EUGENE M. MCCARTHY, PHD GENETICS
Aethomys chrysophilus [Red Rock Rat]
× Rattus norvegicus [Brown Rat] CHR. CON: eastern and southern Africa. Dr. J. W. B. Gunning (1901, p. 263), director of the Pretoria Museum and Zoological Garden, says “I have been very successful in breeding crosses between Mus chrysophilus and M. decumanus and have about twenty-four at present.” Mus chrysophilus is a synonym of Aethomys chrysophilus, and Mus decumanus is a synonym of Rattus norvegicus.
Apodemus flavicollis [Yellow-necked Field Mouse]
× Apodemus ponticus [Black Sea Field Mouse] CHR. A. ponticus individuals captured on the Turkey-Georgia border formed fertile hybrids with A. flavicollis from Austria. Some researchers have proposed that flavicollis and ponticus be treated as conspecific. Internet citation: http://www.iucnredlist.org/details/1892/0.
× Apodemus sylvaticus [Long-tailed Field Mouse | Wood Mouse] CAONHR(Europe, Crimea, Caucasus). Amtmann 1965; Bothschafter 1963; Engländer and Amtmann 1963; Heptner 1940; Kahmann and Bothschafter 1963; Larina 1959, 1961a (listed in Säugetierkundliche Mitteilungen, vol. 11, p. 131), 1961b (cited by Kahmann and Bothschafter 1963); Nascetti et al. 1979; Niethammer 1969a; Peshev and Georgiev 1961; Zimmermann 1965.
× Apodemus uralensis [Pygmy Field Mouse] NHR. CON: eastern Europe, Middle East. Steiner 1979.
Apodemus ponticus [Black Sea Field Mouse] See: Apodemus flavicollis.
Apodemus sylvaticus [Long-tailed Field Mouse | Wood Mouse]
See also: Apodemus flavicollis.
× Apodemus uralensis [Pygmy Field Mouse] NHR. CON: eastern Europe. Steiner 1979.
Apodemus uralensis [Pygmy Field Mouse] See: Apodemus flavicollis; A. sylvaticus.
Mastomys erythroleucus [Guinea Multimammate Mouse]
× Mastomys natalensis [Natal Multimammate Mouse] ENHI. HPF(♀♀). CON: Africa. The close similarity of M. natalensis mtDNA to that of certain cytotypes of M. erythroleucus suggests the occurrence of extensive hybridization (either currently or in the past). Tamrin and Abdullah 2011.
Mastomys natalensis [Natal Multimammate Mouse]
See also: Mastomys erythroleucus.
× Mus musculus (♀) [Eastern House Mouse] CHR. CON: sub-Saharan Africa. Hybrids of both sexes have been reported. Their rapid growth indicated heterosis. Gray 1972 (p. 82).
Maxomys ochraceiventer [Chestnut-Bellied Spiny Rat]
× Maxomys whiteheadi [Whitehead’s Spiny Rat] NHR(Malaysia). Intermediate rats, similar in appearance to M. whiteheadi, have been shown to be genetically highly similar to M. ochraceiventer.
Note: Various populations assigned to Mus (i.e., bactrianus=gansuensis =wagneri, castaneus, domesticus, molossinus, musculus) are often treated as subspecies of Mus musculus, but also at times as distinct species. Here, the latter treatment prevails.
Mus bactrianus [Persian House Mouse]
× Mus musculus (↔ usu. ♀) [Eastern House Mouse] CHR. DRS. HPF(♂&♀). M. bactrianus (sometimes called M. wagneri or M. gansuensis), which is now often lumped under M. musculus, isnot listed by Duff and Lawson.Fortuyn 1931a, 1931b; Gray 1972; Green1930a, 1930b; 1931a, 1931b, 1931c, 1931d; 1933, 1935.
