Periodic Reporting for period 3 - IceAGenT (Ice Age Genomic Tracking of Refugia and Postglacial Dispersal)
Periodo di rendicontazione: 2022-10-01 al 2024-03-31
Understanding rates of migration and resilience to climate change is important for explaining both the distribution of single species and anticipate how ecosystems may respond to climate change. There are two vigorously debated questions about the response of NW European biota to past climate changes: 1) glacial survival vs tabula rasa and 2) Reid´s paradox of rapid plant migration through seed dispersal vs. survival in cryptic refugia just south or east of the ice sheet. These are related as survival in any northern refugia would suggest local dispersal rather than the rapid dispersal rates that are needed from southern refugia.
Methodology
Our lab is at a step-change in answering these questions as we now have a full genome reference library for the entire flora of Norway and adjacent regions composed of >2000 species (Alsos et al. 2020 Plant, Wang et al. 2021 Nature), which will allow us to develop genomic markers identifying not only species, but genetic variation within species, in ancient sediment samples. In addition, we have >20 sediment cores already analysed for vascular plant aDNA using metabarcoding, and a further 20 are in the pipeline.
Goals
Based on these and 12 new cores, we will select samples that contain key species representing different bioclimatic zones (boreal trees, dwarf shrubs, arctic herbs), and re-analyse them for within-species genetic variation. This will be complemented by analyses of contemporary phylogeography of the same species. This will allow us to identify refugia areas and trace migration routes back in time by different components of the ecosystems. The results of this study will open a new era in studies of species abilities to respond to climate changes (palaeo-phylogeography) and enable us to model the effects of current global warming more accurately than before.
Methodology
Our lab is at a step-change in answering these questions as we now have a full genome reference library for the entire flora of Norway and adjacent regions composed of >2000 species (Alsos et al. 2020 Plant, Wang et al. 2021 Nature), which will allow us to develop genomic markers identifying not only species, but genetic variation within species, in ancient sediment samples. In addition, we have >20 sediment cores already analysed for vascular plant aDNA using metabarcoding, and a further 20 are in the pipeline.
Goals
Based on these and 12 new cores, we will select samples that contain key species representing different bioclimatic zones (boreal trees, dwarf shrubs, arctic herbs), and re-analyse them for within-species genetic variation. This will be complemented by analyses of contemporary phylogeography of the same species. This will allow us to identify refugia areas and trace migration routes back in time by different components of the ecosystems. The results of this study will open a new era in studies of species abilities to respond to climate changes (palaeo-phylogeography) and enable us to model the effects of current global warming more accurately than before.
We have analysed ancient DNA from Iceland, N Fennoscandia, the Polar Ural, the European Alps and the Baltic region as well as some samples from many other sites. Our understanding of glacial survival and postglacial dispersal has increased. We detected many arctic-alpine plant species at sites that were ice-free during the Last Glacial Maximum (Andøya in N Norway and the Polar Urals in Russia). Especially, the DNA record from Polar Ural showed a very rich flora during the Last Glacial Maximum, and we regard this as a potentially very important source region for species found in Fennoscandia today. The tree norther regions investigated so far (Iceland, N Fennoscandia and the Polar Urals) show a peak immigration of new species at the onset of the Holocene, but the overall patterns of immigration differed. Notably, very few new species immigrated to Iceland after this first immigration wave, and we think that this may relate to the disappearance of sea ice. In contrast, many species did not arrive to N Fennoscandia until rather recently, suggesting a time lag of several thousands' year from the climate change took place until the ecosystem was built up. For the Alps, human land use strongly affected biodiversity pattern, and especially grazing by cattle in the last few millennia has increased plant richness to a level higher than any time previously in the Holocene.
We recently made a major break-through in method development, as we by multiplexing metabarcoding were able to detect within-species genetic variation from sediment samples (Lammers et al. 2024). We did this for the bog bilberry (Vaccinium uliginosum) and will now extend this to other species.
We recently made a major break-through in method development, as we by multiplexing metabarcoding were able to detect within-species genetic variation from sediment samples (Lammers et al. 2024). We did this for the bog bilberry (Vaccinium uliginosum) and will now extend this to other species.
While we have learned a lot about dispersal routes from phylogeography and about glacial refugia from macrofossils, pollen and, more recently, ancient DNA (aDNA), we have never been able to trace plant migration routes back in time. Our new developed methods and extension of dataset will allow us to identify refugia areas and trace migration routes back in time by different components of the ecosystems. The results of this study will open a new era in studies of species abilities to respond to climate changes (palaeo-phylogeography) and enable us to model the effects of current global warming more accurately than before.