BIO331H5 Lecture Notes - Lecture 5: Intermediate Disturbance Hypothesis, Ecology, Competitive Exclusion Principle
Document Summary
Latitudinal gradients: more species in the tropics than at the poles. Continental species assemblies contact between the continents and why marsupial diversity is greatest in australia. We usually see a hump shaped curve btwn diversity and disturbance. Disturbance and predation increase mortality and decrease abundance. Only species which can either compensate for mortality with high birth rates or with lower mortality rates because they are less vulnerable to predator/disturbance will persist. Why diversity goes down when mortality decreases ^ competitive exclusion. More resources of the same type (ex. nitrogen in soil) leads to competitive exclusion and a hump-shaped curve. Increasing the range of resources (ex. increase phosphorous and potassium) facilitates niche partitioning, species exploit different resources and diversity increases. Environmental gradients shape patterns of diversity and create trade-offs and different species occupy different ends of the gradient. Communities may be defined by strong inter-specific interactions that directly or indirectly affect abundances.
