Download 06 Understanding Populations COMPLETE

NOTES
Understanding
Populations
Ch. 8
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Groups of organisms can move into or out of different areas.
For Example:
200 years ago:
No Quagga Mussels in Lake Michigan
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Blue Whales numbered 275,000 in the world’s oceans
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Now:
Nearly a billion Quagga Mussels disrupt the ecology of Lake Michigan
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Blue Whales now number less than 2,000 in the world’s oceans
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Quagga Mussels- _________________________________________________________________________
invasive fresh water organism from the Ukraine; alters food webs by removing
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plankton used for food by other organisms; clogs water-intake pipes and damages other
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mechanical devices
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Zebra Mussels- ____________________________________________________________________________
invasive fresh water organism similar to Quagga Mussels; alters food webs by
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removing plankton used for food by other organisms; clogs water-intake pipes and damages other
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mechanical devices, including boat motors
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Quagga Mussel
Zebra Mussel
FOUND IN MOST LAKES IN TEXAS ( causing quarantine procedures )
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BLUE WHALE- ____________________________________________________________________________
marine mammal; measure over 30 meters ( over 98 feet ) in length and 180 metric
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tons ( 198 US tons = 396,000 pounds ) or more in weight; largest animal and the heaviest animal
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known to have existed
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POPULATION
__________________________________
- set of individuals in a species living in the same place at the
All the bass
same time. ____________________________________
in Iowa make up one population.
REPRODUCTIVE GROUP
The adults within a population form a ____________________________________________
because
breed with members of their own population
organisms ____________________________________________________________________________.
bass in one lake will breed with each other but will not breed with bass from other
For Example: _____________________________________________________________________________
lakes
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POPULATION SIZE
_________________________________________
- total number of individuals
POPULATION DENSITY
_________________________________________
- total number of individuals per unit of volume
the number of bass per cubic meter of water, or the number of people per square
For Example: _____________________________________________________________________________
mile
_________________________________________________________________________________________
POPULATION DISPERSION
_________________________________________
- describes the arrangement of its individuals in a
even, clumped, or random
given space, which may be _________________________________________________________________
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offspring or birth
Populations gain individuals with each new _____________________________________________
and
death
loses individuals with each ___________________.
GROWTH RATE
____________________________________percentage change in the size of a population over a given
amount of time
Positive Growth = more births than deaths, so the population increases
_________________________________________________________________________________________
Negative Growth = more deaths than births, so the population decreases
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Zero Growth = births equal deaths, so the population stays the same
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BIOTIC POTENTIAL
______________________________________
- fastest rate at which a population can grow, and is
REPRODUCTIVE POTENTIAL
limited by a population’s __________________________________________the maximum number of
offspring each member of the population can produce.
Some species have a higher reproductive potential than others.
For Example:
1. A bacterium can produce 19 million descendants in a few days or weeks
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2. A pair of bowhead whales would take hundreds of years to have that many descendants
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higher
more offspring
Reproductive potential is ______________________
when individuals produce ______________________
reproduce
at one time
reproduce more often
____________________________,
_____________________________________,
or ___________________
earlier in life
_____________________________.
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GENERATION TIME
__________________________________________average time it takes a member of a population to
reach the age when it can reproduce.
1. Some bacteria can reproduce when they are only 20 minutes old
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2. Larger organisms, such as elephants and humans, become sexually mature and are able to
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safely reproduce only after a number of years ( humans = average is about 20 years )
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Humans have a lower reproductive potential than bacteria
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EXPONENTIAL GROWTH
_______________________________________when a population grows faster and faster
For Example:
If a pair of dogs gives birth to 6 puppies, there will be
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6 dogs in one generation. If each dog in that generation
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mates and has a litter of 6 puppies, there will be 36 dogs
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in the next generation.
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Exponential growth occurs in nature only when a
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population has plenty of food and space, and little or
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no competition / predators.
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Natural conditions are not usually constant or ideal, which means most populations in a given area
cannot grow forever and rarely grow at their reproductive potential.
