In the most general terms, biodiversity (a shortened version of the term biological diversity) is a term used to characterize the variety of life on Earth. The concept was developed to encapsulate all living organisms, from humpback whales to rose bushes to bacteria.
Biodiversity also can be used as a term to refer to the abundance of species, how diverse organisms can be within their own species, how many species live and interact in one place, or how many kinds of ecosystems there are on the planet.
Rapid changes in the environment of an ecosystem can drastically change it. One of the most famous examples of this happened during the Cretaceous-Paleogene extinction event, 65 million years ago, which saw a dramatic and very fast change in the environment result in the mass extinction of ¾ of the world’s species, including the dinosaurs. The web of interconnectedness between organisms within ecosystems and of the interconnectedness of each ecosystem with other ecosystems is so complex that it’s nearly impossible to know the full impact of even very small changes.
An example of a change in an ecosystem impacting biodiversity is seed dispersal. From ScienceDaily: “Many plants rely on mammals catching their fruit in their fur and carrying them to new habitats. Where large mammals were forced out of an ecosystem through habitat destruction or hunting, the plants were found to evolve smaller and smaller fruit that could be carried by smaller mammals or birds.”
Another example is an ant native to northern Argentina and a few neighboring countries. Humans traveling from Argentina have unwittingly brought along Argentine ant stowaways, and those ants can now be found all over the world, from Easter Island to Japan. They are aggressive enough to fight off other ants and even other much larger insects. In California, in addition to displacing native ants on which other animals feed, they deter bees and other insects that help pollination, preventing insects from pollinating the flowers of a Californian cactus (Ferocactus viridescens), which has now become endangered.
From the stone age to today, species loss has accelerated dramatically, driven by human activity. Estimates of species losses are at a rate 100-10,000 times as fast as is typical in the fossil record. Biodiversity has declined by more than a quarter in the last 35 years. The Living Planet Index (LPI) showed a decline of 52 percent between 1970 and 2010. Human activity leading to loss of biodiversity has been happening throughout history. Pollution, changing the use of land (i.e., building a city or cutting down trees for fuel or lumber), and global warming lead to the destruction of habitats and the decline of ecosystems. Travel and shipping goods around the world -both accidentally and intentionally, introduces non-native species which can be invasive, disruptive, and destructive to their new environment. Overexploitation of a resource happens when humans consume from an ecosystem at a rate faster than the environment can recover; a critical example is overfishing the oceans at a rate and volume that consumes fish and shellfish faster than they can reproduce.
Rich biodiversity can be critically important, not just to prevent species extinction and preserve natural habitats, but to help sustain human life.
- Agricultural diversity (planting many crops rather than monoculture, which is entire farms full of one crop such as corn), helps keep us from losing our food supply in a drought or due to blight.
- Planned biodiversity in farming or gardening leads to more food. For example, research found that introducing the bacterium Achromobacter piechaudii, found in dry riverbeds, to pepper and tomato plants made them more resistant to drought and salt.
- In come cases, as the number of species declines, the risk of infectious disease in humans rises. This study showed an example: “when forests are fragmented, opossum numbers decline and white-footed mice thrive. Opossums serve as buffers for Lyme disease because they absorb and kill some of the ticks that carry the disease; at the same time, mice amplify both the numbers of ticks and the Lyme disease pathogen.”
- At least 50% of pharmaceutical medicines come from plants, animals, and microorganisms, and about 80% of the world is estimated to depends on naturally-derived medicines for healthcare. Despite the growth of genetic engineering and biosynthesis approaches to pharmaceutical development, loss of biodiversity poses an existential threat.
- Biodiversity is also known to have an important role in reducing disaster risk and in post-disaster relief and recovery efforts.
- The components of biodiversity are important in regulating the chemistry of our air and water supply, to water purification, and fertile soil.
It’s important to understand, nurture, and protect biodiversity. Experiments with controlled environments have shown that humans cannot easily build or restore ecosystems to support human needs.We rely on the biota that populates existing natural ecosystems, which we characterize as “biodiversity”.