L12 - Niches Flashcards
define the niche according to Joseph Grinnel
distributional limits set by physical or climatic barrier
define the niche according to Charles Elton
niche is defined by body size, food habitat and interactions with other species
define the niche according to G Evelyn Hutchinson
combination of both concepts, separation into fundamental and realised niche, where realised niche is where species has optimal richness and fundamental niche is the potential distribution of the species
how can a niche be indirectly measured
morphological and behavioural traits, but abiotic factors are not included
how is it possible that a niche can vary “individually” within one species
it depends on whether the individual is big or small, young or an adult etc.
what is a specialist population
all eat one resource
what are the 2 types of a generalist population
either all individuals in one populations eat everything, or individuals of a population each eat something, but “cover all bases” thus being generalist as a whole
how can habitat loss and monitoring species reaction to habitat loss help understand niches:
habitat loss shows how species adapt to a disturbance in the ecosystem, suggests that a species can be a specialist or a generalist in different habitats, (eg forest cover - species is going to be more sensitive to percentage forest cover when close to an edge), specialist might be more sensitive to habitat loss than generalists, however depends on where they are in the habitat
what is observed niche composed of and what is its use
species occurence + environmental data, used to map over geographic space with a probability of species occurence, can be used to model likelihood of distribution change under climate change, habitat loss, invasive species etc.
how can understanding a species niche help in predicting future scenarious, especially with climate change
malaria example, plotting the present distribution plus all future scenarios, shows that with higher temparaturem the distribution of malaria is likely to spread
how does the concept of niches relate to invasive species
knapweed example - as an invasive species in North America, the plant has a different niche than in original area (eg prefers less precipitation in North America, contrary to Europe)
how can the knapweed “irregularity” in fundamental niche help us understand necessary aspects of niches
need to consider competitors, consumers, predators, which might help us understand why some species have a different “strategy” when put into a new environment
