BIOLOGY 301 EVOLUTION AND
ECOLOGY FINAL EXAM
although communities are in a constant state of flux.... - Correct Answers -the
appearance and composition of communities seems to change little over time
Pacific North West Summary - Correct Answers -1. Mount Saint Helen eruption
2. Nitrogen poor soil (depends on rains following disturbance)
3. early invasive nitrogen fixation
4. alder (pioneer) nitrogen fixation
5. douglas fir (pioneer )nitrogen fixation
6. mature douglas fir
7. cedar/hemlock (climax) around 300 years
8. forest fire occurs- N poor soil reoccurs
when does succession in a community occur? - Correct Answers -when species replace
each other over time
succession - Correct Answers -the process by which species composition of a
community changes over time; can take weeks, months (succession of a dead animal),
hundreds of years (forrest)
mechanism of plants to induce seed disperal - Correct Answers -attract animals to
themself by surrounding seeds with a fruit
ex. painted trillium has seeds with a lipid and protein rich attachment called an
elaisome; ants disperse seeds by taking them to their nests, consuming the fruit, and
discarding the seed
what do many seeds with fruit have? - Correct Answers -a hard coat that resists
digestion so the seed can pass through the animals gut without harm and still be able to
germinate
positive mutualistic interaction - Correct Answers -each individual participates in
mutualism to improve its own fitness
negative mutualistic interaction - Correct Answers -When a species in a mutualism
provides a benefit to another species at a cost, but no longer receives a benefit in return
(turns to herbivory/predation)
,seral stage - Correct Answers -each stage of community change during succession
pioneer species - Correct Answers -earliest species to arrive at a site; typically are able
to disperse long distances and arrive quickly at disturbed sites
climax community - Correct Answers -final seral stage in the process of succession;
generally composed of organisms that dominate in a given biome
what is the clearest way to record succession in a community - Correct Answers -direct
observation of change
example of a direct observation of change - Correct Answers -Krakatau 1883 eruption:
blew away 3/4 of the island; remaining land was covered with ash (all life was gone)
-researchers began observing the island and by 1886 they say that 26 plant species
had colonized through wind and sea dispersal; later colonizers were dispersed by birds
and bats
what method is used when direct observation of succession is not possible? - Correct
Answers -chronosequence
chronosequence - Correct Answers -sequence of communities that exist over time at a
given location; indirect observation
example of chronosequence - Correct Answers -Lake Michigan water level decrease
since last glaciation-old sand dunes were far from shore line and new ones were on
shore's edge: Henry Cowles studied succession by examining chronosequence of sand
dunes
found that younger dunes had early successional species (grasses) where as old dunes
had late successional species (herbs, shrubs) oldest dunes had beech, oak, maple,
hemlock)
pollen preservation - Correct Answers -flowering plants produce pollen grains with
distinct sizes and shapes that travel through the air and land on a lake surface-
researchers can take samples that penetrates through many layers of mud on lake
bottom and look back in time
carbon dating - Correct Answers -used to identify the age of pollen in each layer- helps
determine changes in plant species composition around the area over 100s and 1000s
of years
primary succession - Correct Answers -development of communities in habitats that are
initially devoid of plants/ organic soil (dunes, lava flows, bare rock)
what colonize these types of habitats? - Correct Answers -species that require no soil
and can live on rock surfaces (mosses, drought-tolerant grasses)- produce organic
matter that helps create soil--> generates more hospitable conditions
,secondary succession - Correct Answers -development of communities in disturbed
habitats that contain no plants but contain organic soil (plowed fields, forests uprooted
by a hurricane)
ex. of secondary succession - Correct Answers -Henry Oosting observed secondary
succession in chronosequence of abandoned agriculture fields in Duke Forest (see ppt
for picture)
how does the sequence of seral stages that a site passes on its way to a climax
community differ? - Correct Answers -differs based on the initial conditions (variation in
historic abiotic conditions, soil fertility, disturbances)
example of seral stage sequence differentiation - Correct Answers -ex. Lake Michigan:
an abandoned field is colonized by asters (ex. goldenrod), a sand dune is colonized by
perennial grasses, and a wetland is colonized by cattails
In all three cases, the progression of seral stages begins with a different community but
will end with a forest dominated by beech and maple trees
what do chronosequences assume? why is this assumption wrong? - Correct Answers -
assumes that older and younger sites pass through similar seral stages
-it is difficult or impossible to determine if sites did not differ in ways that affect
succession
how do changes in the plant community cause changes in the animal community?
ex. - Correct Answers -change the habitats that are available to animals
ex. esearchers examined the distribution of bird species along the successional seral
stages on abandoned agricultural fields in North Carolina (see ppt for pic)
why can succession in an intertidal community occur rapidly after a disturbance? -
Correct Answers -short generation time of dominant species
example of succession in intertidal community - Correct Answers -intertidal zone of
California: examination of algae species succession
undisturbed boulder: red algae dominated
when waves overturn the boulder: algae is removed
disturbed boulder: sea lettuce dominates and prevents red algae from colonizing--
>attracts crabs
why do streams undergo rapid succession? - Correct Answers -organisms can move
downstream from sites that are less disturbed
how does rainfall disturb a stream? - Correct Answers -heavy rainfall increases the
volume and speed of water, causing sand and rocks to tumble downstream and wipe
out most plants, animals, and algae
, example of stream community succession after a flood - Correct Answers -initially, all
algae and insects were removed
- the stream rapidly became colonized by diatoms- algae species followed
algae caused insects to lay eggs in the stream
model for pond/ lake succession - Correct Answers -suggests slow transformation:
1. after a lake or pond is created, the edge of the water body is initially colonized by
plants
2. the plants expand laterally across open water and begin accumulating dead plant
matter (peat)
3. continue to expand and the peat layer becomes thicker
4. eventually covers the lake surface and peat sediments fill in the basin
based on research, what is a different model for lake/pond succesion? - Correct
Answers -suggests that a lake may undergo 100s of years of succession with brief
episodes of rapid change:
1. open lake or pond experiences a drought of one or more decades and the water level
falls
2. plants colonize the newly exposed lake sediments
3. as the drought ends, the lake fills and living plants detach from lake sediments and
float on the lake's surface
4. peat sediments eventually fill the basin
how does species richness change from the time of the initial disturbance to the time of
succession (consistent across most cases of succession) - Correct Answers -after the
disturbance: zero species richness
succession: increases rapidly at first, but then plateaus and slightly declines
ex. of pattern of species richness in succession - Correct Answers -Oosting's research:
survey of succession in Duke Forest and in Sousa's study of intertidal succession,
species richness exhibited a pattern of rapid increase, followed by a plateau and a small
decline
why do early and late succession species have differing traits - Correct Answers -result
from trade-off of high dispersal, rapid growth, and early reproduction with enhanced
competitive ability
example of differing traits - Correct Answers -Late-succession trees: produce a few
large seeds that grow well under harsh, low light conditions
early-succession trees: produce many small seeds that grow poorly under low light
conditions, but disperse and grow well in high light conditions
facilitation
ECOLOGY FINAL EXAM
although communities are in a constant state of flux.... - Correct Answers -the
appearance and composition of communities seems to change little over time
Pacific North West Summary - Correct Answers -1. Mount Saint Helen eruption
2. Nitrogen poor soil (depends on rains following disturbance)
3. early invasive nitrogen fixation
4. alder (pioneer) nitrogen fixation
5. douglas fir (pioneer )nitrogen fixation
6. mature douglas fir
7. cedar/hemlock (climax) around 300 years
8. forest fire occurs- N poor soil reoccurs
when does succession in a community occur? - Correct Answers -when species replace
each other over time
succession - Correct Answers -the process by which species composition of a
community changes over time; can take weeks, months (succession of a dead animal),
hundreds of years (forrest)
mechanism of plants to induce seed disperal - Correct Answers -attract animals to
themself by surrounding seeds with a fruit
ex. painted trillium has seeds with a lipid and protein rich attachment called an
elaisome; ants disperse seeds by taking them to their nests, consuming the fruit, and
discarding the seed
what do many seeds with fruit have? - Correct Answers -a hard coat that resists
digestion so the seed can pass through the animals gut without harm and still be able to
germinate
positive mutualistic interaction - Correct Answers -each individual participates in
mutualism to improve its own fitness
negative mutualistic interaction - Correct Answers -When a species in a mutualism
provides a benefit to another species at a cost, but no longer receives a benefit in return
(turns to herbivory/predation)
,seral stage - Correct Answers -each stage of community change during succession
pioneer species - Correct Answers -earliest species to arrive at a site; typically are able
to disperse long distances and arrive quickly at disturbed sites
climax community - Correct Answers -final seral stage in the process of succession;
generally composed of organisms that dominate in a given biome
what is the clearest way to record succession in a community - Correct Answers -direct
observation of change
example of a direct observation of change - Correct Answers -Krakatau 1883 eruption:
blew away 3/4 of the island; remaining land was covered with ash (all life was gone)
-researchers began observing the island and by 1886 they say that 26 plant species
had colonized through wind and sea dispersal; later colonizers were dispersed by birds
and bats
what method is used when direct observation of succession is not possible? - Correct
Answers -chronosequence
chronosequence - Correct Answers -sequence of communities that exist over time at a
