APES Module 15-18

what is ecological tolerance?

the range of abiotic and biotic conditions that an organism can survive and reproduce in

what is the difference between a niche generalist and niche specialist?

generalists can survive across a broad range of conditions, specialists can only survive within a narrow range of conditions

what is an example of a generalist and a specialist species?

generalists: gray kangaroo or white pine, specialist: koala or leaf beetle

how might climate change affect generalists and specialist differently?

climate change may harm specialists more since their narrow tolerance ranges make them less adaptable, while generalists can adjust

which type of species is more likely to survive environmental change?

generalist species are more likely to survive changing conditions because they can utilize a variety of resources and tolerate broader environmental variations

what does “biotic potential” mean?

biotic potential is the maximum possible growth rate of a population under ideal conditions with unlimited resources

what are k-selected species and what is the meaning of “k”?

k-selected species have a low intrinsic growth rate and grow slowly until reaching the carrying capacity (k), the maximum population the environment can sustain

what are typical characteristics of k-selected species?

large body size, long lifespan, late reproductive maturity, few offspring, high parental care

what are r-selected species and what is the meaning of “r”?

r-selected species have high intrinsic growth rate 9r) and reproduce rapidly; they tend to have short lifespans, reach maturity quickly, and product many small offspring with little or no parental care

what are the typical characteristics of r-selected species?

small body size, short lifespan, early reproductive maturity, many offspring, minimal parental care

what is “overshoot” and “dieback”?

overshoot when a population grows larger than its environment’s carrying capacity, dieback: a rapid population decline that occurs after overshoot due to insufficient resources

why are k-selected species more vulnerable to extinction?

they reproduce slowly and have small population sizes; cannot recover quickly from population declines caused by habitat loss, poaching, or enviornmental change

how do r-selected species respond to environomental disturbance compared to k-selected species?

r-selected species often recover quickly due to their high reproductive rate, while k-selected species recover slowly and are more likely to face long-term decline or extinction

what is a survivorship curve?

a graph that shows how the number of individuals in a population decreases with age, representing survival patterns over time

describe a type 1 survivorship curve

high survival early and midlife, followed by a sharp decline in older age

describe a type 2 survivorship curve

constant mortality throughout life; equal chance of dying at any age

describe a type 3 survivorship curve

high mortality early in life but long survival for individuals that reach adulthood

which survivorship curve do humans typically exhibit?

type 1

how do generalists/specialist strategies relate to r/k selection

r-selected species often tend to be generalists, k-selected species are often specialists

why is understanding these species traits important for conservation?

must understand species’ reproductive strategies and tolerances to predict their ability to survive environmental change, habitat loss, and human disturbance

wwhich is carrying capacity (k)?

which of the following is a density-dependent factor?

which population growth model produces a j-shaped curve?

in the logistic growth model, population growth slows as it approaches:

a population that temporarlity exceeds its carrying capacity is experiencing:

true or false: density-independent factors affect populations differently depending on population size

false; they affect populations regardless of size

true or false: a limiting resource is a resource that occurs in quantities lower than a population requires to increase in size

true

true or false: the isle royale moose population was stabilized by the introduction of wolves because wolves acted as a limiting factor

true

what is the difference between density-dependent and density-independent factors?

density-dependent factors affect survival and reproduction based on population size, density-independent factors affect survival and reproduction regardless of population size

what happens in a population experiencing repeated cycles of overshoot and dieback?

the population temporarily exceeds the carrying capacity, leading to resource depletion; causes a dieback in population size

what is an example of a limiting resource for plants and for animals?

plants: water, nitrogen, phosphorus; animals: food, water, nesting sites

how does predator-prey interaction affect carrying capacity?

predators reduce prey population sizes, preventing prey from exceeding the carrying capacity defined by resources

what is biotic potential (r)?

biotic potential is the maximum reproductive rate of a population under ideal conditions with unlimited resources

why do human populations sometimes experience resource limitations even without dieback?

humans can overconsume or unevenly distribute resources, leading to scarcity of land, water, or food

what is the current global population growth rate?

increases by roughly 1.3 million people every 5 days

what caused the rapid population growth beginning around 400 years ago?

improvements in agriculture and sanitation reduced death rates

what is the carrying capacity for humans?

it is the maximum number of people that earth can sustainably support

who was thomas malthus, and what did he propose?

english economist who proposed that human population grows exponentially while food supply grows linearly, eventually leading to famine and population decline

how did technology affect malthus’s prediction?

improved farming tools and mechanized agriculture allowed humans to increase food production and raise earth’s carrying capacity

what is demography?

the study of human populations and population trends

what are the inputs and outputs of a population system?

inputs: births and immigration; outputs: deaths and emigration

what is immigration?

movement of people into a country or region

what is emigration?

movement of people out of a country or region

what is the crude birth rate (cbr)?

number of births per 1,000 people per year

what is the crude death rate (cdr)?

number of deaths per 1,000 people per year

what does a positive population growth rate indicate?

births and immigration outnumber deaths and emigration

what is the net migration rate?

the difference between immigration and emigration per 1,000 people per year

what is life expectancy?

the average number of years an infant born in a particular year is expected to live

what does a high life expectancy typically indicate?

high health care access, adequate food and water, and higher resource use

why do women generally have a higher life expectancy than men?

