| Competition | -interaction between individuals for limited resources
-reduces survival, growth and fertility
-(-/-)
-inevitable consequence of increased population size and limited resources |
| Intraspecific Competition | competition between individuals of same species |
| Interspecific Competition | competition between individuals of different species |
| Which type of competition is most common? | intraspecific --because similar resources, space and reproduction |
| What is interspecific competition important for? | 1. Natural Selection
2. Fixation of adaptive traits in species
3. Phenotypic divergence of species
(all above increase differences between species)
4. abundance and distribution of species |
| What is Interference Competition? | -direct interaction of individuals
-aggressive behaviour ,defending territory, fighting after food
-each individual has a negative impact on the other |
| Avoidance of Competition leads to... | (-/-)
-Interspecific competition decreases overtime
-traits in 1 or both species evolve (character displacement)
-effectively decreases 2 species from competing for limited resources
-harder for intraspecific competition because it would lead to speciation (need to be similar enough to mate) |
| What is Exploitative Competition? | (-/-)
-indirect interaction
-harmed by taking up resources
-one individual more negatively impacted than the other, but still a cost to both |
| What are the 6 mechanisms of interspecific competition? | 1. Consumption
2. Pre-emption
3. Over-growth
4. Chemical Interactions (Allelopathy)
5. Territoriality
6. Encounter Competition |
| What is Consumption? | one species inhibits another by consuming a shared resource |
| What is Pre-emption? | primarily sessile organism occupies physical resource
ex. barnacles |
| What is Over-growth? | one organism grows directly over another, with or without contact
ex. plants competing for light |
| What are Chemical Interactions (Allelopathy)? | chemical growth inhibitors or toxins produced to inhibit competitors growth |
| What is Territoriality ? | aggressive behaviour to exclude others from units of space |
| What is Encounter Competition ? | Non-territorial encounters between foraging individuals
ex. going for same prey |
| What are the differences in competition of plants and animals? | 1. Biological Differences
2. Wide size variation in plants
3. Competition for same resources in plants |
| What are the biological differences of competition between plants and animals? | plants are sedentary so generally a smaller scale / immediate neighbour most important |
| What is the Competitive Exclusion Principle? | -exclusion often occurs between related species
-Gause says no 2 species can co exist
"Complete Competitors Cannot Coexist" |
| What did Gause do/find? | **limited resources increase competitive intensity **
-alone and together
-full and half resources
intraspecific competition determines K
-with one species both survive at half and full resources
-with both species, one species goes extinct in half and full resources
-one species --> lower K with half resources
-both species --> extinct quicker with half resources |
| Why do we use models? | models yield important predictions about conditions promoting coexistence and exclusion |
| Competition Coefficients ? | alpha - effects of species 2 on growth rates of species 1
beta - effect of species 1 on growth rate of species 2
alpha and beta are not always equal to each other |
| if alpha/beta = 1 | species have same effect one each other |
| if alpha/beta =4 | effect of species 2/1 is same effect on growth rate of species 1/2 as adding 4 of species 1/2 |
| if alpha/beta > 1 | per capita effect of interspecific competition is greater than intraspecific competition |
| if alpha/beta < 1 | intraspecific competition is greater than interspecific competition |
| if alpha/beta = 0 | no competitive exclusion |
| State Space Graphs | plots abundance of species 1 on x axis and species 2 on y axis |
| dN1/dt= | rN1(K1-N1-alphaN2/K1) |
| dN2/dt = | rN2(K2-N2-betaN1/K2) |
| When is coexistence possible? | when per capita rates of inter comp are weaker than the per capita rates of intra comp |
| 3 factors that determine distribution? | -environments
-competition
-predation |
| What are 4 ways to see coexistence ? | 1. Spatial Heterogeneity
2. Variation in Competition Ability
3. Competitive Equivalence
4. Non Equilibrium Conditions |
| What is Spatial Heterogeneity? | -Caused by varying resources
-many resources leads to little competition and coexistence
-few resources leads to strong competition and competitive exclusion |
| What is Variation in Competitive Ability? | -caused by genetic variation at species level and environmental conditions |
| What is Competitive Equivalence | when 2 species are competitively equal
species A will out compete Species B and vice versa at equal rates |
| What does Non-Equilibrium Conditions mean? | competitive exclusion is not instantaneous
