Biodiversity: what it is and why it matters
Aprende
Biodiversity is the variety of living things in a place or on the planet. It counts all living things: animals, plants, fungi and microorganisms. It is studied at three levels.
The three levels of biodiversity Species diversity is how many different species there are. We count species, not individuals, which are living things taken one by one. A thousand ants of a single species are less diverse than a meadow with ten species and a hundred individuals.
species individuals plot A 1 1000 plot B 10 100 Plot B is more diverse, even though it has fewer individuals Genetic diversity is the variety within one species. All dogs are one species, but there are very different breeds. Genes are the instructions that each living thing inherits from its parents. Ecosystem diversity is the variety of places with their living things: forests, meadows, lakes or seas.
Biodiversity matters because living things depend on each other. A bee carries pollen from flower to flower, and that is how fruit forms. A varied ecosystem copes better with changes, such as a drought or a plague of pests, because other species keep doing their job. Nature also gives us food, medicines, and clean air and water.
Without bees, less fruit Biodiversity falls when habitats are destroyed, when there is pollution, when there is too much hunting or fishing, when invasive species arrive or when the climate changes. An extinct species is lost for ever. To protect species there are Red Lists, like the IUCN’s or the Swedish one, which classify how much danger each species is in. There are also protected areas, laws, seed banks and gene banks, and captive breeding and reintroduction.
Causes of biodiversity loss
Worked examples
Ejemplo 1
Gus counts insects in two corners of the park. In corner A there are 40 ants, all of one species. In corner B there are 12 insects of 6 species. Which corner has more biodiversity?
| species | individuals | |
|---|---|---|
| corner A | 1 | 40 |
| corner B | 6 | 12 |
- Species diversity is measured by counting different species, not individuals.
- Corner A has 1 species and corner B has 6 species.
- 6 is greater than 1.
Corner B has more biodiversity, even though it has fewer insects.
¡Ojo! Many children think the corner with more individuals wins.
Ejemplo 2
Ellie has three apple trees of different varieties. A fungus attacks variety A, but not B or C. Which level of biodiversity helps her?
- The three varieties are the same species: the apple tree.
- They are different because they have different genes.
- Because they do not all get ill, two of the three are saved.
Genetic diversity: with different varieties, the whole harvest is not lost.
¡Ojo! Many children think they are three different species.
Ejemplo 3
Tony sees that there are hardly any bees left in his vegetable patch. What could happen to the fruit?
- A bee carries pollen from flower to flower.
- Without pollen in the flower, the fruit does not form properly.
- With fewer bees there will be less fruit.
There will be less fruit: bees help it to form.
¡Ojo! Many children think bees are only for making honey.
Un reto para pensar
Choose a corner of a park, a garden or a vegetable patch and mark out a square with four sticks and a piece of string. For ten minutes, write down how many different species you see: plants, insects and other living things. Count species, not individuals. Compare it with another corner. Look without pulling up or treading on anything, and do not touch anything you do not recognise.
Practica
Rondas de 10 preguntas. Elige el nivel: