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New DNA-Based Dispersal Data

Most species distribution models and dynamic global vegetation models ignore long-distance migration effects of plants and thus miss a possibility to predict these aspects of systems behaviour under scenarios of climate and land use change. Activity 3 will provide the theoretical basis and practical application for several plant species to estimate migration rates using novel statistical techniques. These estimates of long-distance dispersal will then be used for model development and improvement in the subsequent modelling activities

Download Briefing Sheet on Work Description of Activity 3

Overview

Although several modelling studies have predicted the way species’ habitat or biome may be shifted, few explicitly included the possibility for species or group of species to actually migrate to new habitats. If species frequently disperse over long distances, colonisation and migration rates can increase considerably.

Most species distribution models and dynamic global vegetation models (DGVMs) ignore such spatial processes. They thus miss an important driver of local-to landscape-scale biodiversity distribution and the ability to predict the transient systems behaviour under scenarios of climate and land use change.

Short-distance dispersal is relatively well-studied in plants. However, the frequency of rare long-distance events is extremely difficult to estimate. But according to pilot studies, dispersal potential of individual species can be estimated from the genetic makeup of the plants.

Integrating dispersal mechanisms in predictive models of species range shift will help identifying which type of species will be able to track climate change occurring at a predicted rate. It will also make possible to check the capacity of species to cross linear obstacles in the landscape to reach suitable habitats, e.g. at higher elevation. This approach is a novel alternative to the traditional inference of migration rates from observed seed dispersal, which fails to capture the rate of long-distance dispersal events.

Activity 3 will – based on molecular markers – provide estimates of migration rates and its effects on the structuring of historical and potential future ecosystems and biomes. These estimates of long-distance dispersal will then be used for model development and improvement in the subsequent modelling activities (mainly Activity 5 and 6).

Objectives

The theoretical part of this activity will assess the potential use of genetic markers to evaluate the rare occurrences of long-distance dispersal for plants, and develop an experimental field protocol for estimating the dispersal abilities of plant species. Following the theoretical part, data for several key species will be sampled and analysed according to the protocol in order to infer long-distance dispersal for these.

Populations of plant species with frequent long-distance are expected to be genetically more similar than the populations of plants with limited long-distance dispersal. Using this principle, a species’ migration rate can be analysed by studying the differences between populations using genetic markers.

Approaches

The first task was to investigate how best to spread the sampling effort, i.e. number of samples (individuals) per locality, spacing of samples within localities, spacing and numbers of localities, and number of genetic markers. Based on these outcomes a protocol for estimating plant dispersal based on molecular markers has been designed. The outcomes showed that many populations and many individuals need to be sampled to get a good idea of the rate of long-distance dispersal.

Within the 2nd part of activity 3, knowledge about long-distance dispersal of several key species should be obtained, by applying the developed protocol. The objective will be to extract DNA from all samples and to analyze the produced data, according to the strategy designed in the theoretical part of Activity 3. In addition, the developed statistical method will be used to estimate the rate of long-distance dispersal for 40 species using existing data from the IntraBioDiv project.

Expected results

• protocol for studying plant dispersal based on molecular markers
• estimate of long-distance dispersal for several key plant species

Results and publications

to follow

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