Exam 3 - Lecture Notes Flashcards
What is the theme of disease and parasitism
Maintaining genetic variation in parasitic resistance through a coevolutionary arms race
hosts selected for…
getting better at dealing with parasites
parasites selected for
improving infection upon hosts and transmission to new hosts
The red queen hypothesis
continued development is needed to maintain fitness relative to what each is coevolving with
Assumptions of the red queen hypothesis model
1) the hosts can detect foreign objects
2) hosts and parasites reproduce sexually
Parasite genetics
The idea that hosts lag behind the parasites while parasites forge ahead due to their greater capacity to renew their genetic diversity
SIR Model define
transmission of microparasites, effects on host shown b/t compartments
SIR Model variables
alpha: per capita rate
beta: transmission rate
v: per capita recovery rate of hosts
Y: rate of loss of immunity
b: births
d: deaths
Ex of SIR Model
Crows infected by west nile virus when first detected in area
in lab: 100% mortality
in wild: some develop immunity, recovery follows
SIR Model function
infections rise to peak of x=Y/beta
then falls to 0 at equilib point
host develops immunity and infection dies out
Ex of macroparasites influencing parasites
Barn swallow and mites - reduction in success of nestling
de Lope and Moller - fumigation of nests showed that treated nests had greater nestling success and the addition of a clutch
Lyme disease
Involves bacteria ticks and mammals
Life Cycle of Lyme disease
2 years in length
females lay eggs on the ground
eggs hatch to larvae which find small mammals and birds to feed on (summer and fall)
molt into nymphs (late spring & summer)
molt into adults (fall)
larvae and nymphs pick up the bacteria while feeding on mammals
Balance of Nature Model - historically
s of plants and animals were fixed and in equilibrium and deviations were seen as punishment from divine powers
Balance of Nature Model
Involves a limiting factor and regulating factor
Limiting factor define
if a change in the factor produces a change in average or equilibrium density
example of limiting factor
Disease in white-tailed deer - if abundance is higher without the disease
Regulating factor define
if the percent mortality caused by the factor increases with population density
example of regulating factor
disease in white tailed deer - if it causes a higher fraction of losses as density increases
Extrinsic factor define
affect population from the outside (predation, disease, physical and chemical aspects)
Intrinsic factor define
affect pop from the inside (int w/in and vary with sex, age, size, behaviour, physiological and genetic traits)
first principle of population regulation
no closed population stops growing unless either the per capita birth rate or death rate is density dependent
Examples of dependence in first principle of population regulation
Birth rate density dependent … if it falls as density rises
death rate density dependent … if it increases as density increases
inversely density dependent rates … if birth rates increase as density rises or if death rates decrease as density rises
Second principle of population regulation
differences between 2 pop in equilibrium density can be caused by variation in either density dependent or density independent per capita birth and death rates
Factors that can alter the second principle of pop reg
Slope - steeper = lower equilib density; general position - raised or lowered
Additive mortality
subtracts individuals (adds to mortality)
compensitory mortality
does not subtract individuals, but replaces those that would have died anyways, ultimately not changing the pop size - to a certain point
Example of additive mortality
Bobwhite Quail
What causes large pop fluctuations in the tent caterpillar
1) weather - produces run of good and bad years
2) insect parasites and predators - attack with delayed density dependent lag effects that become cyclic
3) disease - virus opportunistically spreads during peak years and thendeclines — STRONGEST SUPPORT FROM NPV DISEASE
Match/Mismatch hypothesis
pop regulation in many fish is determined in early life stages;
mismatch is detrimental
Match/Mismatch successes
high - eggs hatch when food abundant curves overlap
low (mismatch) - food scarce and curves separate
Ex of low success/mismatch
Atlantic Cod and copepods
surface T increases; copepods density increase, larval cod metabolism increase, cod success decreased
Why did the alaskan king crab pop crash
high larval mortality -
fem mature @5, males @10 - only males taken (incorrect)
fem molting limits time to copulate & fem prefer to mate with large males
Why do Lobster fisheries in Australia do well
harvest juviniles in shallow water before they spawn, limit traps used based on the number of egg carrying females trapped