exclusion can be in progress but appears like coexistence because so slow |
| Predator Mediated Coexistence | species can be equal in resources if predator keeps them both at low densities because resources will become limiting at a slower rate |
| 2 Outcomes of Competitive Interactions? | 1. Character Displacement
2. Niches |
| What is Character Displacement? | -evolutionary outcome that leads to competitive coexistence
-characteristics continue to become more and more different until the are not the same or so far apart the don't overlap. |
| What are Niches? | 1. needs that allow species to exist (Grinnell)
2. biological interaction and abiotic factors. "role a species plays in a community" (Elton)
3. more quantitative developed Fundamental niche and realized niche (Hutchinson) |
| What is the Fundamental Niche? | physical conditions a given specie requires |
| What is the Realized niche? | fundamental niche with restrictions
recognizes interactions between species in presence of competitor |
| Predation | -(+/-)
-one organism feeds on another
-killing and consuming part or all of it |
| Prey/Victim | organism that gets killed |
| Predator Prey Relationship | - # of predators is effected by # of prey (vice versa)
-prey # is negatively impacted by predation
-prey adapt to decrease predation |
| lynx/hare cycles explanation | 1. food availability
2. predation |
| Process of Prey Capture? | 1. Encounter - in the same place?
2. Detection - see it
3. Identification - is it food
4. Approach - sneaking up
5. Subduing Prey - immobilizing/killing it
6. Consumption - eating it |
| Describe Encounter and how a prey can avoid it | predators have to be physically close to prey to consume it
Avoid by:
go to different area
enter refuge
be active at different time of day/night |
| Describe Detection and how a prey can avoid it | predators need to be able to detect their prey
To avoid:
decrease conspicuousness
move unpredictably or abnormally
confuse pred by being in groups
ex is masting of seeds |
| What is masting? | synchronous production of seeds over long intervals by a population of plants |
| What is identification and how can a prey avoid it | predators need to be able to identify if the detected organism is in fact prey and is edible
to Avoid:
crypsis
aposematism
mimicry |
| What is crypsis? | ability of prey to avoid detection or identification by being able to blend into the background |
| What is Aposematism ? | -opposite of crypsis
-advertising a warning
1. synthesis of toxins that makes an organism unpalatable
2. honest advertising of toxic condition. typically via bright colors |
| What is mimicry? | 2 forms
1. Batesian- one species is palatable (mimic) and the other is not (model)
rely on previous encounters of poisonous model
predator associates bad experience with color
2. Mullerian Mimicry - dangerous species all look similar (ex, bees, wasps and stinging flies)
share same superficial body plan so pred only has to experience one to dislike all |
| Describe Approach and how a prey can avoid it | a predator needs to get close enough to the prey
To Avoid;
outrun predator or retreat to refuge |
| What is the life dinner principle? | the difference between running for your life and running for dinner
prey trying to escape death
predator just trying to catch a meal |
| Process of subduing prey and how prey can avoid it | predator must gain control of or kill the prey
To avoid:
be strong enough to fight
slimy/mucus covered
detach a body part (autotomy) |
| Process of consumption and how a prey can avoid it | can help relatives if consumption of prey allows predator to become sick. May not eat prey in future. Does not help current prey. |
| Herbivory? | - does not always result in death of plant
-effects plant species/community
-leads to counter adaptations
-herbivores are primary consumers
(+/-) interaction |
| Herbivory Can...(4 things) | 1. negatively affect plant fitness
OR
2. promote growth due to overcompensation (plants respond to herbivory with increased productivity)
OR
3. Control the distribution of and abundance of plant species
OR
4. Alter plant community structure and composition (where and which species are found) |
| Altering species dominance | herbivores can preferentially feed on dominate species
this alters species composition in community
ex. bison--> tall grass --> increased light at ground level |
| Specialists | target a few plant species
ex. koala and eucalyptus |
| Generalist | forage on many species
ex. deer |
| Biological Control of Invasive Species | herbivores used to control plants species
-ex. prickly pear cactus and cactus moth
not always successful:
sometimes herbivores can eat anything or not have any predators itself |
| Predator Release | add predator to environment that previously did not have that predator |
| Why is the Earth Green? Why don't herbivore eat more plants? | 1. predators and parasites control plant abundance
2. plants defend against herbivory |
| Green World Hypothesis | Predator or Top down hypothesis
We have three trophic levels
