Environmental Science: Population and Survivorship
(Population) Distribution
Characteristic of population concerning how individuals are spaced out in a population; random, uniform, or clumped; influences measure of density
Survivorship
Characteristic of population concerning mortality scale; 3 types
Sex ratio
Characteristic of population concerning the ratio of males to females; close to 50:50 in most species
Population size
Characteristic of population that includes the number of individuals in a population
population density
Characteristic of population that measures the number of individuals per unit area
Population
Individuals of the same species, living in the same place at the same time
Quadrat sampling
Method of measuring a population's size by measuring the population in a certain area or quadrant; used for sessile species
Capture-mark-recapture
Method of measuring population size in which the organism is captured and marked, usually with a plastic band or number, and then released; uses the Lincoln-Peterson Index to calculate estimation
Sessile
Slow moving or non-mobile organism whose population size can be estimated using the quadrat sampling technique
Type I (Survivorship)
Survivorship curve in which organisms had parental care; not much death during adolescence but population drops around middle age; ex. humans, gorillas, elephants
Type II (survivorship)
Survivorship curve in which parental care was present but not constant (parents leave children alone to find food, allowing predators to attack); constant slops/state of mortality; ex. birds
Type III (survivorship)
Survivorship curve in which there is no parental care; death usually occurs in adolescence with death rates slowing in middle/old age; ex. fish, turtles, frogs
Uniform (distribution)
Type of population distribution in which organisms are dispersed in a sort of pattern, usually because of social behavior
Clumped (distribution)
Type of population distribution in which organisms are in groups for protection purposes
Random (distribution)
Type of population distribution in which organisms are simply scattered in no specific way; happens in trees due to nutrient levels in soil
population ecology
the branch of biology that deals with the number of individuals of a particular species found in an area and how and why those numbers increase or decrease over time