Print PagePlants collections in botanic gardens could be a valuable source for reintroducing rare plants into natural habitats. However, little is known about the effects of cultivation on the genetic diversity and fitness of garden populations, about possible genetic changes due to unconscious selection and potential adaptations to the artificial conditions. We compared the genetic variability and fitness of the rare, monocarpic perennial Cynoglossum officinale (Boraginaceae) from twelve botanic gardens and five natural populations in Germany. Genetic variability was assessed with eight nuclear microsatellites. Plants were grown in a common garden and performance was measured over two years.
Results/Conclusions
Mean genetic diversity was very similar in botanic garden and natural populations. However, four of the garden populations exhibited no genetic variability at all. Moreover, the genetic diversity of garden populations decreased with increasing duration of cultivation, indicating genetic drift. Plant performance from natural and garden populations in terms of growth, flowering and seed production was similar and in garden populations only seed mass was strongly related to genetic diversity. However, several lines of evidence indicated genetic changes in garden populations in response to cultivation. Seed dormancy was strongly reduced in garden populations, and in response to nutrient addition garden plants increased the size of their main inflorescence, while wild plants increased the number of their inflorescences. These changes could be maladaptive in nature and reduce the suitability of garden populations as a source for reintroductions. We conclude that botanic gardens should pay more attention to the problem of potential genetic changes in their plant collections.
