Genetic diversity and the reintroduction of meadow species

Restoration of formerly nutrient-poor and species-rich grasslands generally leads to an increase in species diversity. However, species without a pers istent seed bank and with poor dispersal ability often do not re-establish spontaneously. Here, reintroduction is an option. If existing populations a re comparable in their genetic composition, any population will do. This is not the case if populations have local adaptations. Unfortunately, whether populations are adapted locally is not easily determined, in contrast to a ssessing differentiation using neutral genetic markers. We used AFLP to stu dy genetic diversity of Cirsium dissectum and Succisa pratensis within and among several Junco-Molinion plant communities in the Netherlands (up to 20 0 km apart) that were potential source populations, and followed the reintr oduction using seeds from these populations. Also, vegetative growth phase characteristics of three populations of C. dissectum were analyzed under co ntrolled conditions. Most of the genetic variation in these cross-fertilizi ng species was found within populations. Small but significant genetic diff erences in band frequencies were found among populations (F-st 0.100-0.135) . The first generation of reintroduced plants contained less polymorphic ba nds than the source populations. The genetic differences caused by reintrod uction using a limited number of seeds (founder effects) were significant i n all except one case (F-st 0.012-0.101 between source and corresponding re introduced population), but the magnitude was smaller than the source popul ation differentiation. In assignment tests, reintroduced populations resemb led their source population more than any other population, but all populat ions contained sizeable proportions of plants that were assigned to most si milar plants from other populations, indicating that the populations are on ly marginally distinct. Calculations show that reintroduction from more tha n one source population introduces significantly more polymorphic bands int o the new population, capitalizing on the existence of band frequency diffe rences among populations.