If You Go Down to the Woods Today: Conservation Genetics in a Nutshell

Imagine a young family taking a stroll along a sun-speckled forest path. They take their time, admiring the scenery and taking in the fresh air. Then suddenly, the sound of snapping twigs shatters the leisurely mood. They turn to see a disheveled figure stumbling from the thicket. Little do they know, they are about to come face to face with…a conservation geneticist.

Rachel van Heugten works in the forest and in the laboratory
Left: A conservation geneticist in the wild. Note its trusty backpack and huge coat pockets, both handy for carrying samples or equipment. Observe how it takes notes in an increasingly scruffy notebook, one of its most prized posessions. Photo by Gail Warwick.
Right: Other habitats where you might find a conservation geneticist include a laboratory, arguing with a computer or sharing their findings with others. Photo by Stephanie Galla.

What is this bizarre creature, and what should you do if you find one in the wild? As their name suggests, conservation geneticists are a breed of scientist who use genetics to learn how to conserve plants, animals, and other organisms in nature. They are especially proficient at uncovering information about endangered species that is difficult to collect with other methods, such as behavioral observation.

Ecologists, for instance, normally find it difficult to observe organisms that are restricted to remote habitats, exist only in small populations, occupy large territories, or live nocturnal lifestyles. But a conservation geneticist can find all the information he or she needs through a single molecule: DNA. An organism’s blue prints and hereditary material, DNA, can be collected non-invasively from an organism’s shed skin, hair, feathers, leaves, roots or even feces, and can tell a geneticist almost everything he or she wants to know about a species’ past, present, and future. Additionally, when a conservation geneticist needs to collect blood or tissue samples directly from an individual organism, he or she typically only takes a small amount, which minimizes the distress caused to the organism.

Conservation geneticists don’t study individuals – they study populations of organisms. DNA is useful for studying populations because the genetic relationships among the members of a population – and the population’s genetic diversity – tells a geneticist a lot about the population’s size, growth potential, movement, health, and even its risk of extinction.

Population Size and Growth Rate

Conservation genetics can study the different samples of the DNA recovered from an area to estimate how many individuals live there and whether each member of the population is male or female. This is crucial knowledge, for example when running

captive breeding programs where males and females look very similar. In these programs, conservation geneticist use DNA to calculate the ratio of males to females in a population, which helps them predict how fast that population will grow.

The endangered New Zealand Black Stilt
In the endangered New Zealand Black Stilt or Kaki (Himantopus novaezelandiae), males and females are extremely difficult to distinguish from looks alone. Instead, genetic differences between males and females are used to determine an individual’s sex. Photo provided by Stephanie Galla.

How does this work, you ask? Imagine a population of birds who partner up and raise one clutch of eggs at a time. If the male-to-female is roughly equal, then nearly every bird will pair up and raise chicks. If the male-to-female ratio is uneven, however, many birds will have to fly solo, and the population as a whole will raise fewer chicks.

Genetics also helps track how populations grow and shift over time. This is possible to do because of one central principle of genetics: the closer two individuals are related, the more similar their DNA will be. Knowing this, geneticists can learn about a species’ mating system, including how many mating partners a typical organism in that population typically has. For example, a geneticist can determine if females mate with multiple males, or visa versa.

 

Movement of a Species

Conservation geneticists can also use DNA to find relationships with seemingly disparate populations. It is uncommon that species mate over long distances, so individuals with similar DNA tend to live close together. Therefore, if two individuals share similar DNA but don’t live near each other, it is likely that their ancestors did at some point. If a geneticist finds closely related individuals on either side of a river, for example, they know that the species can cross bodies of water. Revolutionary, I know. However, such information is important for managing the conservation of a species. More specifically, conservationists can save resources if they can manage two populations on either side of the river together.

Poaching

Genetics is also invaluable for busting cases of illegal endangered species trade. For example, geneticist can compare DNA samples of ‘whale’ meat sold at a market to DNA from known species to determine if the meat is from an endangered whale (or a different kind of animal altogether).

Risk of Extinction

Besides poaching, geneticists also study genetic processes that can lead to extinction (as if endangered species didn’t have enough to worry about).  Conservation geneticists investigate two interrelated processes that lead to extinction: 1) mating between relatives, known as inbreeding, and 2) the loss of genetic diversity within a population. Both processes tend to occur in small and isolated populations.

A potato infected with phytophthora infestans
Around the time of the Irish potato famine, Irish farmers only grew one variety of potato. When Phytophthora infestinas, the cause of potato blight, arrived, the lack of genetic diversity amongst the potato plants meant that all fell victim to infection.

Have you ever heard someone say “heart disease” or “breast cancer” runs in their family? Our DNA can make us prone to certain conditions. But humans typically outbreed, or mate with individuals they are not related to, and reducing the risk of illness. Even if one individual carries a gene that makes one more susceptible to heart disease, chances are his or her partner will carry the healthy version of the gene, which may protect their offspring from poor health.

Rather, in small populations of animals and plants often inbreed. Therefore, if one organism carries a disease gene, chances are its mating partner, who it is closely related to, will carry that gene also. Extensive inbreeding increases the number of individuals expressing these negative traits and decreases the overall health of the population. Subsequently, conservation can introduce unrelated individual to the population to reduce inbreeding and increase the health of the population.

Low genetic diversity not only reduces a population’s overall health; it also makes it more difficult for a population to adapt to changing conditions.

The endangered Takahe, a flightless bird in New Zealand
Mating between relatives is a known problem in the endangered Takahe (Porphyrio hochstetteri), one of New Zealand’s flightless birds. Individuals whose parents are closely related are less likely to have chicks of their own that reach adulthood and breed. Photo provided by Rachel van Heugten.

If all the individuals in a population are very similar, they will respond similarly to environmental threats. As a result, without genetic diversity, a change in environment that is lethal to one individual could wipe out the whole population. Since conservation geneticists do not have the resources to protect every single organism on the planet, they usually look at populations’ genetic diversity to determine which group of organisms they will have the best chance of saving.

A Conservation Geneticist in Your Environment

Now that you know a little more about conservation geneticists, if you stumble across one, hopefully you won’t be afraid to say hello. One word of caution though: they might want to share some awesome science with you, just like I did with that family in the forest.

References:

Grueber C. E., R. J. Laws, S. Nakagawa and I. G. Jamieson. 2010. Inbreeding depression accumulation across life-history stages of the endangered Takahe. Conservation Biology 24: 1617-1625

Dr. Rachel van Heugten received her Ph.D. in evolutionary biology at the University of Caterbury in New Zealand. You can follow her on Twitter @rachel_weta.

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