Learning Objectives

13.5.1 Know how parasites can affect the outcome of species interactions and community structure.

13.5.2 Describe how climate change might influence host­pathogen relationships.

The effects of parasites on their hosts can have ripple effects on communities: by reducing the performance of host individuals and the growth rates of host populations, parasites can change the outcome of species interactions, the composition of ecological communities, and even the physical environment in which a community is found.