Consumer-resource interactions are the core motif of ecological
food chains or food webs, and are an umbrella term for a variety of more specialized types of biological species interactions including prey-predator (see
predation), host-parasite (see
parasitism), plant-
herbivore and victim-exploiter systems. These kinds of interactions have been studied and modeled by population ecologists for close on a century, as reviewed in synthetic monographs on this topic by Murdoch et al. and Turchin. Species at the bottom of the food chain, such as
algae and other
autotrophs, consume non-biological resources, such as
minerals and
nutrients of various kinds, and they derive their energy from light (
photons) or chemical sources. Species higher up in the food chain survive by consuming other species and can be classified by what they eat and how they obtain or find their food.