Biological control
use of predators, parasites, or disease to control pests - includes genetic manipulations in crops, sterilization of pests, and mate disruption with phermones
example of biological control
Prickly pear cactus - australia
brought from US and became pest - moth, Cactoblastis cactorum, from argentina, was a successful biological control bc larvae burrow into and feed within pods to allow pathogens to enter
Cultural control
pests are reduced by agricultural manipulations involving rotation, stvp cropping, burning residues, or staggering plantings
What are the three types of pest control
Biological, Cultural, and Integrated
resource concentration hypothesis
crops as monocultures are vulnerable
ex of cultural control
Rice and rice blast fungal disease - plant two varieties of rice
1) traditional - susceptible to blast (tall) in single rows
2) new high-yield - resistant to rice blast (short) in rows of 4
result: rice blast reduced and yield increased by 10-15%
integrated control
integrated pest management, the use of both biological and cultural methods with minimal pesticides and maximal natural control
What do push-pull strategies help behavioural ecology to do
1) push - make a resource unattractive
2) pull - lure pests to an attractive source, then reduced or destroyed
Push-pull ex
Corn and stem boring insects in Africa - problem 10-15% losses
soln: use intercrops and traps in fields - boreres repelled (push) by molasses grass and attracted to (pull) napier grass where they oviposit with success
What are the two paradigms of conservation ecology
1) small pop paradigm
2) declining population paradigm
What are the challenges of the small pop paradigm
1) inbreeding depression
2) genetic drift - changes in allele frequency due to change
3) susceptible to change demographic events due to low genetic variability
exs of small pop paradigm
1) Kakapo - large, late maturing, island dwelling, nocturnal, burrowing, flightless parrot
2) Hawaiian Crow - extinct in wild
What is the goal of small pop paradigm
Escape an extinction vortex - series of positive feedback loops that ratchet already small pop even smaller until extinction
What is the declining pop paradigm
one of the conservation ecology paradigms that involves detecting, diagnosing, and halting a pop decline - action and soln oriented with the most important part being the downward trend, not pop size
Ex of declining pop paradigm
Prairie Chicken pop fragmented by agriculture (millions in 1800s, 25,00 in 1933, and 50 by 1993)
Low hatching success attributed to low genetic diversity - hatching improved after 271 birds translocated over three years from other states
Define biodiversity
of species in a community or region; indices often weighted by relative abundance and evenness
What is a biodiversity hotspot
An area that is more diverse than others
List the factors that cause diversity gradients (6)
1) evolutionary speed hypothesis
2) geographic area hypothesis
3) interspecific interactions hypothesis
4) ambient Energy hypothesis
5) Productivity hypothesis
6) intermediate disturbance hypothesis
What is the evolutionary speed hypothesis and an example
a) Life in tropics more likely to evolve and diversify more rapidly (constant stable conditions)
b) diversity is a product of evolution and thus dependent on t available to develop (mammals)
What is the geographic area hypothesis
larger areas support more species, tropics one big area (increase in # habitats/ m2 as proceed towards equator and therefore lower extinction rates)
What is the interspecific hypothesis
Intense competition and predation pressure in the tropics allows for higher diversity - keystone species
Keystone species
May increase diversity by decreasing competitive exclusion
ex keystone species
pisaster sea star - present, higher diversity; removed, lower diversity
what is the ambient Energy hypothesis
Energy available generates and maintains species diversity gradients above 45-48 degree latitude; below expanded more by water availability; water and E levels interact across changes in temperature
What is the productivity hypothesis
greater primary production results in greater diversity - makes sense but little support from plant community
what is the intermediate disturbance hypothesis
biodiversity will reach a maximum at some intermediate level of disturbance
from A, reduced disturbance higher diversity
from B, reduced disturbance, lower diversity
What is ecological succession
the gradual change in plant and animal composition in an area following disturbance
What is primary succession
succession on newly exposed geological substrates, not significantly modified by organisms
ex of primary succession
after lava flow on glacial recession
