of the head

Description

Like other blesmols, the Damaraland mole-rat has a cylindrical body with short, stout limbs, large feet, and a conical head. It is also similar in size to most other African mole-rats, having a head-body length of 14 to 20 cm (5.5 to 7.9 in), with a short, 2 to 3 cm (0.79 to 1.18 in), tail, and weighing between 100 and 280 grams (3.5 and 9.9 oz). There are no external ears, and the blue-coloured eyes are tiny with thick eyelids. The incisor teeth are large and prominent, with flaps of skin behind them to prevent soil from falling into the throat while the animal is using them to dig. [4]

The fur is short and thick, and varies from fawn to almost black, with shades of brown being most common. There is always a white patch on the top of the head, although its exact shape varies, and there may also be additional blotches of white fur elsewhere on the body. Longer sensory hairs project above the fur over much of the body, with the facial whiskers being particularly long. Females have six teats. [4]

Distribution and habitat

Although named specifically for Damaraland, the mole-rats are found across much of southern Africa, including Botswana, Namibia, South Africa, Zambia, and Zimbabwe. [1] They inhabit warm, semi-arid environments dominated by savannah scrubland or sandy grasslands. They are most commonly associated with red Kalahari psamments, and are found only where there is a sufficient supply of plants with subterranean storage organs. [4]

Biology

Damaraland mole-rats are herbivorous, feeding solely on tubers, corms, and bulbs. Favoured foods include such plants as Acanthosicyos , Star-of-Bethlehem, Ledebouria , and Talinum . Their natural predators include mole snakes, and occasionally other local snakes, such as cobras. [4] They do not drink, obtaining all their water from their food, which is also an important source of minerals. Unlike most other mammals, they can effectively metabolise these minerals without access to vitamin D, which they lack because they are normally never exposed to sunlight. [5] The basal metabolic rate of Damaraland mole rats is also unusually low for mammals of their size, at just 0.66 cm3 O2 / g · h. [4]

Despite living in an entirely subterranean environment, Damaraland mole-rats exhibit circadian rhythms, and are active primarily during the day. [6] Their levels of the hormone melatonin can be altered by artificially changing the length of apparent daylight, suggesting that they are at least able to distinguish light from dark, although their eyesight may otherwise be very poor. [7]

Behaviour

Damaraland mole-rats live in networks of tunnels, [8] which they dig with their front teeth. The tunnels are 65 to 75 mm (2.6 to 3.0 in) in diameter, and may stretch for up to 1 km (0.62 mi). They have no connection to the surface, although their presence can be inferred from dome-shaped molehills of excavated earth pushed up to the surface. [9] As a result, the tunnels develop their own microclimate, containing warm, moist air, with low oxygen levels. [10] Most digging occurs after rainfall, since dry soil is too difficult to excavate. Because they live in arid environments, this means that Damaraland mole-rats can be extremely active over short periods; a typical colony has been estimated to excavate three tons of soil over a two-week period. [11]

The burrow system consists primarily of foraging tunnels, which the rats dig in search of food. While particularly large tubers and bulbs are at least partially eaten where they are found, smaller ones are dragged to food storage chambers beneath the foraging tunnels. The foraging tunnels are typically only 5 to 25 cm (2.0 to 9.8 in) beneath the soil surface, but are connected to a smaller number of deep tunnels that lead down to the storage chambers, latrines, and a central nest that may be as much as 2.5 m (8 ft 2 in) underground. [4]

Each burrow system is inhabited by a single colony of mole rats, typically with about twelve members, although colonies can range from as little as two to as many as forty members. The colony is eusocial, consisting of a single breeding pair and their non-reproductive offspring. The non-reproductive members of the colony spend their time foraging and maintaining the tunnel system, in particular closing any breaches that may occur. Intruders from other colonies are generally rejected, [4] although DNA paternity studies show that at least some non-reproductive members of a colony may have been fathered by outsiders. [12] The colony has a clearly defined hierarchy, with the breeding male dominant, followed by the breeding female, then non-reproductive males, and finally non-reproductive females. [13]

Colonies fragment if the breeding female dies, with most surviving members dispersing to new locations. Particularly large individuals may also leave the colony to establish a new burrow system. In such cases, dispersal usually only occurs during rainy weather, ensuring that digging will be relatively easy once a suitable location has been found. [14] New colonies are established by unrelated males and females, which become the new breeding pair. Dispersing individuals travel above ground, and are therefore vulnerable to predation from a wide range of animals; some studies have shown that only around 10 percent of dispersing individuals are later found in new colonies. [15] For example, while small groups of siblings may sometimes leave a burrow system at the same time, normally only one survives to found a new colony. [4]

