ecology- population growth and regulation

age structure

The number of individuals in each age class in a population at one point in time


All individuals of a population born in the same year.


The average number of births per individual in a population, usually tracked through females only.

generation time (T)

The average number of years for a female in a population to produce all her female offspring in life


Species that breed two or more times in their life

K-selected species

A long-lived species with high survivorship until late in life that produces low numbers of offspring every 1-2 yrs.

life history table

A table that summarizes the demographic variables for a population, can be based on a cohort tracked through time or time-specific data.

net reproductive value (Ro)

The average number of female offspring produced by each female in a population throughout their life.

nonoverlapping generations

When offspring reach breeding age after their parents have stopped breeding in their lives.

overlapping generations

When offspring reach breeding age while parents are still breeding

r-selected species

A species with small size, rapid growth, and that produces high numbers of offspring more than once per year.


Species that breed only once in their lives

stable age distribution

When the relative proportions of individuals in each age class of a population stays the same through time because the growth rate of each age class does not change.

static or time-specific life history table:

A table that summarizes demographic data for a population based on the age structure of the population at one point in time.

survivorship curves

Plots that show the probability of survival with age in a population, usually depicted in three types: Type I, II, and III