APES 5.3 and 6 TEST

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Population dynamics:

Study of how Density, dispersion and Age structure change in response to changes in environmental conditions.

Density:

Number of individuals in a certain area

Dispersion:

how a populations is dispersed in a specific area.

there is Clumping, Uniform and random disperisons.

Clumping is most common.

species cluster where there are resources

More likely to discover resources

protection from predators

hunting in packs can be easier

groups for mating/ caring for young

Age structure:

Proportions of individuals in different age groups

Pre-reproductive (0-14)

Reproductive (15-44)

post-reproductive (45+)

Exponential growth rate:

Occurs when resources are not limiting.

Population increases by a % as a whole in a given time

J shaped curved graph

Most populations under ideal conditions grow at exponential rates

Biotic potential:

Capacity for growth under ideal conditions

Intrinsic rate of growth (r):

rate at which a species would grow if it had unlimited resources and other ideal conditions

High intrinsic growth rate:

Reproduce early in life

many off spring

reproduce many times

short generation times

Logistic growth curve:

Occurs when resources become more and more limiting as population size increases.

S shaped graph- initially grows exponentially but plateaus at carrying capacity

it's not a fixed quantity and can changed with an increase or decrease in it's limiting factor

Carrying capacity:

the maximum number of organisms that a region can support without over using resources

The growth rate decreases as it reaches carrying capacity because the resources become limited

Environmental resistance:

Combination of all factors that act to limit the growth of a population.

it determines the carrying capacity both biotic and Abiotic

Three revolutions that increased Earths carrying capacity for humans:

Agricultural

Industrial

green

Exceeding the carrying capacity

Reproductive time lags:

the period needed for the birth rate to fall and the death rate to rise in response to resource over-consumption: they overshoot or exceed carrying capacity

Negative feedback loops:

result in oscillations or overshooting/ variable carrying capacity

Positive feedback loops:

cause a population to exponentially increase or decrease- not oscillate

Density Dependent:

A factor which limits the population that has a greater effect when populations density increases.

often due to negative feed back loops

tend to regulate the population at stable levels

ex: competition & infectious disease

Density independent:

limiting factor for a population that is not affected by populaiton density.

it does not matter if there is more organisms in the area it will still do the same amount of damage

Ex: Flood/ hurricane/ pollution

Common patterns of growth

Stable:

population that stays close to the carrying capacity

regulated by density dependent limiting factors

Irruptive:

Explosive growth followed by a crash either to a more stable or very low level

short lived/ rapidly reproducing species

Irregular:

No pattern- chaos in system

Cyclic (boom bust):

population fluctuates up and down

Top down control: predator interactions

Bottom up control: resource availability

R-strategist species:

environments where resources are not limiting

high intrinsic growth rates

low parental care

Opportunists- reproduce/ disperse rapidly

unstable/ cyclic cycles

may crash when more competitive species invade

early successional species

K-strategist species:

Environments where resources are limiting

lower intrinsic growth rates

live near their carrying capacity

strong big organisms that can compete for resources

low logistic growth curve

prone to extinction

late successional species

disadvantage- cannot rebound as quickly

Ecological succession:

Gradual change in species composition

replacement of species in a specific area

Primary succession:

establishment of biotic communities in lifeless areas and no soil

Secondary succession:

species grow in places that was wiped out but soil/ bottom sediment remained.

Population change

Population change =

(birth + immigration) – (deaths + emigration)

Crude birth and

death rates are given per 1000 people

Basic demographics

World population is 7.25 billion

US population is greater than 310 million

China and India make up 38% of the world's population

China is 1/5 of the worlds population

2050 the UN predicts that there will either be between 7.8 and 10.8 billion people- the average would be 9.3

top 5 most populated nations: china, India, US, Indonesia and Pakistan

Replacement fertility rate:

Number of children a couple must have to replace themselves.

Higher in developing countries (2.5) than developed countries (2.1) because of higher infant mortality rates.

Total fertility rate:

Average number of kids a woman has

it has decreased over the past few decades, but the amount of children under the age of 15 causes the population to continue increasing (population momentum)

worlds average (2.9) Developed (1.9) Developing (3.3)

Factors that decrease Fertility rate:

Education

Education/ employment opportunities for women

Availability in private/ public pensions

Decrease child labor

Increase urbanization

Decrease infant mortality

Higher average age of marriage

Increased cost of raising and educating children

birth control

legal abortions

Changes in religious beliefs, traditions, culture of encouraging large families

Demographic Transition Model

Preindustrial stage:

both birth and death rates are relatively balanced

population does not increase much

population size slowing

Transitional stage:

Death rate zero due to industrialization, increased food production, and health care

birth rates remain relatively higher

population increases rapidly

Industrial stage:

Birth rates drop

approaches a balance with death rates

slowing population growth

Post industrial stage:

Birth rate and death rates are basically balanced

zero population growth

population size stabilizes much higher than the preindustrial size

In 2002 there was an estimation of 40 million people living with AIDS in the world with 3.1 deaths that year caused by AIDS.

Russia's attempt to slow population decline: people started to really not have any kids and the government attempted to make big families look fun and healthy.

low birth rate, about 1.3

lower than the replacement level

China is expected to reach it's maximum around 1.46 billion in 2030 and start having negative growth in 2050.

India still has about 3.5 kids on average because of high poverty, gender imbalance, and pollution issues.

Developing nation- fast growing population

Future will have stable/ 0 population growth

Japan is a developed nation and has a negative population growth and will continue to have a negative population growth.

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