Population Dynamics Chapter 35. Population Dynamics Key concepts include: interactions within and among populations including carrying capacities, limiting.

Population Dynamics

Chapter 35

Population Dynamics

Key concepts include:

• interactions within and among populations including carrying capacities, limiting factors, and growth curves;

Population: all the individuals of a species that live together in an area

Three Key Features of Populations

Size Density Dispersion

(clumped, even/uniform, random)

Three Key Features of Populations 1. Size: number of individuals in

an area

Estimating PopulationMark – Recapture – used to estimate animal population

Mark Recapture Capture an initial sample,

count and mark them Release the marked individuals Capture and count another

sample count marked individuals

recaptured

Formula

(1st sample x 2nd sample)

Number recaptured

Example: Mark - Recapture

100 ants are captured, marked and released. 90 ants are captured in the 2nd sample. 8 of the ants in the 2nd sample were marked.

100 x 90 = 9000= 1125 ants 8 8

Sample Plot

– used to estimate plant populations

Sample PlotRandomlyRandomly chosen chosen plots are selected and plots are selected and populations counted populations counted and averaged.and averaged.

The The averageaverage is used is used to to estimate the estimate the total total populationpopulation

Example

6

4

8

2

3

8+4+6+3+2= 23

23 = 4.6 5

4.6 x 100 = 460

Three Key Features of Populations 2. Density: measurement of

population per unit area or unit volume

Formula: Dp= N S

Pop. Density = # of individuals ÷ unit of space

Three Key Features of Populations 3. Dispersion: describes their

spacing relative to each other clumped even or uniform random

clumped

even (uniform)

random

Population Dispersion

Exponential Growth ideal, unregulated population growth Produces a J shaped curve

http://usrarecurrency.com/WebPgFl/C00015446A/1934$1000FRNSnC00015446A.jpg

After 4 days, $ 0.16 vs. $ 20,000

After 8 days, $ 2.55 vs. $ 40,000

9 2.56 5,000 10 5.12 5,000 11 10.24 5,000 12 20.48 5,000 TotalTotal $40.95$40.95 $60,000$60,000 13 40.96 5,000 14 81.92 5,000 15 163.84 5,000 16 327.68 5,000 TotalTotal $655.35$655.35 $80,000$80,000

17 655.36 5,000 18 1310.72 5,000 19 2621.44 5,000 20 5242.88 5,000 TotalTotal $10,485.75$10,485.75

$100,000$100,000

21 10,485.76 5,000 22 20,971.52 5,000 23 41,943.04 5,000 24 83,886.08 5,000 Total Total $167,772.15$167,772.15

$120,000$120,000

25 167,772.16 5,000 26 335,544.32 5,000 27 671,088.64 5,000 28 1,342,177.28 5,000 29 2,684,354.56 5,000 30 5,368,709.12 5,000 TotalTotal $10,737,418.23$10,737,418.23

$150,000$150,000

Factors that affect populations

Limiting factor- any biotic or abiotic factor that restricts the existence of organisms in a specific environment.EX.- Amount of water

Amount of foodTemperature

Factors that limit populations

Density-dependent factors- Biotic factors in the environment that have an increasing effect as population size increases

Ex. disease

competition (food supply) parasites

predators

Density-independent factors- Abiotic factors in the environment that affect populations regardless of their density

Ex. temperature

fire habitat destruction

drought

Factors that affect density

Carrying Capacity-

the maximum population size that can be supported by the available resources

There can only be as many organisms as the environmental

resources can support

Logistic Growth

Ideal growth that is slowed by limiting factors as the population increases

Produces an S shaped curve

Carrying Capacity

Carrying Capacity (k)

Nu

m

b

e

r

Time

J-shaped curve (exponential growth)

S-shaped curve (logistic growth)

Boom and Bust Cycles

Some populations fluctuate with regularity

Life History

The series of events from birth, through reproduction to death

2 Life History Patterns

1. R Strategists short life span small body size reproduce quickly have many offspring little parental care Ex: cockroaches,

weeds, bacteria

R strategist

These organisms produce as many offspring as possible.

Invest little in each offspring. In good conditions, populations

explode Good strategy for unpredictable

environments

2 Life History Patterns

2. K Strategists long life span large body size reproduce slowly have few young provides parental

care Ex: humans,

elephants

K strategists

These organisms produce few offspring and invest resources, time and their own safety to ensure survival of offspring

Good strategy for stability K= carrying capacity

Demography

the statistical study of populations, make predictions about how a population will change

1. Immigration- movement of individuals into a population

2. Emigration- movement of individuals out of a population

Movement of Populations

Immigration

Emigration

Natality MortalityPopulation+

+

-

-

Factors That Affect Future Population Growth

Key Features of Populations Growth Rate: Birth Rate

(natality) - Death Rate (mortality)

How many individuals are born vs. how many die

Birth rate (b) − death rate (d) = rate of natural increase (r).

