Zoology quiz on population and community ecology

population

all members of a species within a general area

a general area for a population can be…

anything

population density =

number of individuals in a certain area

population size can be hard to determine because…

we do not want to count every single organism

what method do we discuss in class to estimate the size of a population?

mark recapture

explain mark recapture

capture individuals, mark them and release them in the wild. after a while, try and capture again

mark recapture proportions

x/n = s/N

explain the proportions of mark recapture

prop. of marked individuals to total captured in the second time is equal to the prop of number marked the first time to the population

x in mark recapture is

number of marked in second round

n in mark recapture means

total number caught in the second time

s in mark recapture means

number marked the first time

N in mark recapture means

actual population size

what is an assumption of the mark recapture?

that capturing an individual does not change the probability of catching them again

dispersion

how individuals in population occupies space

three kinds of dispersion

clumped, uniform, random

clumped dispersion

clusters of individuals

what could cause clumped dispersion?

resources or group behaviors

uniform dispersion

even spacing of individuals

what could cause uniform dispersion?

territoriality or competition

random dispersion

individuals are found independent of each other

what could cause random dispersion?

uniform resource dispersal or little interaction between individuals

example of clumped dispersion

sea stars clump near food

example of uniform dispersion

penguins maintain distance when raising young

random dispersion example

grass/seed dispersion

example of plants causing uniform dispersal

plants release chemical to stop others from growing in area

populations are dynamic, meaning that they _____.

change

population is a function of what four things?

emigration, immigration, births, deaths

what two things do we focus on when talking about population as a function?

births and deaths

what is a cohort?

group of individuals from one birthing event

how do we study births/deaths in a population?

life table

what do life tables do?

follow a cohort till they all die

life tables record the number of what?

births per female at different ages

survivorship =

proportion of original cohort alive at each stage

fecundity

number of offspring produced by a female

fecundity ____ with each organism

varies

why do we usually only care about female offspring?

they control population growth

fecundity can also vary by ____.

age

in some, like lobsters, fecundity _____ as they get older.

increases

in others, like humans and squirrels, fecundity _____ with increasing age.

decreases

in some, like oak trees, fecundity is _____.

constant

pop growth is usually, Births + Immigrations - deaths - emigrations, but we only care about this equation.

Birth - death

although the population growth is nice, what is better?

change in size per capita

what is the change in size per capita equation?

r * N

what is r?

change in population size per female

what is N?

population size

when r is greater than 0, the population is…

growing

when r is less than 0, population is…

getting smaller

in exponential growth, the population grows with no…

limitations

exponential growth model is not realistic because..

conditions are not often ideal

what is another equation that includes carrying capacity?

rN(K-N/K)

K =

carrying capacity

density independent factors=

probability of mortality is same regardless of population size

what could a density independent factor be?

natural disaster

density dependent factors are factors that…

change depending on population size

negative density dependent factors cause …

slow growth in population

negative density dependent factors examples

competition, disease, space, interactions with others

positive density dependent factors cause…

mortality rate to decrease

example of positive density dependent factors

protection(safety in numbers)

alee effect

minimum number of population is necessary for reproduction to occur

what happened with passenger pigeons?

so many were killed that they reached a number below the minimum required for reproduction that even after they were not hunted, they died out

life history traits are traits that…

determine survival and fecundity and involve trade offs

life history three main traits

age of first reproduction, number of offspring per attempt, how often reproduction occurs

the loggerhead sea turtle produces their first offspring at around…

30 years

grappier produces first offspring around what age?

one year

what is the trade off of age of first reproduction

species that live longer delay first reproduction

2 ways that describe the how often reproduction occurs

semelparity and iteroparity

semelparity

reproduce once

semelparity occurs where there are…

scarce resources

example of semelparity

salmon

iteroparity

reproduce yearly

species that are described with iteroparity have what trade off?

produce fewer per attempt

r-selected species produce ___ offspring

many

r slected species trade off

not many survive

r selected species have ____ parental care

low

k selected species produce what kind of offspring?

fewer and large

k selected species has __ parental care

high

example of regular fluctuation

predator prey dynamics

non regular fluctuation example

extreme weather

community

population of all species that interact in an area

two factors shape communiteis

biotic and abiotic

both species are negatively impacted, what kind of interspecies interaction is this?

competition

what are the 3 main interactions where at least one species benefits?

mutualism, commensalism, antagonism

mutualism example

pollination

mutualism is (_/_)

+,+

commensalims example

ramora fish

commensalism is (_/_)

+,0

antagonism example

predator prey

antagonism is (_/_)

+,-

ecological niche

how organism fits into environment

ecological niches include all the ____ and _____ resources an organism uses

biotic, abiotic

example of what eco. niche describes

habitat

functional niche

where an animal could live but does not because of other factors

realized niche

where animal actually lives

competition is a -,- interaction because…

resource and fitness are decreased for both

there are two outcomes to competition because competition cannot be maintained for a long time. what are the two outcomes?

competitive exclusion or resource partitioning

competitive exclusion

one species has a small advantage, causing other to die out

resource partitioning

evolution causes niches to diverge until no overlap

resource partitioning is the outcome that allows for…

coexistence