The Damaraland mole-rat is less vocal than the naked mole-rat, making only some birdlike chirps. [8]

Reproduction

As eusocial animals, only the breeding pair within a colony is capable of reproduction. Non-reproductive individuals are not truly sterile, however, and become capable of reproduction if they establish a colony of their own. The reproductive systems of non-reproductive females are underdeveloped, with small, unvascularised uteri and tiny ovaries that contain undeveloped germ cells, but which are incapable of ovulation. [4] Non-reproductive males have smaller testes than their reproductive counterparts and produce little, if any, viable sperm. [16] The non-reproductive status of other adults is maintained by the presence of the breeding female. [17] While her removal causes previously non-reproductive females to become fully fertile, they will only mate with unrelated males, thus avoiding incest within the colony. [18]

The breeding female initiates courtship by calling and drumming with her hind feet. The pair then chase each other in a right circle before mating. Mating occurs frequently over a ten-day period, and gestation lasts 78 to 92 days. [19] Females can produce up to three litters of one to six pups per year. [17] The pups are initially hairless, with closed eyes, and only weigh 8 or 9 grams. They are weaned after 28 days, and reach adult size after around 14 months. [4]

Genetics

The Damaraland mole-rat's karyotype shows 74 or 78 chromosomes (2n). Its fundamental number is 92. [3]

Related Research Articles

<span class="mw-page-title-main">Colony (biology)</span> Living things grouping together, usually for common benefit

In biology, a colony is composed of two or more conspecific individuals living in close association with, or connected to, one another. This association is usually for mutual benefit such as stronger defense or the ability to attack bigger prey.

<span class="mw-page-title-main">Naked mole-rat</span> Burrowing rodent; one of only two known eusocial rodents

The naked mole-rat, also known as the sand puppy, is a burrowing rodent native to the Horn of Africa and parts of Kenya, notably in Somali regions. It is closely related to the blesmols and is the only species in the genus Heterocephalus.

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

The blesmols, also known as mole-rats, or African mole-rats, are burrowing rodents of the family Bathyergidae. They represent a distinct evolution of a subterranean life among rodents much like the pocket gophers of North America, the tuco-tucos in South America, or the Spalacidae from Eurasia.

<span class="mw-page-title-main">Sociality</span> Form of collective animal behaviour

Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies.

<i>Cryptomys</i> Genus of rodents

Cryptomys is the genus of mole-rats, endemic to Africa. Most of the species formerly placed in this genus were moved to the genus Fukomys in 2006.

<span class="mw-page-title-main">Cape mole-rat</span> Species of rodent

The Cape mole-rat is a species of mole-rat endemic to South Africa. It is the only extant species currently described as belonging to the genus Georychus.

<span class="mw-page-title-main">Silvery mole-rat</span> Species of rodent

The silvery mole-rat, silvery blesmol, or silky mole-rat is a species of mole-rat of East Africa which occurs in southern Kenya, Tanzania, southeastern Democratic Republic of Congo, Mozambique and Malawi. Solitary and aggressive, little is known about its ecology or behavior. It is monotypic in the genus Heliophobius. A common species, the International Union for Conservation of Nature has rated it as being of "least concern".

<span class="mw-page-title-main">Cape dune mole-rat</span> Species of rodent

The Cape dune mole-rat is a species of solitary burrowing rodent in the family Bathyergidae. It is endemic to South Africa and named for the Cape of Good Hope.

<span class="mw-page-title-main">Ansell's mole-rat</span> Species of rodent

Ansell's mole-rat is a species of rodent in the family Bathyergidae. It is endemic to Zambia. Its natural habitats are moist savanna and miombo forests. It is noted for its very long tunnels, up to 2.8 km (1.7 mi) for a single colony of only ten individuals. The colonies are made of an eusocial system. They include a main reproductive king and queen that are thought to be faithful to one another.

The Nigerian mole-rat is a species of rodent in the family Bathyergidae. It is found in northern Nigeria and Cameroon. A colonial, subterranean species, its natural habitats are tropical dry lowland grassland, riverside woodland and rocky places.

