Measures of genetic diversity are effective tools for evaluating environmental condition

Mark Bagley, Susan Franson, Suzanne Christ, Eric Waits
Office of Research and Development, National Exposure Research Laboratory, Cincinnati Ohio

How can we evaluate the biological integrity and
long-term sustainability of natural ecosystems?

These qualities are difficult to assess with existing ecological indicators. In essence,
we need to quantify the "buffering capacity" of natural ecosystems and component
populations against environmental changes. The US EPA is currently evaluating
measures of genetic diversity as indicators of biological integrity and sustainability of
populations.

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What is genetic diversity and why is it important?

Genetic diversity is variation in the heritable characteristics of
individuals of a species (e.g., eye color, height,
resistance to pathogens). It is a useful indicator J \
of biological integrity and sustainability because:

•	It is a fundamental component of biodiversity

•	Genetic diversity limits potential responses
to future stressors

•	Recent changes in genetic diversity
are indicative of population-level



Geographic patterns of genetic
diversity define fundamental units
of ecological analysis
(biological populations)

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Genes

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Biodiversity

Recent and ongoing studies

Regional patterns offish genetic diversity in the

Variables Associated with Reduced Variables not associated with
Genetic Diversity Genetic Diversity

Urbanization

Agriculture

Riparian Modification

combustion byproducts (BAP)

Stream Channelization

Tissue metabolites associated with oil
contamination (NAPH)



Enzyme activity associated with
polycyclic aromatic hydrocarbons
(PAHs) (EROD assay)

Genetic diversity offish in a coal mining region

Variables that significantly explain
differences in genetic diversity

¦ Nitrogen/Phos./Carbon
| Latitudinal Clines
| pH/Amnionium
| Unexplained

Temporal assessment offish population sizes and
gene flow in a polluted urban stream: Mill Creek, Ohio

Year of
Thirty	Years Progress

Through Partnering

How do we determine the utility of genetic

diversity measures as ecological indicators?

•	Case studies that link spatial genetic diversity patterns with other
measures of ecological condition at regional and watershed scales

•	Evaluation of temporal and spatial trends in genetic diversity in relation to
known environmental exposures

•	Evaluation of the ability of genetic measures to be integrated into and
improve existing ecological assessment protocols

What have we learned?

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Population genetic measures are critically important for defining populations.

To measure risk to populations, we must first define the populations

Genetic diversity differs greatly within defined fish populations, and is associated

with recognized differences in environmental quality

While we know that genetic diversity affects the vulnerability of populations, we still

don't know how useful these measures are for predicting future sustainability. This

will be the focus of much future research

DNA markers and sequences

Simple Sequence Repeats
(microsatellites)

Multi-locus DNA fingerprints
(Amplified Fragment
Length Polymorphisms)

DNA sequences

Partnering	to Protect	Human

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