Mus booduga [Little Indian Field Mouse]
× Mus domesticus [Western House Mouse] CHR. DRS. Embryonic hybrids have been produced by artificial insemination. However, development is arrested early in gestation. West et al. use the name Mus dunni for Mus booduga. West et al. 1977†.
Mus caroli [Ryukyu Mouse]
× Mus domesticus (♀) [Western House Mouse] CHR. DRS. LFH. Hybrids have been produced by artificial insemination. The percentage of fertilized eggs leading to viable hybrids is very low (about 1/100th the rate seen in pure M. domesticus matings). Most hybrid embryos fail to implant, and most that do die soon after. Most (all?) hybrids surviving to adulthood are female. Frels et al. 1980; West et al. 1977†; 1978†.
Mus castaneus [Asian House Mouse]
× Mus musculus [Eastern House Mouse] ENHR. HPF(♂&♀). On the basis of an mtDNA survey Yonekawa et al. (1988) concluded that the Japanese Wild Mouse (molossinus) is derived from this cross. The most common mtDNA haplotype in molossinus populations is closely similar to that of M. musculus mtDNA. The other common haplotype closely resembles that of M. castaneus. Two other rare variants are probably the result of recent contamination by European M. m. domesticus. The musculus type of mtDNA is found in southern Japan, the castaneus type, in the north. These taxa (castaneus, molossinus, musculus) are often treated as conspecific, but sometimes as separate species (e.g., Marshall and Sage 1981, p. 20).
Note: Mus domesticus has many distinct, hybridizing chromosomal races. Capanna 1973; Corti and Ciabatti 1990; Searle 1991.
Mus domesticus [Western House Mouse]
See also: Mus booduga; M. caroli.
× Mus musculus [Eastern House Mouse] CAENHR. HPF(♂&♀). A narrow hybrid zone extends from Denmark, south through Germany and the Balkans to the Black Sea. Bonhomme et al. (1984, p. 296) say “introgression…occurs all along the hybrid zone.” Extensive gene flow of mtDNA has occurred from M. domesticus to Scandinavian M. musculus populations. These taxa are often lumped. Bonhomme et al. 1983; 1984; Ferris et al. 1983; Forejt and Ivanyi 1975; Hunt and Selander 1973; Macholán et al. 2003; Marshall and Sage 1981 (p. 20); Selander et al. 1969; Ursin 1952; Zimmermann 1949.
× Mus spicilegus (♂) [Mound-building Mouse] CHR. HPF(♀♀). DRS. In backcrosses to M. domesticus 28% of the resulting male hybrids were at least partially fertile (and had larger testicles than infertile males). Bonhomme et al. 1983, 1984; Sokolov et al. 1982.
× Mus spretus (↔ usu. ♂) [Algerian Mouse] CANHR. HPF(♀♀). CON: Spain, Portugal, northeastern Africa. Probable hybrids have been reported from Portugal. This cross was used extensively to produce linkage maps for M. musculus. Male F₁ hybrids are viable, but sterile (or at least of very low fertility). Bonhomme et al. 1978, 1979, 1984; Ceci et al. 1994; Copeland and Jenkins 1991; Copeland et al. 1993; Engels 1983; Hale et al. 1993; Siracusa et al. 1989; Zechner et al. 1996.
Mus macedonicus [Macedonian Mouse]
× Mus spicilegus [Mound-building Mouse] CHR. CON: Balkan Peninsula. Lavrenchenko 1990; Lavrenchenko et al. 1989; Sokolov et al. 1998.
Mus molossinus [Japanese Wild Mouse]
× Mus musculus [Eastern House Mouse] CHR. HPF(♂&♀). CON: Japan. In the past, the population molossinus has been treated as a species (Mus molossinus Temm. et Schleg), but in recent years it has usually been treated as a race of M. musculus. Yonekawa et al. (1988) showed that molossinus is of hybrid origin. See: Mus castaneus × M. musculus. According to Austin et al. (p. 30), hybridization "between these two forms gives a completely fertile hybrid, whose courses of spermatogenesis and oogenesis proceed quite regularly." Austin et al. 1948; Fujihara 1958; Makino 1940, 1941.