<span class="mw-page-title-main">Mechow's mole-rat</span> Species of rodent

Mechow's mole-rat is a species of rodent in the family Bathyergidae. It is found in Angola, Democratic Republic of the Congo, Zambia, and possibly Malawi. Its natural habitats are moist savanna, subtropical or tropical dry shrubland, and subtropical or tropical dry lowland grassland. This mole-rat was first described by the German naturalist Wilhelm Peters in 1881. The specific epithet honours the Prussian explorer and naturalist Friedrich Wilhelm Alexander von Mechow.

The Ghana mole-rat or Togo mole-rat is a species of rodent in the family Bathyergidae. It is endemic to Ghana.

<span class="mw-page-title-main">Northeast African mole-rat</span> Species of rodent

The northeast African mole-rat is a species of rodent in the family Spalacidae and is found in Ethiopia, Somalia, and northwest Kenya. Its natural habitats are subtropical or tropical moist montane forests, dry savanna, high-altitude shrubland and grassland. It lives a solitary existence underground and produces a small litter of pups twice a year, in the two rainy seasons. Some taxonomic authorities lump this species, along with a number of others in the genus, in which case the English name East African mole-rat is used.

<span class="mw-page-title-main">Rodent</span> Order of mammals

Rodents are mammals of the order Rodentia, which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity.

<span class="mw-page-title-main">Common mole-rat</span> Species of rodent

The common mole-rat, African mole-rat, or Hottentot mole-rat, is a burrowing rodent found in Southern Africa, in particular in the Western Cape province of South Africa. It also occurs in Eswatini, Lesotho, Malawi, Mozambique, Tanzania, Zambia, and Zimbabwe. It is a species in the subfamily Bathyerginae.

<span class="mw-page-title-main">Eusociality</span> Highest level of animal sociality a species can attain

Eusociality, the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care, overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform at least one behavior characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.

<i>Fukomys</i> Genus of rodents

Fukomys is a genus described in 2006 of common mole-rats, containing several species that were formerly placed in the genus Cryptomys; its species are endemic to Africa. The species contained in the genus includes :

The Matabeleland mole-rat is a species of mole-rat found in Zimbabwe.

<span class="mw-page-title-main">Evolution of eusociality</span> Origins of cooperative brood care

Eusociality evolved repeatedly in different orders of animals, particularly the Hymenoptera. This 'true sociality' in animals, in which sterile individuals work to further the reproductive success of others, is found in termites, ambrosia beetles, gall-dwelling aphids, thrips, marine sponge-dwelling shrimp, naked mole-rats, and the insect order Hymenoptera. The fact that eusociality has evolved so often in the Hymenoptera, but remains rare throughout the rest of the animal kingdom, has made its evolution a topic of debate among evolutionary biologists. Eusocial organisms at first appear to behave in stark contrast with simple interpretations of Darwinian evolution: passing on one's genes to the next generation, or fitness, is a central idea in evolutionary biology.

<span class="mw-page-title-main">Halictinae</span> Subfamily of bees

Within the insect order Hymenoptera, the Halictinae are the largest, most diverse, and most recently diverged of the four halictid subfamilies. They comprise over 2400 bee species belonging to the five taxonomic tribes Augochlorini, Thrinchostomini, Caenohalictini, Sphecodini, and Halictini, which some entomologists alternatively organize into the two tribes Augochlorini and Halictini.

