These species are often systematically isolated
taxa, whose distribution areas represent the remnants of originally
larger distribution ranges that have been reduced due to environmental
changes. Check-out this phenomenon on the figure! The Ice Age,
for example, led to the extinction of many species in the European
Alps. However, several species could survive in non-glaciered
areas at the south-western and the south-eastern end of the Alpine
chain. Today, these two regions represent centres of paleoendemic
species. Berardia subacaulis, for example, is one of them;
it grows today as a relict of the Tertiary period in a part of
the French Alps.
These species result from the divergent adaptation
to differing environmental conditions thereby leading to the formation
of new species that are locally distributed. The evolution of
neoendemic plant species is often triggered by polyploidy.
The endemic species may have a higher ploidy level than its related
taxa (apoendemics), or it may be diploid while its related taxa
have a higher ploidy level (patroendemics). In cases where the
endemic taxon and its related taxa are of equal ploidy level,
the endemic species are called schizoendemics. Apo-, patro-, and
schizoendemics are further subdivisions of neoendemics. Achillea
erba-rotta s.str. and Achillea erba-rotta ssp. moschata
are typical examples for neoendemics.