2.2c - co-evolution

• co-evolution

  the process by which two or more species evolve in response to selection pressure imposed by each other
• a change in traits in one species acts as a selection pressure on the other
• co-evolution is seen as pairs of species that have symbiotic interactions
• parasitism

  + / -
• in parasitism, the parasite has a positive beneficial relationship with the host, which is negatively impacted by the relationship
• in parasitism, the parasite gains habitat and resources, while the host loses these
• mutualism

  + / +
• in mutualism, both species are positively impacted by the relationship and in most cases cant survive without each other
• commensalism

  + / 0
• in commensalism, one species derives a positive benefit while the other is neither positively or negatively affected, so its described as negative
• the red queen hypothesis

  the change in traits in one species can act as selection pressure on the other in a co-evolutionary relationship
• in the red queen hypothesis, both species must adapt to avoid extinction