Chapter
1. What is biodiversity?

1. What is biodiversity?

Biodiversity is a major topic right now, not just because of the threats it faces, but also because we now understand better than ever just how little we in fact know about it.

In the video, we learn about the definitions of biodiversity and the scale of diversity in different groups of organisms.

The clip comes with subtitles in English. Just click play, select the gear icon on the lower right and select subtitles in English.

Read more in scientific articles

Read more in scientific articles where researchers have tried to estimate the number of species we still don’t know about.

  1. How many species are there on Earth and in the ocean?
    Original article
    Mora, C., Tittensor, D. P., Adl, S., Simpson, A. G. B. & Worm, B. 2011: How many species are there on Earth and in the ocean? PLoS Biology 9(8): e1001127. DOI: 10.1371/journal.pbio.1001127.

  2. How many tons of each organism group are there on Earth?
    Original article
    Bar-On, Y. M., Phillips, R. & Milo, R. 2018. The biomass distribution on Earth. PNAS 115(25): 6506-6511. DOI: 10.1073/pnas.1711842115

  3. A study that counted the number of arthropod species in one rainforest
    Original articleArticle on ResearchGate
    Basset, Y., ym. 2012: Arthropod diversity in a tropical forest. Science 338(6113): 1481-1484. DOI: 10.1126/science.1226727.

Find out

How many species are there? Why can we still not answer this question precisely? Find out for yourself. When we talk about biodiversity, we usually mean the number of species. Yet diversity of habitats and the genetic diversity within species are also important dimensions of biodiversity.

How long do you have to look to find all the species?

Look at Figure 1 in the Mora et al. article, where the horizontal axis represents time and the vertical axis the number of species groups known at the particular point in time. The lines in the graphs curve, because the longer we have already spent finding out the number of species groups, the more slowly we find new species. In principle if you look long enough, you will eventually find all the species groups. As the line curves and becomes more and more horizontal, you can make a good estimate of the eventual number species you would find.

Try this yourselves in groups of 3-8 people:

Does your line curve? Does it curve enough for you to estimate, what the actual number of species in the area might be?

How did the classification go – did you disagree? Biologists sometimes disagree a great deal about how to classify individuals into different species.

Project ideas in biodiversity

1. How can we know what we do not know?

Search the internet for different estimates of how many species are still to be found on Earth. How were the estimates made? How can we know what we do not know?

2. Genetic diversity within species

While species number are talked about the most, genetic diversity within species is also important.

Go to the grocery store and photograph different kinds of tomatoes, chilies, apples etc., and to the park to photograph different dog breeds or different coloured pigeons. Make photo collages. Make another trip to a natural environment, and make a separate collage of the genetic diversity you find there.

Examples are harder to find in nature, but try something like measuring the flowers on individual plants. When the season is changing, you can find differences in when individual trees come into leaf or turn yellow. If you have snails in your garden, their shells can have a lot of variety.

Take a look at the diversity you find in species bred by humans and species found in nature. Why is it harder to find variation in nature?

What do you think could be useful about having lots of variation between individuals within a species?