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107-440: The arid thicket rat ( Grammomys aridulus ) is a species of rodent in the family Muridae . It is found only in Sudan . Its natural habitat is subtropical or tropical dry shrubland . This species is currently listed on the "Nearly Threatened" list in its ranking of endangerment. Offspring of this species are commonly referred to as "kittens" or "pups". The female is referred to as
214-424: A mating plug which prevents further copulation. The plug is not necessary for pregnancy initiation, as this will also occur without the plug. The presence or absence of the plug will not affect litter size either. This plug stays in place for some 24 hours. The gestation period is about 19–21 days, and they give birth to a litter of 3–14 young (average six to eight). One female can have 5 to 10 litters per year, so
321-414: A "doe", while the male is referred to as a "buck". These creatures commonly roam in groups, called a "horde", "pack", or "storm". This Grammomys article is a stub . You can help Misplaced Pages by expanding it . Rodent Rodents (from Latin rodere , 'to gnaw') are mammals of the order Rodentia ( / r oʊ ˈ d ɛ n ʃ ə / roh- DEN -shə ), which are characterized by
428-520: A behavior known as muricide. Despite this, free-living populations of rats and mice do exist together in forest areas in New Zealand, North America, and elsewhere. House mice are generally poor competitors and in most areas cannot survive away from human settlements in areas where other small mammals, such as wood mice , are present. However, in some areas (such as Australia), mice are able to coexist with other small rodent species. The social behavior of
535-414: A burrow and one male defending a territory around the burrow. At high population densities, this system breaks down and males show a hierarchical system of dominance with overlapping ranges. Female offspring remain in the colony while male young disperse. The prairie vole is monogamous and forms a lifelong pair bond. Outside the breeding season, prairie voles live with others in small colonies. A male
642-491: A colony of their own. Rodents use scent marking in many social contexts including inter- and intra-species communication, the marking of trails and the establishment of territories. Their urine provides genetic information about individuals including the species, the sex and individual identity, and metabolic information on dominance, reproductive status and health. Compounds derived from the major histocompatibility complex (MHC) are bound to several urinary proteins. The odor of
749-400: A day. If several females are held together under crowded conditions, they will often not have an estrus at all. If they are then exposed to male urine, they will come into estrus after 72 hours. Male house mice court females by emitting characteristic ultrasonic calls in the 30 kHz–110 kHz range. The calls are most frequent during courtship when the male is sniffing and following
856-472: A decrease in body size and variation in body size. Since inbreeding is detrimental, it tends to be avoided. In the house mouse, the major urinary protein ( MUP ) gene cluster provides a highly polymorphic scent signal of genetic identity that appears to underlie kin recognition and inbreeding avoidance. Thus there are fewer matings between mice sharing MUP haplotypes than would be expected if there were random mating. Another mechanism for avoiding inbreeding
963-406: A distinct "chirping", has been likened to laughter , and is interpreted as an expectation of something rewarding. In clinical studies, the chirping is associated with positive emotional feelings, and social bonding occurs with the tickler, resulting in the rats becoming conditioned to seek the tickling. However, as the rats age, the tendency to chirp declines. Like most rat vocalizations, the chirping
1070-485: A few are predators. The field vole is a typical herbivorous rodent and feeds on grasses, herbs, root tubers, moss, and other vegetation, and gnaws on bark during the winter. It occasionally eats invertebrates such as insect larvae. The plains pocket gopher eats plant material found underground during tunneling, and also collects grasses, roots, and tubers in its cheek pouches and caches them in underground larder chambers. The Texas pocket gopher avoids emerging onto
1177-575: A few have become specialized to rely on a diet of animal matter. A functional-morphological study of the rodent tooth system supports the idea that primitive rodents were omnivores rather than herbivores. Studies of the literature show that numerous members of the Sciuromorpha and Myomorpha, and a few members of the Hystricomorpha, have either included animal matter in their diets or been prepared to eat such food when offered it in captivity. Examination of
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#17328803102741284-444: A high-fiber diet; their molars have no roots and grow continuously like their incisors. In many species, the molars are relatively large, intricately structured, and highly cusped or ridged. Rodent molars are well equipped to grind food into small particles. The jaw musculature is strong. The lower jaw is thrust forward while gnawing and is pulled backwards during chewing. Gnawing uses incisors and chewing uses molars, however, due to
1391-535: A means of intra-specific communication during courtship among the Cape mole rat . Footdrumming has been reported to be involved in male-male competition; the dominant male indicates its resource holding potential by drumming, thus minimizing physical contact with potential rivals. Some species of rodent are monogamous, with an adult male and female forming a lasting pair bond . Monogamy can come in two forms; obligate and facultative. In obligate monogamy, both parents care for
1498-686: A part in social communication between dormice and are used when the individuals are out of sight of each other. House mice use both audible and ultrasonic calls in a variety of contexts. Audible vocalizations can often be heard during agonistic or aggressive encounters, whereas ultrasound is used in sexual communication and also by pups when they have fallen out of the nest. Laboratory rats (which are brown rats, Rattus norvegicus ) emit short, high frequency, ultrasonic vocalizations during purportedly pleasurable experiences such as rough-and-tumble play, when anticipating routine doses of morphine , during mating, and when tickled. The vocalization, described as
1605-455: A predator depresses scent-marking behavior. Rodents are able to recognize close relatives by smell and this allows them to show nepotism (preferential behavior toward their kin) and also avoid inbreeding. This kin recognition is by olfactory cues from urine, feces and glandular secretions. The main assessment may involve the MHC, where the degree of relatedness of two individuals is correlated to
1712-499: A predator warning or defensive action. It is used primarily by fossorial or semi-fossorial rodents. The banner-tailed kangaroo rat produces several complex footdrumming patterns in a number of different contexts, one of which is when it encounters a snake. The footdrumming may alert nearby offspring but most likely conveys that the rat is too alert for a successful attack, thus preventing the snake's predatory pursuit. Several studies have indicated intentional use of ground vibrations as
