ecologyexam4

• snowball earth theory=600 million years ago, the earth was completely frozen
• cold climate=low sea level
• Denver was a tropical rainforest about 60 million years ago
• oscelate between cool&warm periods(ice ages)

• Related to what happens to the earth as it revolves around the sun, causes of climate change
• Eccentricity of orbit=orbit changes from elliptical to circular every 100,000 years
• Tilt of axis=goes from 22-24.5, happens every 40,000 years
• Wobble=short term change in global climate, earth is directly pointing to the sun, happens every 10-100 thousand years

• Drop-off of animals
• Not long after humans arrived, the animals were gone.

• a group of populations of plants and animals in a given place and time
• or association of interacting species inhabiting some define area
• HAS TO BE LIVING!

• the developmental process that a community goes through, disturbances tend to reset succession
• changes physical and species make-up of that environment
• disturbances reset succession to get back to the pioneer environment

• succession from an area that has not been previously occupied
• no seed bank, no soil, no lichens, no nitrogen fixers
• bare rock, or volcanic islands

• the re-establishment of a community following a disturbance that does not remove everything to bare rock
• seed bank, trunk regeneration, or mature soils

• when a species makes it more likely that another species will colonize the community
• lichens

• when a species makes it less likely that another species will colonize the community
• predator

an early sere(stage) of succession with a high degree of r-selected species

• the final sere of succession with a high degree of k-selected species
• changes little ones it is reached, until a disturbance resets the succession

intermediate seres characterized by r and k selected species, or species with intermediate traits along the r-k continuum

all species living together in an organized, systematic manner to form a super organism

• communities even evolved in a way analogous to species over millions of years
• succession is like organismic development to get to final sere(oak forests became oak forests just as organisms becomes adults)
• -in equilibrium= each species does its part(balance)
• -saturated with species= all parts present
• -strong biotic interactions= predation in harmony
• -resource limited&optimal performance= used completely
• -deterministic= same endpoint where started

• history, chance, and randomness are important in community structure.
• a community isn't a super organism, but haphazard of organisms that have the same interests
• after cutting an oak forest, a pine forest returns
• a community is a fortuitous association of organisms whose adaptions allowed them to live together under the particular physical and biological conditions that characterize a particular place
• -nonequilibrium
• -many open niches, random
• -abiotic stresses are important(storms, droughts, fires)
• -opporutnism, new species come in
• -stochastic effects

• clements=same range
• gleason=not same range, real world, more accurate

• trophic relationships within a community
• lots of trophic levels=lots of odd plants
• even # of trophic levels=not a lot of plants
• simplified food web=more numerous, important, and more interacting species

• any species that has a greater impact on community structure than one would predict from it's abundance/biomass
• if keystone species reduce likelihood of competitive exclusion, their activities would increase the number of species that could coexist in communities

• Sea stars made the shallow subtidal diverse, with no seastars present mussels took over, species richness dropped without sea stars
• Sea otters eat urchins which eat kelp, when sea otters were removed bc of overhunting, kelp forests disappeared. Sea otters control urchin population which allows kelp to thrive.
• Kelp&corals have a large biomass, but a large impact(not keystone)
• Clownfish have a low biomass and a small impact(not keystone)

• when the impact of a top trophic level cascades down to lower trophic levels
• flow from high to low

• influence of one species on another through immediate interaction
• orca eating sea otter

• influence of a species on another species in a roundabout matter, mediated by a change in population size of a third intermediate species
• orcas indirectly influence kelp

• influence of a species on another species in a roundabout manner, mediated by a change in behavior of a third intermediate species
• change in behavior

• Removing fish will increase plant abundance
• Keeping fish decreases plant abundance

• remove exploitive species
• example=sea stars eat barnacles&mussels, mussels are a competitive dominant species, barnacles and seaweed compete, chitin eats seaweeds, and welks eat barnacles

• exotic species have dramatic impacts on communities because they were outside the evolutionary experience of local prey
• nile perch-government introduced exotic fish predator to lake victoria, fish fauna dramatically reduced. the food web was simplified with the new fish.
• many problems with this fish, it was too big to catch, had to cut down forest to smoke it, dissolved oxygen concentrations decreased, and cultural eutrophication.