PRE-REPRODUCTIVE

REPRODUCTIVE

POST-REPRODUCTIVE

Population of a Stable Country

Demographic Transition The movement from high birth and

high death rate to low death rate then lower birth rate

Human Population Growth

Human Population Growth

Time unit Births DeathsNatural

increase

Year 130,013,274 56,130,242

73,883,032

Month 10,834,440 4,677,520 6,156,919

Day 356,201 153,781

202,419

Hour 14,842 6,408 8,434

Minute 247

107 141

Second 4.1

1.8 2.3

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Chapter 36 Ecosystem Structure and Dynamics

Biodiversity

The number of different species in a community

Competition

Interspecific competition – two species compete for the same resource

Niche

is how an organism makes its living, or how it uses resourcesWhat it eats Its habitat

Competitive Exclusion

When two species occupy the same niche, one is displaced

Resource partitioning

In order for two species to inhabit the same area, they divide resources

Symbiotic Relationships

Symbiosis- two species living together

3 Types of

1. Commensalism

2. Parasitism

3. Mutualism


Commensalism- one species benefits and the other is neither harmed nor helped

Ex. orchids on a tree


Commensalism- one species benefits and the other is neither harmed nor helped

Ex. polar bears and cyanobacteria


Parasitism- one species benefits (parasite)

and the other is harmed (host)

Parasite-Host relationship


Parasitism- parasite-hostEx. lampreys, leeches, fleas,ticks,tapeworm


Mutualism- beneficial to both species

Ex. cleaning birds and cleaner shrimp


Mutualism- beneficial to both species

Ex. lichen

Type of relationship

Species harmed

Species benefits

Species neutral

Commensalism

Parasitism

Mutualism

= 1 species

Trophic Levels

Each link in a food chain is known as a trophic level.

Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem.

Herbivores – eat only producers

Cows, Deer, Horses, Grasshoppers

Carnivores – eat only the flesh of other animalsWolves, Tigers, Bass, Orca

Detritovores – eat only dead organisms or wastes

Vultures, Carrion Beetles

Omnivores – eat both animals and plants

Bears, Pigs, Humans

Trophic Levels

Biomass- the amount of organic matter comprising a group of organisms in a habitat.

As you move up a food chain, both available energy and biomass decrease.

Energy is transferred upwards but is diminished with each transfer.

Energy Lost

90% is lost as heat

10% is passed on to the next level

Trophic Levels

Producers- Autotrophs

Primary consumers- Herbivores

Secondary consumers-small

carnivores

Tertiary consumers-

top carnivores

E

N

E

R

G

Y

EE

EE

EE

Trophic LevelsFood chain- simple model that

shows how matter and energy move through an ecosystem

Trophic Levels

Food web- shows all possible feeding relationships in a community at each trophic level

Represents a network of interconnected food chains

Food chain Food web(just 1 path of energy) (all possible energy

paths)

Nutrient Cycles

Cycling maintains homeostasis (balance) in the environment.

3 cycles to investigate:1. Water cycle2. Carbon cycle3. Nitrogen cycle

Water cycle-

Evaporation – liquid to gas Transpiration- evaporation through

leaves of plants Condensation- gas to liquid Precipitation- snow, rain, etc.

Water cycle-

Carbon cycle-

Photosynthesis and respiration cycle carbon and oxygen through the environment.

Carbon cycle-

Photosynthesis

Energy + CO2 + H2O C6H12O6 + O2

Cellular Respiration

C6H12O6 + O2 Energy + CO2 + H2O

Nitrogen cycle- Atmospheric nitrogen (N2) makes up

nearly 78%-80% of air. Organisms can not use it in that form. Lightning and bacteria convert nitrogen

into usable forms.

Nitrogen cycle-

Only in certain bacteria and industrial technologies can fix nitrogen.

Nitrogen fixation -convert atmospheric nitrogen (N2) into ammonium (NH4

+) which can be used to make organic compounds like amino acids.

N2 NH4+

Nitrogen cycle-

Nitrogen-fixing bacteria:

Some live in a symbiotic relationship with plants of the legume family (e.g., soybeans, clover, peanuts).

Some nitrogen-fixing bacteria live free in the soil.

Nitrogen-fixing cyanobacteria are essential to maintaining the fertility of semi-aquatic environments like rice paddies.

Atmospheric nitrogenLightning

Nitrogen fixing

bacteria

Ammonium Nitrification by bacteria

Nitrites Nitrates

Denitrification by bacteria

Plants

Animals

Decomposers

Nitrogen Cycle

Toxins in food chains- While energy decreases as it moves up

the food chain, toxins increase in potency.

This is called biological magnification

Succession- a series of changes in a

community in which new populations of organisms gradually replace existing ones

Primary succession-

colonization of new sites by communities of organisms – takes place on bare rock

Primary succession- New bare rock comes from 2

sources: 1. volcanic lava flow cools and

forms rock

Primary succession- New bare rock comes from 2

sources: 2. Glaciers retreat and expose

rock

Pioneer species- the first organisms to colonize a

new site Ex: lichens are the first to colonize

lava rocks

Primary Succession-

Rock

Climax community- a stable, mature community that

undergoes little or no succession

Primary succession-

Secondary succession- sequence of community changes

that takes place when a community is disrupted by natural disaster or human actions – takes place on existing soil

Secondary succession- Ex:

fire

Secondary succession- Ex:

farming

Secondary succession-

Secondary succession-

Population Dynamics Chapter 35. Population Dynamics Key concepts include: interactions within and among populations including carrying capacities, limiting.

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