Mus musculus [Eastern House Mouse] (2n = 40)
See also: Family Dipodidae; Mus bactrianus; M. castaneus; M. domesticus; M. molossinus.
× Dipodidae sp. Ackermann (1898) lists this cross, but the cited article (Berichte des Naturwissenschaftlich-medizinischen Vereines in Innsbruck, Jahrgang 1893-1896, vol. 22, p. xvii) does not refer to a hybrid of this type. The following quoted material is the passage to which Ackermann refers: “In der sich anschliessenden Besprechung berichtet Prof. Heider von Erfahrungen, die bei Kreuzung von Spring- und weissen Mäusen sich ergeben und dahin zu deuten seien, dass bei der concurrenz zweier verschiedener neuerer Keimeigenthümlichkeiten die alte nicht abgeänderte Keimanlage den Sieg erlange, und gleichsam in Verlegenheit gebracht, die Natur die alte, ursprüngliche Art zur Geltung gelangen lasse.” Gray (1972) lists this cross as Jaculus jaculus × Mus musculus and mistakenly cites Ackermann.
× Gallus gallus [Domestic Fowl] See the separate article: "A Mouse-chicken Hybrid?"
× Jaculus jaculus [Egyptian Gerboa] See Mus musculus × Dipodidae sp.
× Mus poschiavinus [Tobacco Mouse] CHR. HPF(♂&♀). CON: Paschiavo Valley, Griscons, Switzerland (tobacco mice occur nowhere else). Although hybrids are partially fertile in both sexes, they are markedly less fertile than pure types. Chromosomal chains and rings are formed during meiosis. These hybrids are easily obtained in captivity. F₁ hybrids have a diploid chromosome count of 2n=33. These taxa are occasionally lumped (e.g., Duff and Lawson 2004). Gropp et al. 1969, 1970; Klein 1971; Tettenborn and Gropp 1970; Hauffe and Searle 1993.
× Mus spicilegus [Mound-building Mouse] CHR. HPF. CON: eastern Europe, southwestern Russia. Bullatova et al. 1986; Sokolov et al. 1998.
× Rhabdomys pumilio [Four-striped Grass Rat] CHR. CON: southern Africa. Gunning (1901) writes that “the result of a cross between the ordinary albino Mus musculus with the Striped Mouse (Arvicanthis pumilio) is a peculiarly cream-coloured, not striped specimen, which looks very much like a cream albino Mouse with black eyes which stand out very distinct against the cream-coloured fur.” Arvicanthis pumilio is a synonym of Rhabdomys pumilio.
Mus poschiavinus [Tobacco Mouse] (2n = 26) See: Mus musculus.
Mus spretus [Algerian Mouse] See: Mus domesticus.
Mus spicilegus [Mound-building Mouse] (=hortulanus) See: Mus domesticus; M. macedonicus.
Pseudomys delicatulus [Delicate Mouse]
× Pseudomys novaehollandiae [New Holland Mouse] CHR. ENHR. CON: coastal Australia (the region of contact is at the easternmost point of the continent). The Pilliga Mouse, a mouse widely recognized as a species (Pseudomys pilligaensis), and derived from this cross, is present in the Pilliga Nature Reserve and the Pilliga State Forest. The IUCN says, “Unpublished DNA sequencing indicates that P. pilligaensis [the Pilliga Mouse] is the result of hybridisation between P. delicatulus and P. novaehollandiae. … A recovery plan was prepared but never published. Further studies are needed into the taxonomy, ecology, and threats to this apparently hybrid species.”
Pseudomys novaehollandiae [New Holland Mouse] See: Pseudomys delicatulus.