References

  1. 1 2 Child, M.F.; Maree, S. (2016). "Fukomys damarensis". IUCN Red List of Threatened Species . 2016: e.T5753A22185003. doi: 10.2305/IUCN.UK.2016-3.RLTS.T5753A22185003.en . Retrieved 12 November 2021.
  2. ↑ Kock, D.; et al. (2006). "On the nomenclature of Bathyergidae and Fukomys n. gen. (Mammalia: Rodentia)" (PDF). Zootaxa. 1142: 51–55. doi:10.11646/zootaxa.1142.1.4.
  3. 1 2 Woods, C.A.; Kilpatrick, C.W. (2005). "Infraorder Hystricognathi". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 1540. ISBN   978-0-8018-8221-0. OCLC   62265494.
  4. 1 2 3 4 5 6 7 8 9 10 Bennett, N.C.; Jarvis, J.U.M. (2004). "Cryptomys damarensis". Mammalian Species. 756: Number 756: pp. 1–5. doi: 10.1644/756 .
  5. ↑ Skinner, D.C.; et al. (1991). "Is vitamin D3 essential for mineral metabolism in the Damara mole-rat (Cryptomys damarensis)?". General and Comparative Endocrinology. 81 (3): 500–505. doi:10.1016/0016-6480(91)90178-9. PMID   1647351.
  6. ↑ Oosthuizen, M.K.; et al. (2003). "Circadian rhythms of locomotor activity in solitary and social species of African mole-rats (family Bathyergidae)". Journal of Biological Rhythms. 18 (6): 481–490. CiteSeerX   10.1.1.470.704 . doi:10.1177/0748730403259109. PMID   14667149. S2CID   18357823.
  7. ↑ Richter, T.A.; et al. (2006). "Melatonin secretion in a strictly subterranean mammal, the Damaraland mole-rat (Cryptomys damarensis)". Journal of Zoology. 261 (3): 313–319. CiteSeerX   10.1.1.689.3797 . doi:10.1017/S0952836903004254.
  8. 1 2 Naked and Not: Science News Online, June 24, 2006
  9. ↑ Lovegrove, B.G.; Painting, S. (1987). "Variations in the foraging behaviour and burrow structures of the Damara mole-rat Cryptomys damarensis (Bathyergidae) in the Kalahari Gemsbok National Park". Koedoe. 30 (1): 149–163. doi: 10.4102/koedoe.v30i1.508 .
  10. ↑ Roper, T.J.; et al. (2001). "Environmental conditions in burrows of two species of African mole-rat, Georychus capensis and Cryptomys damarensis". Journal of Zoology. 254 (1): 101–107. doi:10.1017/S0952836901000590.
  11. ↑ Jarvis, J.U.M.; et al. (1998). "Food availability and foraging in wild colonies of Damaraland mole-rats, Cryptomys damarensis: implications for sociality". Oecologia. 113 (2): 290–298. doi:10.1007/s004420050380. PMID   28308209. S2CID   20472674.
  12. ↑ Burland, T.M.; et al. (2004). "Colony structure and parentage in wild colonies of co-operatively breeding Damaraland mole-rats suggest incest avoidance alone may not maintain reproductive skew". Molecular Ecology. 13 (8): 2371–2379. doi:10.1111/j.1365-294X.2004.02233.x. PMID   15245409. S2CID   11778275.
  13. ↑ Jacobs, D.S.; et al. (1991). "The colony structure and dominance hierarchy of the Damaraland mole-rat, Cryptomys damarensis (Rodentia: Bathyergidae) from Namibia". Journal of Zoology. 224 (4): 553–576. doi:10.1111/j.1469-7998.1991.tb03785.x.
  14. ↑ Molteno, A.J.; Bennett, N.C. (2002). "Rainfall, dispersal and reproductive inhibition in eusocial Damaraland mole-rats (Cryptomys damarensis)". Journal of Zoology. 256 (4): 445–448. doi:10.1017/S0952836902000481.
  15. ↑ Jarvis, J.U.M.; Bennett, N.C. (1993). "Eusociality has evolved independently in two genera of bathyergid mole-rats but occurs in no other subterranean mammal". Behavioral Ecology and Sociobiology. 33 (4): 253–360. doi:10.1007/BF02027122. S2CID   37118289.
  16. ↑ Maswanganye, K.A.; et al. (1999). "Oligospermia and azoospermia in non-reproductive male Damaraland mole-rats". Journal of Zoology. 248 (3): 411–418. doi:10.1111/j.1469-7998.1999.tb01039.x.
  17. 1 2 Bennett, N.C.; et al. (1996). "Reproductive suppression in subordinate, non-breeding female Damaraland mole-rats: two components to a lifetime of socially-induced infertility". Proceedings of the Royal Society B . 263 (11): 1599–1603. doi:10.1098/rspb.1996.0234. PMID   8952096. S2CID   25303746.
  18. ↑ Rickard, C.A.; Bennett, N.C. (1997). "Recrudescence of sexual activity in a reproductively quiescent colony of the Damaraland mole-rat by the introduction of a genetically unrelated male—a case of incest avoidance in "queenless" colonies". Journal of Zoology. 241 (1): 185–202. doi:10.1111/j.1469-7998.1997.tb05508.x.
  19. ↑ Bennett, N.C.; Jarvis, J.U.M. (1988). "The social structure and reproductive biology of colonies of the Damaraland mole-rat, Cryptomys damarensis (Rodentia, Bathyergidae)". Journal of Mammalogy. 69 (2): 293–302. doi:10.2307/1381379. JSTOR   1381379.

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