Chesson's Contributions: Lottery Model, Variable Environment Theory, and Storage Effect, Slides of Ecology and Environment

Download Chesson's Contributions: Lottery Model, Variable Environment Theory, and Storage Effect and more Slides Ecology and Environment in PDF only on Docsity! A Session On Chesson Docsity.com Contents • Background • Interest and Role in Community Ecology • His work – The Lottery Model – Variable Environment Theory – The Storage Effect – Scale-Transition Theory • Issues Docsity.com The Sale’s Lottery System • L is the number of larvae of species i available • c is a constant representing the relative competitive ability of species i Docsity.com Chesson’s Population Model Portion of homes filled by species “i” Surviving individuals in species “i” Dead individuals of all other species Birthrate of “i” divided by the birthrate of the rest Incorporates stochasticity variable among species Docsity.com Variable Environment Model • ri = Long term growth rate of species i • ΔE = relative mean effect of the environment • ΔC = relative mean effect of competition • ΔI = relative mean of the interactions between environment and competition. Docsity.com The Storage Effect • Competing species can coexist when intraspecific competition outweighs interspecific competition • Fluctuation-dependent 3 part mechanism (ΔI) – Fluctuation must effect birth rate, death rate, or recruitment – Buffered population • Examples = seed banks, hibernation, long-lived adults, refuges for spatial storage effect Docsity.com Buffered population growth • Subadditive results from previous model. Docsity.com The equation Long term growth rate at low populatons Equalizing mechanism Stabilizing mechanism Docsity.com Scale-transition equation Variability introduced by nonlinearity on population density Variability introduced to local dynamics or physical environment Number of individuals in following time point Docsity.com Scale-transition models • Allows you to incorporate emergent variability produced into a model where data is scaled up to a larger perspective. • Produces testable prediction as to how those emergent properties will relate to smaller scale data (i.e. through nonlinearity and variation) • Propose as a potential alternative to meta- community theory for large scale ecological systems Docsity.com Issues with models • No Allee effects • No extinction possible • No effect of location on dispersal • Deriving actual numbers to represent variables still difficult Docsity.com