Pseudomys pilligaensis [Pilliga Mouse] See: Pseudomys delicatulus × P. novaehollandiae
Otomys irroratus [Common Vlei Rat] Pillay et al. (1995) found that hybrids between two chromosomal races (Kamberg and Karkloof) of this rat were nearly sterile. Of 57 hybrids either backcrossed or mated inter se only one produced young. In a separate study (Pillay et al. (1992), they found that the fertility of hybrids was severely impaired in crosses between several such chromosomal races (Committee’s Drift ×Hogsback, Committee’s Drift ×Karkloof, Hogsback ×Karkloof).
Rattus colletti [Dusky Rat]
× Rattus sordidus [Canefield Rat] CHR. DRS. These taxa are sometimes lumped. Watts (in Honacki et al. 1982, p. 554).
× Rattus tunneyi [Pale Field Rat] CHR. HPF. CON: northwestern Northern Territory, Australia. Baverstock et al. 1983, 1986; Watts (in Honacki et al. 1982, p. 554).
× Rattus villosissimus [Long-haired Rat] CHR. HPF? Parapatric contact zone in northwestern Northern Territory, Australia. These taxa are sometimes lumped. Watts and Aslin 1981 (p. 250); Watts (in Honacki, et al. 1982, p. 554).
Note: Taylor and Calaby (1988a, p. 1) note that “Australian Rattus may not be true Rattus as the genus is inadequately defined.”
Note: Three distinct types of rats were formerly treated as separate species Rattus assimilis Gould, 1857 (Australian Bush Rat | Allied Rat), Rattus fuscipes Waterhouse, 1839 (Dusky-footed Rat | Western Swamp Rat), and Rattus greyii Grey, 1841 (Grey’s Rat). The three were, however, lumped as races of Rattus fuscipes after it was found in captive experiments that they were able freely to interbreed. Horner and Taylor 1965; Taylor and Calaby 1988a.
Rattus fuscipes [Australian Bush Rat]
× Rattus lutreolus (♀) [Australian Swamp Rat] CHR. CON: coastal southeastern Australia. HPF(♂&♀). Though generally intermediate F₁ hybrids are more similar to R. lutreolus. Fox and Murray (1979) give a detailed description of the hybrids. These rats differ in karyotype. R. lutreolus has 2n = 42, R. fuscipes has 2n = 38 and has two pairs of submetacentrics not found in R. lutreolus. F₁ hybrids had 2n = 40. The same authors state (p. 694) that an F₁ male mated with an R. lutreolus female.The latter gave birth to seven healthy young. This partial fertility in a hybrid male suggests hybrid females, too, are probably partially fertile (by Haldane’s Rule). In an earlier report, Horner and Taylor (1965) failed to obtain hybrids. R. fuscipes and R. lutreolus have diploid chromosome numbers of 2n = 38 and 2n = 42, respectively. In their F₁ hybrid 2n = 40. Taylor and Calaby1988a, 1988b.
Rattus lutreolus [Australian Swamp Rat] See: Rattus fuscipes.
Rattus macleari [MacLear’s Rat] (Extinct)
× Rattus rattus [Black Rat/Roof Rat]ENHR(Christmas Island). Pickering and Norris (1996) studied documents about Maclear’s Rat uncovered at Oxford University, as well as specimens from the Zoological Collections, University Museum, Oxford University, and the University Museum of Zoology, Cambridge. On this basis they concluded that the extinction of the endemic rat, Rattus macleari, around 1900 was caused by extensive hybridization with the introduced black rat and by disease. The documents examined were written by a certain Dr. Durham, who collected 19 rat specimens, which were R. macleari, R. rattus, and a few that showed varying degrees of intermediacy between the two. However, see contra: Aplin (2008); Musser and Carleton (2005).
Rattus norvegicus [Brown Rat] (= Mus decumanus)
See also: Aethomys chrysophilus.
