Unit 3: Populations Flashcards
smallest to biggest ecological levels
- individual
- population
- community
- ecosystem
If People Care Enough
population
all the individuals of a PARTICULAR SPECIES(10 bunnies)
individual
a singular type of species(1 bunny)
community
all the species interacting (2 bunnies, 2 bears, 2 birds)
ecosystem
community + abiotic factors(animals/plants + dirt, sand, air)
Things we look at in a population
- size
- density
- pop. distribution
size doesn’t penis-dick
what factors affect population
- reproduction rate
- resources
how to calculate density
of indiv/area
density dependent factors
impact size of population as a response to how dense the pop is(the more dense, the greater impact on size of pop) EX: disease(the more dense, the faster the disease can spread)
density independent factors
would happen regardless of how dense pop is
EX: natural disasters
population distribution
how spread out people are within the area
types of population distribution
- nearly uniform (everyone equidistance) —– evidence of ppl trying to est. territory/hunting ground
- random (not as common, no benefit, ex: weeds/generalist species)
- clumped (schools of fish, hunting packs)
k selected v r selected SPECTRUM(species in between)
k= quality care, few offspring r= quantity(no care) care, many offspring
k selected
-reproduce many times(give birth many seperate times)
-long lifespan
-SLOW population growth rate
-SLOW sexual maturity
-more likely TO BE DISRUPTED
EX: mammals, birds
r selected
-reproduce once
-short lifespan
-QUICK sexual maturity(high biotic potential)
-FAST population growth rate
-more likely TO BE INVASIVE
-better suited for fast changing env conditions
EX: insects, fish, plants
survivorship curves
show patterns of survival/lifespan
-fast drop in line=quicker die off
-slow drop in line=longer avg. lifespan(live till old age/die of old age)
(doesn’t have years on bottom j cuz all have diff lifespans)
type 1 survivorship curve
Ex: humans w access to medicine (most of the time will see species w same curve BUT depends on location, develop v nondevelop countries)
-rapid decrease at the end(die of old age)
type 2 survivorship curve
constant death rate(linear negative line down)
-equally likely to die at any age
EX: squirrels
type 3 survivorship curve
EX: weeds
-die alot
what type of curve do K species have
type 1 (good parental care makes sure they live long)
what type of curve do R species have
type 3(bad parental care doesn’t help them live)
carrying capacity(K)
maximum population that a habitat can support over a given period of time
what pushes exponential growth forward
biotic potential
What keeps a population from exponentially growing infinitely
environmental resistance, keeps the carrying capacity down
examples of environmental resistance a.k.a. keeping population down
predation, disease, competition
what keeps exponential growth up
food, resources, space
how does the fact that resources are finite impact population
- can’t have exponential growth forever
- lack of resources increases competition
exponential growth
j curve, constantly going up and can continue to grow forever if there are enough resources
logistic growth
s curve, looks like j curve in the beginning but there’s an asymptote keeping the population down
what made population growth grow in the first place
agriculture revolution (feed more ppl at one time, grow more food)
what is causing population to flatten out
lack of space water and food
what led to the exponential growth of human population
medicine sanitation tech
prophecy of malthus
predicted widespread death and famine (food growing linear, population growing exponentially =point they jnterestect bad things happen)
why do ppl disagree with malthus
tech will save us (gmo foods, agriculture tech)— we’ll make enough food to survive
what types of countries have high IPAT scores
developed countries (US, china) — india’s would b lower bc even tho big population they’re not rich/big tech
what does IPAT measure
impact on the worlds resources and environment
Impact = pop size x affluence x tech
will TFR be lower or higher if u have kids late
lower because there is less time to have more kids after that
what factors influence total fertility rate
- how old women are when they have their first child
- educational opportunities for women(women valued more/occupied by work so they’re not j baby makers)
- access to family planning(understand sex ed)
What does infant mortality look at
number of children per 1,000 live births who die before one year of age
what does TFR mean
total fertility rate: the average number of children a woman has
What does CBR mean
crude birth rate: number of births per 1000 people
why do countries w low infant mortal y rate have high tfr
trying to have more kids cuz they know they’re gonna die cuz lack of medical resources —- results: high percent of pop under 15 bc having lots of kids — results those 15 yr olds will reach reproductive age
who has higher percentage of old ppl, developed or developing
developed has higher because they have the resources(social security, medicine) to keep old people live
what TFR rate would result in no population growth
2 because those two kids will replace mom and dad a.k.a. they’ll cancel out
what will you always see in an age structure diagram
A tapering at the top because we don’t live forever
what does a wide base in a population pyramid mean
The population is growing rapidly, there are a lot of babies a.k.a. young people
big gaps between 0-5 and 5-10 means?
hi infant mortality rate. Babies aren’t living to become children
What type of country has slow growth
developed, the discrepancies between the lower age tiers are smaller a.k.a. people are living to old age
shape of a zero growth pyramid
bullet shaped, mainly developed countries (0-5 and 5-10 is basically even)
shape of declining population pyramid
kit shape, big top small bottom, developed countries (Bad because there will be no young people to fill jobs and take care of old people)- negative impacts on economy
what is replacement fertility
a little more than 2, u need to replace mom and dad and extra deaths
