Global patterns and overall levels of biodiversity are important for a variety of reasons. Humans benefit directly and indirectly from biodiversity in many ways.
The Value of Biodiversity
Humans rely on a variety of products that are produced by plant and animal communities for food, clothing, shelter, medicine, textiles, and thousands of other products. These products are not only important for human sustenance and culture, but also a foundational component of many economies worldwide. Medicine in particular has greatly benefited from the discovery of therapeutic compounds discovered naturally-occurring in organisms. For example, the drug Taxol has been critical in treating cancer through its ability to disrupt the mitotic division of cancerous cells. This compound was discovered in the bark of yew trees, though in such low quantities that it would require cutting down a hundred different 100-year-old trees in order to treat a single patient. Fortunately, scientists were able to recreate the compound in the lab, allowing us to produce Taxol synthetically without having to cut down trees. Similarly, painkillers have been derived from the skin toxins of poison dart frogs, memory enhancers to treat Alzheimer’s were isolated from the larvae of a marine bryozoans, diabetes medications were developed from venom in gila monster saliva, and perhaps the most famous, antibiotic compounds were discovered in moldy bread and used to produce penicillin (Fig 2.7.1).
The discussion around medical advances from naturally-occurring compounds highlights another way in which humans benefit from biodiversity – scientific research. Pharmaceutical companies invest billions of dollars annually in research on therapeutic compounds, though there are many other ways that studying the diversity of organisms on earth benefits humans. The National Science Foundation funds $6 billion worth of research grants every year, and even with that budget funds only ~5% of the grant proposals that are submitted to it by researchers. Much of this research is focused on better understanding how organisms operate, interact, evolve, etc and many of these studies have also led to advances in technology and medicine. For example, studies of how the structure of the peregrine falcon’s nasal passages allow it to breathe while diving at upwards of 200 miles per hour led to advances in jet engine air flow design. Studies of the chemical composition of coral skeletons led to the development of new techniques for human bone grafts that reduce the patient’s immune reaction to the graft. Studies of the adhesive compounds that allow mussels to cling to underwater surfaces led to the development of a non-toxic furniture glue, which replaced previous glues that had been found to be carcinogenic (cancer-causing). Several of these discoveries have received the Golden Goose Award from the American Association for the Advancement of Science (AAAS). These awards are chosen by AAAS to acknowledge federally-funded basic research that has led to important applications in biomedical research, medical treatments, and technology. Often, scientific research can seem obscure, esoteric, or even wasteful to the general public, yet these studies can lead to advances in medicine, technology, and other fields that benefit human health and society.
In addition to studying the natural world, many people enjoy experiencing nature and wild organisms on an emotional or personal level. Ecotourism is a booming industry; in the United States and Europe, adventure travel generates over $260 billion annually. The US National Park Service reports that in 2018 alone, 318 million people visited a national park or national recreation area. Perhaps influencing this trend, recent studies have reported a calming or destressing effect from spending even a little time in nature, even a city park. The UC Davis Arboretum and Public Garden holds a series of nature-related relaxation events called Nature Rx (such as plein air yoga) as well as encouraging the use of outdoor ‘classroom’ space in the Arboretum, and outdoor exercise through the UC Davis campus waking loops (Fig 2.7.2).
In addition to providing products, income, and aesthetic value directly to humans, diverse habitats support a number of other beneficial outcomes, collectively termed ecosystem services. These services include the food, medicine, and raw materials already described, as well as other important factors such as improving air and water quality, moderating disturbances such as coastal storm surges and flooding, preventing erosion and maintaining soil fertility, and providing breeding and nursery habitat for other species. Studies have shown that more diverse ecosystems are more stable (less responsive to disturbance), more productive (in terms of biomass produced), and provide more of the ecosystem services described above. We will return to this concept and discuss why higher diversity has these impacts in the section on ecosystem ecology.
More philosophically, biodiversity may also be seen as having intrinsic value, meaning that species have value simply due to the fact of their existence and not because of the services, products, or financial gain that humans can draw from them. A perspective of intrinsic value motivates many conservation organizations and environmental groups. UC Davis has several campus organizations dedicated to nature and the environment, including SEEDS, The Environmental Club, The Wildlife Society, and the Climate Action Project.
Threats to Biodiversity
Currently, biodiversity faces a number of serious factors that threaten the future of species on Earth. These threats include habitat alteration and destruction, introduced and invasive species, pollution, climate change, and overharvesting. Together, these threats have increased the rates of extinction and species loss to the point that scientists now report we are that early stages of a mass extinction event. Earth has experienced five mass extinction events throughout its history. The current 6th mass extinction is unique in that each of the factors listed above is anthropogenic (human-driven) in origin, meaning that we as a species are responsible for these extinctions. We will discuss the drivers and impacts of each of these threats throughout the quarter, starting with the next chapter on climate change.