1819-611: A reduced chromosome count arising from Robertsonian fusion . Suzuki et al. , 2013 confirms the theory that M. musculus originates in Southwestern Asia and identifies 5 subspecies and their origins: musculus in northern Eurasia , castaneus in India and Southeast Asia , a previously unknown subspecies from Nepal , domesticus in western Europe , and gentilulus in Yemen . A recent study using 89 whole-genome sequences revealed that
1926-403: A single female monopolizes mating from at least three males. In most rodent species, such as brown rats and house mice, ovulation occurs on a regular cycle while in others, such as voles, it is induced by mating . During copulation, males of some rodent species deposit a mating plug in the female's genital opening, both to prevent sperm leakage and to protect against other males inseminating
2033-678: 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 Antarctica , and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity. Rodents are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat, including human-made environments. Species can be arboreal , fossorial (burrowing), saltatorial /ricochetal (leaping on their hind legs), or semiaquatic. However, all rodents share several morphological features, including having only
2140-412: A single upper and lower pair of ever-growing incisors. Well-known rodents include mice , rats , squirrels , prairie dogs , porcupines , beavers , guinea pigs , and hamsters . However, rabbits , hares , and pikas , which also have incisors that grow continuously (but have two pairs of upper incisors instead of one), were once included with rodents, but are now considered to be in a separate order,
2247-549: A small part of its diet is plant material. It has a chunky body with short legs and tail, but is agile and can easily overpower prey as large as itself. Rodents exhibit a wide range of types of social behavior ranging from the mammalian caste system of the naked mole-rat , the extensive "town" of the colonial prairie dog , through family groups to the independent, solitary life of the edible dormouse . Adult dormice may have overlapping feeding ranges, but they live in individual nests and feed separately, coming together briefly in
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#17328803102742354-420: A switch from territorial behaviour to a hierarchy of individuals. When populations have an excess of food, there is less female-female aggression, which usually occurs to gain access to food or to prevent infanticide. Male-male aggression occurs in commensal populations, mainly to defend female mates and protect a small territory. The high level of male-male aggression, with a low female-female aggression level
2461-461: A thin covering of hair as it is the main peripheral organ of heat loss in thermoregulation along with—to a lesser extent—the hairless parts of the paws and ears. Blood flow to the tail can be precisely controlled in response to changes in ambient temperature using a system of arteriovenous anastomoses to increase the temperature of the skin on the tail by as much as 10 °C (10 K; 18 °F) to lose body heat. Tail length varies according to
2568-484: Is a small mammal of the order Rodentia , characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus Mus . Although a wild animal , the house mouse has benefited significantly from associating with human habitation to the point that truly wild populations are significantly less common than the semi-tame populations near human activity. The house mouse has been domesticated as
2675-502: Is also more common in larger populations than smaller populations, because there is a larger number of mates and more diverse mates to choose from. Within a population, males and females show different levels of multiple mating. Females show bias toward unrelated males rather than related males during sexual selection, resulting in more genetically diverse offspring and a reduction of inbreeding depression. Inbreeding depression increases genetic incompatibilities, levels of homozygosity, and
2782-404: Is at frequencies too high for humans to hear without special equipment, so bat detectors have been used for this purpose. Rodents, like all placental mammals except primates, have just two types of light receptive cones in their retina, a short wavelength "blue-UV" type and a middle wavelength "green" type. They are therefore classified as dichromats ; however, they are visually sensitive into
2889-407: Is basically similar to that of humans but differs in that they are dichromats and have only two types of cone cells whereas humans are trichromats and have three. This means that mice do not perceive some of the colors in the human visual spectrum. However, the ventral area of the mouse retina has a much greater density of ultraviolet -sensitive cones than other areas of the retina, although
2996-464: Is common in polygamous populations. The social unit of commensal house mouse populations generally consists of one male and two or more females, usually related. These groups breed cooperatively, with the females communally nursing. This cooperative breeding and rearing by related females helps increase reproductive success. When no related females are present, breeding groups can form from non-related females. In open areas such as shrubs and fields,
3103-641: Is evident in particular subgroups of rodents like kangaroo rats , hamsters, chipmunks and gophers which have two bags that may range from the mouth to the front of the shoulders. True mice and rats do not contain this structure but their cheeks are elastic due to a high degree of musculature and innervation in the region. While the largest species, the capybara , can weigh as much as 66 kg (146 lb), most rodents weigh less than 100 g (3.5 oz). Rodents have wide-ranging morphologies, but typically have squat bodies and short limbs. The fore limbs usually have five digits, including an opposable thumb, while
3210-475: Is evident when a female house mouse mates with multiple males. In such a case, there appears to be egg-driven sperm selection against sperm from related males. A region of mouse chromosome 16 is associated with thyroid function in mice. However, mice with a knockout of 16 genes - 550kb - in this region produced a normal phenotype, excluding these genes in particular from the dysfunction being pursued in that study. House mice usually live less than one year in
3317-402: Is mostly driven by the brain stem, which is itself provoked by the cortex. However Legg et al. 1989 find an alternate circuit between the cortex and whiskers through the cerebellar circuits, and Hemelt & Keller 2008 the superior colliculus. Some rodents have cheek pouches , which may be lined with fur. These can be turned inside out for cleaning. In many species, the tongue cannot reach past
