Advances in New Zealand mammalogy 1990–2000: European rats

Biology and Impacts of Pacific Island Invasive Species. 11.Rattus rattus,the Black Rat (Rodentia: Muridae)

“…data). These Pacific-wide R. rattus body size measurements were similar to those summarized across New Zealand (Innes 2005a). Unlike other invasive Rattus species ( YomTov et al 1999, Atkinson andTowns 2005), there does not appear to be a Pacific-wide pattern of greater body size with increasing latitude for R. rattus ( Yom-Tov et al 1999; A.B.S., J. Russell, and W.C.P., unpubl.…”

“…data). Adult male R. rattus are larger in both mass and body length than adult females (Innes 2005a, Shiels 2010, whereas average tail length has been recorded as similar between sexes (Innes 2005a) or slightly greater in males than in females (Shiels 2010).…”

“…Past synonyms have included Mus rattus Linnaeus, 1758; Mus alexandrines Geoffroy, 1803; Musculus frugivorus Rafinesque, 1814; Mus novaezelandiae Buller, 1870; plus numerous others (Innes 2005a). In evolutionary terms, the genus Rattus originated about 2 -3 million years ago .…”

“…Without molecular analysis of individuals within the R. rattus complex, it is very difficult to separate the species, and R. rattus and R. tanezumi are almost impossible to distinguish morphologically . In addition, three interbreeding color morphs of R. rattus have been described in the Pacific (Tomich 1986, Innes 2005a: R. r. rattus (black individuals), R. r. frugivorous (whitebellied), and R. r. alexandrinus (gray-bellied). For simplicity, we have not distinguished among species or color morphs within the R. rattus complex and therefore consider all of those species within the complex as the black rat, R. rattus.…”

“…The Oceania group of R. rattus generally has 2n = 38 chromosomes (Musser and Carleton 2005), and it was this species that was thought to have originated in the Indian Peninsula and reached Britain by the 3rd century A.D. (Innes 2005a). The second group of R. rattus is an Asian form that has 2n = 42 chromosomes and is indigenous to Southeast Asia; today it is also found in Japan, Taiwan, the Philippines, New Guinea, Fiji, and other islands (Robins et al 2007).…”