Understanding Biodiversity: Concept and Key Definitions

The word “biodiversity” is everywhere – in news headlines, policy documents, school textbooks, and conservation campaigns. But where did the term actually come from, and what does it precisely mean in a scientific and legal sense? Understanding the concept and definition of biodiversity is the first step toward appreciating why it matters so deeply – for ecosystems, for human survival, and for the planet’s long-term health.

The origin of the term “biodiversity” 🔗

The story of how the word “biodiversity” entered the scientific vocabulary is surprisingly recent. The longer form – biological diversity – was first used by Thomas Lovejoy, a tropical conservation biologist, in 1980. Lovejoy used it to describe the variety of species found within a particular group or region, and the term gradually gained traction among ecologists and conservationists who needed a precise way to talk about the richness of life.

The contraction “biodiversity” came slightly later. According to a detailed historical account published in BioScience, the term was introduced during the planning of the National Forum on BioDiversity held in Washington, D.C., from 21 to 24 September 1986. Walter G. Rosen of the National Academy of Sciences is credited with coining the contraction, initially using it in internal paperwork, though he soon recognized its potential to resonate with the general public and help the cause of conservation.

However, research shows the term had already appeared in print before Rosen’s forum. Two earlier published instances of the word “biodiversity” appeared in 1985 and 1986, both in BioScience – one in an article by Laura Tangley summarizing a federal report on biological diversity conservation, and another by Robert L. Peters in a response to a piece on global warming. Neither author recalled consciously coining the term, suggesting, as Peters speculated, that it evolved organically as shorthand in informal discussions among scientists.

What truly launched the word into widespread use was E.O. Wilson. A symposium in 1986 and the follow-up book BioDiversity (Wilson, 1988), edited by Wilson, heralded the popularity of the concept. By 1993, “biodiversity” appeared seventy-two times as a keyword in Biological Abstracts, compared to not appearing at all in 1988 – a reflection of how rapidly the term had been adopted.

Thomas Lovejoy: The “godfather of biodiversity” 🔗

Thomas Lovejoy’s contributions went far beyond coining the phrase. Lovejoy conducted much of his foundational research in the Amazon, studying the connection between biodiversity loss and a changing climate. He brought public attention to the extinction crisis through service as an advisor to several U.S. presidents and through his involvement with organizations including the United Nations Foundation, the World Bank, the Smithsonian Institution, and National Geographic Society.

E.O. Wilson, on the other hand, was the communicator who turned biodiversity into a cause. As conservation scientist Stuart Pimm of Duke University noted, “Tom was the first person to use ‘biological diversity,’ but Ed, through his extraordinary writing talent, was able to make it a household word.” Together, they shaped an entire field of scientific and policy thought.

What biodiversity encompasses: genes, species, and ecosystems 🔗

From early on, scientists recognized that biodiversity was not simply a count of species. It became widespread practice to define biodiversity in terms of genes, species, and ecosystems – encompassing the abundance, variety, and genetic constitution of native animals and plants. Wilson himself defined it as the variety of organisms considered at all levels, from genetic variants within a species up through arrays of species and through to the variety of ecosystems within which they live.

This three-part framework – genetic diversity, species diversity, and ecosystem diversity – became the standard way scientists and policymakers discussed and measured biodiversity. It acknowledged that life’s complexity operates at multiple scales simultaneously, and that protecting one level without considering the others is insufficient.

The United Nations definition and the CBD 🔗

The most widely accepted and legally binding definition of biodiversity came with a landmark international agreement. The Convention on Biological Diversity (CBD) was adopted at the Earth Summit in Rio de Janeiro in June 1992 and entered into force in December of that year. It represented the first time the international community had come together under a single, comprehensive framework specifically to address the conservation and sustainable use of biological diversity.

Under Article 2 of the CBD, biological diversity is formally defined as “the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.” This definition is significant because it is not confined to any single type of habitat or group of organisms – it is deliberately broad and inclusive.

This definition encompasses three distinct levels of biodiversity: diversity between and within ecosystems and habitats; diversity of species; and genetic variation within individual species. The linkage between species and their habitats is vital – changing a habitat will usually affect the diversity of species contained within it, while conversely a change in species number and composition may well alter the habitat itself.

