Using soil seed banks to assess temporal patterns of genetic variation in invasive plant populations

Abstract

Most research on the genetics of invasive plant species has focused on analyzing spatial differences among existing populations. Using a long-established Gunnera tinctoria population from Ireland, we evaluated the potential of using plants derived from seeds associated with different soil layers to track genetic variation through time. This species and site were chosen because (1) G. tinctoria produces a large and persistent seed bank; (2) it has been present in this locality, Sraheens, for ∼90 years; (3) the soil is largely undisturbed; and (4) the soil's age can be reliably determined radiometrically at different depths. Amplified fragment length polymorphic markers (AFLPs) were used to assess differences in the genetic structure of 75 individuals sampled from both the standing population and from four soil layers, which spanned 18 cm (estimated at ∼90 years based on 210Pb and 137Cs dating). While there are difficulties in interpreting such data, including accounting for the effects of selection, seed loss, and seed migration, a clear pattern of lower total allele counts, percentage polymorphic loci, and genetic diversity was observed in deeper soils. The greatest percentage increase in the measured genetic variables occurred prior to the shift from the lag to the exponential range expansion phases and may be of adaptive significance. These findings highlight that seed banks in areas with long-established invasive populations can contain valuable genetic information relating to invasion processes and as such, should not be overlooked.

Population genetic dynamics of an invasion reconstructed from the sediment egg bank

“…An alternative approach that allows for high‐resolution reconstruction of the entire invasion process is the analysis of archives of resting stages, for example seed or resting egg banks (Fennell et al . ; Ortells et al . ).…”

“…Ortells et al 2014). An alternative approach that allows for high-resolution reconstruction of the entire invasion process is the analysis of archives of resting stages, for example seed or resting egg banks (Fennell et al 2014;Ortells et al 2014). In the present work, we therefore combined available historical information (Einsle 1980(Einsle , 1987Stich & Maier 2007) and genetic analyses of a sediment resting egg bank to reconstruct population history and genetic processes during invasion and establishment of a non-native Daphnia species in Lower Lake Constance (LLC) from its first appearance during peak eutrophication 40 years ago up to recent years.…”

Introduction history and population genetics of intracontinental scotch broom (Cytisus scoparius) invasion

“…Nearly all of the genetic variation was found within the populations, and much less was found among populations (Table ), a pattern that has been observed in other invasive alien species (Ellstrand & Schierenbeck, ; Kelager et al, ). Multiple introduction events from different origins can also facilitate biological invasions when these diverse sources hybridise (Ellstrand & Schierenbeck, ; Rius & Darling, ), resulting in increased genetic diversity at the population and individual level (Colautti & Lau, ; Dlugosch & Parker, ; Fennell, Gallagher, Vintro, & Osborne, ) and possibly creating novel invasive genotypes (Bock et al, ).…”

Cyanobacteria in Terrestrial Symbiotic Systems

“…A Gunnera manicata is originally native to Brazil and Columbia but now widely grown as a garden ornamental in temperate and tropical regions. B The growing tips of the rhizomes of mature Gunnera plants are well protected by scale leaves species are cultivated as garden ornamentals, and especially Gunnera tinctoria, originally a native of Chile, has naturalized and become invasive in several regions with humid temperate climates, including Ireland, the UK, the Azores, the USA, and New Zealand (Osborne and Sprent 2002;Osborne 2009, 2013;Fennell et al 2013Fennell et al , 2014.…”