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3424-915: Is not aggressive towards other males until he has mated, after which time he defends a territory, a female, and a nest against other males. The pair huddles together, grooms one another, and shares nesting and pup-raising responsibilities. Among the most social of rodents are the ground squirrels, which typically form colonies based on female kinship, with males dispersing after weaning and becoming nomadic as adults. Cooperation in ground squirrels varies between species and typically includes making alarm calls, defending territories, sharing food, protecting nesting areas, and preventing infanticide. The black-tailed prairie dog forms large towns that may cover many hectares. The burrows do not interconnect, but are excavated and occupied by territorial family groups known as coteries. A coterie often consists of an adult male, three or four adult females, several nonbreeding yearlings, and
3531-400: Is not understood why this pattern occurs, but in the case of yellow-pine chipmunks , males may have selected larger females due to their greater reproductive success. In some species, such as voles , sexual dimorphism can vary from population to population. In bank voles , females are typically larger than males, but male-bias sexual dimorphism occurs in alpine populations, possibly because of
3638-532: Is some question as to whether these mothers can distinguish which young are theirs. In the Patagonian mara , young are also placed in communal warrens, but mothers do not permit youngsters other than their own to nurse. Infanticide exists in numerous rodent species and may be practiced by adult conspecifics of either sex. Several reasons have been proposed for this behavior, including nutritional stress, resource competition, avoiding misdirecting parental care and, in
3745-465: Is the act of breeding with several males in the same season. Variation in number of males that females mate with occurs among a population. Polyandrous behavior is a common mating pattern in the subspecies Mus musculus musculus as well as its relative Mus musculus domesticus . Polyandry occurs in 30% of all wild populations of house mice. Litters from multiple sires tend to be more genetically diverse than litters of single sires. Multiple paternity
3852-425: Is vacant. If two or more males are housed together in a cage, they often become aggressive unless they have been raised together from birth. House mice primarily feed on plant matter, but are omnivorous . They eat their own faeces to acquire nutrients produced by bacteria in their intestines. House mice, like most other rodents, do not vomit. Mice are generally afraid of rats which often kill and eat them,
3959-406: The Cape ground squirrel , the male's testes can be 20 percent of its head-body length. Several rodent species have flexible mating systems that can vary between monogamy, polygyny and promiscuity. Female rodents play an active role in choosing their mates. Factors that contribute to female preference may include the size, dominance and spatial ability of the male. In the eusocial naked mole rats,
4066-599: The Great Plains of North America, the burrowing activities of prairie dogs play important roles in soil aeration and nutrient redistribution, raising the organic content of the soil and increasing the absorption of water. They maintain these grassland habitats, and some large herbivores such as bison and pronghorn prefer to graze near prairie dog colonies due to the increased nutritional quality of forage. Extirpation of prairie dogs can also contribute to regional and local biodiversity loss , increased seed depredation, and
4173-805: The Lagomorpha . Nonetheless, Rodentia and Lagomorpha are sister groups , sharing a single common ancestor and forming the clade of Glires . Most rodents are small animals with robust bodies, short limbs, and long tails. They use their sharp incisors to gnaw food, excavate burrows, and defend themselves. Most eat seeds or other plant material, but some have more varied diets. They tend to be social animals and many species live in societies with complex ways of communicating with each other. Mating among rodents can vary from monogamy , to polygyny , to promiscuity . Many have litters of underdeveloped, altricial young, while others are precocial (relatively well developed) at birth. The rodent fossil record dates back to
4280-576: The Paleocene on the supercontinent of Laurasia . Rodents greatly diversified in the Eocene , as they spread across continents, sometimes even crossing oceans . Rodents reached both South America and Madagascar from Africa and, until the arrival of Homo sapiens , were the only terrestrial placental mammals to reach and colonize Australia. Rodents have been used as food, for clothing, as pets , and as laboratory animals in research. Some species, in particular,
4387-609: The Whitten effect ). Odours of unfamiliar male mice may terminate pregnancies, i.e. the Bruce effect . Mice can sense surfaces and air movements with their whiskers which are also used during thigmotaxis . If mice are blind from birth, super-normal growth of the vibrissae occurs presumably as a compensatory response. Conversely, if the vibrissae are absent, the use of vision is intensified. Female house mice have an estrous cycle about four to six days long, with estrus itself lasting less than
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4494-430: The anogenital distance in males is about double that of the female. From the age of about 10 days, females have five pairs of mammary glands and nipples ; males have no nipples. When sexually mature, the most striking and obvious difference is the presence of testicles on the males. These are large compared to the rest of the body and can be retracted into the body. The tail, which is used for balance, has only
4601-408: The brown rat , the black rat , and the house mouse , are serious pests , eating and spoiling food stored by humans and spreading diseases. Accidentally introduced species of rodents are often considered to be invasive and have caused the extinction of numerous species, such as island birds, the dodo being an example, previously isolated from land-based predators. The distinguishing feature of
4708-410: The eastern grey squirrel , have a large deep masseter , making them efficient at biting with the incisors. The Myomorpha , such as the brown rat, have enlarged temporalis and masseter muscles, making them able to chew powerfully with their molars. In rodents, masseter muscles insert behind the eyes and contribute to eye boggling that occurs during gnawing where the quick contraction and relaxation of
4815-635: The vomeronasal organ (Jacobson's organ), located at the bottom of the nose. The urine of house mice, especially that of males, has a characteristic strong odor. At least 10 different compounds, such as alkanes , alcohols , etc., are detectable in the urine. Among them, five compounds are specific to males, namely 3-cyclohexene-1-methanol, aminotriazole (3-amino-s-triazole), 4-ethyl phenol, 3-ethyl-2,7-dimethyl octane and 1-iodoundecane. Odours from adult males or from pregnant or lactating females can speed up or retard sexual maturation in juvenile females and synchronise reproductive cycles in mature females (i.e.
4922-580: The Japanese house mouse ( M. m. molossinus ). A notable region of hybridization is a region in general Europe where M. m. domesticus and M. m. musculus are often found to hybridize. However, male hybrid mice typically experience hybrid sterility, which maintains reproductive separation between the two subspecies. The standard species karyotype is composed of 40 chromosomes . Within Western Europe there are numerous populations – chromosomal races – with
5029-621: The MHC genes they have in common. In non-kin communication, where more permanent odor markers are required, as at territorial borders, then non-volatile major urinary proteins (MUPs), which function as pheromone transporters, may also be used. MUPs may also signal individual identity, with each male house mouse ( Mus musculus ) excreting urine containing about a dozen genetically encoded MUPs. House mice deposit urine, which contains pheromones, for territorial marking, individual and group recognition, and social organization. Territorial beavers and red squirrels investigate and become familiar with
5136-441: The amount of UV that is reflected decreases with time, which in some circumstances can be disadvantageous; the common kestrel can distinguish between old and fresh rodent trails and has greater success hunting over more recently marked routes. Vibrations can provide cues to conspecifics about specific behaviors being performed, predator warning and avoidance, herd or group maintenance, and courtship. The Middle East blind mole rat
5243-501: The biological significance of this structure is unknown. In 2007, mice genetically engineered to produce the third type of cone were shown to be able to distinguish a range of colors similar to that perceived by tetrachromats . House mice also rely on pheromones for social communication, some of which are produced by the preputial glands of both sexes. The tear fluid and urine of male mice also contains pheromones, such as major urinary proteins . Mice detect pheromones mainly with
5350-524: The breeding season to mate. The pocket gopher is also a solitary animal outside the breeding season, each individual digging a complex tunnel system and maintaining a territory. Larger rodents tend to live in family units where parents and their offspring live together until the young disperse. Beavers live in extended family units typically with a pair of adults, this year's kits, the previous year's offspring, and sometimes older young. Brown rats usually live in small colonies with up to six females sharing
5457-709: The case of males, attempting to make the mother sexually receptive. The latter reason is well supported in primates and lions but less so in rodents. Infanticide appears to be widespread in black-tailed prairie dogs, including infanticide from invading males and immigrant females, as well as occasional cannibalism of an individual's own offspring. To protect against infanticide from other adults, female rodents may employ avoidance or direct aggression against potential perpetrators, multiple mating, territoriality or early termination of pregnancy. Feticide can also occur among rodents; in Alpine marmots , dominant females tend to suppress
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#17328803102745564-416: The chance of expression of deleterious recessive alleles. Polyandry has been shown to increase offspring survival compared to monandry. The fitness of females increases in polyandrous lines due to more genetic diversity and greater litter size. Due to polyandry, males can be confused by the identity of new offspring. Multiple mating by females and paternity confusion can decrease rates of infanticide. If
5671-460: The closest relatives of humans other than lagomorphs , treeshrews , flying lemurs and other primates . The three widely accepted subspecies are increasingly treated as distinct species by some: Two additional subspecies have been recognized more recently: Many more subspecies' names have been given to house mice, but these are now regarded as synonyms of the five subspecies. Some populations are hybrids of different subspecies, including
5778-479: The cranial anatomy of rodents these feeding methods cannot be used at the same time and are considered to be mutually exclusive. Among rodents, the masseter muscle plays a key role in chewing, making up 60% – 80% of the total muscle mass among masticatory muscles and reflects rodents' herbivorous diet. Rodent groups differ in the arrangement of the jaw muscles and associated skull structures, both from other mammals and amongst themselves. The Sciuromorpha , such as
5885-412: The current year's offspring. Individuals within coteries are friendly with each other, but hostile towards outsiders. Perhaps the most extreme examples of colonial behavior in rodents are the eusocial naked mole rat and Damaraland mole rat . The naked mole rat lives completely underground and can form colonies of up to 80 individuals. Only one female and up to three males in the colony reproduce, while
5992-594: The degu less visible to predators. Ultraviolet light is abundant during the day but not at night. There is a large increase in the ratio of ultraviolet to visible light in the morning and evening twilight hours. Many rodents are active during twilight hours (crepuscular activity), and UV-sensitivity would be advantageous at these times. Ultraviolet reflectivity is of dubious value for nocturnal rodents. The urine of many rodents (e.g. voles, degus, mice, rats) strongly reflects UV light and this may be used in communication by leaving visible as well as olfactory markings. However,
6099-432: The diseases of aging. In another study, two types of DNA damage (8-hydroxy-2’-deoxyguanosine and DNA-protein crosslinks) were found to increase with age in mouse brain and liver. House mice usually live in proximity to humans, in or around houses or fields. They are native to India , and later they spread to the eastern Mediterranean about 13,000 BC, only spreading into the rest of Europe around 1000 BC. This time lag
6206-415: The environmental temperature of the mouse during postnatal development, so mice living in colder regions tend to have shorter tails. The tail is also used for balance when the mouse is climbing or running, or as a base when the animal stands on its hind legs (a behaviour known as tripoding ), and to convey information about the dominance status of an individual in encounters with other mice. In addition to