• introduced oppossum shrimp to lake to increase profit
• increased amount of trout because trout eats oppossum shrimp
• example of scaling
• oppossum shrimp ate zooplankton then hid
• became competitors with trout.
• trout died=no fishermen, no eagles=no money

• DDT=ideal pesticide, cheap, persistent, soluble in diesel fuel, highly toxic to insects, but non toxic to people
• developed prior to WWII, widespread use, banned in USA now
• found in inuit breast milk
• almost 2 million tons produced throughout history, 5000 tons still used

• bioaccumulation=storage of chemicals in adipose tissue
• biomagnification=increase in pollutant concentration as you move up the foodweb

• Before pesticide use, about 30-35% of crops were lost to pests
• After decades of persistent use of pesticides, the same percent was still lost to pests.
• Some pesticides kills herbivores and predators, but herbivores adapt easier
• Humans have exposed ourselves and nature to many poisons with untested consequences
• Gain no agricultural benefit

• Biological control=the use of living organisms to control the population size of pest usually with predation or parasitism
• Many pests are exotic species
• Classical biological control=going to the pest's native range to find a predator&treating an exotic species with a different exotic species
• Conservation biological control=control of exotic pest using a native biocontrol agent

• Can be a good idea
• Example: prickly pear and moths in australia, too many rabbits, introduced virus to rabbits

• A bad idea
• Example: introduced frog but it eats everything, can't get rid of it

• A great idea
• good because its native
• praying mantis&ladybug controls pests
• Birds of prey control rodents

• The application of ecology to manage the population sizes of pests
• Uses a variety of tools
• -chemicals are used judiciously, apply little
• -trap crops, plants an area of crop early to attract pests and spray them
• -biocontrol agents are encouraged, ladybugs/spiders
• -crop rotation returns
• -monocultures replaced with polycultures, crop rotations
• -sterile males, no eggs/reproductive failure
• -vacuums instead of tractors

• Sousa studied effects of disturbance on diversity of algae and invertebrates growing on boulders in the intertidal zone
• Predicted level of disturbance depends on boulder size, large boulders require more force to move
• Boulders supporting greatest diversity of species were those subject to intermediate levels of disturbance=consistent with intermediate disturbance hypothesis
• Size of boulder represented the degree of disturbance

Richness correlated with island/lake size

• looks at how island properties affect species richness
• chances of colonizing is greater when richness is low because of open niches
• immigration is high when richness is low
• few species=low extinction, more species=greater extinction

• small island=increase in extinction
• close islands=increase in immigration
• large, close islands have an increase in amount of species

• remote islands have fewer bird species
• near mainland has more species
• has no effect on ferns

there is more tropical area than polar area

• frontier forests=original forests
• leading cause of species extinction=habitat loss&exotic species
• species need undisturbed frontier forests to survive

• 25 hot spots
• 1.4% of the earth, houses 40-60% of species
• to qualify as a hotspot, an area must contain 1,500 or 300,000 endemic plant species in the world and must have lost at least 70% or more of their natural vegetation and habitat
• areas of concern because lots of diversity, these areas are in a developmental pressure

• planthoppers have a habit of aggregating, rapid growth, and the mobile nature of their food supply
• demonstrated intraspecific competition within populations of planthopper Prokelesisia marginata(probably result of limited resources)
• increased populations=lower survivorship, increased development time, and reduced body size

• Hutchinson defined a niche as an n-dimensional hyper-volume(n equates the number of environmental factors important to survival and reproduction of a species)
• Are variables that define an environment
• Environmental factors that influence growth, survival, and reproduction of a species

• Degree of competition depends on this
• Not much overlap=less competing
• Endimensional hypervolume=beyond 3D
• Niches are abiotic

• fundamental=physiological tolerance, ideal lab conditions, hypervolume, determined by physiological adaptions and parameters
• realized=ecological tolerance, real situation with competitors/predators, includes interactions such as competition that may restrict environments where a species may live(reality)

• two species with identical niches cannot coexist indefinitely
• one will be a better competitor and thus have higher fitness and eventually exclude the other
• exception is a warbler=resource partitioning

• Study of interspecific competition between T. confusum and T. castaneum under varied environmental conditions
• Growing two together suggested interspecific competition restricts the realized niches of both species to fewer environmental conditions
• When grown alone, both species thrived

• Grant found differences in beak size among ground finches related to diet
• Size of seeds eaten can be estimated by measuring beak depths(individuals with deepest beaks fed on hardest seeds)
• After a drought, remaining seeds were very hard, so mortality was heavy in birds with smaller beaks
• Can separate niches by separating seed size
• Shows natural selection&intraspecific competition

• If competition among rodents is mainly for food then small granivorous rodent populations would increase in response to removal of larger granivorous rodents(insectivorous rodents would show little or no response=noncompetitor)
• results supported this hypothesis, removed competition and numbers of small granivores increased

