APES unit 3 population

generalist species characteristics

wide variety of conditions, consume a broad range of foods, and adapt to different habitats. Flexible; tolerant

specialist species characteristics

limited diet and habitat, narrow range of conditions. Highly adapted, vulnerable to changes. Narrow range, stable environment.

In a changing ecosystem, is a generalist or specialist species advantageous?

generalist

range of tolerance (diagram)

more vulnerable to being endangered on the left, less vulnerable on the right

generalist species

variety of resources, high range of tolerance, advantageous when conditions change, broader niche, adaptable, less likely to become extinct

specialist species

narrower niche, less adaptable, more likely to become extinct, specific resources, easily affected by changing conditions, advantage when conditions are consistent

K-selected species

few, large offspring. High parental care, later reproductive age, large adults, stable climate, low population growth, specialist species

r-selected species

many offspring, little parental care, early reproductive age, many offspring die before reproductive age, small, generalist species, high growth rate

survivorship curve

displays the relative survival rates of a cohort in a pop. from birth to death

cohort

group of individuals of the same age

Type 1 on survivorship curve

• Mostly K-selected

• High survivorship early in life due to high parental care

• High survivorship in mid life due to large size and defensive behavior

• Rapid decrease in survivorship in late life as old age sets in

• Sideways J curve (opposite of Type 3)

carrying capacity

Max number of individuals in a pop. that an ecosystem can support based on limiting resources like food, water, and habitat

overshoot

when a pop briefly exceeds carrying capacity, causes resource depletion

die-off

sharp decrease in pop size when resource depletion (overshoot) leads to many individuals dying, population crash

how can an ecosystem’s carrying capacity change?

based on the number of resources (food, water, habitat, gas, etc.) that are available. Natural disasters can happen or the ideal conditions can change (rain, sunlight, temp, etc.)

Why are K-selected species more likely to survive childhood

they have more parental care

What is exponential growth

when a variable is increasing exponentially instead of linearly. It’s shaped like a J because the number gets bigger and multiplies to a larger number. Growing by percentage and the more you have, the faster you grow.

size

how big the population is

density

# of individuals per a given area

distribution

how individuals in a population are spaced out compared to each other

random distribution

randomly placed trees

uniform distribution

territorial animals; organized in columns or rows

clumped distribution

herd/group of animals; grouped or clumped together

what are some causes of high density?

high competition, possibility for disease outbreak, possibility for depletion, food source

sex ratio

ratio of males to females, ideal is 50%

density-dependent factors

factors influence population growth based on size

ex: food, competition for habitat, water, light, disease

density-independent factors

factors that influence population growth

ex: natural disaster, doesn’t matter how big or small a population is

biotic potential

exponential growth, max potential growth rate, no limiting resources. May occur initially, but limiting resources slow growth and eventually limit population to carrying capacity.

logistic growth

initial rapid growth, then limiting factors limit the population.

Population size equation

(immigrations + births) - (emigrations + death)

percent change equation

(N - O / O) X 100

age cohorts (diagram)

groups of similarly aged individuals

demography

study of populations in a country

what are problems associated with a population growing rapidly

limited resources (food, housing, gas) for everybody and a carrying capacity. To fix increasing population spend resources to fulfill food, housing, gas.

what are problems associated with a decreasing population

less people to work jobs or pay taxes. To fix decreasing population, could open up to immigration to increase population.

why is a higher population in developing countries and decreasing population in developed countries

developing countries need security and children to support them when they’re old. Developed countries don’t need that feeling of security because they realize they have national security and kids are expensive.

TFR

total fertility rate

what are the causes of a high TFR

higher birth rate, higher pop growth rate (generally)

replacement level fertility

TFR required to offset deaths in a population and keep population size stable

IMR

infant mortality rate

what factors into IMR

access to clean water, access to healthcare, more reliable food supply

what factors affect TFR

development (affluence) and government policy

development keys

wealthy nations have lower TFR, more education for women, more reproductive education, more economic opportunity for women, more family planning, later age of 1st pregnancy

government policy keys

paid for sterilization, kids limit laws

Infant mortality rate (IMR)

# of deaths of kids under 1 per 1,000 people in a pop.

why is IMR higher in less developed countries

due to lack of access to healthcare, clean water, and food.

