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Population Ecology


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Population Ecology
The study of populations in relation to the environment, including density, distribution, age structure, and size.
A group of organisms of a single species living in the same general area; members rely upon the same resources, are influened by similar environmental factors, and have a high likelihood of interacting with each other.
Population Density
The number of individuals per unit area of volume
Methods of Estimating Population Density (3)
Sample and Extrapolate
Sample Indicators
Mark and Recapture
Sample and Extrapolate Method
Individuals are counted in random areas of standard size and averaged, then multiplied by the number of areas within the domain.
Sample Indicator Method
Population size is estimated based on some index of population size; number of nests, burrows, tracks, fecal droppings, etc.
Mark and Recapture Method
A sample of animals are captured within the boundaries of the population area and marked (tagged, collared, dyed, etc.) and released. After enough time to allow marked individuals to remix with the group, traps are reset and the number of marked animals captured are compared to the number of unmarked animals captured.

Marked/Total Pop = Marked Recaptured / Number Recaptured
Methods of Population Addition (2)
Methods of Population Reduction (2)
Population Dispersion
The pattern of spacing among individuals within the boundaries of the population.
Patterns of Population Dispersion (3)
Aggregation of individuals in spaced patches; most common form of dispersion; can increase mating, protection against predators, and efficiency of resource gathering
An even distribution of organisms; primarily results from interactions between population individuals
The defense of a bounded physical space against enroachment by other individuals; primary cause of uniform dispersion
Unpredictable spaing that occurs either
1) in the absence of strong attractions or repulsions among individuals of a population
2) where key physical or chemical factors are homogenous across a study area.
The study of vital statistics of populations and their change over time.
Life Tables
Age-specific summaries of the survival pattern of a population presented as a table.
A group of individuals of the same age followed from birth until death; used in the construction of a life table
Survivorship Curve
A graphical representation of data in a life table; a plot of the proportion or numbers in a cohort still alive at each age.
Type I Curve
A curve taht demonstrates a small death rate at early ages and increases toward later ages; reflects a population that produces few number offspring but provides care for its young
Type II Curve
A curve that demonstrates an consistent death rate throughout the entire span of ages
Type III Curve
A curve that demonstrates large death rates at early ages and decreases toward later ages; reflects a population that produces vast numbers of offspring but provides little care.
Reproductive Table
An age specific summary of reproductive rates in a population presented as a table
Life History
The traits that affect an organism's schedule of reproduction and survival; tracks birth, growth and development, reproduction, senescence, and death.
The point at which an organism is capable of producing offspring.
The amount of offspring an organism is capable of producing.
The number of times an organism is able to reproduce.
Oviporous Animals
Animals that produce eggs through which offspring develop independent of the mother.
Viviporous Animals
Animals that give birth to live young.
On average, how many offspring does a viviporous mammal produce in one reproductive cycle?
One less than the number of mammary glands.
True or False: Fecundity holds a direct relationship with the amount of care given to its offpsring
False: Fecundity holds an inverse relationshi with the amount of care given to offspring; the more offspring produced, the less care the parent provides.
"Big Bang" Reproduction; reproduction that only occurs once in the lifetime of an organism.
Repeated reproduction; reprooduction that can occur multiple times in the life of an organism.

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