× Rattus rattus (♀) [Black Rat/Roof Rat] CHR? NHR? Adamo reported three serendipitous pregnancies resulted when four black rat females, mis-identified as brown rats, were caged with an R. norvegicus male. The first two hybrid litters were killed by bites to the head soon after birth. A third litter died through maternal neglect. Adamo says, “babies were all born alive, and moved and squeaked loudly.” However, this is an informal Internet report and may not be reliable. A series of papers by Japanese researchers (Hiraiwa and Yoshida 1955; Yosida and Taya 1977, 1979, 1980) investigated the reciprocal cross; they report that only embryos were obtained. Yosida and Taya (1980, p. 145) promise to report results of experiments with the cross the other way around (R. norvegicus male× R. rattus female) , but never seem to have done so. Southwell (1889) argued that the Irish rat, formerly treated as a separate species (Mus hibernicus), had probably arisen from hybridization between the black and brown rats. Barrett Hamilton 1888; Craft 1938; Miljutin 1989. .
Note: Three types treated as races of R. rattus (frugivorus, back brown, belly white; alexandrinus back brown, belly dark gray; rattus, back and belly both dark gray), were once treated as separate species. They have all been crossed in captivity and intermediate types occur, too, in a natural setting. Caslick 1956; Darwin (1883, p. 43); Worth 1950.
Rattus rattus [Black Rat]
See also: Rattus macleari; R. norvegicus.
× Felis catus [Domestic Cat] See the separate article: "Domestic Cat × Black Rat."
× Neotoma albigula [White-throated Woodrat/Packrat] ENHR. BRO: southwestern U.S., Mexico. Hybrids of this type are proliferating so rapidly in and around Phoenix, Arizona, that they have become a major nuisance. Pest control workers say they are invading homes and are more destructive than either roof rats or packrats. This is an intersubfamilial cross (Sigmodontinae × Murinae). Video: https://www.youtube.com/watch?v=Y7EQlR4MtYg
× Rattus tanezumi [Oriental House Rat] CHR. HPF. CON: eastern Asia. Chinen et al. 2005.
× Rattus turkestanicus [Turkestan Rat] Parapatric and altitudinal contact zones in Nepal and eastern Afghanistan. Although no hybrids have been explicitly reported, data presented by Niethammer (1975, pp. 326-328) suggests rats in eastern Afghanistan are geographically and morphologically intermediate. Here, turkestanicus = Niethammer’s rattoides. See also: Rattus colletti.
× Rattus villosissimus [Long-haired Rat] CHR. HPF? Parapatric contact zone in eastern Queensland, Australia. These taxa are sometimes lumped. Watts and Aslin 1981 (p. 250); Watts (in Honacki, et al. 1982, p. 554).
Rattus tanezumi [Oriental House Rat] See: Rattus rattus.
Rattus tunneyi [Pale Field Rat] See: Rattus colletti.
Rattus turkestanicus [Turkestan Rat] See: Rattus rattus.
Rattus villosissimus [Long-haired Rat] See: Rattus colletti; R. sordidus.Watts and Aslin (1981, p. 250) say R. villosissimus “will cross-breed readily with both the dusky rat [R. colletti] and canefield rat [R. sordidus], and one of the hybrids [Watts and Aslin do not indicate which one of the two types of hybrids] has bred. However, these hybrids are likely to have reduced fertility because of the large difference in chromosome numbers between the species (50 in the long-haired rat, 42 in the dusky rat and 32 in the canefield rat)…many of the hybrids have abnormal jaws in which one or more molars are missing or deformed in some way.”
Rhabdomys dilectus [Mesic Four-striped Grass Rat]
× Rhabdomys pumilio [Four-striped Grass Rat] CHR. CON: South Africa. These taxa have often been lumped. Internet: Stippel 2009.
Rhabdomys pumilio [Four-striped Grass Rat] See: Mus musculus.
If you know of other murine crosses not listed on this page, please contact this website.
By the same author: Handbook of Avian Hybrids of the World, Oxford University Press (2006).
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