Population Ecology
-ecology:the study of how organisms interact with their environment
5 levels of ecological study
-Global: how is the biosphere affected by global changes in nutrient and climate
-Ecosystem:how does energy flow and how do nutrients cycle through the local environment
-community:how do species interact
-population:how an why does population size change over time
-organismal: how do individuals interact with each other and with their physical environment
Processes that affect population size
1.Birth(+)
2.Death(-)
3.Immigration(+)
4.Emigration (-)
-demography-the study of factors such as these that determine the size and structure of
populations throughout time
Life table
-summarizes the probability that an individual will survive and reproduce in any given time
interval over the course of its lifetime
-number of survivors (Nx): the number of individuals that survived to reach each age
class
-survivorship (1x): proportion of the offspring produced that survive, on average, to a
particular age
, Three general types of survivorship curves
-examples of species with each type of survivorship curve:
-type I:humans, pets, most big mammals
-type II:songbirds, deer
-type III:frogs, fish, turtles, ants
-age-specificity (mx):the average number of female offspring produced by female in each
age class
-net reproductive rate (R0): average number of female offspring produced per female per
lifetime. Indicates whether a population is increasing or decreasing (as long as
immigration and emigration are insignificant)
-R0>1:increasing
-R0<1:decreasing
-R0=1:stable
Life history fitness trade offs
-office because every individual has a restricted amount of time and energy at its
disposal-its resources are limited
-life-history traits form a continuum
High fendictity/low survivorship Low fenductity/high
survivorship
# of offspring many few
Size of offspring small large
maturity Early late
Disease and predator low high
resistance
Life span short long
-ecology:the study of how organisms interact with their environment
5 levels of ecological study
-Global: how is the biosphere affected by global changes in nutrient and climate
-Ecosystem:how does energy flow and how do nutrients cycle through the local environment
-community:how do species interact
-population:how an why does population size change over time
-organismal: how do individuals interact with each other and with their physical environment
Processes that affect population size
1.Birth(+)
2.Death(-)
3.Immigration(+)
4.Emigration (-)
-demography-the study of factors such as these that determine the size and structure of
populations throughout time
Life table
-summarizes the probability that an individual will survive and reproduce in any given time
interval over the course of its lifetime
-number of survivors (Nx): the number of individuals that survived to reach each age
class
-survivorship (1x): proportion of the offspring produced that survive, on average, to a
particular age
, Three general types of survivorship curves
-examples of species with each type of survivorship curve:
-type I:humans, pets, most big mammals
-type II:songbirds, deer
-type III:frogs, fish, turtles, ants
-age-specificity (mx):the average number of female offspring produced by female in each
age class
-net reproductive rate (R0): average number of female offspring produced per female per
lifetime. Indicates whether a population is increasing or decreasing (as long as
immigration and emigration are insignificant)
-R0>1:increasing
-R0<1:decreasing
-R0=1:stable
Life history fitness trade offs
-office because every individual has a restricted amount of time and energy at its
disposal-its resources are limited
-life-history traits form a continuum
High fendictity/low survivorship Low fenductity/high
survivorship
# of offspring many few
Size of offspring small large
maturity Early late
Disease and predator low high
resistance
Life span short long
