Periodic Reporting for period 1 - CloneInvasion (Eco-evolutionary dynamics of biological invasions reconstructed from ancient DNA)
Reporting period: 2022-01-01 to 2023-12-31
Invasive species are an important component of global environmental change because they alter ecosystem processes and services and disrupt the communities they invade. Genetic surveys of invasive plant species can provide an evidence-based platform to conduct informed and applied management programs. We combined herbarium genomics and bioinformatics to generate historical DNA sequence information from preserved specimens of Japanese knotweed (a polyploid species complex comprising Reynoutria japonica, R. sachalinensis and their hybrid R. x bohemica, which are among the worst invasive weeds of the temperate world). We conducted population genomic analysis to reconstruct the invasion history and gain insights into the ecological and molecular determinants of the species invasion success.
We identified the oldest herbarium specimens of these species and reconstructed the species early invasion dynamics into Europe and the US. We established a large temporal collection of leaf herbarium samples of Japanese knotweed spanning the species distribution in the native range in Asia and the introduced range in Europe and the US. We isolated historical DNA from herbarium specimens of different ages and successfully built ancient DNA libraries. We generated time series genomic data and calculated population genetic structure, inferred the genetic relationships between different accessions and taxa and identified the source of the introduced populations. The project results were presented at several international conferences and invited lectures.
Mapping the distribution of Japanese knotweed taxa in Europe and the US prior to 1900 revealed different invasion dynamics in the two ranges. We also found evidence of separate introductions into Europe and the US. Further, we expect to be able to discover mutations and genetic regions associated to the species success and invasiveness. The findings of this project hold potential implications for the EU policies on the management and control of invasive species. By including information about the genetic variation present in natural populations of invasive species in management plans, we can better understand the population-level differences in evolutionary potential and their contribution to the invasion process and design control programs that effectively work at different spatial levels (i.e. local and regional).