Data from: Thank you for not flowering: conservation genetics and gene flow analysis of native and non-native populations of Fraxinus (Oleaceae) in Ireland

The risks of gene flow between interfertile native and introduced plant
populations are greatest when there is no spatial isolation of pollen
clouds and phenological patterns overlap completely. Moreover, invasion
probabilities are further increased if introduced populations are capable
of producing seeds by selfing. Here we investigated the mating system and
patterns of pollen-mediated gene flow among populations of native ash
(Fraxinus excelsior) and mixed plantations of non-native ash (F.
angustifolia and F. excelsior) as well as hybrid ash (F. excelsior × F.
angustifolia) in Ireland. We analysed the flowering phenology of the
mother trees and genotyped with six microsatellite loci in progeny arrays
from 132 native and plantation trees (1493 seeds) and 444 potential
parents. Paternity analyses suggested that plantation and native trees
were pollinated by both native and introduced trees. No signs of
significant selfing in the introduced trees were observed and no evidence
of higher male reproductive success was found for introduced trees
compared with native ones either. A small but significant genetic
structure was found (φft=0.05) and did not correspond to an
isolation-by-distance pattern. However, we observed a significant temporal
genetic structure related to the different phenological groups, especially
with early and late flowering native trees; each phenological group was
pollinated with distinctive pollen sources. Implications of these results
are discussed in relation to the conservation and invasiveness of ash and
the spread of resistance genes against pathogens such as the fungus
Chalara fraxinea that is destroying common ash forests in Europe.