Data from: Neo-allopatry and rapid reproductive isolation

Over the last three centuries many species have been dispersed beyond
their natural geographic limits by humans, but to our knowledge
reproductive isolation has not been demonstrated for such neo-allopatric
species. We grew seeds from three species of Centaurea (C. solstitialis,
C. calcitrapa, and C. sulphurea) that are native to Spain and have been
introduced into California, and tested to what extent seed production was
affected by pollen source. Compared to within- population crosses, seed
production decreased by 52 and 44 percent when C. solstitialis and C.
sulphurea from California were pollinated with conspecific pollen from
native populations in Spain. This implies rapid evolution of reproductive
isolation between populations in their and native and non-native ranges.
Whether reproductive isolation has evolved following the introduction of
other species is unknown, but additional cases are likely considering the
large number of neo-allopatric species.