Data from: Pollinator-mediated gene flow connects green roof populations across the urban matrix: a paternity analysis of the self-compatible forb Penstemon hirsutus

Gene flow between populations can help maintain genetic diversity and
prevent inbreeding, which is especially important for small, fragmented
habitats. Many plant species rely on pollinators to move pollen between
populations. In urban areas, insufficient pollinator services may result
in limited gene flow, which can have negative consequences such as genetic
drift and inbreeding depression. Furthermore, restored populations that
are established with few founders of low genetic diversity may have
limited long-term population persistence. Here, we tested the hypotheses
that populations of a self-compatible forb established on urban green
roofs fromnursery stock are genetically depauperate and that limited gene
(pollen) flow between populations will result in increased inbreeding. We
compared the neutral genetic diversity of Penstemon hirsutus, using nine
microsatellite loci, between three green roof populations established from
nursery stock and three natural populations. We also established ten
experimental populations on green roofs and measured rates of outcrossing
and inbreeding and identified the movement of pollen within and between
roofs using a paternity analysis. We found that neutral genetic diversity
of populations established from nursery stock was lower than that of
natural populations, although the level of inbreeding was also lower on
the green roofs. In our experimental populations, we found that the rates
of outcrossing and inbreeding varied between the roof populations. Our
results suggest that inbreeding may be correlated with cover of
co-flowering species but not with any of the other measured site
properties. The location of likely pollen donors suggested that on
average, 75% of pollen was derived from plants within the population
(including self) and 25% came from plants on different roofs. Our results
document realized pollen movement within and between green roofs,
demonstrating that these habitats provide important connectivity in a
fragmented environment.