Biodiversity: the richness of nature

Fast facts: biodiversity

• 1.4 species on land and in the oceans are catalogued. There are estimations, that only 10% are described.
• Hot spot areas have high biodiversity than other areas.
• Agriculture and fishing are one of the main reasons for 30% of biodiversity losses till 2050 (CBD).
• Losses in biodiversity (genetics) are a risk for the need of permanent adaptation (resistance, resilience) and novel food systems.
• Agriculture has created manmade biotopes with domesticated biodiversity.

Soil, water, energy and suitable climate are the principle needs of life. It doesn’t matter if this life is a virus, bacteria, algae, protozoa, mushroom, or plant. They are all primary life. Herbivore animals eat plants and other primary life to survive, omnivore (including humans) digest both plants and animals and carnivores eat mainly other animals. The food chain can be very long: from herbivore to carnivore: the caterpillar eats leaves, the blackbird eats the caterpillar, the hawk eats the blackbird. Each link in the chain requires energy for digestion and the body's own conversion of the building blocks. Thus, at the end of many food chains, only a few hundred thousandths of the solar energy irradiated onto the earth's surface is left in the body. This is the cycle of life.

Figure: Global biodiversity: species numbers of vascular plants.
Source: Mutke and Barthlott (2005)

Since life is on earth, more than 99% of all living species ever lived are extinct. New and extinc-tion of species is a normal procedure of evolution. Targets to stop biodiversity losses is not nat-ural. Mass extinction is the question. There have been several mass extinctions of biodiversity on earth (Figure 15). Well known is the impact of a meteorite impact on the dinosaurs about 60 million years ago. A recent mass extinction of species is due to human expansion. Clearly, ever loss of a species is a loss in bio-diversity and will never come back. Nevertheless, the biodiversity today has never been bigger than today.

In the last decades the speed of biodiversity and biotope losses increased. In only 50 years, the biodiversity is decreased by more than 50%. Intensified agriculture and fishing to supply growing food demand of a fast (exponential) growing global population is the main rea-son today (Figure 16), like the meteorite 60 million years ago. With less biodiversity the human surviving is under threat because everything in nature is interdependent (CBD 2022). And hu-mans are part of the global biodiversity.

Figure: Mass extinctions of biodiversity
Source: Cowie et al. (2022)

Figure: Biodiversity and agriculture
Source: CBD (2022)

There are 380,000 known plant species  in the world. Around 3,000 wild plants are considered as edible  (BLE 2024)). However, only a few (about 200) of these have been domesticated and bred by humans  (Rehm and Espig 1991). Over 80 per cent of human food comes from just 12 cultivated plants and is therefore of major economic importance. In most societies, only three plant species form the basis of the diet: Wheat, rice, and maize. However, there are many varie-ties of these crops. There are 3,000 varieties of wheat, 5,000 varieties of rice and 6,000 varieties of maize alone. However, only very few varieties have any significance in cultivation. Most of them are hybrid high-performance varieties. Old varieties are only sown sporadically. There is talk of genetic impoverishment among cultivated plants (Khoury et al. 2014).

About 1.6–1.7 million animal species have been described so far, but this is only a fraction of what exists. Current biological estimates suggest 7–8 million animal species on Earth in total, meaning over 80% are still unknown and entirely wild. In contrast, true domestication is ex-tremely rare. Only ~30–40 animal species worldwide (0.001% of all known fauna species) are considered genuinely domesticated in a biological sense (showing heritable genetic and behav-ioral change under human selection). Of these, about 15–20 are major livestock species, includ-ing cattle, sheep, goats, camels, llamas, pigs, horses, water buffalo, reindeer, rabbits, chickens, ducks, turkeys, guinea fowl, carp, tilapia, salmon, trout, bees, silkworm and others. There are some more domesticated animal species, but as pets or for other purposes: dogs, cats, rats, mice, many bird and fish species, and others.

Even though individuals may suffer and be slavishly exploited by humans, they are the real winners from the co-evolution of humans and animals and have spread worldwide. Livestock and humans comprise about 95% of the total mammal biomass on earth. Today, only cattle make up half of the total biomass of mammals in the world.

Figure: Earth's mammals by total biomass: cattle are the most important species

Source: Greenspoon et al. (2023)

Mushrooms (fungi) are not animals but are often considered alongside them in food systems. Roughly 150,000 fungal species have been scientifically described, about 2–4 million species will exist globally. Only a few dozen fungi are domesticated or industrially cultivated, including yeasts (Saccharomyces cerevisiae), button mushrooms (Agaricus bisporus), shiitake, oyster mushrooms, and Penicillium species used in cheese and antibiotics. These represent far less than 0.01% of fungal diversity.