Tony Scoular, of Kings High School asks :-

Amy, of Sawston Village College (UK), asked:-

Can one species of animal reproduce with a different species?

Hugh Blair, an Animal Scientist at Massey University, responded.

A species may be defined as a genetically distinctive group that share a common pool of genes and that are reproductively isolated from other groups of organisms. This isolation typically restricts the interchange of genetic material between species.

Reproduction between species is normally unsuccessful for two reasons. First, the two species may have different courting/behavioural patterns which means the opposite sexes of the species are never "interested" in eachother. Secondly, even if the two species do mate, the mating may not result in a full-term pregnancy. This is because the two species either have a different number of chromosomes or if they do have the same number of chromosomes, the genetic information is distributed differently amongst the chromosomes. The outcome for both of these situations is that the fertilised egg will not have a complete set of "recipes" (due to some missing genetic material) to enable a fully-functioning organism to be produced, and hence the mating will be infertile.

However, these rules are sometimes violated and fertile matings may produce offspring. An example is the cross between a female horse (64 chromosomes) and a male donkey (62 chromosomes) which results in the well-known mule (63 chromosomes). Male mules are typically infertile but, there are reports of fertile female mules. Another inter-species cross can occur between cattle and American bison (both have 60 chromosomes). Some fertile females from this cross have been used to establish the Beefalo which is used for meat production.