Lucshman Raveendran

Dhruv Jasani

14.2 MEASURING AND MODELLING POPULATION CHANGES

Factors that Affect

Population

Natality

Mortality

Immigration

Emigration

Population

Population Dynamics

Open vs. Closed Population

Natality Mortality

Closed Populatio

n

Open Populatio

n

Natality

Immigration Emigration

Mortality

Fecundity• The potential for a species to produce offspring in one

lifetime.• Species that live older can have more reproductive cycles but

usually produce less offspring.

Age

Nu

mb

er

of

Su

rviv

ors

Age

Nu

mb

er

of

Su

rviv

ors

AgeN

um

ber

of

Su

rviv

ors

High Mortality At Older Age

Uniform Mortality

High Morality At Young Age

High Fecundity

Low Fecundity

Formula:Changes in Population Size

Omg math!

Population Growth Models

Geometric

Exponential

Logarithmic

Geometric GrowthA pattern of population growth where

organisms reproduce at fixed intervals at a constant rate.

)λ λ-Geometric Growth Rate)-Reference Population-Population one cycle ahead of reference

populationBasically same thing asSO EZ!

Omg more math!

Exponential GrowthA pattern of population growth where organisms reproduce

continuously at a constant rate

-instantaneous growth rate at a specific time or population

r-biotic potential; maximum rate a population can increase under ideal conditions

Time

Pop

ula

tion

N=2500r=o.03 per hour750/hour

N=500r=o.03 per hour

math y u do dis

Logarithmic Growth A model of population growth that levels off as the size of

the population approaches its carrying capacity Carrying Capacity-The maximum number of organisms

that can be sustained by available resources over a given period of time

- population growth rate at a given time- maximum growth rateN-population size at a given timeK- carrying capacity of the environment

Produces Sigmoid Curve ‘S’ Shaped

Slow Growth

i cry evertim math

Lag Phase

Log Phase

Stationary Phase

The initial stage in which population growth rates are slow as a result of a small population size

The stage in which population growth rates are very rapid

The phase in which population growth rates decrease as the population size reaches the carrying capacity; the defining characteristic of logistic population growth

Dynamic EquilibriumBirth rate=Death rate No net change in population size