Studied by 0 people
Population
The individuals that belong to the same species and live in a given area at a particular time
Community
All of the populations of organisms within an given area
Population ecology
The study of factors that cause population to increase or decrease
Population size (N)
The total number of individuals of a particular species in a defined area at a specific time.
Population Density
The number of individuals per unit area at a given time
Population distribution
A description of how individuals are distributed with respect to one another
Sex ratio
The ratio of males to females in a population
Age structure
A description of how many individuals fit into particular age categories in a population
Limiting resource
A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size
Density-dependent factor
A factor that influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population.
Carrying capacity (K)
The limit of how many individuals in a population the environment can sustain
Density-independent factor
A factor that has the same effect on an individual’s probability of survival and the amount of reproduction at any population size
Population growth models
Mathematical equations that can be used to predict population size at any moment in time
Population growth rate
The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period
Intrinsic growth rate r
The maximum potential for growth of a population under ideal conditions with unlimited resources
Exponential growth model (Nt = N0ert)
A growth model that estimates a populations future size (Nt) after a period of time (t), based on the intrinsic growth rate r and the number or reproducing individuals currently in the population (N0)
J-shaped curve
The curve of the exponential growth model when graphed
Logistic growth model
A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment
S-shaped curve
The shape of the logistic growth model when graphed
Overshoot
When a population becomes larger than the environment’s carrying capacity
Die-off or Dieback
A rapid decline in a population
K-Selected species
A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches the carrying capacity
r-selected species
A species that has a high intrinsic growth rate, which often leads to population overshoots followed by die-offs
Survivorship curve
A graph that represents the distinct patterns of species survival as a function of age
Type I survivorship curve
A pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age.
Type II survivorship curve
A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span
Type III survivorship curve
A pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood
Corridor
Strips of natural habitat that connect populations
Metapopulation
A group of spatially distinct populations that are connected by occasional movements of individuals between them
Inbreeding depression
when individuals with similar genotypes produce offspring with impaired abilities to survive and/or reproduce
The theory of demographic transition
The theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth
Phase I
Slow population growth, because birth rates and death rates are both high, pre-industrialization
Phase II
Rapid population growth, because birth rates remain high while death rates decline
Phase III
Stable population growth, birth rates decline
Note 
Flashcard (22)