EVSC30006 Lecture Notes - Lecture 14: House Finch, Ecological Niche, Introduced Species
1 Jun 2018
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Professor
LECTURE 14: URBAN COMMUNITY ECOLOGY
• Individualistic community concept: many species interact & change over time
o Allow us to consider ecological communities across any spatial or temporal scale
• Novel ecological communities are arising in cities
COMMUNITY LEVEL PROCESSES
Type
Description
Selection
Arises from differences between species & individuals of the same species to influence fitness in a
given environment
• Known as species-environment or niche relationships
• Species rarely occupy their fundamental niche, only their realised niche
• Fitness varies over environmental gradients
• Competition for resources:
• Ecological Guild: a group of sympatric species that exploit the same class of resource
(resource competition)
• Coexistence Theory: heterogeneity (habitat complexity) and disturbance assist
coexistence
Dispersal
The movement of individuals from one place to another
• Constrained by roads, train lines, fences
• Local pool influenced by regional pool, which is influenced by global pool & introduced species
• Same Indigenous species always persist, but rather homogenous communities in cities
Evolutionary
Diversification
Evolution of new lineages, including new species over time
• Mexican House Finch: observed in Arizona, lives both in & out of the city, fed sunflower seeds, bill
morphology changes, placed selection pressure on bill of bird, natural selection for bigger &
stronger bills
Drift
Change from randomness or stochasticity over time within communities
• May become more important as dispersal is restricted in urban environments
• May have greater effect as number of individuals in community declines
Community: a group of potentially interacting species that occur together in space & time
Community Dynamics: changes in composition of communities over space & time
Document Summary
Community: a group of potentially interacting species that occur together in space & time. Individualistic community concept: many species interact & change over time: allow us to consider ecological communities across any spatial or temporal scale, novel ecological communities are arising in cities. Community dynamics: changes in composition of communities over space & time. Arises from differences between species & individuals of the same species to influence fitness in a. Species rarely occupy their fundamental niche, only their realised niche given environment: competition for resources: Ecological guild: a group of sympatric species that exploit the same class of resource (resource competition: coexistence theory: heterogeneity (habitat complexity) and disturbance assist coexistence. Local pool influenced by regional pool, which is influenced by global pool & introduced species. The movement of individuals from one place to another: constrained by roads, train lines, fences.