1. plants - limited by resource availability
2. Herbivores- limited by predators and parasites
3. Carnivores- food limited
HYP: herbivores don't consume all plants because predators keeps their numbers in check
density is controlled by predators. |
| Plants Fight Back! (defenses) | bottom up effect, arms race, co adaptation
Plants have defenses:
1. Mechanical - structures on plants (passion vines have cones to trap pred)
2. Biotic - animal "gaurds" (Acacia trees and ant guards)
3. Biochemical - synthesis of toxins |
| Symbiosis | long term, close interaction between at least two species
Mutualism(+/+)--> Commensalism (+/0)--> Parasitism (+/-) |
| Parasites | spends all/part of life cycle in/on another organism, which suffers some reduction in fitness
parasite typically have some extreme specialization to successfully stay on host
coevolution between host and parasite |
| Types of Parasites | MICRO-
small, short generation, reproduces with host, usually diseases (malaria)
MACRO-
long/large generation, does not complete life cycle in host (tick/ flatworm)
ENDO-
found inside hosts body
ECTO-
found outside hosts body |
| Parasite Specializations (4) | 1. mechanism of attaching to host
2. withstand host's defensive response (animals-immune system, plants-chemical response)
3. contend with natural enemies
4. reproduction and dissemination difficulty (offspring right next to them) |
| Brood Parasitism | female finds nest of 'host', lays eggs when host is gone, host raises offspring
eggs must look similar to hosts real eggs |
| Host-Parasite Coevolution | change in one may initiate change in other
1. Reciprocal Speciation : when host speciation leads to parasite speciation
2. Niche Partitioning: different parts of host body leads to speciation |
| Parasitoids | similar to parasites that live in/on a host, one big difference
-larvae develop in/on host
-development of larvae eventually kills or consumes host
-usually hymenopterans (bees/wasps) |
| Direct Transmission | -directly from one host to another
-definitive/primary host (DH)-organism the parasite matures and reproduces in
-Intermediate Host (IH) - organism required for developmental stages of parasite, allows parasite to get back to DH
-parasites can also have accidental hosts |
| Vector Transmission | -vector usually not harmed
-facilitates transfer to host
ex. malaria and mosquitoes |
| Commensalism | interaction between two species in which one benefits, one is unaffected
hard to demonstrate that one is actually unaffected |
| Mutualism | mutually beneficial interactions between members of different species
also known as reciprocal exploitation or controlled parasitism
benefits outweigh the costs |
| Facultative Mutualism | two species provide fitness benefits to each other but the interaction is not necessary to the persistence of either specie
ex. ants and aphids |
| Obligate Mutualism | two species provide fitness benefits to each other and require interaction to persist
ex lichen and fungus |
| Resource -Resource Relationships | one type of food resource traded for another
nutritional mutualism (AKA)
ex. legumes and nitrogen fixing bacteria |
| Service - Resource Relationships | ex. pollination where nectar and pollen are traded for pollen dispersal
can lead to reciprocal selection and coevolution of plant and pollinator |
| Zoochory | dispersal of seeds by animals
plant dispersal by animals often associated with traits that are presumably adaptive like color |
| Service - Service Relationships | rare to find cases of this
maybe clownfish in anemones |
| Exploiting of Mutualism | exploiters gain benefits of mutualism without any costs
involves cheating
at low levels cheating is sustainable
excessive exploitation causes mutualism to break down |
| What is a Community? | assemblage of interaction species inhabiting a defined area at a given time
typically consists of many species effected by competition, parasitism, herbivory, predation |
| Factors that influence community structure | number of indiv. in species
number of species
abundance of species |
| Biodiversity | diversity in genotype structure of communities, species diversity, ecosystem diversity and organization
Two components
1. Species Richness
2. Species Evenness |
| Species Richness | number of species found within a community
hard to determine because some species are rare |
| Species Evenness | relative abundance of different species within a community
more even communities are more diverse
opposite of dominance, a species with high evenness has low dominance |
| Rank Abundance Curves | assess both species richness and evenness
number of different species (r) on x axis
abundance of each species on y axis |
| Lognormal Distribution | few rare species, many moderate species, few abundant species (creates parabola )
found it was common across all taxon
if you didn't get parabola shape then you didn't do enough sampling |
| Preston's Veil Line | as you sample more you will unveil more species
