Chapter 53 and 54: Populations and Communities

Question 1

model of exponential population growth

Answer 1

unchecked growth; unrealistic in most circumstances, can lead to habitat destruction

Question 2

carrying capacity

Answer 2

number of individuals that a habitat can sustain; limited by energy, shelter, nutrients, territories, water, etc.

Question 3

logistic population growth model

Answer 3

incorporates carrying capacity; s-shaped curve

Question 4

K-selection

Answer 4

for traits that are helpful at high densities; typical for populations that exist at the carrying capacity

Question 5

r-selection

Answer 5

for traits that are helpful at low densities; maximizes population growth rate

Question 6

density dependent

Answer 6

birth or death rates change with population size

Question 7

density independent

Answer 7

birth and death remain constant regardless of density

Question 8

equilibrium

Answer 8

births equal deaths in a population

Question 9

causes of density-dependent regulation

Answer 9

competition, disease, predation, accumulation of wastes, and intrinsic factors

Question 10

competition

Answer 10

finite resources shared among more individuals

Question 11

disease

Answer 11

pathogens spread easier in crowded conditions

Question 12

predation response to density

Answer 12

predator preferences may change at high prey numbers

Question 13

accumulation of wastes

Answer 13

large population may produce waste faster than it degrades

Question 14

intrinsic factors

Answer 14

physiological responses to crowding

Question 15

population fluctuations

Answer 15

long term cycles associated with population size; dynamic

Question 16

metapopulations

Answer 16

linked populations

Question 17

sources

Answer 17

successful populations; lots of emigration to sinks

Question 18

sinks

Answer 18

less successful populations; lots of immigration from sources

Question 19

interspecific interactions

Answer 19

any interactions that occur between individuals of different species

Question 20

broad categories of ecological interactions

Answer 20

competition (-/-), exploitation (+/+), and positive interactions (+/+ or +/0)

Question 21

niche

Answer 21

sum of the biotic and abiotic needs of a species; place/role in a habitat

Question 22

competition

Answer 22

(-/-) species compete for resources needed for growth, reproduction, etc. results from overlapping niches

Question 23

principle of competitive exclusion

Answer 23

two species cannot coexist permanently in a community if their niches are identical

Question 24

resource partitioning

Answer 24

differentiation of niches that enables similar species to coexist in a community

Question 25

realized niche

Answer 25

the portion of a species fundamental niche that is used in actuality

Question 26

exploitation

Answer 26

refers to any +/- interaction in which individuals of one species benefit by feeding on individuals of the other species (which are harmed); predation, herbivory, and parasitism

Question 27

predation

Answer 27

(+/-) one animal eats another; predator adapted to locate and subdue, prey adapted to hide and escape

Question 28

cryptic coloration

Answer 28

camoflague

Question 29

aposematic coloration

Answer 29

bright coloration as a warning; generally poisonous, venomous

Question 30

batesian mimicry

Answer 30

harmless resembling venomous

Question 31

Mullerian mimicry

Answer 31

two or more venomous organisms resembling each other

Question 32

herbivory

Answer 32

(+/-) special case of predation; animal eats a plant/algae

Question 33

parasitism

Answer 33

parasite (+) lives off the hose (-); directly or indirectly affects host survival and reproduction

Question 34

mutualism

Answer 34

(+/+) both species benefit

Question 35

commensalism

Answer 35

(+/0) one species benefit and the other is not affected

Question 36

trophic structure

Answer 36

feeding relationships among species; energy moves up from lower trophic levels

Question 37

food chain

Answer 37

producers→primary consumers→secondary consumers

Question 38

food web

Answer 38

better representation of feeding relationships; multiple connections among levels

Question 39

energetic hypothesis

Answer 39

inefficiency of energy transfer between levels; about 10%

Question 40

dynamic stability hypothesis

Answer 40

longer chains are less stable than shorter chains

Question 41

dominant species

Answer 41

most abundant species or species with greatest biomass in a community

Question 42

biomass

Answer 42

total mass of entire population

Question 43

keystone species

Answer 43

key niches maintaining community structure; not necessarily dominant

Question 44

facilitators

Answer 44

ecosystem engineers

Question 45

nonequilibrium model

Answer 45

nature is not balanced or at equilibrium; community is a collection of things and disturbance keeps things in flux

Question 46

intermediate disturbance hypothesis

Answer 46

some disturbance increases species diversity; allows for a mix and creates patches of different habitats

Question 47

ecological succession

Answer 47

first colonizers replaced by other species, which are replaced by other species

Question 48

primary succession

Answer 48

beginning without soil; eg. after volcanic eruption, glacier

Question 49

secondary succession

Answer 49

succession with soil; takes less time than primary successions

Question 50

species-area curve

Answer 50

curve that shows correlation between increase in area and increase in number of species

Question 51

latitudinal gradient

Answer 51

more species closer to the equator; higher tropical diversity

Question 52

island equilibrium model

Answer 52

island size and distance away from source determine number of species; large islands closer to the mainland have a greater number of species