3 Types of Biodiversity: Overview and Importance

Biological diversity, or "biodiversity," refers to variability found at all levels of biology. Biodiversity is commonly broken down into three levels or types: genetic diversity, species diversity, and ecosystem diversity. While these types of biodiversity are each interrelated, the forces driving each type of biodiversity vary.

Around the world, biodiversity at all levels is declining. While climate change certainly has a role in these losses, there are a number of other factors at play, as well. Today, scientists are working to better understand biodiversity, its tipping points, and ways to counteract losses.

Even if something catastrophic and unexpected occurs, like a disease that affects an entire species, genetically diverse populations are more likely to carry genetic code that leaves some members of the population less vulnerable. So long as those carrying the genetic benefit are able to reproduce, the disease resistance can be passed along to the next generation to keep the species going.

The Three Types of Biodiversity

Species, ecosystems, and the health of the planet all benefit when there is a lot of variability at each level of biodiversity. Greater biodiversity provides something of an insurance policy for the planet's environment; when disaster strikes, biodiversity can be essential to survival.

Genetic Diversity

Genetic diversity refers to the diversity of the gene pool of a given species, or diversity at the DNA level. Genetic diversity can be inferred from what an animal looks like, but is more accurately determined through direct assessments of a species' DNA.

Populations that are genetically diverse are well-equipped to handle change. For example, if a deadly disease strikes a population, high levels of genetic diversity increase the likelihood that there are members of the population who are less affected by the disease. By protecting a portion of the population, genetic diversity can prevent the population from going extinct.

Species Diversity

Species diversity is not only based on the number of different species present in a community, but also the relative abundance of each species and the role they have in the community. For example, a community may be composed of many different species, but may only have one predator that pursues a certain prey species. When the predator's population levels are healthy, its prey's population numbers remain at a level the community can handle.

However, if the predator's population suddenly shrinks, the prey species' population may explode in response leading it to overconsume its own prey and generate a ripple effect that shakes up the entire community. Instead, if a community has more species diversity, it may have multiple predators that chase the same prey. Then, if one predator population undergoes a sudden change, the community is protected from downstream destabilizing effects.

Ecosystem Diversity

Ecosystem diversity refers to variability in habitats within a geographic area. Unlike genetic diversity and species diversity, ecosystem diversity considers both biological drivers and non-biological drivers of variability, like temperature and sunlight. Areas high in ecosystem diversity create a geographic mosaic of communities that help protect an entire area from drastic changes.

For example, an area of dry vegetation may be susceptible to wildfire, but if it's surrounded by a diversity of less-sensitive ecosystems, the wildlife may be unable to spread to other areas of dry vegetation in the same year, leaving the species that make up the burned ecosystem a chance to move to an unscathed habitat while the burned land recovers. In this way, ecosystem diversity helps to maintain species diversity.

Biodiversity Agreements and Policies

To protect the three types of biodiversity, several policies and protocols are in place that function to prevent species and habitat destruction and foster genetic diversity.

The Convention of Biological Diversity

The Convention of Biological Diversity, also known as the Biodiversity Convention or CBD, is an international treaty between over 190 nations around the world for the international management of sustainable development. Specifically, the Convention of Biological Diversity seeks "the fair and equitable sharing of the benefits arising out of the utilization of genetic resources." The Biodiversity Convention was signed in June 1992 and went into effect at the end of the following year.

The Convention of Biological Diversity's governing body is the Conference of Parties, or COP. All 196 nations that have ratified the treaty meet every two years to set priorities and commit to work plans. In recent years, the COP meetings have primarily focused on climate change.

The Cartagena Protocol is a supplementary agreement to the Convention of Biological Diversity that went into effect in 2003. The Cartagena Protocol specifically aims to regulate the movements of living organisms modified by modern technology, like genetically modified plants, for safety purposes.

A second supplementary agreement, the Nagoya Protocol, was adopted in 2010 to provide a clear legal framework for the equitable sharing of genetic resources between participating nations to help with the conservation of global biodiversity. The Nagoya Protocol also set a goal of cutting the 2010 extinction rate in half by 2020. Unfortunately, the research suggests the global rate of extinction has only increased since 2010.

The Endangered Species Act

On a domestic scale, the U.S. Endangered Species Act, or ESA, is a key federal policy for the protection of biodiversity. The ESA provides protection to species threatened with extinction and establishes species-specific recovery plans. As part of these endangered species recovery plans, the ESA works to restore and protect vital habitats.

Threats to Biodiversity

Even with policies in place, threats still persist and contribute to biodiversity losses.

Habitat Loss

Habitat loss is considered a primary cause of modern declines in global biodiversity. By clearing forests and building highways, human activities destroy what could be vital habitats to a variety of species, damaging ecosystem diversity. These landscape changes can also generate barriers between previously connected habitats, severely damaging ecosystem diversity. In addition to restoring habitat, efforts are underway to create wildlife corridors that reconnect habitats isolated by modern human development.

Invasive Species

Both intentionally and accidentally, humans have introduced species to new habitats around the world. While many introduced species go unnoticed, some become far too successful in their newfound homes with consequences for the biodiversity of the entire ecosystem. Given their ecosystem-shifting impacts, introduced species that dominate their new habitats are known as invasive species.

For example, in the Caribbean, the lionfish was accidentally introduced in the 1980s. In its native habitat in the Pacific, lionfish populations are regulated by predators, preventing lionfish from over-consuming smaller fish on a reef. However, in the Caribbean, lionfish have no natural predators. As a result, lionfish are taking over reef ecosystems and threatening native species with extinction.

Given the ability of non-native species to damage biodiversity and cause native species to go extinct, regulations are in place to reduce the chance of accidentally introducing new species. In marine environments, regulating ships' ballast water may be essential to curbing marine invasions. Ships acquire ballast water before they depart a port, carrying the water and any species within it to the ship's next destination.

To prevent species within the water from taking over at the ship's next stop, regulations require ships to release their ballast water miles offshore where the environment differs greatly from where the water originally came from, making it unlikely any life within the water will be able to survive.