APES - Unit 3 Textbook

Ecological Tolerance

Ecological Tolerance

range of conditions in which organisms can live

Generalists

live under a wide range of abiotic or biotic conditions

Specialists

live under a narrow range of conditions

persist well when environmental conditions remain relatively constant, or if the food source they specialize in is abundant

more vulnerable to reductions in number of individuals and possible extinction

Global climate change

 expected to cause shifts in temperature and precipitation which at least habitats to change in food abundance to fluctuate

 Niche generalists should be more adaptable and resilient

 success of a species

the population size of the species

 population / intrinsic growth rate

the number of offspring an individual can produce in a given time period minus the death of the individual or it's offspring during the same period

K-selected species

 species with low intrinsic growth rate that causes the population to increase slowly until it reaches the carrying capacity

carrying capacity

the limit to the number of individuals that can be supported by an existing habitat or ecosystem

denoted as k

K-Selected species characteristics

typically large organisms that reach reproductive maturity relatively late

produce few large offspring during each reproductive event

expend significant energy providing prenatal care

low population growth rate and long lifespans

populations are relatively stable and remain close to the carrying capacity of the ecosystem

vulnerable to adverse impacts from invasive species due to high competition

r-selected species

 High intrinsic growth rate

populations increase rapidly reproduce often and produce large numbers of offspring

rapidly surpass their carrying capacity and reach a population larger than the environment’s carrying capacity

 overshoot

when a population becomes larger than the environment’s carrying capacity

dieback/dieoff

a rapid decline in population due to death

r-selected species characteristics

 reach reproductive age early produce many offspring little to no prenatal care populations fluctuate widely above and below the carrying capacity of the ecosystem 

Survivorship curves

graphs that represent the distinct survival patterns of species

Type 1 survivorship curve

high survival throughout most of lifespan, but individuals start to die off in large numbers when they reach old age

Type 2 survivorship curve

there is a constant decline of survivorship throughout most of lifespan

Type 3 survivorship curve

low survivorship, high death rates early in life with few individuals reaching adulthood

Density-dependent factors

factors that influence an individual’s probability of survival and reproduction in a way that depends on the size of the population (competition for resources, predation, disease, etc.)

Density-independent factors

factors that have the same effect on an individual’s probability of survival and the amount of reproduction at any population size (natural disasters, droughts, pollution, climate change, etc.)

population growth models

mathematical equations that can be used to predict population size at any moment in time

fecundity

the ability to produce an abundance of offpsring

Exponential growth model

growth model that estimates a population’s future after a period of time, based on the biotic potential and the # of reproducing individuals currently in the population

biotic potential

maximum rate at which a population can grow under ideal conditions, with unlimited resources and no limiting factors like disease or predation

J-shaped curve

the change of a growing population over time, population grows slowly at first and then rapidly increases due to unlimited resources

logistic growth model

growth model that described a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment

limiting resource

resource that a population cannot live without and occurs in amounts lower than the population would require to increase in size

exponential growth slows/stops when

environmental limit is reached

Malthus’ observation

human population grows exponentially while the food supply we rely on grows linearly

Malthus hypothesis

human population size will eventually exceed the food supply

demography

the study of human population and population trends

Crude Birth Rate (CBR)

number of births per 1000 individuals per year

Crude Death Rate (CDR)

number of deaths per 1000 individuals per year

Global population growth rate equation

(CBR-CDR)/10

net migration rate

difference between immigration and emigration in a given year per 1000 people in a country

positive net migration

more immigration than emigration

national population % growth rate

{(CBR + immigration) - (CDR - emigration)}/10

life expectancy

average # of years that an person born in a particular country can be expected to live given the current life span and death rate in their country

Infant mortality rate

number of deaths of infants under the age of 1 per 1000 live births

environmental justice

the study of how people of color, recent immigrants, and low-income individuals are more likely to be exposed to environmental hazards

age structure diagram

visual representation of the number of individuals in a specific age group for a country

population pyramid

age structure diagram that illustrates the distribution of a population based on age and gender

developing countries

countries that have relatively low levels of industrialization and income

developed countries

countries that have a large level of industrialization and income

inverted pyramid

greater # of older people than younger people, decreasing and negative growth rates

population momentum

continued population growth after growth reduction measures have been implemented

pyramid shaped population

population has a higher proportion of younger people that has rapidly expanded and will continue to grow

column shaped population

indicates that a country has begun to experience slowing population growth

total fertility rate

an estimate of the average # of children that each woman in a population will bear throughout her child bearing years

family planning

regulation of the number of spacing of offspring through different incentives and policies

replacement level fertility

total fertility rate required to offset the average # of deaths in a population in order to maintain population size

china’s “one-child” policy

government enforced family planning program

factors that contribute to population growth

high CBR, high TFR, low infant mortility rate, early marriage, lack of access to family planning, access to adequate nutrition, low overall death rate

doubling time

the # of years it takes a population to double

rule of 70

dividing the growth rate by 70 can determine a population’s doubling time

theory of demographic transition

a country moves from high to lower birth rates as development occurs and that a country moves from a pre-industrialized to an industrialized economy

Stage 1 (demographic transition)

slow population growth, high birth and death rates

Stage 2 (demographic transition)

rapid population growth, birth rates high and death rates decreasing

Stage 3 (demographic transition)

stable population growth, birth and death rates decreasing

Stage 4 (demographic transition)

declining population growth, low birth and death rates

IPAT

a conceptual representation of 3 major factors that influence environmental impact

IPAT equation

impact = population x affluence x technology