Chapter 13 Population Ecology Hour 1 Edited

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Powerpoint@lecture Slides Are Prepared By Biology Lecturer, KMPk

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13.1 Population

Growth

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Ecosystem management through conservationand preservation

Nature reserves national parks Planned land

Legal protection of endangered species Commercial farming

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At the end of this topic, students should be

able to;

Explain biotic potential (r) and environmentalresistance and their effect on population growth

Explain carrying capacity and its importance

Describe natality and mortality and their effects

on the rate of population growth

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The increase in the number of

individuals in a population

A population will increase in number

when the available resources are

greater than required at that particular

time.

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a) Natality (birth rate)

- The rate at which a particular species or

population produces offspring

:

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b) Mortality (death rate)

- The rate at which a

particular species

or population dies,

whatever the cause.

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Biotic Potential (r)

Maximum number ofoffspring an organism can

produce under idealconditions.

" power of organisms to

reproduce and survive"Chapman (1925)

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Ideal condition :

- plenty of space for each

member

- unlimited resources

- no resistance

Important in population

growth- to sustain unlimited growth

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Reality- exponential

growth cannot continue

for long because of

environmental

resistance

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Environmental Resistance

All those environmental conditions

that prevent populations from

achieving their biotic potential.

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Interplay between biotic

potential and

environmental resistance- determines the size of

a population of a

species

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When populations become

too large,

- Run out of some limiting

resource

As a result,

- Growth slows to zero

- Population size tends to

stabilize

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Limited supply offood

Accumulation ofwaste products

Increasedcompetitionbetweenmembers

Predation

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Temperature

pH

Light

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The effect of environmental resistance

on the population growth

A growth curve with an S-shape

The effect of environmental resistance

on the population growth

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Carrying Capacity(K)

Maximum number of individuals of apopulation that can be supported by a

particular habitat

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The closer population size gets to the Carrying

Capacity, the greater will be the environment

resistance.

(bioticpotential)

Carrying Capacity

Num

berofIndi

viduals

Time

ExponentialGrowth

Equilibrium

(environmental resistance)

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Determined by both biotic

potential and environmental

resistance

Changes in response to

environmental changes

Eg; During drought

The amount of vegetation will

decrease

Lower the carrying capacity

for deer

Determined by both biotic

potential and environmental

resistance

Changes in response to

environmental changes

Eg: During drought

The amount of vegetation

will decrease

Lower the carrying capacity

for deer

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Important limit on

populations

To prevent population

crash

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Discuss these terms :

Biotic potential (r)

Natality and mortality

Environmental

resistance

Carrying capacity

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Question 1

What is the meaning of carrying capacity(K) of the population?

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Population Growth Curves

Limiting Factors Affecting

the Population Size