Population Distribution & Abundance Flashcards
A group of individuals of a single species inhabiting a specific area.
Population
Why does ecologists study populations? (5)
- Saving endangered species
- Controlling pest population
- Managing fish and game populations
- Offer clues to understanding and controlling disease epidemics
- Growth of human population
Characteristics of Population (5)
- DISTRIBUTION of population includes size, shape, and location of the area it occupies.
- Characteristic PATTERN OF SPACING of the individuals within it.
- Characterized by the NUMBER OF INDIVIDUALS within it and their DENSITY (no. of individuals per unit area)
- Age distribution, birth&death rates, immigration & emigration rates, rates of growth
- Abundance (total no. of individuals/biomass of species in a specified area.
Consist all of the factors necessary for its existence; the role an organism plays in a community
Niche
The concept of niche was independently developed by (2), and used it slightly different.
- Joseph Grinnell (1917-1924) - centered around the influences of the physical environment
- Charles Elton (1927) - included biological interactions, as well as abiotic factors
Physical conditions under which a species might live, in the absence of interactions with other species.
Fundamental niche
The actual niche of a species whose distribution is limited by biotic interactions (competition, predation, disease, & parasitism)
Realized niche
He described how along the coast of Scotland, adult Chthamalus stellatus - restricted to upper levels of intertidal zone , while Balanus balanoides - limited to middle and lower levels.
Joseph Connell (1961)
The small distances over which there is little environmental change significant to the organism under study.
Small scale
Areas which there is substantial environmental change (patterns over entire continent/mountain slope/environment gradient)
Large scale
3 Basic Patterns of Distribution Observed in Small Scale
- RANDOM
- REGULAR
- CLUMPED
Distribution in which individual has an EQUAL probability of occuring in an area (NEUTRAL interactions)
Random
Distribution is uniformly spaced through the environment (ANTAGONISTIC interactions between individuals or local depletion of resources)
Regular
Distribution in which individuals LIVE in areas of HIGH LOCAL ABUNDANCE, SEPARATED by areas of LOW ABUNDANCE (attraction between individuals/attraction of individuals to a common resource).
Clumped
How does desert shrubs distributed as they grow?
Clumped - Random - Regular