Destroying or changing habitats can endanger the animals, plants, and other organisms
that live there. By effective managing these ecosystems, we can help preserve threatened
and endangered species.
The science of Conservation Biology looks at individuals and populations that
have been affected by habitat loss, exploitation, and/or environmental change.
Information gained from studying these organisms informs decisions that will
ensure their survival into the future.
The science of Genetics looks at inherited characteristics and the genes that underlie them.
Put the two together and you get the science of Conservation
What is Conservation Genetics?
Conservation genetics uses a combination of ecology, molecular biology, population
genetics, mathematical modeling, and evolutionary taxonomy (the study of family
relationships). It is both a basic and an applied science. First, scientists must
understand the genetic relationships among the organisms they're studying. Then
wildlife managers use techniques to preserve biological diversity in these species.
The organisms that conservation geneticists study usually belong to endangered or
threatened populations. To develop ways to help these populations, scientists ask
two questions: What has brought these populations to the brink of extinction, and
what steps can we take to reverse this trend? Information about the genetic diversity
of the organisms under study helps scientists and managers form strategies to
preserve and protect the diversity of plants and animals worldwide.
Past conservation efforts have addressed populations from a mathematical, evolutionary,
or taxonomic point of view. Modern efforts include genetic studies, giving conservation
scientists and ecological managers much more information about the diversity among
the individuals in a population. Without genetics, we may conserve the wrong population
or waste valuable resources on a population that isn't endangered!
To measure the genetic diversity of a particular gene, scientists look at how many
different versions of it (called alleles) are present in a population. For example,
one gene may determine the flower color of a plant. Different alleles may exist
for that gene (e.g., a pink allele, a purple allele, and a white allele). In each
case, the same gene determines flower color—but the exact order of DNA letters
that make up the gene are different for each allele. When all or nearly all members
of a population have the same allele, that population is said to have low genetic
diversity at that gene. But when many different versions of the gene exist in a
population, the population has high genetic diversity at that gene.
Why is genetic diversity important?
Populations or species with low genetic diversity at many genes are at risk. When
diversity is very low, all the individuals are nearly identical. If a new
environmental pressure, such as a disease, comes along, all of the individuals
within the population may get the disease and die. But in a population with high
genetic diversity, chances are better that some individuals will have a genetic
makeup that allows them to survive. These individuals will reproduce, and the
population will survive.
The genetic diversity of a species is always changing. No matter how many variants
of a gene are present in a population today, only the variants that survive in the
next generation can contribute to species diversity in the future. Once gene variants
are lost, they cannot be recovered.
When is Conservation Genetics Used?
When habitat destruction or other factors put a population at risk, scientists and
conservation managers may target that population for investigation. For example,
they may study a population of plants whose habitat will be destroyed by the
building of a new shopping mall. Or they may study duck and geese populations
when new hunting regulations have been put in place.
Human interference is not the only danger to plants and animals. Natural factors,
such as storms and diseases, can also cause populations to dwindle.
Change in Population Size
Surveillance of small populations is critical, because they are particularly sensitive
to change. Random or unpredictable events such as natural catastrophes, environmental
changes, or genetic mutations can cause a sudden decrease in population size. When the
population of a species is small to begin with, further reduction of their remaining
numbers can sharply reduce genetic diversity.
Small populations are also more sensitive to genetic drift, as well as the problems
that come with geographic isolation and establishing a new population from only a
few individuals (founder effect). Each of these factors affects which individuals
will give rise to the next generation, and therefore which alleles will be passed on.
With each generation, some individuals survive to reproduce and pass on their genes,
while others are eliminated. Over time, individual alleles can become more or
less common in a population. When inherited characteristics determine who will
survive and who will not, the process is called natural selection. When random
factors determine who will survive, the process is called genetic drift. Through
genetic drift, some alleles can entirely disappear from a population.
A small population is more susceptible to genetic drift than a large population.
When just a few individuals carry a particular allele, it becomes more likely
that just by chance those individuals will not reproduce, and the allele will be lost.
Sometimes even a large population can lose genetic diversity. One way loss can
happen is through geographical isolation. Geographical isolation can happen if
a new barrier is imposed through a habitat. For example, if a river changes
course or a new housing subdivision is built, a population of plants or animals
may be divided into two groups. Just by chance, the pool of gene variants in the
two separated populations may differ from one another.
As an example, imagine a flower species with two forms that share a habitat. A
new subdivision, including new houses and roads, divides the habitat, isolating
the two forms to different areas. The first form, a tall, sturdy plant with few
flowers, is isolated to the north end of the subdivision, while the second form,
a more delicate plant with prettier flowers, is isolated to the south end. Even
though the new homeowners may preserve both populations, the two are sufficiently
isolated from each other that they can no longer exchange genes. In this situation,
each type is exposed to environmental pressures without the ability to crossbreed
with the other type to form plants with new, perhaps more advantageous, combinations
of genes. The new pressures created by building the development may affect the two
types of plants differently. For example, the more-delicate variety might die from
a lack of shade caused when trees were cut down for the subdivision. When they are
gone, so is the allele responsible for the attractive flower—and the overall
population size decreases.
How is Conservation Genetics Done?
Conservation geneticists use DNA data from an organism to inform management choices.
As in any scientific field, conservation scientists use a defined approach to their work:
Identification, Inventory, and Analysis
Define populations and areas of interest. Because there are so many species of
organisms, endangered or threatened species usually take priority.
Observe the population. What are the known forms of the species? What are known
or suspected relatives of the species? What are the physical characteristics used
to classify the different forms and species?
Form hypotheses about relationships between populations and/or species and test
these hypotheses by examining genetic characteristics of the organisms (DNA or protein data).
Use mathematical models to analyze the data. Determine how much diversity exists
in separate populations of the species, as well as the rate at which genes are
exchanged among populations (gene flow).
Interpretation and Management
Scientists and managers work together to identify endangered organisms. To begin to
develop a management strategy, they investigate the organism's habitat:
Determine the degree to which the organism is adaptable to various temperatures, soils, and water conditions.
Examine factors that influence genetic diversity, such as the identity and characteristics of plant
pollinators. The health and welfare of pollinating species may be critical to the survival of an endangered
Study threats to the integrity of the species' habitat, including human, climatic, and other factors.
Once all of the aspects of the population and its environment are understood, scientists and managers can develop an intelligent preservation plan.