if you sample enough Preston's line should disappear
if you have a Preston's line you didn't sample enough |
| Distribution - Abundance Model | 1. widespread species are likely to occur at high densities locally
2. species restricted in their distribution tend to be scarce |
| Why does the distribution - abundance relationship appear? | 1. Meta-Population Approach - positive feedback between local abundance and regional distribution of species
larger populations produce more offspring, increasing the chance they disperse to other locations
2. Niche Differences Among Species- density assumed to reflect species tolerance to environment condition at that location
better tolerance means better range |
| Biological Resources | products we harvest from nature |
| Ecosystem Functions | ecological processes that control fluxes of energy, nutrients and organic matter through the environment |
| Ecosystem Services | process provided by nature that support human life
ex. decomposition of waster, water purification |
| Natural causes of Biodiversity decline | small population size
competition
predation
parasitism
natural selection
environmental stochasticity
habitat loss |
| Anthropogenic causes of Biodiversity Decline | land use/change of habitat (agricultural)
exotic species invasion
resource overexploitation
climate change |
| Consequences of Biodiversity Decline | loss of ecosystem function and ecosystem stability |
| 3 Hypotheses on Ecosystem Function | 1. Sampling/Selection effect- as number of species increasing, the chance of having a species that performs all roles needed for ecosystem function increases
2. Complementarity- also niche theory, each specie has a role and having a mix of species will increase ability to extract specific resources
3. Facilitation - increased diversity means more change one species will help benefit the other species. |
| Biodiversity and stability | more biodiversity = more stability |
| Non linear effects of biodiversity | r shaped curve on graph
this shows that at mean of graph an increase in biodiversity doesn't change much but a small drop in biodiversity results in drastic change |
| What is a food web? | describes feeding relationships of organisms in all or part of the community |
| What are the links in a food web? | indicate a consumptive relationship between two species |
| Limitations of Food webs? | only a summary of one interaction
overemphasize large organisms
underemphasize small organisms (harder to quantify)
generally ignore decomposers, detritovores, parasites and parasitoids |
| So what is the value of food webs? | 1. can reveal great complexity
2. help differentiate between strong and week food relationships
3. can reveal indirect relationships between organisms |
| What do food webs tell us? | Trophic Positions- whether a species is basal species, intermediate species or a top predator |
| What is a basal species? | feed on no other species but are feed on by others
primary producers |
| What is an Intermediate species | feed on other species and are prey themselves
consumers |
| What is a Top Predator? | have no other pred |
| What is Omnivory ? | when species feed on prey located at more than one trophic level
ex. black bear (eats plants and fish) |
| What limits the number of trophic levels in a community | energy loss |
| Where does all energy come from? | primary produces |
| Energy loss from level to level | 1% of energy from the sun is used by plants
a further 10% from that 1% gets transferred to the net levels |
| How is energy lost? | lots is unusable and lost through feces or inedible structures
respiration and entropy
only small fraction used for new biomass |
| How does energy transfer knowledge help us? | biomass of herbivores is positively correlated with biomass of primary producers
communities with higher primary productivity will have more herbivores
more productive habitats will be able to sustain more consumers
more productive community will support more trophic levels in general |
| Bottom up Regulation | producers regulate consumers |
| Top Down Regulation | higher order trophic level regulate lower trophic levels
green world hypothesis |
| What is a Keystone Species? | species that exert strong effects even with a small biomass and low relative abundance
keystone species do not have to be a top predator
(most other species have proportional effects and biomass/relative abundance) |
| What is a trophic cascade? | -removal of a top predator
-powerful indirect interactions that influence ecosystem
-occurs when predators limit prey abundance, which enhances survival of lower trophic levels
-must be in at least three trophic level ecosystem |
| What is runaway herbivory ? | when predators are removed or reduced |
| Two classes of trophic cascades | 1. Population - overgrazing leads to local extinction of plant, replaced with less palatable plant
2. Community - overgrazing of entire community, large scale loss of ecosystem function |
| What makes a community susceptible to trophic cascades? | simple aquatic habitats
