Introduction to Ecology: Population Ecology Notes
Mrs. Laux AP Biology
I. Ecology
Æthe study of all relationships among organisms and their abiotic
environment
A. Population
1. all the members of a particular species that live together in the same
area at the same time
B. Community
1. all the populations of different species living in the same area
2. ecosystem
a. a community and its environment
C. Biosphere
1. global ecological system that comprises all the communities on Earth
2. includes interactions among all Earth’s communities and the Earth’s
atmosphere, lithosphere, and hydrosphere
II. Population Ecology
Æbranch of biology that deals with the number of individuals of a particular
species that are found in an area and how and why those numbers change over
time
Æpopulations have certain properties, such as birth rates and death rates,
that individual organisms lack
A. Population density
1. the number of individuals of a species per unit of area or volume at a
given time
B. Population dispersion (spacing) may be:
1. random
a. unpredictably spaced
2. clumped
a. clustered in specific parts of the habitat
3. uniform
a. evenly spaced
C. Population Size-affected by:
Æ number of births (b)
Ænumber of deaths (d)
Æimmigrants (i)
Æemigrants (e)
1. growth rate (r) of a population
a. its rate of change in size
b. r = b – d (on a global scale, when migration is not a factor)
1
, Introduction to Ecology: Population Ecology Notes
Mrs. Laux AP Biology
2. populations increase in size as long as
a. birth rate (natality) is greater than death rate (mortality)
3. r = (b –d) + (i –e) for a local population (where migration is a factor)
III. Biotic potential
Æmaximum rate at which a species or population could increase in number
under ideal conditions
Æexponential population growth
Æsome populations exhibit
Ælimited period of time
ÆJ-shaped curve
Æeventually growth rate decreases to around zero or becomes negative
A. Environmental resistance
1. population size is modified by limits set by the environment
B. Carrying capacity (K) of the environment
1. the largest population that can be maintained for an indefinite time
by a particular environment
a. Earth for people-6 to 14 billion?
IV. Logistic population growth
Æwhen graphed, shows an S-shaped curve
A. Initial lag phase
1. population is small
B. Exponential phase
1. population increases rapidly
C. Leveling phase
1. carrying capacity of environment is reached
Æseldom do natural populations follow this growth curve
2
Mrs. Laux AP Biology
I. Ecology
Æthe study of all relationships among organisms and their abiotic
environment
A. Population
1. all the members of a particular species that live together in the same
area at the same time
B. Community
1. all the populations of different species living in the same area
2. ecosystem
a. a community and its environment
C. Biosphere
1. global ecological system that comprises all the communities on Earth
2. includes interactions among all Earth’s communities and the Earth’s
atmosphere, lithosphere, and hydrosphere
II. Population Ecology
Æbranch of biology that deals with the number of individuals of a particular
species that are found in an area and how and why those numbers change over
time
Æpopulations have certain properties, such as birth rates and death rates,
that individual organisms lack
A. Population density
1. the number of individuals of a species per unit of area or volume at a
given time
B. Population dispersion (spacing) may be:
1. random
a. unpredictably spaced
2. clumped
a. clustered in specific parts of the habitat
3. uniform
a. evenly spaced
C. Population Size-affected by:
Æ number of births (b)
Ænumber of deaths (d)
Æimmigrants (i)
Æemigrants (e)
1. growth rate (r) of a population
a. its rate of change in size
b. r = b – d (on a global scale, when migration is not a factor)
1
, Introduction to Ecology: Population Ecology Notes
Mrs. Laux AP Biology
2. populations increase in size as long as
a. birth rate (natality) is greater than death rate (mortality)
3. r = (b –d) + (i –e) for a local population (where migration is a factor)
III. Biotic potential
Æmaximum rate at which a species or population could increase in number
under ideal conditions
Æexponential population growth
Æsome populations exhibit
Ælimited period of time
ÆJ-shaped curve
Æeventually growth rate decreases to around zero or becomes negative
A. Environmental resistance
1. population size is modified by limits set by the environment
B. Carrying capacity (K) of the environment
1. the largest population that can be maintained for an indefinite time
by a particular environment
a. Earth for people-6 to 14 billion?
IV. Logistic population growth
Æwhen graphed, shows an S-shaped curve
A. Initial lag phase
1. population is small
B. Exponential phase
1. population increases rapidly
C. Leveling phase
1. carrying capacity of environment is reached
Æseldom do natural populations follow this growth curve
2
