Download Appendix 3 - EDU5TEA

Chapter 15
Learning Objectives
Characterising
Species
distribution
• Abundance and Population
• Age Structure
• Rate of Growth
• Distribution
• Birth and Death Rate
Factors that determine the size of a
population
Carrying
capacity
population
rate of growth
Mortality
Biotic/abiotic
factors
predation &
competition
Population: Abundance and
Sampling
Abundance: The number of individuals of a species
per unit area (Density)
Sampling Techniques:
1. Mark-recapture technique
1.
Total number= (# marked x total caught)/ # marked ones caught
2. Sampling through quadrats.
3. Transects (changes in environment)
DynamicScience – Population sampling information
Distribution: Uniform, Random, Clumped
Sampling allows us to map distribution and density
of organisms
Population distribution
 Abundance assists us with
determining distribution.
 What factors affect
Distribution?
 Food source
 Predation/ hunting/ habitat
destruction
 Climate, temp, environment
 Reproductive factors
 What factors Abiotic/Biotic might be
affecting the distribution of the elephant
population  (Questions from internet)
Population: Age Structure
Age
Structure
Prereproductive
age
Reproductive
age
Postreproductive
age
Population Growth Curves
 Usually there are 3
phases:
1. Slow growth as
numbers are built up
2. Rapid growth
3. Population growth
decreases, population
is approximately
stable.
Stable, no
growth
Rapid
growth
Slow
growth
Population Growth Patterns
 J Shaped Curves: Exponential growth
 Lag phase
 Acceleration phase
 Population (next generation)= Rate of increase x Population (previous
gen.)
Population Growth Patterns
 S Shaped Curves: Logistic Growth
 Deceleration phase: growth slows due to environmental resistance,
competition, organism death
 Growth rate is stopped by the Carrying Capacity of the environment
 Carrying Capacity: maximum population that can be sustained by the
environment
- Affected by Biotic and abiotic factors
Birth rate Vs. Death Rate
Population explosions
• Reproduction (many new offspring) & lower death rate
• Abiotic environment (lots of food)
• Predator control (lack of predators)
• Dispersal (spreading into new areas)
Factors affecting growth rates
 Density- dependent factors (Intraspecific): (food/ resources) Increased
influence in higher populations
 Density- Independent factors: floods, drought.
 Interspecific Factors: (Competition with other species)
 Predation & Habitat Destruction
 Growth Rate (intrinsic)- K-selected/ R-selected strategy (pg 493)
Feature
R-selected
Strategy
K-selected
strategy
Life span
Shorter-lived
Longer-lived
No. offspring
Many
few
Energy req. for
reproduction
Small energy
Large energy
Survival Rate
Low
High
Sexual maturity
Earlier in life
Later in life
Incubation period
Short/ none
Extensive (mths)
Parental care
Little/none
Extensive
Population Interactions
 Competition: Food, resources (nests, sunlight)
 Predator + Prey relationships
• Which population
peaks first?
• In the absence of
adequate predators
what happens?
• Without predators,
how is prey population
regulated?
• How many ‘boom-bust’
cycles can we see?
• What other factors not
visible on this graph
could be influencing
populations
Application Questions
 Complete questions online at
http://rasozbiologyresources.weebly.com
Chapter 15 & 16
Population Evaluations
 Population growth = (births + immigration) – (deaths +
emigration)
 Percentage population growth rate in a given period = (pop.
change during the period/ pop. At start of the period) x 100
Example
100 dolphins in 2012. 3 years later they found 143 dolpins. What is the population
growth per year?
Pop. Change= 143-100 = 43.
% Growth Rate = (43/100) x 100 (remember this is over 3 yr period)
Per year = 43/3 (gives us the % per year) = 14.3% growth per year
Population Elements
Birth Rate
Death Rate
• Birth rate = (number of
births per year/ tot. pop in
the same year) x 1000
• Death rate= (no. of deaths
per year/ total. Pop. In the
same year) x 1000
Factors affecting Birth rate in Humans
Factors affecting Death Rate In humans
Political policies & economic conditions
War and natural disasters
Cultural & Religious background
Food supply
Birth control
Safe Drinking water & sanitation
Education level
Life expectancy and Age profile (more
oldies = higher death rate)
Social elements and pressures
Disease and access to medical care
Population Analysis
Relate the changes to
population:
- Death rate
- Birth rate
- Overall growth
Changes in Ecosystems
Is the change environmental
 Regular (tides, seasons)
 Sporadically / Irregular (floods in tropical areas)
 One-off events (100 year flood or fire, volcanic eruption)
 Disease or a flow on from population change in another interacting
organism.
 Is the change the result of humans
 Oil spill
 De-forestation
 Habitat Destruction
 Global Warming
 Introduction of new species (deliberate, accidental or ‘classical biocontrol’)


Examples and effects.
Management: Biocontrol (biopesticides- bacteria, fungi), Immunocontraception.
Human Impact on Ecosystems