given location; indirect observation
example of chronosequence - Correct Answers -Lake Michigan water level decrease
since last glaciation-old sand dunes were far from shore line and new ones were on
shore's edge: Henry Cowles studied succession by examining chronosequence of sand
dunes
found that younger dunes had early successional species (grasses) where as old dunes
had late successional species (herbs, shrubs) oldest dunes had beech, oak, maple,
hemlock)
pollen preservation - Correct Answers -flowering plants produce pollen grains with
distinct sizes and shapes that travel through the air and land on a lake surface-
researchers can take samples that penetrates through many layers of mud on lake
bottom and look back in time
carbon dating - Correct Answers -used to identify the age of pollen in each layer- helps
determine changes in plant species composition around the area over 100s and 1000s
of years
primary succession - Correct Answers -development of communities in habitats that are
initially devoid of plants/ organic soil (dunes, lava flows, bare rock)
what colonize these types of habitats? - Correct Answers -species that require no soil
and can live on rock surfaces (mosses, drought-tolerant grasses)- produce organic
matter that helps create soil--> generates more hospitable conditions
,secondary succession - Correct Answers -development of communities in disturbed
habitats that contain no plants but contain organic soil (plowed fields, forests uprooted
by a hurricane)
ex. of secondary succession - Correct Answers -Henry Oosting observed secondary
succession in chronosequence of abandoned agriculture fields in Duke Forest (see ppt
for picture)
how does the sequence of seral stages that a site passes on its way to a climax
community differ? - Correct Answers -differs based on the initial conditions (variation in
historic abiotic conditions, soil fertility, disturbances)
example of seral stage sequence differentiation - Correct Answers -ex. Lake Michigan:
an abandoned field is colonized by asters (ex. goldenrod), a sand dune is colonized by
perennial grasses, and a wetland is colonized by cattails
In all three cases, the progression of seral stages begins with a different community but
will end with a forest dominated by beech and maple trees
what do chronosequences assume? why is this assumption wrong? - Correct Answers -
assumes that older and younger sites pass through similar seral stages
-it is difficult or impossible to determine if sites did not differ in ways that affect
succession
how do changes in the plant community cause changes in the animal community?
ex. - Correct Answers -change the habitats that are available to animals
ex. esearchers examined the distribution of bird species along the successional seral
stages on abandoned agricultural fields in North Carolina (see ppt for pic)
why can succession in an intertidal community occur rapidly after a disturbance? -
Correct Answers -short generation time of dominant species
example of succession in intertidal community - Correct Answers -intertidal zone of
California: examination of algae species succession
undisturbed boulder: red algae dominated
when waves overturn the boulder: algae is removed
disturbed boulder: sea lettuce dominates and prevents red algae from colonizing--
>attracts crabs
why do streams undergo rapid succession? - Correct Answers -organisms can move
downstream from sites that are less disturbed
how does rainfall disturb a stream? - Correct Answers -heavy rainfall increases the
volume and speed of water, causing sand and rocks to tumble downstream and wipe
out most plants, animals, and algae
, example of stream community succession after a flood - Correct Answers -initially, all
algae and insects were removed
- the stream rapidly became colonized by diatoms- algae species followed
algae caused insects to lay eggs in the stream
model for pond/ lake succession - Correct Answers -suggests slow transformation:
1. after a lake or pond is created, the edge of the water body is initially colonized by
plants
2. the plants expand laterally across open water and begin accumulating dead plant
matter (peat)
3. continue to expand and the peat layer becomes thicker
4. eventually covers the lake surface and peat sediments fill in the basin
based on research, what is a different model for lake/pond succesion? - Correct
Answers -suggests that a lake may undergo 100s of years of succession with brief
episodes of rapid change:
1. open lake or pond experiences a drought of one or more decades and the water level
falls
2. plants colonize the newly exposed lake sediments
3. as the drought ends, the lake fills and living plants detach from lake sediments and
float on the lake's surface
4. peat sediments eventually fill the basin
how does species richness change from the time of the initial disturbance to the time of
succession (consistent across most cases of succession) - Correct Answers -after the
disturbance: zero species richness
succession: increases rapidly at first, but then plateaus and slightly declines
ex. of pattern of species richness in succession - Correct Answers -Oosting's research:
survey of succession in Duke Forest and in Sousa's study of intertidal succession,
species richness exhibited a pattern of rapid increase, followed by a plateau and a small
decline
why do early and late succession species have differing traits - Correct Answers -result
from trade-off of high dispersal, rapid growth, and early reproduction with enhanced
competitive ability
example of differing traits - Correct Answers -Late-succession trees: produce a few
large seeds that grow well under harsh, low light conditions
early-succession trees: produce many small seeds that grow poorly under low light
conditions, but disperse and grow well in high light conditions
facilitation