6313-489: The establishment and spread of invasive shrubs. Burrowing rodents may eat the fruiting bodies of fungi and spread spores through their feces, thereby allowing the fungi to disperse and form symbiotic relationships with the roots of plants (which usually cannot thrive without them). As such, these rodents may play a role in maintaining healthy forests. In many temperate regions, beavers play an essential hydrological role. When building their dams and lodges, beavers alter
6420-812: The female. Females can remove the plug and may do so either immediately or after several hours. Metabolism of thyroid hormones and iodine in the mediobasal hypothalamus changes in response to photoperiod . Thyroid hormones in turn induce reproductive changes. This is found by Watanabe et al. 2004 and 2007, Barrett et al. 2007, Freeman et al. 2007, and Herwig et al. 2009 in Siberian hamsters , Revel et al. 2006 and Yasuo et al. 2007 in Syrian hamsters , Yasuo et al. 2007 and Ross et al. 2011 in rats, and Ono et al. 2008 in mice. Rodents may be born either altricial (blind, hairless and relatively underdeveloped) or precocial (mostly furred, eyes open and fairly developed) depending on
6527-489: The female; however, the calls continue after mating has begun, at which time the calls are coincident with mounting behaviour. Males can be induced to emit these calls by female pheromones. The vocalizations appear to differ between individuals and have been compared to bird songs because of their complexity. While females have the capability to produce ultrasonic calls, they typically do not do so during mating behaviour. Following copulation, female mice will normally develop
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#17328803102746634-498: The females that live within the territories are known as "resident" females. In the case of marmots, resident males do not appear to ever lose their territories and always win encounters with invading males. Some species are also known to directly defend their resident females and the ensuing fights can lead to severe wounding. In species with non-defense polygyny, males are not territorial and wander widely in search of females to monopolize. These males establish dominance hierarchies, with
6741-513: The few animal groups that can break open the large capsules of the Brazil nut fruit. Too many seeds are inside to be consumed in one meal, so the agouti carries some off and caches them. This helps dispersal of the seeds as any that the agouti fails to retrieve are distant from the parent tree when they germinate. Other nut-bearing trees tend to bear a glut of fruits in the autumn. These are too numerous to be eaten in one meal and squirrels gather and store
6848-600: The finding that rodents entirely lack the ability to vomit. In many species, the penis contains a bone, the baculum ; the testes can be located either abdominally or at the groin. Sexual dimorphism occurs in many rodent species. In some rodents, males are larger than females, while in others the reverse is true. Male-bias sexual dimorphism is typical for ground squirrels , kangaroo rats, solitary mole rats and pocket gophers ; it likely developed due to sexual selection and greater male–male combat. Female-bias sexual dimorphism exists among chipmunks and jumping mice . It
6955-463: The fore to the hind limbs. The agouti is fleet-footed and antelope -like, being digitigrade and having hoof-like nails. The majority of rodents have tails, which can be of many shapes and sizes. Some tails are prehensile , as in the Eurasian harvest mouse , and the fur on the tails can vary from bushy to completely bald. The tail is sometimes used for communication, as when beavers slap their tails on
7062-481: The frequency of polyandrous events and fertilizations. Polyandry has evolved to increase reproductive success. Male mating behavior is also affected in response to the practice of polygamous behavior. Compared to monogamous house mice, polygamous house mice mate for longer periods of time. This behaviour allows for an increase in both the transfer of sperm and paternity success, which in turn increases male fitness. As opposed to polygyny, polyandrous behavior in females
7169-444: The high-ranking males having access to the most females. This occurs in species like Belding's ground squirrels and some tree squirrel species. Promiscuity , in which both males and females mate with multiple partners, also occurs in rodents. In species such as the white-footed mouse, females give birth to litters with multiple paternities. Promiscuity leads to increased sperm competition and males tend to have larger testicles. In
7276-690: The hind limbs have three to five digits. The elbow gives the forearms great flexibility. The majority of species are plantigrade , walking on both the palms and soles of their feet, and have claw-like nails. The nails of burrowing species tend to be long and strong, while arboreal rodents have shorter, sharper nails. Rodent species use a wide variety of methods of locomotion including quadrupedal walking, running, burrowing, climbing, bipedal hopping ( kangaroo rats and hopping mice ), swimming and even gliding. Scaly-tailed squirrels and flying squirrels , although not closely related, can both glide from tree to tree using parachute-like membranes that stretch from
7383-638: The house mouse is not rigidly fixed into species-specific patterns but is instead adaptable to the environmental conditions, such as the availability of food and space. This adaptability allows house mice to inhabit diverse areas ranging from sandy dunes to apartment buildings. House mice have two forms of social behaviour, the expression of which depends on the environmental context. House mice in buildings and other urbanized areas with close proximity to humans are known as commensal . Commensal mice populations often have an excessive food source resulting in high population densities and small home ranges. This causes
7490-501: The house mouse population is known as noncommensal. These populations are often limited by water or food supply and have large territories. Female-female aggression in the noncommensal house mouse populations is much higher, reaching a level generally attributed to free-ranging species. Male aggression is also higher in noncommensal populations. In commensal populations, males come into contact with other males quite frequently due to high population densities and aggression must be mediated or