what is secondary succession
succession in areas where disturbance destroys a community without destroying the soil (geological substrate)
exs of secondary succession
after a forest fire or abandoned agricultural fields
What is a pioneer community
the 1st plants and animals to colonize an area, say the first 20yr or so
what is the climax community
succession generally ends with relatively stable conditions until disruptive again
ex of a climax community
mature forest
List the models of what could drive succession
1) The facilitation model
2) the tolerance model
3) the inhibition model
Who created the models that could drive succession
Connell and Slatyer
What is the facilitation model
A model that could drive succession that states that pioneer species colonize available space
modify the environment
less suitable for themselves
more suitable (facilitate) for other species that take over (replacement species)
replacement species no longer facilitate colonization of other species and may end a chain of facilitations
What is the tolerance model
A model of what could drive succession that is characterized by early stages not limited to pioneer species - species colonizing early stages do not facilitate colonization of species characteristic of later stages
What is the inhibition model
A model of what could drive succession that states early occupants modify environment
less suitable for both the early and late successional species
they “inhibit” colonization of late arrivals
other late species can only invade after further disturbance (community of long-lived resistant species)
ex of tolerance model
primary succession on Mount St. Helens - eruption 18 May, 1980
colonization above tree line slow, lower mudflow, no surviving plants
8 species colonized by 1990s
# species leveled off by late 90s
plants must overcome erosion, low nutrients, and drought
first to exploit do well –> tolerance model
ex of facilitation model
primary succession on volcanic island of surtsey
new island in 1963
first higher plants - trouble with volcanic sand & severe winters; nutritional conditions limited plant colon until 86
Gulls arrived in 70s and birds and plants increased:
- brought seeds on three longs
- deposited nutrients (N+) from feces
1995 shrubs appeared
first lower plants - concentrated around warm sea vents
ex of inhibition model
primary succession on Lake MI Sand Dunes @ wilderness state park
72 dune ridges formed, disturbed by fire and logging since then
wind moves the dunes
first - dunes grasses; hold sand but die out in 20 yr
then shrubs and pine trees
mixed pine forest by 200yr
hardwoods after 400yr
small seeds by wind but low survivial
large seeds more hardy but rodents eat them
Define food web
summary of feeding interactions within a community
define food chain
a single line from prey to subsequent predator, and to next predator, etc.; (becomes web as more species discovered)
trophic levels
source of energy for organisms divided into hyperparasites and mesoparasites
what are hyperparasites
parasitize parasites
what are mesoparasites
below tertiary consumers
What is a guild
a group of species exploiting a common resource base in a similar fashion
what is an example of a guild
nectar feeders
define functional role
what they do in the community
broad and specific example of functional roles
broad - decomposers or producers
specifically - pollinators
What two things do guilds and functional roles do
1) simplify the components of communities to help us understand how they are organized
2) reminder that ecological units are not taxonomic units
what are two examples of both guilds and functional roles
shredders - aquatic invertebrates that are the 1st to eat leaf litter
Nitrogen fixers - prokaryotes that convert atomspheric nitrogen to ammonium
what is a dominant species
exert strong effects on community by virtue of their high biomass (abundance)
exs of dominant species
trees in a forest
grass in grasslands
corals in reefs
kelp in marine habitats
define keystone species
despite low biomass, exert strong effects on their community
predator example of keystone species
Sea Otters- predator of Northwest Kelp forest; kept sea urchins in check
fur trade resulted in severe otter declines by 1900, kelp forest near destruction due to herbivory by sea urchins
herbivore example of keystone species
African Elephant- herbivore of open woodland; nondiscriminately browse on grass, tress and shrubs keeping them all in check; cyclic process maintains an open woodland
List the models of community organization
1) top down
2) bottom up
what is a top down model
trophic cascade, predation controls community organization; plants control nutrients
example of a top down model (general)
