So in conclusion, what can we say about Abiotic factors, especially climate? (1)Abiotic factors influence species’ distribution and abundance But it also – (2) Shapes organisms: morphology, physiology, and behavior

But, we can ask: “Are most organisms always found where their abiotic needs are met”? Dispersal limited We’d expect no Arboretums We’d expect no zoos We’d expect no Invasive spp While abiotic factors represent a filter for what can exist at a given time and in a given space, BIOTIC factors play a pivotal role (another filter) on what does exist

Balanus and Chthamalus show zonation in tidal habitats Joseph Connell 1961 Experimental - caged predators - removed competitors - transplanted rocks w/barnacles - monitored responses

Always submerged Always exposed

Conclusions of Connell’s study (1) Organisms are limited by abiotic conditions that set ‘hard’ limits on their distribution (for barnacles it’s the upper tidal zone). (2) Organisms are also limited in their distribution by the biotic components of their environment (competitors, predators) that may set ‘softer’ limits (esp. Chthamalus – competition). (3) Removal of biotic factors can result in expansion in the distribution an organism – its geographic range, range of habitats where it occurs (Connell’s study), abiotic conditions in which its found, and so on… ‘hard’ = absolute ‘soft’ = dependent on the presence of another organism

Concept of the NICHE Let’s synthesize the material so far in the Let’s consider the concept of niche – If I knew what it meant I’d be rich. Its dimensions are n But a knowledge of Zen Is required to fathom the bitch - Grant Cottam and David Parkhust The environmental factors that influence the growth, survival, and reproduction of a species – Molles Textbook Functional role of a species in the community, including activities and relationships – Smith and Smith Textbook

The environmental factors that influence the growth, survival, and reproduction of a species – Molles Textbook Functional role of a species in the community, including activities and relationships – Smith and Smith Textbook Species have requirements (water, temp, food, mates, etc…) Species have impacts (they eat things, i.e., deplete resources, they build things, they destroy things, etc…)

minmax Temp Abundance A single Niche axis Species abundance

minmaxminmax minmax min max Temp Water Abundance Two Niche axes

minmaxminmax minmax min max Temp Water Abundance Two Niche axes with interactions between variables

minmaxminmax Temp Water minmax PH Temp PH Water Three Niche axes

minmaxminmax Temp Water minmax PH minmax Calcium A multi-dimensional mess!! Hutchinson’s n-dimensional niche

minmaxminmax Temp Water minmax PH minmax Calcium The niche can be visualized, conceptually, as an n-dimensional volume that defines all the conditions in which an organism can survive

The Fundamental Niche is the total niche volume determined solely by Abiotic factors The Realized Niche is a subset of the F. Niche that an organism actually occupies – the difference being the influence of Biotic factors: e.g., predators, competitors, food More definitions:

Fundamental Niche Realized Niche R 0 > 1.0 R 0 < 1.0 The Niche concept place in a Population Framework predation competition Factor One Factor Two The environmental factors that influence the growth, survival, and reproduction of a species – Molles Textbook