7597-442: The incisors. Rodents have efficient digestive systems, absorbing nearly 80% of ingested energy. When eating cellulose , the food is softened in the stomach and passed to the cecum , where bacteria reduce it to its carbohydrate elements. The rodent then practices coprophagy , eating its own fecal pellets, so the nutrients can be absorbed by the gut. Rodents therefore often produce a hard and dry fecal pellet. Horn et al. 2013 makes
7704-812: The lack of predators and greater competition between males. One of the most widespread groups of mammals, rodents can be found on every continent except Antarctica. They are the only terrestrial placental mammals to have colonized Australia and New Guinea without human intervention. Humans have also allowed the animals to spread to many remote oceanic islands (e.g., the Polynesian rat ). Rodents have adapted to almost every terrestrial habitat, from cold tundra (where they can live under snow) to hot deserts. Some species such as tree squirrels and New World porcupines are arboreal , while some, such as gophers , tuco-tucos , and mole rats, live almost completely underground, where they build complex burrow systems. Others dwell on
7811-502: The leaves, buds, and inner bark of growing trees, as well as aquatic plants. They store food for winter use by felling small trees and leafy branches in the autumn and immersing them in their pond, sticking the ends into the mud to anchor them. Here, they can access their food supply underwater even when their pond is frozen over. Although rodents have been regarded traditionally as herbivores, most small rodents opportunistically include insects, worms, fungi, fish, or meat in their diets and
7918-406: The males are uncertain if the offspring are theirs, they are less likely to kill the offspring. Intrauterine insemination causes an evolutionary consequence resulting from polyandrous behavior. When multiple males mate with one female, there are multiple sets of sperm gametes in a female mouse. Offspring fertilized by multiple males can compete more strongly for mother's resources and can lead to
8025-760: The males do not provide direct parental care and stay with one female because they cannot access others due to being spatially dispersed. Prairie voles appear to be an example of this form of monogamy, with males guarding and defending females within their vicinity. In polygynous species, males will try to monopolize and mate with multiple females. As with monogamy, polygyny in rodents can come in two forms; defense and non-defense. Defense polygyny involves males controlling territories that contain resources that attract females. This occurs in ground squirrels like yellow-bellied marmots , California ground squirrels , Columbian ground squirrels and Richardson's ground squirrels . Males with territories are known as "resident" males and
8132-556: The maternal investment is similar between female mice that have mated once versus multiply. The polygamous behavior of female house mice promotes sperm competition , which affects both male and female evolutionary fitness . Females who mate with multiple males tend to produce both pups in greater numbers, and with higher survival rates, increasing female fitness. Sperm competition that arises from polygamy favors males with faster, more motile sperm in higher numbers, increasing male fitness. The competitive aspect of insemination increases
8239-538: The modern day Mus musculus castaneus emerged from an ancestral Mus musculus population in Indian subcontinent some time around 700 kya. From there, this ancestral population migrated to Iran around 360 kya to form Mus musculus domesticus and then to Afghanistan around 260 kya to form Mus musculus musculus . House mice usually run, walk, or stand on all fours, but when eating, fighting, or orienting themselves, they rear up on their hind legs with additional support from
8346-1054: The mouse population can increase very quickly. Breeding occurs throughout the year. (However, animals living in the wild do not reproduce in the colder months, even though they do not hibernate .) The pups are born blind and without fur or ears. The ears are fully developed by the fourth day, fur begins to appear at about six days and the eyes open around 13 days after birth; the pups are weaned at around 21 days. Females reach sexual maturity at about six weeks of age and males at about eight weeks, but both can copulate as early as five weeks. Although house mice can be either monogamous or polygamous, they are most commonly polygamous . They generally show characteristics of mate-defense polygyny in that males are highly territorial and protective of their mates, while females are less agonistic . The communal nursing groups that result from these behaviors lead to lower numbers of infanticide since more females are able to protect greater numbers of offspring. Both evolutionary and behavioral consequences result from
8453-451: The muscle causes the eyeballs to move up and down. The Hystricomorpha , such as the guinea pig, have larger superficial masseter muscles and smaller deep masseter muscles than rats or squirrels, possibly making them less efficient at biting with the incisors, but their enlarged internal pterygoid muscles may allow them to move the jaw further sideways when chewing. The cheek pouch is a specific morphological feature used for storing food and
8560-521: The nature of the precise threat. The urgency of the threat is also conveyed by the acoustic properties of the call. Social rodents have a wider range of vocalizations than do solitary species. Fifteen different call-types have been recognized in adult Kataba mole rats and four in juveniles. Similarly, the common degu , another social, burrowing rodent, exhibits a wide array of communication methods and has an elaborate vocal repertoire comprising fifteen different categories of sound. Ultrasonic calls play
8667-675: The nest a few days after they have opened their eyes and initially keep returning regularly. As they get older and more developed, they visit the nest less often and leave permanently when weaned. In precocial species, the mothers invest little in nest building and some do not build nests at all. The female gives birth standing and the young emerge behind her. Mothers of these species maintain contact with their highly mobile young with maternal contact calls. Though relatively independent and weaned within days, precocial young may continue to nurse and be groomed by their mothers. Rodent litter sizes also vary and females with smaller litters spend more time in
