Download ELECTRICAL ENGINEERING

EST 4
THE LIVING WORLD
CHAPTER 9
Populations and Communities
(pp. 291 –309)
1 Studying Populations
A population is a group of individuals of the same _________________, living in a
_____________ space at a specific _______________ in time.
Examples:
 Green frogs in a marsh
 Balsam fir on a mountainside
 __________________________________________
Why do ecologists study populations?
______________________________________________________________________________
______________________________________________________________________________
Three main characteristics that describe a population:
1. ___________________________
2. ___________________________
3. ___________________________
1.1 POPULATION SIZE
Population size refers to the __________________ of individuals in a _____________________.
Why is it useful to know the size of a population?
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
Over time, the size of a population may ____________________, ____________________ or
remain _____________________.
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FOUR FACTORS AFFECTING POPULATION SIZE
Factor
Description
Births of individuals within a population
Births
Deaths of individuals within a population
Deaths
Immigration
Arrival among the population of individuals from other regions
Emigration
Departure of individuals to other regions
What two factors increase population size? Births & Immigration
What two factors decrease population size? Deaths & Emigration
 If the births and immigration rates are greater than the death and emigration rates, then the
population ______________________.
 If the births and immigration rates are less than the death and emigration rates, then the
population ______________________.
 If the births and immigration rates are equal to the death and emigration rates, then the
population ______________________.
METHODS OF MEASURING THE SIZE OF A POPULATION
1. Counting individuals
2. Counting by sample area
This method consists of counting the individuals in _____________________ selected
_________________ of the study area and estimating the total population size with the
following equation:
__________________________________________________ = ___________________________
What are quadrats? _____________________________________________________________
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For what types of populations are quadrats a useful counting technique?
______________________________________________________________________________
3. Mark and recapture
This method is commonly used to count populations of very __________________ animals, such
as, ____________________, _____________________, ___________________ and
_____________________.
It consists of the following stages:
 Installing ___________________ or nets in the populated region
 Counting the ____________________ animals and __________________ them with
________________, _________________, __________________ or ___________________
 _______________________ the marked animals
 Reinstalling __________________ or _________________
 Counting the captured individuals again, with a separate count for ___________________
individuals
 ________________________ the size of the population using the following calculation:
________________________________________________ = _________________________________
1.2 POPULATION DENSITY
Population density refers to the number of individuals per unit of ______________ or
___________________.
__________________________________ = _________________________________________
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Some factors affecting population density
 Good supply of food and water
 __________________________
 Presence of _____________________, _______________________ or __________________
 Natural or human-caused _____________________
1.3 POPULATION DISTRIBUTION
Population distribution is the way in which individuals are ____________________ within their
____________________.
There are three main patterns of population distribution
1. ____________________ distribution
Example: Many ______________ move
around in _________________.
2. _____________________ distribution
Example: Northern ________________ space
their nests at regular ____________________.
3. ______________________ distribution
Example: _________________ in a field
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1.4 ECOLOGICAL FACTORS
An ecological factor is an aspect of a habitat that can affect the ____________________
living there and thus the population ____________________.
There are two types of ecological factors:
1.
___________________ (non-living) factors: These are __________________ or
_________________ aspects of the environment.
2.
____________________ (living) factors: These are related to the ______________ of
living organisms in a habitat.
EXAMPLES OF ABIOTIC FACTORS
Abiotic Factors
Biotic Factors
Disease
Terrain
Competition
Air Humidity
A ____________________ FACTOR is an ecological factor that causes the density of a
population to decrease.
Examples:
 Exposure to _________________ ____________________ is a limiting factor in the growth
of rose bushes.
 Amount of _________________ in the ground is a limiting factor in the growth of cacti.
 The size of the _____________ _____________________ is a limiting factor for the snake
population.
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1.5 BIOLOGICAL CYCLES IN POPULATIONS
The biological cycle of a population consists of the alternating periods of ______________ and
______________ in its size. These periods are of ______________ duration and are
__________________ continually.
The most commonly studied biological cycles in Quebec are those of the lynx and the snowshoe
hare. (See figure 9.14 on p. 302)

When the hare population rises, the lynx have _____________ food, so they become
healthier and __________________ more causing their population to
______________________.

When the number of lynx increases, they hunt _____________ hares causing the hare
population to ________________________. With fewer hares to hunt, the lynx
population will eventually ____________________ as well.

Finally, as the lynx population decreases, fewer hares will be hunted, so the hare
population will _____________________ again and the whole cycle ________________.
2 Studying Communities
A community is a set of __________________________ of different ________________ sharing
the same ______________________.
The squirrels, fungi, trees and mosquitoes in the forest are thus part of the same
_________________________.
2.1 BIODIVERSITY
Biodiversity describes the variety of ___________________ living in a
______________________.
There are two components to consider when measuring the biodiversity of a community:
1. _____________________ __________________________: the number of species in the
community.
2. The relative _______________________ of each species.
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The biodiversity of a community is high when two conditions are met:
1. The number of species is ___________________.
2. The relative abundance of different species is _______________________.
What is the IUCN?
________________________________________________________________________
Of the 41415 species identifies in the 2007 IUCN survey, how many are threatened with
extinction? _________________________
How are species protected from extinction?
________________________________________________________________________
2.2 INTERACTION BETWEEN INDIVIDUALS IN A COMMUNITY
There are four main types of interaction that may occur between individuals of a community:
1. ____________________________
2. ____________________________
3. ____________________________
4. ____________________________
COMPETITION
Competition is the interaction between living organisms that seek access to the
_________________ ________________________ in their habitat.
There are two types:

_____________________________ competition: occurs between individuals of the same
species.

_____________________________ competition: occurs between individuals of different
species.
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PREDATION
Predation is the interaction between living organisms in which one _______________ on the
other.
The individual that feeds on another living organism is called the ___________________.
The individual being eaten is called the _________________.
Parasitism is a form of ______________________. The parasite feeds of the ____________ and
in turn, the ________________ is ____________________ in some way. (Examples include:
_______________________, _______________________, & ________________________)
MUTUALISM
Mutualism is the interaction between two living organisms that ___________________ both
organisms. (Example: ______________________ and __________________________)
COMMENSALISM
Commensalism is the interaction between two living organisms in which one organism
____________________ while the other remains _________________________.
Example: A warblers nest in a ______________ tree.
THE EFFECTS OF INTERACTION BETWEEN POPULATIONS ON THEIR DENSITIES
Type of Interaction
Competition
Effect on population A
Effect on population B
Predation and Parasitism
Mutualism
Commensalism
END OF CHAPTER 9
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