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
Reasons why young desert shrubs clumped. (3)
- Seeds germinate in a limited number of “safe sites”.
- Seeds are not dispersed far from the parent plant.
- Asexually produced offsprings are necessarily close to the parent plant.
Individuals within a population in large scale are _______.
Clumped
In 1988, he mapped patterns of bird abundance across North America using the _________
- Terry Root
- Christmas Bird Counts (begin at 1900)
High population density area which appear as red patches (on map).
Hot spots
Why does bird population in North America clumped? (2)
- The environment varies.
- Individuals aggregate in areas where the environment is favorable.
Population density _________ with increase organism size.
DECLINES
- Density (population’s) is INVERSELY related to size (organism’s).
In 1981, he produced one of the most clear demonstration of the relationship between body size and population density (HERBIVOROUS MAMMALS).
John Damuth
In 1985, He pointed out that plant ecologists have been studying the relationship between plant size and population density for a longer time.
James White
One of the most fundamental aspects of population biology.
Size-Density Relationship
