AIM: How do interactions between a species and its environment define the species niche. Do Now: What is a species niche? Give an example. HW: Article #1 due Friday End of notes questions The environment in one part of an ecosystem is different from the environment in another part. Organisms living in each part of an ecosystem differ from eachother. Each organism is adapted to the conditions in the part of the environment in which it lives. Habitat The place in an ecosystem where an organism lives They can be large or small depending on the size of the organism and how much it travels Niche The role of an organism in it’s ecosystem The actions of an organism define it’s niche- a niche is more than an organisms habitat. It’s also what the organism does within a habitat A niche includes both biotic and abiotic factors Biotic Factors (living things) – Food sources – Predators All of the biotic and abiotic factors taken Abiotic Factors-nonliving things together – Temperature define the – Sunlight organisms – Water niche All members of a species are adapted to the same habitat • No two species can share the exact same niche in the same habitat but two species can occupy niches that are very similar • The different species can live sideby-side because they occupy different niches Competitive Exclusion • If two species try to share the same niche, they will compete for resources • One of them will have to move to another area or the population will die out. • The extinction of a population in a specific area due to direct competition with another species for a resource is called competitive exclusion The activity of one species can help define another species niche. Scientist J.H. Connell performed an experiment to study how one barnacle species affects the niche of another Species A- lives on rocks exposed to air Species B- lives on rocks covered in water most of the time He removed all of species B from a small area of the shore He found that species A began to grow on the lower rocks Cornell hypothesized that species A could live on all parts of the shore, but that species B drove out species A wherever species B can survive. The A population was limited to the higher rocks by B, even though A could live on all the rocks in the absence of B He hypothesized that the niche of one species can affect the niche of another Fundamental niche = theoretical niche •Niche that an organism can ideally have (wherever it is able to survive) Realized niche •The niche that the organism actually has (Where the organism is really living) Niche Diversity • The number of different niches in an ecosystem • Determined by the abiotic factors in an environment • Ex: – Marsh- many organisms, few niches • Constant abiotic factors – Desert- few organisms, many niches • Fluctuating abiotic factors Predators •Play an important role in increasing niche diversity by decreasing the population size of their prey •When more resources become available for another species, a new niche will have been created Predator- actively hunts another organism Prey- the hunted organism Keystone Predator A predator that promotes niche diversity in it’s habitat 1. What is a species niche? 2. What factors help to define a niche? Give examples of each. 3. What prevents two species from sharing the same niche? What is this called? 4. Explain the difference between an organisms fundamental niche and its realized niche? 5. What is the role of predators in determining niche diversity? 6. Identify abiotic factors that contribute to niche diversity.