With which species do rats interbreed? - briefly
Rats reproduce exclusively with conspecifics; members of the genus «Rattus» may occasionally mate with other species such as «Rattus norvegicus» × «Rattus rattus», but hybrids are typically sterile. Viable interbreeding does not occur with non‑Rattus rodents or other mammals.
With which species do rats interbreed? - in detail
Rats belong to the genus Rattus, and interspecific breeding is limited to closely related members of this genus. Documented hybridization occurs primarily between the Norway rat (Rattus norvegicus) and the black rat (Rattus rattus). Crosses between these two species have produced embryos and, in rare cases, live offspring when conducted under laboratory conditions. Viability of the hybrids is low, and surviving individuals are generally sterile because of mismatched chromosome numbers (2n = 42 in R. norvegicus versus 2n = 38 in R. rattus).
Other Rattus species have been involved in experimental crosses:
- «Rattus norvegicus» × «Rattus argentiventer» (ricefield rat) – limited successes, hybrids exhibit reduced fertility.
- «Rattus norvegicus» × «Rattus exulans» (Pacific rat) – occasional embryonic development, post‑natal survival rare.
Hybridization with genera outside Rattus is not reported. Attempts to cross Rattus with house mice (Mus musculus) or other murid rodents fail due to greater genetic divergence and incompatible reproductive mechanisms. Consequently, natural interbreeding among rats is confined to species within the same genus, and even then results in low‑frequency, often sterile hybrids.