“Ecological niche” - historical definitions/usage of the “niche” concept are varied, and the concept fell from grace in ~1970s because some definitions were too narrow, and because the concept was not validated experimentally.
Contemporary use of the term “niche” require: 1) incorporation of biotic/abiotic influences such as competition, predation, etc; 2) distinction between species requirements and species’ impact on environments
Niche Model – Uses associations between species occurrence data and environmental variables or uses direct measures of physiological variables to identify a species environmental space/ecological niche
Spatial Distribution Models – Uses environmental variables in geographic space to describe a species potential distribution based on its modeled niche
Q – What factors or limitations to niche modeling would cause a species’ potential distribution to differ from its actual distribution?
Q - In what ways would you predict ecological niche modeling to perform differently for occurrence data sets composed of…
a) prairie dogs b) cutthroat trout c) migratory birds d) your study organism
Modeling Algorithms - Several modeling algorithms exist (e.g. GARP, MAXENT). One of the many ways they differ is in the type of input data they require 1) presence-absence data 2) presence – pseudo absence data 3) presence only
Q – What are some problems with absence data? For example, think about occurrence data collected after human-induced extirpations?
Q – What are some research questions that could be answered using niche modeling? For which questions is it more useful to know a species actual vs. potential distribution?
Q- What is assumed using CEMs? Are these valid assumptions when predicting species responses to future climate change? (e.g. biotic interactions will remain constant)
Q- How do you validate the accuracy of predictive climate envelope models?
Q- Given the potential sources of error, are climate envelope models still useful to predict changes in species distribution resulting from climate change?