Download Biology Chapter 14: Interactions in Ecosystems

Section One: Habitat and Niche
 Habitat: all the abiotic and biotic factors in the area
where an organism lives
 Ecological Niche: all the physical, chemical, and
biological factors that a species needs to survive, stay
healthy, and reproduce.
 Includes food, abiotic conditions, and behavior
 Also known as the role a species plays in the community
(job)
Section One: Habitat and Niche
Section One: Habitat and Niche
 Competitive Exclusion: when two species compete for
the same resources, one species will be better suited to
the niche
 Happens when different species share the same habitat
Section One: Habitat and Niche
 Niche Partitioning
 Dividing the niche based on the needs of each organism
 Ecological Equivalents: species that occupy similar
niches but live in different geographical regions.
Section Two: Community
Interactions
 Competition: occurs when two organisms fight for the
same limited resources
 Predation: one organism captures and feeds upon
another organism
Section Two: Community
Interactions
 Symbiosis: a close
ecological relationship
between two or more
organisms of different
species that live in direct
contact with one another
 Mutualism
 Commensalism
 Parasitism
Section Two: Community
Interactions
 Mutualism: interspecies
interaction in which
both organisms benefit
from each other
 Both organism benefit
 Ex: Bees and Flowers
Section Two: Community
Interactions
 Commensalism: a
relationship between
two organisms in which
one receives an
ecological benefit and
the other is not
benefitted or harmed
 Ex: Shark and Remora
Section Two: Community
Interactions
 Parasitism: one organism
benefits and the other is
harmed
 Different from
predation because the
host is not killed
 Ex: Humans and
Mosquitoes
Section Three: Population Density
and Distribution
 Population Density: a
measurement of the
number of individuals
living in a defined space
Section Three: Population Density
and Distribution
 Population Dispersion:
the way in which
individuals of a
population are spread in
an area or a volume
 Clumped
 Uniform
 Random
Section Three: Population Density
and Distribution
 Survivorship Curve: a generalized diagram showing
the number of surviving members over time from a
measured set of births
Section Three: Population Density
and Distribution
 Types of Survivorship
Curves
 Type I: low level of infant
deaths and a population
that will generally survive
till old age
 Type II: survivorship is
roughly equal at all stages
 Type III: high birth rate
and high infant mortality
rate
Section Four: Population Growth
Patterns
 What effects population size?
 Immigration: movement of individuals into a population
 Births
 Emigration: movement of individuals out of a
population
 Deaths
Section Four: Population Growth
Patterns
 Population Growth
 Based on available resources
 Exponential growth: when population size increases
dramatically over time
 Logistic growth: populations begin to grow slowly, then
go through exponential growth, then slow down and
level off



Creates an s-shaped curve
Occurs because of carrying capacity
Carrying capacity: the max number of individuals of a
particular species that the environment can support
Section Four: Population Growth
Patterns
Section Four: Population Growth
Patterns
 Population crash: a dramatic decline in the size of the
population over a short period of time
 Occurs when the carrying capacity suddenly drops
Section Four: Population Growth
Patterns
 Limiting Factors: a factor the limits population size
 Density Dependent: factors affected by the number of
individuals in a given area

Ex: competition, predation, parasitism, disease
 Density Independent: factors of the environment that
limit population growth no matter how large or small it
is

Ex: unusual weather, natural disasters, human activities
Section Five: Ecological Succession
 Succession: the sequence of biotic changes that
regenerate a damaged community or create a
community in a previously uninhabited area
 Occurs after a disturbance in the ecosystem
 Two Types:


Primary Succession
Secondary Succession
Section Five: Ecological Succession
 Primary Succession: the development of a new
ecosystem where there was none before
 Ex: Volcanic eruptions caused the formation of the
Hawaiian Islands
 Pioneer Species: the first organisms to live in a
previously uninhabited area
 Secondary Succession: the reestablishment of a
damaged ecosystem where the soil was left intact
 Ex: Forests growing back after wild fires
Section Five: Ecological Succession
Section Five: Ecological Succession