Chapter 9 Flashcards
What is population growth, and what is it controlled by?
- number of individuals in a population increasing or decreasing over time
- controlled by rate of new individuals added through birth and immigration, and removed through death and emigration
What is an open population?
populations in which immigration or emigration occurs
What is a closed population?
those with movement into and out does not occur
What is the equation for population size at a given time?
population at the start of the experiemnt + birth - death
What is the equation for per capita birthrate?
birth/ population size at a given time
what is geometric population growth?
population size as a function of time
population change * population size
What is exponential population growth?
instantaneous per capita rate of growth
what is a life table?
age specific account of mortality
tracks them over a period of time, tracking how much has died
What is a cohort?
group of individuals born in the same period
What is survivorship?
probability at birth of surviving at any given age (fx)
What is dx in a lifetable>
difference between number of individuals alive for any age class (nx) and the next older age class (number that dies)
What is age-specific mortality rate?
(qx)- the number of individuals that died during a given time/ number alive at the beginning of the interval
What is a dynamic life table?
uses cohorts to determine fate of a group of individuals
What is dynamic composite life table?
cohort from individuals born over several time periods instead of just one
What is a time-specific life table?
samples population in some manner to obtain a distribution of age classes during a single time period
What does time-specific life table assume?
assumes age class was sampled in proportion to its numbers in the populations
How are life tables of insects and single breeding seasons tracked?
stages of life is tracked
What is studied in plant life tables? (3)
- seedling mortality and survival
- population dynamics of perennial plants marked as seedlings
- life cycles of annual plants
What is a type 1 survivorship, and what is it seen in?
- when population survives, survival rate is high through life span follwoed by heavy mortality at the end (type 1)
- humans, mammals, and some plants
WHat is type 2 survivorship curve, and what animals exhibits it?
- if survival rates do not vary with age, it can be straight (type 2)
- adult birds, rodents, reptiles, and perennial plants
What is type 3 survivorship, and what animals have it?
- early mortality (type 3)
- oysters, fish, invertebrates, and trees
What is crude birthrate?
dividing number of births in a period of time by estimated population size by the time period
What is age-specific birthrate?
function following mean number of females born to a female in each age group
What is gros reproductive rate?
average number of female offspring produced
What is facundity table?
uses survivorship column and age-specific birthrates
What is net reproductive rate? (3)
- average number of females that are produced during a lifetime by a newborn female
- at 1, females will replace themselves (produce one daughter)
- if 0, females do not replace themselves
What is population projection table?
ollows a given female population at birth
What factor other than age can be used to describe life stages?
size
What is age distribution?
proportion of individuals in the various age classes for any on year
What is a stable age distribution?
- population attains an unchanging number
- proportion of each age group stays the same even if population is increasing
What is a finite multiplication rate?
- total number of individuals in year t+1/ total number of individuals in the previous year
- greater than 1 means growing
- equal 1 is stable
What is demographic stochasticity?
- random variations in birth and death rates from year to year
- causes population deviation from prediction
What is environmental stochasticity?
random variations in the environment that influences birth and death rates
What factors can lead to population extinction? (4)
- small populations are more susceptible to extinction
- extreme environmental events can increase mortality
- shortage of supply or overexploitation
- invasive species
