co-evolution Co-evolution is frequently seen in pairs of species that interact frequently or closely. A change in the traits of one species acts as a selection pressure on the other species.

activity 1 - co-evolution Your task is to research the examples of co-evolution shown on the following slides. Be prepared to discuss your findings at the next lesson.

pollinators and plants mutualistic co-evolution

mutualism mutualistic co-evolution

herbivores and plants competitive co-evolution

seed-eater and plant competitive co-evolution

predators and their prey competitive co-evolution

parasites and their hosts competitive co-evolution

the ‘arms race’

activity 2 – the ‘arms race’ You will now read and discuss an article on the ‘arms race’ between the human host and the parasite Plasmodium falciparum. malaria’s evolutionary arms race

the red queen hypothesis The co-evolutionary ‘arms race’ between a parasite and host is known as the Red Queen Hypothesis as both organisms must ‘keep running in order to stay still’. At the top of the hill, the Red Queen begins to run, faster and faster. Alice runs after the Red Queen, but is further perplexed to find that neither one seems to be moving. When they stop running, they are in exactly the same place. Alice remarks on this, to which the Red Queen responds: "Now, here, you see, it takes all the running you can do to keep in the same place". malice in wonderland

the red queen hypothesis Hosts better able to resist and tolerate parasitism have greater fitness. Parasites better able to feed, reproduce and find new hosts have greater fitness. parasitic wasp / housefly PPQ