Populations 1: Fundamental/ realized niches and climate envelopes Flashcards
Quotes from Hutchinson and eco-evo dynamics
“The ecological theatre and an evolutionary play”.
Definitions of Niche
1: Fundamental and realised niche
2: A niche as a hyper volume (Hutchinson)
3: Niche width (MacArthur)
Fundamental vs realized niche
Fundamental niche: A fundamental niche is the full range of environmental conditions that a viable population of species can occupy and use, without any other limiting factors present which could constrain the population
Realized niche: A realized niche is range of environmental conditions that a viable population of species can occupy and use, when constrained by limiting factors the population.
Hutchinson’s definition of a niche
Hutchinson defined a niche as a region (n- dimensional hypervolume) in a multi- dimensional space of environmental factors that affect a species
Why might we question Hutchinson’s definition
(1) measurement of niche volume is a subjective procedure,
(2) some important dimensions of the niche may be not known,
(3) niches change in the life-cycle,
(4) niches change from one geographical region to another.
MacArthur’s extenstion on the niche thoery
macArthur’s studies on the feeding zones of warblers introduced the idea that niches can have a limited similarity between species (there is a possibility for competitive exclusion)
He introduced the idea of niche width
Climate envelopes
Climate envelopes use climate variable to make spatial predictions and extrapolation of environmental suitability for a species.
Example: greater sage grouse
- compared risk in strawberry valley and sheep rock in Utah -> sheep rock more at risk due to coupled degradation stressors
- Major loss and degradation of habitat, wild fires, invasive species, human disturbance
- species climate envelopes were evaluated and additional stressors considered
How to use a climate envelope
1) Sample climate data for species occurrence/absence (e.g. use logistic regression)
2) Create a prediction map based on contemporary climate suitability
* What is the probability of finding a species in an area based on a climate factor
3) Extrapolate prediction map under future climate
LImitations of climate envelopes
Lack of traditional/ expert knowledge: Climate envelopes ignore expert knowledge on animal behaviour, weather patterns and plants/ animal distributions
Biotic factors: Climate envelopes ignore the impact of biotic interactions
Example: A study looked at how the number of species present impacted the distribution of Drosophila between fridges when the temperature increased. The number of species present altered the distirbution of Drosophila
Physiological factors: Climate envelopes ignore the varied physiological effects that climate has on species
Example: L.digitalis and L.austrodigitals are two species of limpet that have different abilities to endure changing temperatures . The amino acid structure of L.austrodigitalis means that it can endure rising temperatures better than the other species.
Example: study compared heat tolerance of quail and dove. Dove is a lot more tolerant to high temperatures as they sweat. Lost 30-45% more water than quail. Could retain body temp 14*c below air temp
Modelling fundamental and realised niches
Fundamental and realised niches can be modelled.
Fundamental: This uses the simple population growth model and does not take into account any limiting factors.
Realised: This used the logistic growth model and limiting factors can be integrated (e.g. carrying capacity, species competition)
Overview
There are multiple definitions for ‘Niche’ that have been adapted and built upon throughout history. Niches can be modelled and used to understand how niches willl change with a changing environment.
Climate envelopes are a key modelling technique used to predict how species distribution will change with a changing climate but the method does have limitations.
