Download LIMITING FACTORS QQ

LIMITING FACTORS QQ
How are population sizes limited?
QQ#1:
REVIEW: EXPLAIN THE DIFFERENCE
BETWEEN THESE TWO GRAPHS IN
RELATION TO POPULATION GROWTH
HOW CAN POPULATION GROWTH BE SLOWED?
 a
populations carry capacity limits the population’s
size based on the amount of resources present.
 Population
sizes can also be limited by two types of
factors called limiting factors
TWO TYPES OF LIMITING FACTORS
 Density
 limiting factors that do not depend upon a population’s size.
 Density
 Independent Limiting Factors
Dependent Limiting Factors
limiting factors that depend upon the population size.
 The
“density” of a population is determined by how many
individuals are living in a set amount of space
 QQ#2:
what do you think the difference
between these two factors are?
DENSITY INDEPENDENT FACTORS
Density Independent Factors are limiting factors that do
not depend upon a population’s density.
Examples include:
   Natural Disasters (i.e. earthquakes)
Seasonal Variation (i.e. drought)
Human activities such as deforestation
DENSITY DEPENDENT FACTORS
Unlike density independent factors, these will play
are larger or smaller part in limiting growth
depending on how dense the population is.
Examples include:
    Competition
Predation
Parasitism
Disease
COMPETITION
 When
populations become crowded (more dense)
organisms compete
 They
compete for food, water, space, sunlight, and
other essentials.
 Completion
among members of the same species is
a density-dependent limiting factor.
 QQ#3:
what kinds of things
do you think individuals of the
same species compete for?
PREDATION
 Populations
 The
in nature are often controlled by predation
regulation of a population by predation takes place
within a predator-prey relationship, one of the best-known
mechanisms of population control
 QQ#4:
explain what trends you notice
between the predator and prey
relationship below in regards to
population sizes
PARASITISM AND
DISEASE
 A
 QQ#5:
Why do you think Disease is
considered a density dependent
limiting factor?
parasite lives in or on another organism (the host)
and consequently harms it
 Parasites/Diseases can limit the growth of a
population by killing their hosts
 Parasites/disease are more easily spread in highly
dense populations
CHECK FOR UNDERSTANDING
(YOU DO NOT NEED TO WRITE THESE)
 A limiting factor that affects all populations in similar
ways regardless of their size might be
drought.
 disease.
 predation.
 crowding.
 CHECK FOR UNDERSTANDING
 Within a limited area, if the population of a predator
increases, the population of its prey is likely to
increase.
 decrease.
 remain about the same.
 become extinct.
 CHECK FOR UNDERSTANDING
 Which of the following is a density-independent factor
affecting populations?
predation
 disease
 a destructive hurricane
 parasites