• Because degree of competition is assumed to depend upon degree of niche overlap, interspecific competition has been predicted to lead to directional selection for a reduced niche overlap
• Directional selection=a mechanism to minimize interspecific competition
• Character of species shift in one direction to minimize competition and move niches further apart

• Interaction between populations that enhances fitness of one individual while reducing fitness of the exploited individual(bad for individual being consumed)
• Predators kill and consume other organisms
• Parasites live on host tissue and reduce host fitness, but do not generally kill the host
• Parasitoid is an insect larva that consumes the host(same size as host)
• Pathogens induce disease

• Rust fungus(Puccinia) manipulates growth of host mustard plants.
• Puccinia infects plant rosettes and invades actively dividing meristematic tissue
• Rosettes rapidly elongate and become topped by a cluster of bright yellow leaves
• Pseudo flowers are fungal structures including sugar containing spermatial fluids(attracts pollinators)

• the presence/absence of a protozoan parasite(adeline) influences competition in flour beetles(tribolium)
• parasite lives as an intercellular parasite(reduces density of castaneum but has little effect on confusum)
• castaneum is usually the strongest competitor but with the presence of the parasite, confusum becomes the strongest competitor(exploitation alters competition and other factors-parasites reverse competitive ability of species)

• Introduced cactus and herbivorous moth
• Prickly pear cactus was introduced to australia, which established populations in the wild
• Needed to control cactus, moth was found to be an effective predator(reduced 3 orders of magnitude in 2 years)
• Example of plastical/biological control

• snowshoe hares&lynx
• extensive trapping records
• proposal that abundance cycles are driven by variation in solar radiation
• another proposal suggested overpopulation theories(decimation by disease&parasitism, physiological stress at high density, starvation due to reduced food)

• predator-prey competition/oscillation
• lynx #'s increased when hare #'s decreased
• affected by predation, food, etc

• Both in effect=dramatic change, centeragism
• Combined effect is greater than a single effect
• top down=predators
• bottom up=food

• normal oscillation=predator&prey numbers vs. time
• but removing time off the x-axis and replacing it with prey reveals an elliptical oscillation

• to persist in the face of exploitation, hosts and prey need refuges
• in a simple environment, both prey and predators become extinct without refuges
• with a refuge, the prey populations survived but the predator population went extinct
• immigration/introduction of predators would cause regular oscillations

• prey mites and predator mites placed in a box with oranges and rubber balls with partial barriers to mite dispersal
• predator crawls while prey balloons
• provision of small wooden posts to serve as launching pads maintained population oscillations for 6 months
• shows habitat complexity and migration on its own
• they can maintain themselves

• periodical cicadas emerge as adults every 13-17 years
• large densities
• mass emergence of cicadas=predators overwhelmed
• cicada way to survive is to overwhelm
• predators kill a significant amount when cicada density is low
• as cicada density increases, predation is low
• as cicada numbers drop, the amount killed by predators increase
• predator-pey oscillation

• interactions between individuals of different species that benefit both partners
• facultative mutualism occurs when a species can live without its mutualistic parter(not dependent, but benefits)
• obligate mutualism occurs when a species is dependent on a mutualistic relationship(dependent for survival)
• there's evidence that eukaryotes originated as mutualistic associations

• Hardie suggested mycorrhizal fungi improve water relations by providing more extensive contact with moisture in rooting zone and providing extra area for water absorption
• fungus dissolve minerals, which mean better nutrients
• experiments show that plants with mycorrhizae maintained higher leaf water potential throughout a hot summer day

• Herbivores attempting to forage on acacia plants occupied by acacia ants are met by a large number of fast, agile, highly aggressive defenders
• Ant benefits: thorns provide living space, folliar nectaries provide sugar, beltian bodies are a source of oils and protein
• Example of obligate mutualism
• Performance of trees was better with ants, grew much faster w/ the removal of herbivores&competitors
• Survival of trees was greater&their were less herbivorous insects with the ants

• Zooxanthallae live within coral tissues
• Receives nutrients from coral, in return, coral receives organic compounds synthesized by zooxanthallae during photosynthesis
• Corals induce release of organic compounds with "signal compounds" that alter permeability of zooxanthallae cell membrane
• Corals control rate of zooxanthallae population growth and density by influencing organic matter secretion
• Zooxanthallae uptakes potassium and especially nitrogen(ammonium) excreted by the coral

• Facultative mutualism
• shrimp chases away sea stars that try to attack coral
• predation is higher with out snapping shrimp
• coral is healthier with shrimp, increased fat body production.