________________________________________________________________________________________
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1. Resources are used up
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2. Environment changes occur
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3. Deaths increase or births decrease
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DENSITY DEPENDENCE
____________________________________when high population density causes lower birth rates or
higher death rates
CARRYING CAPACITY
____________________________________population size where birth rates and death rates are equal
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COMPETITION
______________________________________when members within a population or when more than
population depend on the same resources for survival
LIMITING RESOURCE
_____________________________________when a natural resource supply affects the growth of a
species that depends on the resource
For Example:
Plant growth is limited by supplies of water, sunlight, and mineral nutrients
________________________________________________________________________________________
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The supply of the most severely limited resources determines the carrying capacity of an
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environment for a particular species at a particular time.
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TERRITORY
________________________________area defended by one or more individuals against other
individuals
The territory is of value for:
1. Available space
______________________________________
2. Available shelter
______________________________________
3. Available food
______________________________________
4. Available breeding sites
______________________________________
______________________________________
______________________________________
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density dependent
Rates of births or deaths may be _________________________________________________
or
density independent
_________________________________________________.
more quickly in a crowded population than in a sparse
Density dependent deaths occur ___________________________________________________________
population; usually because of limited resources, predators, or disease
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regardless of the population density; affects all members of
Density independent deaths occur _________________________________________________________
the population in a general or uniform way; can be caused by sever weather or natural
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disasters
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Organisms in the wild interact with many different species.
Example:
On the African Savanna1. Lions hunt zebras
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2. Lions fight with Hyenas
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3. Fleas and ticks feed on the lions and the hyenas
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In the Ocean1. Cleaner fish remove parasites from fish living on coral reefs
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Interactions between different species can be positive, negative, or both
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NICHE
_____________________the range of conditions in which a species can survive AND the resources they
use and the species they feed on
Example:
1. Zebras are large herbivores on African grasslands
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2. Kangaroos occupy a similar niche in Australia
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3. Herbivores interact with carnivores in the same habitat
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TYPES SPECIES INTERACTION
COMPETITION
1. ___________________________relationship when different individuals or populations attempt to
use the same limited resource; each individual has less access to the resource and is harmed by the
competition
Example:
1. Seed-eating birds compete with each other for seeds under a bush
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2. The bush competes with the tree next to it for nutrients in the soil
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COMPETITIVE EXCLUSION
_________________________________when two species have requirements that are too similar, one
species may eliminate the other from the habitat
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If two species have identical resource needs in the same ecosystem, the more successful species might
drive out the less successful species.
NICHE RESTRICTION
________________________________when the two species use less of the niche than they are capable
dividing up the niche
of using; the two species are basically _________________________________________________
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PREDATION
2. _________________________________when one organisms hunts and eats another organism
PREDATOR
______________________________an organism that feeds on another organisms
PREY
____________________the organism that is hunted and eaten by another organism
Examples:
1. Sharks eating fish
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2. Bats eating insects
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3. Wolves eating deer
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In the predator-prey relationship, the sizes of each population
tend to increase and decrease in linked patterns.
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PARASITISM
3. _________________________________when one organism lives on or in another organism and
feeds on it
PARASITE
________________________the organism that lives on or in another organism
HOST
________________________the organism that has another organism living on or in it
ticks, fleas, tapeworms, bloodsucking leeches, mistletoe
Examples of parasites: ____________________________________________________________________
____________________________________________________________________
harmed by the parasite, but not killed
The host is usually _______________________________________________________________________
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MUTUALISM
4. _______________________________a close relationship between two species in which each
species provides a benefit to the other
Certain bacteria in your intestines help break down food that you would otherwise
Example: _______________________________________________________________________________
be unable to digest or produce vitamins that your body cannot make
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In return, your body provides the bacteria with a warm, food-rich habitat for the
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bacteria to survive
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COMMENSALISM
5. ___________________________________a relationship in which one species benefits and the other
species is neither harmed nor helped
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SYMBIOSIS
_____________________________a relationship in which two species live in close association
parasitic,
Many types of species interactions are symbiotic, including those that are __________________________
commensal, or mutual
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COEVOLUTION
_____________________________when species in close relationship evolve adaptations as a direct
result of the relationship itself
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