8774-564: The nest than those with larger litters. Mother rodents provide both direct parental care, such as nursing, grooming, retrieving and huddling, and indirect parenting, such as food caching, nest building and protection to their offspring. In many social species, young may be cared for by individuals other than their parents, a practice known as alloparenting or cooperative breeding . This is known to occur in black-tailed prairie dogs and Belding's ground squirrels, where mothers have communal nests and nurse unrelated young along with their own. There
8881-430: The normal gait is a run with a stride of about 4.5 cm ( 1 + 3 ⁄ 4 in), though they can jump vertically up to 45 cm (18 in). The voice is a high-pitched squeak. House mice thrive under a variety of conditions; they are found in and around homes and commercial structures, as well as in open fields and agricultural lands. Newborn males and females can be distinguished on close examination as
8988-437: The offspring and play an important part in their survival. This occurs in species such as California mice , oldfield mice , Malagasy giant rats and beavers. In these species, males usually mate only with their partners. In addition to increased care for young, obligate monogamy can also be beneficial to the adult male as it decreases the chances of never finding a mate or mating with an infertile female. In facultative monogamy,
9095-518: The paths of streams and rivers and allow for the creation of extensive wetland habitats. One study found that engineering by beavers leads to a 33 percent increase in the number of herbaceous plant species in riparian areas . Another study found that beavers increase wild salmon populations. Meanwhile, some rodents are seen as pests , due to their wide range. Most rodents are herbivorous , feeding exclusively on plant material such as seeds, stems, leaves, flowers, and roots. Some are omnivorous and
9202-415: The pet or fancy mouse , and as the laboratory mouse , which is one of the most important model organisms in biology and medicine. The complete mouse reference genome was sequenced in 2002. House mice have an adult body length (nose to base of tail) of 7.5–10 centimetres (3–4 in) and a tail length of 5–10 cm (2–4 in). The weight is typically 11–30 g ( 3 ⁄ 8 –1 oz). In
9309-464: The polygamous nature of the house mouse. One consequence is the paternal investment , which is lower in polygamous mice than in mice that are monogamous. This occurs due to the fact that males spend more time involved in sexual competition than do females, leaving less time for paternal care. Polygamous male house mice spend less time alone with pups. They are also less likely and slower to retrieve lost pups than males of monogamous mice. In contrast,
9416-455: The regular pea-sized thymus organ in the chest, house mice have a second functional pinhead-sized thymus organ in the neck next to the trachea. Rodentia (rodents) Lagomorpha (rabbits, hares, pikas) Scandentia (treeshrews) Dermoptera (flying lemurs) Primates († Plesiadapiformes , Strepsirrhini , Haplorrhini ) Mice are mammals of the Glires clade , which means they are amongst
9523-539: The reproduction of subordinates by being antagonistic towards them while they are pregnant. The resulting stress causes the fetuses to abort. Rodents have advanced cognitive abilities. They can quickly learn to avoid poisoned baits, which makes them difficult pests to deal with. Guinea pigs can learn and remember complex pathways to food. Squirrels and kangaroo rats are able to locate caches of food by spatial memory , rather than just by smell. House mouse Mus abbotti The house mouse ( Mus musculus )
9630-414: The rest of the members are smaller and sterile, and function as workers. Some individuals are of intermediate size. They help with the rearing of the young and can take the place of a reproductive if one dies. The Damaraland mole rat is characterized by having a single reproductively active male and female in a colony where the remaining animals are not truly sterile, but become fertile only if they establish
9737-553: The risk of injury becomes too great. Both commensal and noncommensal house mouse males aggressively defend their territory and act to exclude all intruders. Males mark their territory by scent marking with urine. In marked territories, intruders showed significantly lower aggression than the territory residents. House mice show a male-biased dispersal; males generally leave their birth sites and migrate to form new territories whereas females generally stay and are opportunistic breeders rather than seasonal. The visual apparatus of mice
9844-408: The rodents is their pairs of continuously growing, razor-sharp, open-rooted incisors . These incisors have thick layers of enamel on the front and little enamel on the back. Because they do not stop growing, the animal must continue to wear them down so that they do not reach and pierce the skull. As the incisors grind against each other, the softer dentine on the rear of the teeth wears away, leaving
9951-798: The scents of their neighbors and respond less aggressively to intrusions by them than to those made by non-territorial "floaters" or strangers. This is known as the " dear enemy effect ". Many rodent species, particularly those that are diurnal and social, have a wide range of alarm calls that are emitted when they perceive threats. There are both direct and indirect benefits of doing this. A potential predator may stop when it knows it has been detected, or an alarm call can allow conspecifics or related individuals to take evasive action. Several species, for example prairie dogs, have complex anti-predator alarm call systems. These species may have different calls for different predators (e.g. aerial predators or ground-based predators) and each call contains information about
10058-441: The sharp enamel edge shaped like the blade of a chisel . Most species have up to 22 teeth with no canines or anterior premolars . A gap, or diastema , occurs between the incisors and the cheek teeth in most species. This allows rodents to suck in their cheeks or lips to shield their mouth and throat from wood shavings and other inedible material, discarding this waste from the sides of their mouths. Chinchillas and guinea pigs have
