Adapted from Polis et al. 1998 Researchers were interested i…
Adapted from Polis et al. 1998 Researchers were interested in the spider populations on island communities. For several years they measured spider population density along with a number of other ecological factors. The spiders on the islands were part of a system diagrammed below. Spiders eat insects, and are eaten by the larvae of parasitoid wasps (the adult wasps lay their eggs on the spiders, then the larvae eat the spider). For most of the years of the study, the abundance of insects was positively correlated with the abundance of spiders. However one year (notably, a year that had an “El Niño” weather pattern that caused extra rain), the population of spiders went down dramatically even though there were abundant insects. Using the observations above and the interaction map below: Use the terms “top-down” and “bottom-up” to describe the regulation of The spider population in a non- El Niño year The spider population in an El Niño year The parasitoid wasp population For each of these give a brief (1-2 sentence) explanation of your reasoning