Data from: Does the reduction of seed dormancy during ex situ cultivation affect the germination and establishment of plants reintroduced into the wild?

1. Plants or seeds produced in botanic gardens or nurseries have become an
important source of plant material for reintroductions or population
reinforcements. However, recent research has shown that these living
collections bear the risk of being genetically impoverished and adapted to
the artificial habitat. In particular, many studies have reported a
decline of seed dormancy during ex situ cultivation, which may compromise
their suitability for reintroduction programs. However, the impact of
those ex situ-derived changes on the germination and establishment of
reintroduced plant populations is still unclear. 2. We studied the
germination behaviour, population establishment and plant fitness over
three years of reintroduced plants of the short-lived perennial Digitalis
lutea, comparing plants grown from (1) a 30-year botanic garden
population, (2) seeds from a seed bank representing the initial starting
point of the botanic garden culture, and (3) a re-sampled corresponding
wild population. 3. Under laboratory conditions, wild-collected seeds
required cold stratification to germinate, whereas seeds from the garden
population germinated without stratification. This pattern was strongly
reduced in an outdoor pot experiment, where only a few garden seeds
germinated before winter, and all seeds remained dormant when seeded in
the natural area of origin. In a transplant experiment, reintroduced
plants from the wild population outperformed both, the garden and the seed
bank plants, in their fitness in the first 3 years after reintroduction
suggesting adaptation to current climatic conditions. 4. Synthesis and
Applications: Our study demonstrates that trait changes that occurred
during ex situ cultivation can negatively impact the establishment of
reintroduced plants. We conclude that wild plant material collected from
contemporary populations is best suited for reintroduction and should be
preferred over ex situ-cultivated and seed bank stored material,
especially when the cultivation spanned multiple generations. However, our
study also shows that germination requirements change in complex ways, and
the loss of dormancy observed under laboratory conditions may not always
be directly transferable to natural conditions. When established standards
are respected, ex situ propagated material may thus still be a valuable
resource, especially when wild material is not available in sufficient
quantities.