ch 11 population growth and regulation

demography

the study of populations

growth rate

in a population, the number of new individuals that are produced in a given amount of time minus the number of individuals that die

intrinsic growth rate

the highest possible per capita growth rate for a population. denoted as r

exponential growth model

a model of population growth in which the population increases continuously at an exponential rate

J-shaped curve

the shape of exponential growth when graphed

geometric growth model

a model of population growth that compares population sizes at regular time intervals

doubling time

the time required for a population to double in size

density independent

factors the limit population size regardless of the population’s density

density dependent

factors that affect population size in relation to the populations density

negative density dependence

when the rate of population growth decreases as population density increases

positive density dependence

when the rate of population growth increases. also known as inverse density dependence or the allee effect

self thinning curve

a graphical relationship that shows how decreases in population density over time lead to increases in the mass of each individual in the population

carrying capacity, K

the maximum population size that can be supported by the environment

logistic growth model

a growth model that describes slowing growth of populations at high densities

s-shaped curve

the shape of the curve when a population is graphed over time using the logistic growth model. or, sigmoidal

inflection point

the point on a sigmoidal curve at which the population achieves its highest growth rate

age structure

in a population, the proportion of individuals that occurs in different age classes

type I survivorship curve

depicts a population with low mortality early in life and high mortality in life

type II survivorship curve

occurs when a population experiences relatively constant mortality throughout its lifespan

type III survivorship curve

depicts a population with high mortality early in life and high survival later in life

life tables

tables that contain class-specific survival and fecundity data. the actual population is twice as large as that estimated by a life table

stable age distribution

when the age structure of a population does not change over time

net reproductive rate

the total number of female offspring that we expect an average female to produce over the course of her life

generation time (T)

the average time between the birth of an individual and the birth of its offspring

cohort life table

a life table that follows a group of individuals born at the same time from birth to the death of the last individual

static life table

a life table that quantifies the survival and fecundity of all individuals in a population during a single time interval