biological differences and social factors; men historically faced more dangerous jobs and wars

what is infant mortality rate?

deaths of children under 1 year old per 1,000 live births

what is child mortality rate?

deahs of children under age 5 per 1,000 per live births

what does a high infant mortality rate suggest about a country?

limited health care, sanitation, and access to water and nutrition

what is environmental justice?

the study and social movement addressing the unequal exposure of marginalized groups to environmental hazards

what is an age structure diagram?

a graph showing the distribution of a population by age and gender

what are the 3 main age categories in an age structure diagram?

pre-productive (0-14), reproductive (15-44), post-reproductive (45+)

what does a population pyramid indicate?

a rapidly growing population with many young people (developing countries)

what does a column-shaped age structure indicate?

a stable population with slow or zero growth (developed countries)

what does an inverted pyramid indicate?

a declining population with more elderly than young

what is population momentum?

continued population growth after birth rates have declined due to a large num ber of people in reproductive age groups

what is total fertility rate (tfr)?

the average number of children a women will have during her reproductive years (15-49)

what is replacement-level fertility?

the tfr needed to replace the parents and maintain a stable population size (2.1 in developed countries)

why is replacement-level fertility higher in developing countries?

higher infant and child mortality rates

what is the global average tfr?

about 2.3

how does income level affect tfr?

tfr decreases as income and education levels increase

what role does family planning play in tfr?

access to family planning and contraception lowers tfr by giving women control over reproduction 

what is an example of a successful family planning campaign?

kenya reduced its tfr from 8 to 3.5 through education and contraception use

what is the expected global population by 2050 and 2100?

2050: 8-10 billion; 2100: 7-11 billion

what does it mean if a country’s tfr is below 2.1 and there is no net immigration?

the population will decline over time

how do age structure diagrams reflect tfr?

high = pyramid, replacement = column, low = inverted pyramid

what demographic pattern does georgia exhibit?

declining population due to a tfr below replacement level and negative net migration rate

how do diseases regulate population size?

infectious disease like hiv/aids, malaria, and covid-19 increase death rates and reduce population growth

what region is most affected by hiv/aids?

sub-saharan africa

what are developing countries?

nations with low industrialization and income

what are developed countries?

nations with high industrialization, income, and access to resources and health care

why is understanding population strucutre important for environmental science?

population trends influence resource use, pollution, and sustainability challenges

what is china’s current tfr and hwo does it compare to replacement fertility?

1.5, which is below replacement fertility

what are 2 major methods china used to limit population growth under the one-child policy?

financial rewards for couples with one child, and sanctions such as salary reductions for families with 3 or more children

how does increasing affluence affect resource consumption even if population growth slows?

higher affluence leads to greater consumption of goods such as cars, home appliances, and electronics, which require energy and raw materials to produce, increasing pollution and environmental impact

what is an example of china’s environmental progress and one continuing environmental challenge?

progress: higher fuel efficiency standards; challenge: high levels of air pollution

what are 2 examples of density-independent factors that limit human population growth?

fires, droughts

what are 2 examples of density-dependent factors that can limit human population growth?

access to clean water, food, and air; protection from infectious diseases

how does infant mortality indirectly influence population growth?

when infant mortality decreases, families may choose to have fewer children because more are likely to survive, reducing the tfr over time

what % of the world’s population lives in urban areas, and what is the projected % by 2030 in developing countries?

over 56% live in urban areas; in developing countries the % is projected to increase from 48% to  56% by 2030

using the rule of 70, how do you estimate doubling time if the population growth rate is 2% per year?

doubling time = 70/2 = 35 years

why can we never determine a countries doubling time with a complete certainty?

growth rates fluctuate over time due to economic, social, political, and environmental changes

what are th 4 stages of demographic transition in order?

slow population, rapid population, stable population, declining

what are main population characteristics of stage 1?

high birth rates and high death rates, population nearly stable, short life expectancy, high infant mortality, preindustrial economy

what causes rapid population growth in stage 2 countries?

death rates decline due to improved sanitation, healthcare, and nutrition, but birth rates remain high

why do birth rates decline in stage 3 countries?

economic development, higher education, increased affluence, and access to family planning make large families less necessary and desirable

what demographic challenges arise in stage 4 countries?

aging population, higher dependency ratio, potential labor shortages, increased social security and healthcare costs, and a need for immigration or incentives to boost birth rates

what is the ipat equation?

impact = population x affluence x technology

what do the ipat equation components represent?

population: # of people, affluence: resource consumption per person, technology: how resources are used

how can one person in a developed country have a greater environmental impact than two people in a developing country?

greater affluence leads to more consumption of energy, goods, and services, which increases the environmental footprint

what is an example of how techonology can both increase and decrease environmental impact?

increase: CFCs for refrigeration damaged the ozone layer; decrease: hybrid electric cars reduce fuel consumption and emissions

which countries are growing more rapidly, developed or developing?

developing countries are growing more rapidly due to higher fertility rates and lower levels of affluence, whereas developed countries have near-zero growth

which of the following is not a charcteristic of k-selected species?

which type of survivorship curve is typical of many insects and fish?

in the logistic growth model, the population growth begins to slow when the population size approaches:

a population is growing at 2% per year will approximately double in: