Infanticide in rodents
Encyclopedia
"Infanticide
" is the term used for the termination of a neonate after it has been born, and in zoology
this often applies to the termination and/or consumption of newborn animals by either a parent or an unrelated adult. In rodent
s, it is not uncommon for the mother to commit infanticide shortly after parturition (giving birth) under conditions of extreme stress (parental infanticide), or for an unrelated male to kill neonates not his own (nonparental infanticide).
The occurrence of infanticide seems to vary within rodent species between parents. For example, male meadow voles
and house mice can be classed as either 'infanticidal' or 'non-infanticidal' depending on their history with other litters they have sired, although studies have shown that females do not discriminate between these classes when choosing a mate.
improving reproductive opportunities and the retainment of energy and resources that might otherwise be spent on unrelated offspring. A common causal factor of infanticide, particularly among sciurid rodents, is direct resource competition, therefore killing the pups of an unrelated neighbour would prevent resource competition with those individuals in the future.
, myomorphs
and caviomorphs
.
Not all rodent species commit infanticide, and in fact some species are remarkable for their lack of this behaviour. One such species is the degu
, a highly social caviomorph rodent from central Chile. Degus have been found not to harm even unfamiliar pups, and male degus will even accept other males' litters into a group without problems. This is thought to be related to the communal nesting habits of the species and reflects genetic trends rather than a lack of the conditions that lead to infanticide.
Infanticide
Infanticide or infant homicide is the killing of a human infant. Neonaticide, a killing within 24 hours of a baby's birth, is most commonly done by the mother.In many past societies, certain forms of infanticide were considered permissible...
" is the term used for the termination of a neonate after it has been born, and in zoology
Infanticide (zoology)
In animals, infanticide involves the killing of young offspring by a mature animal of its own species, and is studied in zoology, specifically in the field of ethology. Ovicide is the analogous destruction of eggs. Although human infanticide has been widely studied, the practice has been observed...
this often applies to the termination and/or consumption of newborn animals by either a parent or an unrelated adult. In rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, it is not uncommon for the mother to commit infanticide shortly after parturition (giving birth) under conditions of extreme stress (parental infanticide), or for an unrelated male to kill neonates not his own (nonparental infanticide).
Parental infanticide
Parental infanticide is perhaps the most confusing behaviour to understand, as in many cases it can seem maladaptive for a parent to terminate offspring carrying its own genetic material. However, studies in mice have indicated infanticide may be a gentically heritable trait, and may even have a learned element, so there is clearly more to the behaviour than might be expected.The occurrence of infanticide seems to vary within rodent species between parents. For example, male meadow voles
Meadow Vole
The Meadow Vole , sometimes called the Field Mouse or Meadow Mouse, is a North American vole found across Canada, Alaska and the northern United States. Its range extends further south along the Atlantic coast. One subspecies, the Florida Salt Marsh Vole , is found in Florida, and is classified as...
and house mice can be classed as either 'infanticidal' or 'non-infanticidal' depending on their history with other litters they have sired, although studies have shown that females do not discriminate between these classes when choosing a mate.
Nonparental infanticide
Some rodent species (most typically males) will take the chance to kill neonates that are unrelated to them should opportunity permit. There is thought to be several benefits by doing so, which not only include nutrition benefits (particularly where food is in short supply) but also non-direct benefits, such as allowing access to more resources,improving reproductive opportunities and the retainment of energy and resources that might otherwise be spent on unrelated offspring. A common causal factor of infanticide, particularly among sciurid rodents, is direct resource competition, therefore killing the pups of an unrelated neighbour would prevent resource competition with those individuals in the future.
Species known to commit infanticide
Work by Blumstein (2000) highlighted the following rodent species which have previously been associated with infanticide in published scientific literature. Assessment of these traits lead Blumstein to conclude that infanticide evolved independently in sciuromorphsSciuromorpha
The term Sciuromorpha has referred to numerous groups of rodents, but the only family common to all variations is the Sciuridae, the squirrels. Most definitions also include the Mountain Beaver....
, myomorphs
Myomorpha
Suborder Myomorpha contains 1,137 species of mouse-like rodents, nearly a quarter of all mammal species. Included are mice, rats, gerbils, hamsters, lemmings and voles. They are grouped according to the structure of the jaw and the structure of the molar teeth. Both their medial and lateral...
and caviomorphs
Caviomorpha
Caviomorpha is the rodent infraorder or parvorder that unites all South American hystricognaths. It is supported by both fossil and molecular evidence.-Origin:...
.
