Ecosystem Monitoring via Genetic Diversity Surveys of Dandelions using VNTR multi-locus DNA probesEPA Grant Number: R826602
Title: Ecosystem Monitoring via Genetic Diversity Surveys of Dandelions using VNTR multi-locus DNA probes
Investigators: Rogstad, Steven , Keane, Brian
Institution: University of Cincinnati
EPA Project Officer: Hahn, Intaek
Project Period: July 14, 1998 through July 13, 2001 (Extended to July 13, 2003)
Project Amount: $291,045
RFA: Ecological Indicators (1998) RFA Text | Recipients Lists
Research Category: Ecosystems , Ecological Indicators/Assessment/Restoration
New methodologies in molecular genetics may provide novel types of ecological indicators for monitoring the integrity of natural ecosystems and the sustainability of ecosystems that are affected by anthropogenic influences. One type of ideal ecological indicator would be an organism that grows in a wide variety of habitats that could easily be used to monitor for the presence of mutagens or anthropogenic factors that alter population genetics. Dandelions (Taraxacum officinale Weber; Asteraceae) is a model ecological indicator organism because: 1) dandelions have an extremely wide ecological amplitude, growing almost worldwide from sea-level to alpine biomes, and from the tropics to north-temperate habitats; 2) dandelions grow rapidly and populations can be easily manipulated and monitored; 3) it has been documented that a variety of pollutants can be sequestered in dandelion tissues; 4) dandelion seeds are produced asexually rendering the detection of mutations easy; and 5) we have generated preliminary data using variable-number-tandem-repeat (VNTR) DNA probes that suggest that mutation rates and population genetic diversity parameters can be analyzed successfully with dandelions. The specific hypothesis to be tested is: dandelions can be used as a sensitive ecological indicator species via comparative analyses of VNTR genetic markers used to examine anthropogenic changes in genetic diversity of both, 1) mutation rates, and 2) population genetics, at pollution impacted versus non-impacted sites.
Risk management: We will test whether dandelions may provide a rapidly analyzable and manipulable ecological indicator that, through analyses of changes in mutation rates and population genetics, can be used to monitor the ecological integrity and sustainability of a wide range of habitats across multiple spatial scales throughout the world.
Dandelions will be sampled from 12 sites: 6 relatively pristine sites versus 6 sites with chronic, high levels of contaminants. To determine whether rates of mutation differ between these two types of sites, leaf tissue and 10 seeds will be collected from each of 10 plants per site. Dandelion seeds are produced via agamospermy, a process in which all seedlings from a maternal plant should be genetically identical to that maternal plant. Our preliminary results demonstrate that although the previous statement is true, a low level of mutation (ca. 0.005% of bands transmitted) is detectable. We thus will test, by surveying the parent-to-offspring transmission of tens of thousands of VNTR markers, whether mutation rates differ between pristine versus contaminated sites. These markers can also be used to examine whether populations differ in genetic diversity. Our preliminary results demonstrate that very local populations harbor a large amount of genetic diversity, often with no two individuals out of 22 nearest neighbors sampled sharing the same set of VNTR markers. We have designed a computer program, GELSTATS, that can analyze various population genetic parameters (differences in VNTR marker number per plant, degree of similarity (VNTR marker sharing) within and between populations, estimated heterozygosity, etc.), and thus we can examine whether pristine sites differ from contaminated sites in these parameters.
We expect to demonstrate that VNTR markers in dandelions can be used as sensitive indicators of anthropogenic changes in population genetic diversity due to either altered mutation rates or stressor induced selection.