BIS 2B Study Guide - Final Guide: Intermediate Disturbance Hypothesis, Keystone Species, Competitive Exclusion Principle

• School: UC-Davis
• Department: Biological Sciences
• Course: BIS 2B
• Professor: Schreiber, Sebastian

Document Summary

Direct effects of species interactions include predation, mutualism, competition. Indirect effects of species interactions: effects can be determined through multiplying signs from one species to another: keystone predation (trophic cascades): one species has indirect positive effect on another species through direct negative effect on one species. Keystone species have major effect on ecosystem/community structure disproportionate to abundance (includes sea stars, otters, and wolves) Otters control urchin populations which affect kelp populations, islands without otters became urchin barrens while islands with otters allowed the development of kelp. Maintenance of biodiversity: niche partitioning of resources allows greater numbers of species to coexist and greater resource diversity allows greater ecological niches for greater number of species. Intermediate disturbance hypothesis: low disturbance means k-selected species dominate while high disturbance means r-selected species/disturbance resistant species dominate. Rocky intertidal boulders (small boulders with high disturbance frequency and large boulders with low disturbance frequency have less species diversity than medium boulders with intermediate disturbance)