Transcript Ecology Intro - Lake Stevens High School

 Good Morning AP Bio!!
 We will go over the Safety Contract first today…please have it out 
 We will also finish our notes from yesterday.
 Pillbug lab prep is tomorrow…bring bugs by Thursday.
 You will need your comp lab notebook for tomorrow.
 You will get reading questions for Chapter 51 today. These will be
due TUESDAY along with your summer homework. (No reading
questions for Ch. 53-54)
 This is the day we will be taking our first Quiz! YAY!!
AP Biology
Chapters 53.1-3, 53.5
54.1-2
 Population: group of individuals of a single species living in the
same general area who interact and interbreed
 density: number of individuals per unit area

not a static number...constantly changing (births, deaths,
immigration, emigration)
 dispersion: pattern of spacing among individuals, indicates
social interactions in a population

clumped, uniform, or random

territoriality also influences dispersion
 Not easy to count all individuals in a population...use mark-
recapture method to estimate population sizes
 Survivorship Curves
 graphical representation of number of organisms alive in a population over
time in age ranges (death rate)
 Type I: low death rates early in life, increases in older age-groups

humans, elephants, primates and other organisms with lots of parental
care
 Type II: constant death rate over life span

squirrels, rodents, plants
 Type III: high death rate in younger ages, death rate declines (levels off) in
older age groups

organisms with large numbers of offspring and little parental care
(invertebrates and fishes)
 Exponential Growth
 rapid growth, occurs in
times of unlimited resources
(no carrying capacity)
 produces a J-shaped curve
Formula:
population growth= rmax (N)
(births-deaths)
rmax = maximum per capita
growth rate of a population
N= population size
 Logistic Growth
 growth limited by a
carrying capacity
(number of individuals
an ecosystem can
support)
 varies with changing
resources
 growth rate approaches
zero as the carrying
capacity is reached
r= r max = maximum per capita growth
rate
N= population size
K= carrying capacity
 Factors regulating population size
 density-independent: does not influence the birth or death rate
 natural disasters, weather, sunlight, temperature
 density-dependent: increases death rate, decreases birth rate
 competition, predation, intrinsic physiologic factors, waste
buildup, territoriality, disease
 negative feedback!
 Species Interactions
 two or more species interacting in a positive, negative, or neutral
relationship
 competitive exclusion: two species competing for the same
resource cannot coexist permanently; one species will use the
resource more effectively and outcompete the other species
 symbiosis: individuals of two or more species live in direct close
contact with one another
 cooperative behavior: organisms work together for mutual benefits
(social animals, insects)
Species
Interaction
+/-
interspecific
competition
individuals of a different species
-/- compete for a resource that limits
their growth and survival
Description
Example
Bison and grasshoppers both
compete to eat grass
Predation
+/-
one species (predator) kills and
eats the other (prey)
Herbivory
+/-
an organism eats all or part of a cows and sheep eat grass; manatee
plant/algae
eating sea grass
Parasitism
+/-
an organism (parasite) eats and tapeworms in small intestine; fleas
lives on or inside another (host)
on outside of dog
Mutualism
+/+
Commensalism +/0
lion attacking and eating an
antelope
benefits both species
nitrogen fixing bacteria and
legumes, bacteria in digestive
system
one species benefits, the other is
neither hurt/benefited
birds and grazing animals,
barnacles and whales