10165-422: The species. The altricial state is typical for squirrels and mice, while the precocial state usually occurs in species like guinea pigs and porcupines. Females with altricial young typically build elaborate nests before they give birth and maintain them until their offspring are weaned . The female gives birth sitting or lying down and the young emerge in the direction she is facing. The newborns first venture out of
10272-639: The stomach contents of the North American white-footed mouse , normally considered to be herbivorous, showed 34% animal matter. More specialized carnivores include the shrewlike rats of the Philippines, which feed on insects and soft-bodied invertebrates, and the rakali or Australian water-rat, which devours aquatic insects, fish, crustaceans, mussels, snails, frogs, birds' eggs, and water birds. The grasshopper mouse from dry regions of North America feeds on insects, scorpions, and other small mice, and only
10379-536: The surface of the ground, but may have a burrow into which they can retreat. Beavers and muskrats are known for being semiaquatic, but the rodent best adapted for aquatic life is probably the earless water rat from New Guinea. Rodents have also thrived in human-created environments such as agricultural and urban areas . Though some species are common pests for humans, rodents also play important ecological roles. Some rodents are considered keystone species and ecosystem engineers in their respective habitats. In
10486-435: The surface to feed by seizing the roots of plants with its jaws and pulling them downwards into its burrow. It also practices coprophagy. The African pouched rat forages on the surface, gathering anything that might be edible into its capacious cheek pouches until its face bulges out sideways. It then returns to its burrow to sort through the material it has gathered and eats the nutritious items. Agouti species are one of
10593-484: The surplus in crevices and hollow trees. In desert regions, seeds are often available only for short periods. The kangaroo rat collects all it can find and stores them in larder chambers in its burrow. A strategy for dealing with seasonal plenty is to eat as much as possible and store the surplus nutrients as fat. Marmots do this, and may be 50% heavier in the autumn than in the spring. They rely on their fat reserves during their long winter hibernation . Beavers feed on
10700-693: The tail – a behavior known as "tripoding". Mice are good jumpers, climbers, and swimmers, and are generally considered to be thigmotactic , i.e. usually attempt to maintain contact with vertical surfaces. Mice are mostly crepuscular or nocturnal ; they are averse to bright lights. The average sleep time of a captive house mouse is reported to be 12.5 hours per day. They live in a wide variety of hidden places near food sources, and construct nests from various soft materials. Mice are territorial, and one dominant male usually lives together with several females and young. Dominant males respect each other's territories and normally enter another's territory only if it
10807-469: The ultraviolet (UV) spectrum and therefore can see light that humans can not. The functions of this UV sensitivity are not always clear. In degus , for example, the belly reflects more UV light than the back. Therefore, when a degu stands up on its hind legs, which it does when alarmed, it exposes its belly to other degus and ultraviolet vision may serve a purpose in communicating the alarm. When it stands on all fours, its low UV-reflectance back could help make
10914-474: The water surface or house mice rattle their tails to indicate alarm. Some species have vestigial tails or no tails at all. In some species, the tail is capable of regeneration if a part is broken off. Rodents generally have well-developed senses of smell , hearing, and vision. Nocturnal species often have enlarged eyes and some are sensitive to ultraviolet light. Many species have long, sensitive whiskers or vibrissae for touch or "whisking" . Whisker action
11021-469: The wild they vary in color from grey and light brown to black (individual hairs are actually agouti coloured), but domesticated fancy mice and laboratory mice are produced in many colors ranging from white to champagne to black. They have short hair and some, but not all, sub-species have a light belly. The ears and tail have little hair. The hind feet are short compared to Apodemus mice, only 15–19 mm ( 9 ⁄ 16 – 3 ⁄ 4 in) long;
11128-404: The wild, due to a high level of predation and exposure to harsh environments. In protected environments, however, they often live two to three years. The Methuselah Mouse Prize is a competition to breed or engineer extremely long-lived laboratory mice. As of 2005 , the record holder was a genetically engineered mouse that lived for 1,819 days (7 days short of 5 years). Another record holder that
11235-475: Was attributed to an age related increase in the sensitivity of these tissues to oxidative stress . Dietary restriction is known to increase the lifespan of rodents and to retard aging . Dietary restriction was found to significantly reduce the age-related accumulation of 8-oxo-dG levels in nuclear DNA of all tissues studied in mice. Thus it was suggested that oxidative DNA damages that arise from normal cellular metabolism could be highly relevant to aging and
11342-459: Was kept in an enriched environment but did not receive any genetic, pharmacological, or dietary treatment lived for 1,551 days (4 years, 90 days). In several different mouse strains, a significant increase was observed with age in 8-Oxo-2'-deoxyguanosine (8-oxo-dG) levels in nuclear DNA from liver , heart , brain , kidney , skeletal muscle and spleen . This increase in DNA damage
11449-412: Was the first mammal for which seismic communication was documented. These fossorial rodents bang their head against the walls of their tunnels. This behavior was initially interpreted as part of their tunnel building behavior, but it was eventually realized that they generate temporally patterned seismic signals for long-distance communication with neighboring mole rats. Footdrumming is used widely as
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