Disjunct distribution

Other conditions that can produce disjunct distributions include: flooding, or changes in wind, stream, and current flows, plus others such as anthropogenic introduction of alien introduced species either accidentally or deliberately (agriculture and horticulture).

This kind of disjunct distribution of a species, such that it occurs in Iberia and in Ireland, without any intermediate localities, is usually called "Lusitanian" (named after the Roman Province Lusitania, corresponding roughly to modern-day Portugal).

Examples of animal species with a Lusitanian distribution are: the Kerry slug Geomalacus maculosus and the Pyrenean glass snail Semilimax pyrenaicus.

The theory behind the name "Lusitanian" is now discredited; it posited that there was an ice-free land mass that served as a refugium off of the south-west of Ireland during the Quaternary (last) glaciation.

The authors concluded that it had been introduced in the early (Paleolithic) or middle (Mesolithic) Stone Age, by boat, probably from south-west Europe.