• cleaning behavior is an association in which various species of shrimp or small fishes clean larger fishes of ectoparasites
• facultative mutualism
• cleaner fish gets consumed to clean mouth of big fish
• cleaner fish gets a meal and big fish gets rid of parasites
• Blenny is nasty, imitates cleaner fish but rips out chunk of gill of big fish

• natural human mutualism
• honeyguides are african birds which feed on beeswax and insects, guides mammals(including humans) to bees nests
• mammal robs nest for honey and honeyguide forages on bee larvae&wax
• honeyguide flies near mammal and makes a distinctive call
• bird flies away in a given direction then reappears, perches or flies again in the same direction, establishing a route, badgers produce whistles as they follow(native humans use similar whistles), bird behavior changes near site, search time is reduced to about 5 hours, nests would be inaccessible to birds without gatherer
• Honeyguides are brood parasites=lies eggs in another nest then those parents have to raise them, has sharp beaks to kill nest mates.

• -Land(insects) make up a majority of described species
• -Marine species are less studied and well known because most are deep sea organisms(pelagic)

• trend of more species towards equator
• tropical rain forests and coral reefs have high species diversity(50-80% of all extant species)
• 1 hectare(2.4 acres) of rainforest can have 400 species of trees
• higher latitudes=less diversity
• pollinators are important in tropical rain forests(specific pollinators)

includes attributes such as number of species, relative species abundance, and species diversity

• group of organisms that all make their living in the same fashion(all seed eating animals in the desert)
• not taxonomic, depends on lifestyle

richness and relative distribution of their abundance

• graphed abundance of species in collections as frequency distributions
• bell-shaped curves
• in most lognormal distributions, only a portion of bell-shaped curve is apparent(sample size has large effect&significant effort to capture rare species)
• three parts=rare, intermediate(most species), and common
• graphs show # of moth species vs. # of individuals in a species

• two factors define species diversity
• species richness(can be diversity also)=number of species in the community
• species evenness=relative abundance of species, doesn't equal species richness

• a two tree community shows importance of abundance
• greater species evenness=greater species diversity

• can also portray relative abundance and species diversity within a community by plotting relative abundance of a species against their rank in abundance
• greater evenness=lower slope

• in general, species diversity increases with environmental complexity or heterogeneity
• MacArthur found warbler diversity increased as vegetation stature increased(measured complexity as foliage height)
• habitat complexity positively contributes to species diversity

• biodiversity=many different kinds of species, not species richness
• character diversity
• functional diversity
• community/ecosystem diversity
• genetic diversity
• population diversity
• family/order/phylum diversity
• species diversity

• different morphologies
• don't take into account taxonomy

different tasks/jobs

amount of adapting alleles within group

different amounts of populations

# of family, order, phylum

• richness&evenness
• alpha=diversity within habitat
• beta=measure of diversity within habitat

• hutchinson=phytoplankton are an exception to the competitive exclusion principle because they live in simple environments and compete for the same nutrients
• many species coexist without competitive exclusion
• environmental complexity may account for significant portion of the diversity
• other kinds of interactions(credation) can prevent competitive exclusion

• repeatedly observed negative relationship between nutrient availability and algal and plant species diversity
• adding nutrients to water or soils generally reduces diversity of plants and algae(reduces number of limiting nutrients)
• highest number of species are found in areas with lowest soil fertility
• number of ectomycorrhizal fungal taxa declined with amount of soil nitrogen content

disturbance is difficult to define as it involves departure from "average conditions"(average conditions may involve substantial variation)

discrete, punctuated, killing, displacement, or damaging one or more individuals that directly or indirectly creates an opportunity for new individuals to be established.

• any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment
• two major characteristics=frequency&intensity

• resource
• interference
• intraspecific
• interspecific

• competition for a shared limiting resource
• anything in environment that's consumed

• direct aggressive interaction between individuals
• antagonist behavior towards individuals of another species

• intraspecific=competition with members of own species
• interspecific=competition between individuals of two species, reduces fitness of both

• both species compete for a limiting resource
• both species are harmed

• asymmetric competition for limiting resource
• one species is harmed, the other is not
• phytoplankton&macrophages, macrophages harmed in presence of phytoplankton

• herbivory
• species eats another species
• one species benefits, while the other is harmed

• plant benefits from decomposers
• follicle mite=lives on our faces but doesn't affect us.
• one species benefits, while there's no effect on the other species

• zooxanthallae and coral
• fungus and algae in lichen
• seed dispersers
• symbiotic
• both benefits!!!

• plant growth rates and weights increase as density decreases
• competition for resources is more intense at higher population densities
• usually leads to mortality among competing plants(self-thinning)
• weaker individuals=higher mortality