no replacement predators
poorly defended primary producers
*simple and homogenous communities* |
| What is an ecosystem engineer? | species that modifies habitat for many species
loss of this specie would have drastic effects to many other species |
| What are the essential nutrients ? | carbon, nitrogen, phosphorous, sulfur, water |
| Macro vs Micro Nutrients | MACRO- required in large amount for proper growth and development (C,H,O,P)
MICRO- element required in trace amounts for normal growth and development
* macro and micro can vary between organisms depending on their needs |
| What are Biogeochemical cycles? | nutrient flow from non living to living in a cyclical path
life on earth recycles essential nutrient (closed system) |
| Two major types if biogeochemical cycles? | differ due to primary source of nutrient into the ecosystem
1. Gaseous - main pool of nutrients is from atmosphere and oceans
2. Sedimentary -main pool of nutrients is from soil rocks and minerals, weathering of these is mechanism to release nutrients
*water is medium that helps move everything* |
| What is flux? | movement of nutrients from one component of the cycle to another
measured in nutrient per unit time |
| What is wetfall? | precipitation (snow, rain) bring nutrients |
| What is Dryfall? | nutrients is brought in by airborne particles (wind) |
| The Carbon Cycle | -respiration makes carbon
-photosynthesis uses carbon
-decomposers recycle carbon
-gaseous
-no wet or dry fall
-humans create combustion of fossil fuels |
| The Nitrogen Cycle | -fixation (symbiont and free living)
-decomposition
-denitrification
-gaseous (main pool is N2)
-both wetfall and dryfall from atmospheric deposition
-industrial nitrogen fixation for fertilizer causes eutrophication |
| The Phosphorus Cycle | -decomposition and uptake by plants
-sedimentary
-dust and sea spray (dryfall)
-mining for agriculture for fertilizer leads to eutrophication |
| The Sulfur Cycle | -chemosynthetic and photosynthetic bacteria
-gaseous and sedimentary
-wetfall (acid rain)
-coal mining releases sulphur into air creating acid rain |
| What is a landscape? | heterogenous area consisting of distinctive patches organised into a mosaic like pattern |
| Land elements | ecosystems in a landscape the generally form a mosaic of patterns |
| How are mosaics made | process of geological processes (volcanism, sedimentation, erosion, glaciation) and ecosystem engineers |
| Effect of Glaciers? | dramatic physical effect
crazy ability to move soil and rocks to directly reshape landscape
-U-shaped valley
-Eskars (streams flowing under the glacier)
-Drumlin Fields (lines from material of glaciers)
-Till Plane -debris left by glacier |
| Glacial Refugia | areas where populations persisted during glaciations, only places free of ice |
| Sky Islands | mountain peaks that were surrounded by but not covered by glaciers
populations from sky islands can recolonize after the glaciation
causes a cut off of gene flow
means glaciers can also change diversity |
| Landscape Structures | size, shape, number, position and composition of patches within a landscape
Patch - relatively homogenous area that differs from surrounding
Background/Matrix - element within a landscape that is mostly spatially continuous |
| Quantifying Landscape Structure | 1. Percent Cover
2. Relative Shape - how close is it to a circle |
| Edge Effect and fragmentation | exposed to greater amounts of solar radiation and wind
greatly increases negative effects
associated with higher rates of local extinction |
| The Age Argument | tropics are older than other biomes so longer time for speciation to occur
tropics less affected from glacial periods |
| Land Area in Biomes | almost as much area in tropics as in the whole Northern hemisphere combined
more land mean more habitats to sustain more species |
| Temperature | temp is warmer and more constant so less seasonal variation
more solar radiation means more mutations leading to new species
higher production rates which can support more food webs |
| 2 factors that effect species richness on large scale areas | 1. island area
2. isolation |
| island area and species richness | island size is positively associated with species richness |
| Islands and isolation | degree of isolation of an island is generally negatively associated with species richness |
| Equilibrium Model of Island Biogeography (EMIB) | predicts species diversity and rates of turnover on islands as a function of island size and location
species diversity on any island is a balance between immigration and emmigration |
| EMIB - extinction rates | rate of extinction should rise with number of species present because..
larger pool of potential extinction
more competition
increase of intra/interspecific competition |
| EMIB - equilibrium point | where immigration and emigration lines cross is the predictable number of species at equilibrium
point where species composition changes but number of species stays the same |