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Arctic Ground Squirrel The Arctic ground squirrel is a species of ground squirrel native to the Arctic.-Subspecies:Listed alphabetically.*S. p. ablusus Osgood, 1903... Columbian Ground Squirrel The Columbian ground squirrel is a species of rodent in the Sciuridae family. It is found in Canada and the United States.... Townsend's Ground Squirrel The Townsend's ground squirrel is a species of rodent in the Sciuridae family. It is found in high desert shrublands in several areas of the United States.-Distribution:... Meadow Vole The Meadow Vole , sometimes called the Field Mouse or Meadow Mouse, is a North American vole found across Canada, Alaska and the northern United States. Its range extends further south along the Atlantic coast. One subspecies, the Florida Salt Marsh Vole , is found in Florida, and is classified as... Montane Vole The Montane Vole is a species of rodent in the family Cricetidae.It is found in the western United States and British Columbia in Canada.-References:... Townsend's Vole Townsend's Vole is a species of rodent in the family Cricetidae.It is found in British Columbia in Canada and in Washington and Oregon in the United States.Its natural habitat is temperate grassland.-References:... Gray-tailed Vole The Gray-tailed vole is a common small mammal that inhabits grasslands in the Willamette Valley of western Oregon . Gray tailed voles are polygamous: females are territorial, males have large home ranges that overlap those of several females, and juvenile emigration is male biased... California Vole The California vole is a type of vole which lives throughout much of California and part of southwestern Oregon. It is also known as the California meadow mouse. It averages in length although this length varies greatly between subspecies.-Description:The California vole is a medium sized vole,... Prairie Vole The Prairie Vole is a small vole found in central North America. The vole has long, coarse grayish-brown fur on the upper portion of the body and yellowish fur on the lower portion of the body... Woodland Vole The Woodland Vole, Microtus pinetorum, is a small vole found in eastern North America. It is also known as the Pine Vole.-Description:... Field Vole The field vole or short-tailed vole, Microtus agrestis, is a grey-brown vole, around 110mm in length, with only a short tail. They are one of the most common mammals in Europe, ranging from the Atlantic coast to Lake Baikal. They are found in moist grassy habitats, such as woodland, marsh, or... |
Sagebrush Vole The Sagebrush Vole is a tiny vole found in western North America. This is the only member of genus Lemmiscus.... Brandt's Vole Brandt's vole, , also known as the steppe vole, is a species of rodent in the family Cricetidae.It is found in China, Mongolia and Russia.-Morphology:... Northern Red-backed Vole The northern red-backed vole, Myodes rutilus, is a small slender vole found in Alaska, northern Canada, Scandinavia and northern Russia.-Description:... Red-backed vole The red-backed voles are the members of the genus Myodes, a group of small slender voles found in North America, Europe and Asia. The genus name comes from the Greek "keyhole mouse". In the past, the genus has been called Evotomys or Clethrionomys, but Myodes takes precedence.They inhabit northern... Bank Vole The bank vole is a small vole with red-brown fur and some grey patches, with a tail about half as long as its body. A rodent, it lives in woodland areas and is around in length. The bank vole is found in western Europe and northern Asia... Muskrat The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats... Water Vole The European Water Vole or Northern Water Vole, Arvicola amphibius , is a semi-aquatic rodent. It is often informally called the Water Rat or Ratty, although it only superficially resembles a true rat... Collared lemming Dicrostonyx is a genus of rodent in the family Cricetidae. It contains the collared lemmings.It contains the following species:* Northern Collared Lemming * Ungava Collared Lemming... Norway lemming The Norway lemming , Lemmus lemmus, is a common species of lemming found in northern Scandinavia and adjacent areas of Russia. It is the only vertebrate species endemic to the region. The Norway lemming dwells in tundra and fells, and prefers to live near water. Adults feed primarily on... Djungarian hamster The Djungarian hamster , also known as the Siberian hamster or Russian winter white dwarf hamster, is a species of hamster in the genus Phodopus. It is ball-shaped and typically half the size of the Syrian hamster, and therefore called a dwarf hamster along with all Phodopus species... |
Desert Woodrat The Desert Woodrat is a small species of pack rat native to desert regions of western North America, ranging from southeastern Oregon and southwestern Idaho, south to California in the U.S., and Baja California and extreme northwestern Sonora in Mexico.This pack rat is 8.5 to 15 inches long... White-footed mouse White-footed Mouse is a rodent native to North America. It ranges from Ontario, Quebec, Labrador and the Maritime Provinces to the southwest USA and Mexico. It is also known as the Woodmouse, particularly in Texas.Adults are in length, not counting the tail, which can add another . A young adult... California Mouse The California Mouse is a species of rodent in the family Cricetidae. It is the only species in the Peromyscus californicus species group. It is found in north-western Mexico and central to southern California... Wood mouse The wood mouse is a common murid rodent from Europe and northwestern Africa. It is closely related to the yellow-necked mouse but differs in that it has no band of yellow fur around the neck, has slightly smaller ears, and is usually slightly smaller overall: around 90 mm in length... Spiny mouse The term spiny mouse refers to any species of rodent within the genus Acomys. Similar in appearance to mice of the genus Mus, spiny mice are small mammals with bare, scaled tails... Guinea pig The guinea pig , also called the cavy, is a species of rodent belonging to the family Caviidae and the genus Cavia. Despite their common name, these animals are not in the pig family, nor are they from Guinea... Cui -People:* Cui, Chinese surname.* César Cui , a Russian composer* Jorge "Cui" Cuello, British historian Oxford University, 1995 Pulitzer Prize winner-Other uses:* Cui , a Peruvian term for the guinea pig, when used as food... |
Exceptions
Degu
The degu is a small caviomorph rodent that is endemic to central Chile.It is sometimes referred to as the brush-tailed rat, and is also called the common degu, to distinguish it from the other members of the genus Octodon. Other members are also called degus, but they are distinguished by...
, a highly social caviomorph rodent from central Chile. Degus have been found not to harm even unfamiliar pups, and male degus will even accept other males' litters into a group without problems. This is thought to be related to the communal nesting habits of the species and reflects genetic trends rather than a lack of the conditions that lead to infanticide.