Community structure Physical structure Dispersal-driven structure Predation-driven structure Competition-driven structure

Physical structure Physical template Biological template –Paradox of the plankton –Dominant species Trees Corals Surfaces –Ecological engineers impoundments cavities mounds

Habitat template

Whittaker’s analysis of the Smoky Mountains

Dominant species provide structure

Ecological engineers Dams Holes Mounds

Dispersal-based structure Supply-side ecology Propagule pressure Predictability Carousel mode Temporal mass effects

River Floodplain River Bedrock Scour Bar Scoured Island

Carousel model

Temporal mass effect The tingle tree in SW Australia has not reproduced in over 1000 years.

Seed banks as a form of temporal mass effect

Dispersal-based structure Supply-side ecology Propagule pressure Predictability Carousel model Temporal mass effects

Competition-based structure Niche differentiation In space In time Assembly rules Diamond’s birds Brown’s mice Lawlor’s and Wilson’s null models Ghost of competition past

Niche theory Grinnell The ultimate distributional unit. Physical and climatic limits Elton Fundamental role of a species. It’s occupation, or how it makes its living. Hutchinson N-dimensional hypervolume. Hutchinson. Fundamental & Realized Niche Whittaker, Levin & Root Niche, habitat & ecotope

Consider the concept of niche, if I knew what it meant I'd be rich Its dimensions are n, and a knowledge of Zen is essential to fathom the bitch Cottam and Parkhurst

And NUH is the letter I use to spell Nutches Who live in small caves, known as Nitches, for hutches. These Nutches have troubles, the biggest of which is The fact that there are many more nutches than niches. Each nutch in a Nitch knows that some other Nutch Would like to move into his nitch very much. So each Nutch in a nitch has to watch that small Nitch Or Nutches who haven't got nitches will snitch. Dr. Zuess On beyond zebra

Niche structure as a consequence of competitive displacement Brown 1975

Diamond 1975

Null models – Reorganization algorithms RA1: species number and resource categories retained. Randomly assign values for proportion of diet (between 0 & 1 such that for a species values sum to 1). Since 0 is rare, niche breadth was too high RA2: Retained 0s, and randomly assigned other values (perhaps should have randomly assigned 0s?).

RA3: Retained not only the original degree of specialization, but also the original consumer nichne breadths – randomly reassigned all values including 0s. RA4: Reassigned only the non-0 values

Competition-based structure Niche differentiation In space In time Assembly rules Diamond’s birds Brown’s mice Lawlor’s and Wilson’s null models Ghost of competition past

Predation-based structure Food web structure Complexity and stability Representation Keystone species Factors influencing food web stability Top-down/bottom up control Fertilizations and cages Are food webs all wet?

Multiple steady states