Freshwater systems - removing the top predator (bass) leads to an increase in primary carnivore (minnows), then decrease in herbivores (zooplankton), increase in phytoplankton, defense plants depress amounts of available nutrients
What is the bottom-up model
nutrients control community organization; nutrients control plant #, to control herbivore #s
example of a top down model
Zion National Park - human pop rose to levels to suppress puma pop, mule deer pop exploded, increased browsing on cottonwoods, soil stability decrease causing stream banks to erode, large loss of cattails, frogs and toads
What is ecosystem metabolism
the sum of the metabolism of individual organisms; organisms as machines that process E and associated materials
autotrophs - E and ex
Energy from the sun and materials from nonliving sources; green plants
heterotrophs- E and ex
Energy and materials from eating living matter; herbivores and carnivores
What is an ecosystem
organisms and the abiotic environment, including movement of E and materials
what is the goal of an ecosystem
goal is to ID foodweb and associated species that significantly contribute to metabolism
List the measurements used to define metabolic significance
1) biomass
2) flow of chemical materials
3) flow of Energy
biomass and ex
weight or standing crop; timber industry
flow of chemical materials
ecosystem as a super organism with inputs and outputs;
can be recycled
flow of energy
ecosystem as an Energy transformer;
takes solar E and fixes some of it in photosynthesis
transmit plant to herbivore to carnivore
E passes through only once to be released as heat
define compensation point
where photosynthesis = respiration
define grass primary production
energy or carbon fixed through photosynthesis per unit time
define net primary production
energy or carbon fixed through photosynthesis minus energy or carbon used in respiration per unit time
true or false, plants only conduct photosynthesis as a means of E
False; plants also do respiration
List the two methods of measuring primary production
Harvest Method
Gas exchange method
What is the harvest method
a method of measuring primary production that is the amount of plant material produced during a given unit of time (whole plant or at meristems) that is converted to E by measuring calories in a bomb calorimeter
Example of the harvest method
timber production or crop yield
What is the gas exchange method
a method of measuring primary production that is usually measured as O2 release (easier) rather than CO2 uptake (harder); repeat procedure in the dark to measure respiration - allows for both gross and net estimates
State the equation for the gas exchange method
Efficiency of gas = (E fixed by gross)/(E in incident sunlight)
What are the factors that limit productivity in aquatic systems (4)
depth to which light penetrates
water absorbs solar radiation
Temperature affects light intensity
Nutrients: N and P linked to fertilization of small farm ponds which leads to an increase in fish pop
what is eutrophication
excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen
Evidence of eutrophication
Schindler experiment in Lakes; phosphate and nitrate for 5 years –> 50-100 times phytoplankton
Another lake basin added phosphorus –> algal bloom
What did Charles Darwin suggest about primary production and plant diversity
Increase production = increase in diversity
What did Tilman suggest about primary production and plant diversity
Different plant species get along better if different niches, thus resources would get completely used with high diversity
more species –> more competition —> reduced diversity
Evidence for Tilman’s model of primary prod & plant diversity
Park Grass experiments, England
Production is high, diversity drops to right side of curve
(some cases might just flatten eg. tropic areas)
What are the two fates of plant biomass (2nd production)
a) eaten by herbivore later eaten by carnivore
b) eaten by detritvore
what is the assimilation rate
the sum of the respiration rate and productivity
what is the respiration rate (lab)
estimated by measuring O2 consumed, CO2 output, and heat production
what is basal metabolic rate
amount of E expended while at rest, regulate T and post-absorptive
what does gross productivity of a plant equal
assimilation rate
what is the respiration rate (field)
injecting animal with doubly labeled water to estimate the difference b/t loss of H+ and O2 isotopes (observed CO2 loss)
what is net production
measured in population growth of individuals or reproduction of new animals, usually as biomass or kcals
ex of net production
African Elephants in Uganda
results: over 99% of E used in maintenance or lost in feces
high variation, difficult to replicate
List the three problems estimating 2nd production
1) not always adhere to specific trophic levels
2) what to do w/detritus?