Genetic diversity 🔗

Genetic diversity refers to the variation in genes within a single species. It includes differences in DNA sequences between individuals in a population. Genes in the DNA of individual plants and animals encode the information on biodiversity, and genetic diversity means the degree of variability within and between species. This type of diversity is what allows species to adapt to changing environments. A population with high genetic diversity is more resilient – if disease or environmental change hits, some individuals are more likely to survive and pass on their traits. A crop variety with low genetic diversity, by contrast, can be devastated by a single pathogen.

Species diversity 🔗

Species diversity is the most familiar level – the variety of different species living in a given area. Species diversity reflects the level of species richness in a given area and their taxonomic diversity. It encompasses everything from the insects in a meadow to the fish in a coral reef to the bacteria in a handful of soil. Scientists estimate there are millions of species on Earth, the vast majority still undiscovered and undescribed. As of 2021, the IUCN Red List had described 2.13 million species – a figure that represents just a fraction of what researchers believe actually exists.

Ecosystem diversity 🔗

Ecosystem diversity refers to the variety of habitats, biological communities, and ecological processes that occur across landscapes. Ecosystem diversity means the variety of different ecosystems, such as deserts, forests, wetlands, mountains, lakes, rivers and agricultural landscapes. It also encompasses the multiplicity of interactions between all living and non-living components within one ecosystem. Each ecosystem type supports a distinct assemblage of species and performs unique ecological functions – from carbon storage in forests to nutrient cycling in wetlands to coastal protection by mangroves.

Why the CBD’s definition matters 🔗

The CBD’s definition gave biodiversity a legal and political weight it had never carried before. At the 1992 Earth Summit in Rio de Janeiro, world leaders agreed on a comprehensive strategy for sustainable development – meeting human needs while ensuring a healthy and viable world for future generations. The Convention on Biological Diversity was one of the key agreements adopted at Rio, setting out commitments for maintaining the world’s ecological underpinnings while pursuing economic development.

The CBD has three objectives: the conservation of biological diversity; the sustainable use of its components; and the fair and equitable sharing of benefits arising out of the use of genetic resources. Parties are obligated to inventory and monitor biodiversity, incorporate the concepts of conservation and sustainable development into national strategies, and preserve indigenous conservation practices.

Nearly every nation on Earth has signed on. To date, there are 193 parties to the Convention, encompassing all the various forms of life on Earth, including ecosystems, animals, plants, fungi, microorganisms, and genetic diversity. The CBD is often described as the cornerstone of global environmental governance for biodiversity, and its three-level framework – genes, species, ecosystems – remains the standard lens through which scientists, policymakers, and educators understand what biodiversity is and why it must be protected.

Biodiversity as the foundation of life 🔗

Biodiversity is not just a scientific concept – it is the infrastructure upon which all life depends. Healthy ecosystems filter water, stabilize soils, regulate climate, pollinate crops, and provide medicines. Biodiversity underlies the goods and services provided by ecosystems that are crucial for human survival and well-being, even if some of these services are not traded in the market and thus are not priced to inform society of changes in their supply.

As E.O. Wilson wrote, biodiversity is “one of the greater riches of the planet.” Yet rates of species extinction today are estimated to be far above natural background levels, driven largely by habitat destruction, pollution, invasive species, and climate change. Understanding what biodiversity means – precisely and comprehensively – is essential before we can begin to protect it in any meaningful way. The terminology developed by Lovejoy, refined by Wilson, and codified by the United Nations has given the world a shared vocabulary to do exactly that.

What do you think? Given that biodiversity operates at three distinct levels – genetic, species, and ecosystem – which level do you think receives the least attention in conservation efforts, and why? And should a legally binding international definition, like the one in the CBD, be updated to reflect new scientific understanding of life’s complexity?

References

1. https://eowilsonfoundation.org/news-posts/e-o-wilson-biodiversity-foundation-statement-on-the-death-of-thomas-lovejoy/
2. https://daily.jstor.org/e-o-wilson-and-biodiversity/
3. https://biodiv.de/en/biodiversitaet-infos/ueberschriften.html