It looks very peaceful in the savannah. Yet there is a arms race going on. Shortly the lion will go hunting. Those antilopes, that are the fastest and the most manoeuvrable, have the best chance to escape and thus to bring up their offspring. Their descendants will have this hereditary trait too, with the consequence that the species as a whole will become faster and more manoeuvrable. Therefore the lion must also become faster and more manoeuvrable because otherwise it cannot catch the antilopes anymore. The fastest lion has a better chance to propagate than the slow one. And so on. This is called the arms race. Both species are under pressure of each other to adapt: they undergo evolution together at the same time. There are many examples of the arms race. Think of plants developing spines or poison in response to eating by animals. Or think of animals and their parasites. Know more? Arms race

This kind of evolving together is called coevolution. A somewhat more sympathetic kind of coevolution is the one of the 'flowers and the bees', or the plants and the insects. Plants are (often) dependent on insects for the pollination of  the flowers, whereas the insects depend on the plants for their food (honey, pollen). This mutual dependence has gradually increased in the course of time. There are even insect species being totally specialized on one plant species. Some orchids have developed a flower which looks exactly like the female of a certain species of a wasp. They imitate even the smell. Male wasps are attracted by these flowers and take care for the pollination. Insects are also often involved in the dispersion of the seeds of plants. The ultimate form of coevolution is the symbiosis in which two organisms live together and cannot live without one another. An example are the lichens, which are a symbiosis of an alga and a fungus. Know more? Coevolution

Evolution 22

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