what is caused by high IMR

high TFR

why do some developing countries have a higher birth rate

• stability

• someone to take care of you when you’re older (boys wanted → can’t choose gender)

• potential help

• future workers

• security

When girls are educated and given career opportunities, what tends to happen

birth rates decrease. Less time for kids because of school/job, more opportunities, give themselves stability, security, and care.

estimated population size equation

(# captured and marked) X (# captured 2nd day) / (# that was marked on 2nd day)

what ecological and economical impacts occur with a rapidly growing human population

more people to feed and house, limited resources, resources would decrease, value of houses increase because there’s probably more interest buyers, need more land, deforestation for resources, job creation

what are strategies to slow human population growth

put a law in place that limits the amount of kids a couple can have, give more education and opportunities to women, access to reproductive healthcare and education, government incentives for smaller families or incentives for women getting sterilized. Attempt to reduce birth rate.

what’s the difference between specialist and generalist species

generalist species are flexible when it comes to diet, habitat, and environment conditions. They can tolerate a larger range than specialist species. Specialist species have a narrower range of abiotic factors they can tolerate.

is a generalist or specialist species more advantageous with a grassland ecosystem that’s frequently disrupted by fires

generalist because they can adapt easier

what is the reproductive strategy of r-selected species

many offspring, little parental care, early reproductive age

what is the reproductive strategy of K-selected species

later reproductive age, high parental care, few offspring, large offspring, adapted to stable climate

is r-selected or K-selected species more likely to be an invasive species

r-selected species because of their high reproductive rate, little parental care, short lifespan, and generalist species are better adapted.

Survivorship

probability of an organism surviving to a specific age within a population

Type 1 of survivorship

high survivorship early and midlife, rapid decrease in late life

Type 2 of survivorship

steadily decreasing survivorship

Type 3 of survivorship

low survivorship early, midlife, and late life

carrying capacity

max # of individuals in a population that an ecosystem can support based on limiting resources.

what does TFR refer to

number of kids a women will have in her lifetime.

what can the government do to reduce TFR

give incentives

• Carrot approach: incentive for smaller families

• Stick approach: penalization for larger families

or give women more education and economic opportunities

Crude birth rate (CBR)

how many people have been born per 1000 in a population

crude death rate (CDR)

how many people have died per 1000 in a population

percent change equation

(CBR - CDR) / 10

doubling time equation

DT = 70/ percent growth

Malthusian theory

• Earth has a human carrying capacity (based on food population)

• populations grow exponentially while food supply increases

• if the population continues to grow without a increase in food production, it will eventually lead to shortages, resulting in famine, disease, and other checks on population growth

• population growth would always surpass food

Why did Malthusian’s theory not come true

agricultural technology increased food production, population control measures (family planning and increased education) have helped to stabilize population growth. Many developed countries have lower birth rates, better healthcare, and rising living standards.

growth rate ( r )

% increase in a population (per year)

rule of 70

method used to est. the # of years for a pop. to double based on yearly growth rate.

what are the causes of increased population growth

• high immigration level

• increased access to clean water

• increased access to healthcare

what are the causes of decreased population growth

• high death rate

• high IMR

• postponement of marriage age

standard of living

what the quality of life is like for people of a country based

Gross domestic product (GDP)

measures market value of goods and services produced during a quarter and it’s used as an indicator of a country’s overall economic health.

why do societies with low IMR have fewer children

feel more secure that their children will survive to adulthood

why do societies with high IMR have more children

to ensure that some survive.

what factors cause lower IMR

access to healthcare, clean water, and reliable food supply

why do developed nations have lower IMR and replacement level fertility rates

better access to healthcare, clean water, and reliable food sources. Greater security that their kids will survive to adulthood → fewer children. Women may have more educational and economical opportunities, or the country may have gov’t incentives for smaller families.

Type 2 on survivorship curve

In between r and K selected

Steadily decreasing survivorship throughout life

Type 3 on survivorship curve

• mostly r-selected species

• High mortality & low survivorship early in life due to little to no parental care

• Few make it to midlife, slow and steady decline in survivorship in midlife

• Even fewer make it to adulthood, slow decline in survivorship in old age

• J curve