population growth and regulation Flashcards
what is a life table
tables which show how survival and reproductive rates vary with age, size or life cycle stages
what is a cohort life table
follows the fate of a group of individuals born at the same time
what is a static life table
used to see survival and reproduction of individuals of different ages during a single time period
why is a static life table sometimes better to use than a cohort life table
organisms which are highly mobile or have long life spans can be hard to observe from birth to death
what is a survivorship curve
a plot of the number of individuals from a hypothetical cohort that will survive to reach different ages
what are the different Types seen in a survivorship curve
type I= most individuals survive to old age
type II= the chance of surviving remains constant throughout the lifetime
type III= individuals die at high rates when young, those which reach adulthood survive well
define age structure
the proportion of the population in each age class which influences whether a population will increase or decrease in size
what needs to be calculated in order to predict population size for the following year
1) number of individuals which will survive to the next time period
2) number of newborns those survivors will produce in the next time period
what happens when age-specific survival and fecundity rates are constant over time
the populatin grows at a fixed rate and the age structure doesnt change
what is geometric growth
when a populatin reproduces in synchorny at regular time intervals and growth rate remains the same
define geometric growth
when the pop increases by a constant proportin so the number of individuals added to the population becomes larger with each time period
what happens when populations increase by constant proportions
the populating is showing exponential growth