3) difficult to sample adequately
What is not adhere to trophic level?
one of the three problems in estimating 2nd production that states the higher up in the food chain a species is, the more difficult it is to categorize species
ex of not adhere to trophic level
Squirrels as herbivores, yet eat meat opportunistically
plants are producers
define detritus
plant production not consumed by herbivores
what to do about detritus?
one of the three problems in estimating 2nd production that states that this does not belong in 1st trophic level w/dung & that it is outside typical levels
Creates a complex food web
What is difficult to sample adequately
one of the three problems in estimating 2nd production that states that it is challenging to get adequate measurements, especially during non equilib conditions in changing ecosystems
Ex of difficult to sample adequately
Aquatic systems w/plankton and macroinvertebrates
requires much time and $$$ to get good data
What is nutrient cycling
Use, transformation, movement and reuse of nutrients
Energy in an ecosystem
Makes a one-way trip through ecosystems
Define nutrients
elements required for the development, maintenance, and reproduction of organisms that are used over and over in an ecosystem
Examples of nutrients
Phosphorus (P), Carbon (C), Nitrogen (N), Potassium (K), and Iron (Fe)
What is a tracing exercise
Trace a single ion through an ecosystem
Example of a tracing exercise (steps)
1 - diatom in surface water absorbs the ion and integrates it in DNA
2- one of the diatom daughter cells eaten by Cladoceran and –> ATP
3 - eaten by a minnow and –> combined with a lipid and placed in cell membrane
4 - eaten by Northern Pike and –> into its skeleton
5 - dies in winter –> dissolved into the water during decomposition
6- spring diatom takes up ion and cycle begins again
Why is the phosphorus cycle important
essential to energetics, genetics, and structure of living systems
Where do you find phosphorus
mostly in mineral deposits and marine sediments
eg. sedimentary rocks, weathering rocks
Phosphorus cycle
most often released from weathering rocks, used and recycled
Why is geological uplift important to the phosphorus cycle
It is over the sedimentary rock that allows for new land formation causing the cycle to be complete
Why is the nitrogen cycle important
important to structure and functioning of organisms
What does phosphorus form parts of?
ATP, RNA, DNA, and phospholipids
What does nitrogen form parts of?
aa, nucleic acids, and parts of the chlorophyll and hemoglobin
What nutrient may limit primary production?
nitrogen
T or F Lightning can fix nitrogen
true
What is denitrification
conversion of nitrate to molecular nitrogen (n2) by bacteria
What is the nitrogen cycle?
Nitrogen fixed, enter animal consumers, cycles back, exits organic matter thru denitrification, back to atmosphhere, fixed again …
Where is nitrogen in a warm ecosystem
found in understory, then woody biomass
where is nitrogen in a cool ecosystem
found in understory, yet forest floor continues to build (decomposition is slower in cool climates)
How should logs be processed? Why?
Logs should be processed in the field to leave bark and branches behind so that the entire nitrogen pool isn’t taken away
Why is the carbon cycle important
essential part of all organic molecules
How does carbon move between the atmosphere and organisms
Photosynthesis and respiration
What is the process of removing atmospheric carbon
photosynthesis (CO2)
What is the process of returning atmospheric carbon
respiration (CO2)
How is CO2 available in aquatic ecosystems?
It must first be dissolved before it is available to primary producers –> carbonate will precipitate out and eventually be buried in ocean sediments
Where does carbon take a long time to return back to the atmosphere?
in soils, peat, fossil fuels, and carbonate rock
What are the 5 main ecological lessons?
1) predator-prey interactions
2) competition
3) population cycles
4) ecosystems
5) energy and nutrition
What is the small population paradigm
One of the two conservation ecology paradigms that focuses on rare species & the pop consequences of being rare and the problems that come with it
