ecology exam 4

soil micronutrients

B, Mn, Zn, Cu, Mo

Why is preservation of biodiversity important? Support your answer.

- diverse ecosystems are more resilient to disturbance. bc of increase of human disturbance in the last few centuries, diversity is needed more than ever to keep ecosystems alive. ex. logging in rainforests to make farmland replaces highly diverse ecosystem with 1 species of plant and 1 species of animal - sense of responsibility as dominant species - some complex ecological relationships are hard to mimic/replace once destroyed as species become extinct

primary production (PP)

transformation of inorganic compounds (ex. CO2) to organic compounds (ex. sugar)

Liebig's Law of the Minimum

yield of plants is limited/determined by nutrient that is present in the ecosystem least relative to its demands for plants growth yield of plants is limited by most limiting nutrient - nutrient in least supply

Redfield ratio

106 C: 16 N: 1 P - ratio of molar masses - this is optimum ratio for plankton growth in the ocean. in low/high concentrations of these nutrients, the ratio will be the same, but more will grow in higher concentrations

Describe how energy flows from trophic level to level.

1st level is always sun - plants absorb 50%. the next level consumes plants and is consumed by level after that. continues and 90% of energy is lost from level to level

How many species have or are currently listed? How many have been de-listed? Does the law "work"? Support your answer.

2363 species currently listed, 91 delisted species (of 91, 59 recovered, 14 due to new info, 11 due to extinction, 7 due to reclassification) the law generally works the best it can being a federal environmental regulation - not a perfect mechanism for recovering these species but at least identifies them and names that we are responsible for recovering them as best as we can of the amount that has been delisted, majority are recovered, though the number of delisted at all is low not necessarily super effective but need at least as a symbol that endangered species are important at the federal level

soil macronutrients

C, N, P, K, S, Mg, Ca, S, Cl, Fe

community ecology

The study of the organization and functioning of communities, which are assemblages of interacting populations of the species living within a particular area or habitat.

release from exploitation

a mechanism that removes a stressor on an organism ex. ants release acacia from exploitation of herbivory

nutrient pool

a pool of a nutrient that has yet to be oxidized/transformed

nutrient source

a pool where a nutrient is released faster than it is absorbed

Describe the mutualistic association between ants and the Acacia.

acacia secretes syrup that the ants can eat and has pods that the ants can live in. ants in turn will sting any animal that tries to eat the plants. studies showed that animals would eat that species of acacia if the ants were not there, so it is the ants that cause this reaction

Shannon's Diversity Index

accounts for both abundance and evenness of the species present in diversity. higher numbers mean higher diversity/evenness and higher heterogeneity

character displacement

an evolutionary change that occurs when two similar species inhabit the same environment. Under such conditions, natural selection favors a divergence in the characters--morphology, ecology, behavior, or physiology--of the organisms. starts with interspecific competition - niches of species overlap and rather than compete, evolve to differentiate niches

predator-prey oscillations

as prey populations increase, more food is available for the predators so their population increases. as the predator population increases, they eat more prey and the prey decreases. The predators therefore have less food so their populations decrease. when not being eaten, prey populations increase and cycle repeats.

transformation

building of biomolecules within an organism; consumption of one organism by another. in the cow, when microbes or worms consume remains

respiration

chemical processes that oxidize sugars into usable energy forms - transforms sugars into CO2

Arthur Tansley

coined the term ecosystem; soil pH determined winner in competition between two species. both germinated but only one lasted; quote about how ecosystem ecology combines biotic and abiotic attributes

how many species exist in the biosphere; how many interactions

conservatively 10 million species, 50x that amount is interactions

Describe the relationship between coral and zooxanthellae.

coral open and feed at night, providing nutrition to the zooxanthellae. during the day, zooxanthellae do photosynthesis and provide corals with energy. when coral does not like the conditions, they reject the zooxanthellae and subsequently die

Robert Redfield

developed Redfield ratio which identifies optimum ratio of C, N, P for plankton growth in ocean

Justus Liebig

developed law of the minimum - yield dependent on most limiting nutrient

What are some tools to quantify food webs?

diagrams that indicate how strongly different organisms depend on/affect others ex. with arrows

What is the difference between energy flow and nutrient cycling in a food web?

energy flow is unidirectional - goes from level to level and not back bc there is a constant source at the beginning nutrient cycling is limited to cycle bc there is only a certain amount of nutrients that were put into the Earth when it was created and we are limited to use/store/reuse those nutrients in those amounts. so not unidirectional but cyclical

consequences of fertilization on mycorrhizal diversity

fertilization means that mycorrhizae are not as necessary to provide nutrients. less are needed, so less chance for genetic changes to occur, less chances for speciation. also species that grow on plants that are regularly fertilized will stop growing and potentially die out, lowering diversity

nitrogen cycle

fluxes are lightning, N fixation which is mediated by nitrogen fixing microbes growing on legumes as mycorrhizae and blue-green microbes (anaerobic algae)

Mary Power

found that fish in streams are keystone species

Jane Lubchenko

found that snails in tide pools are keystone species

Robert Paine

found that starfish in tidepools are keystone species

why are mycorrhizae important to plants and what are the two main types

help them to gain more nutrients/moisture from the surrounding soil. less energy/growth can go to roots bc less work is needed to get same amount of nutrients and more energy can go towards above ground growth. arbuscular = grows within roots. ectomycorrhizal = grows outside of roots.

protection in numbers

in a large group, you are more likely to be protected from and less likely to be eaten/harmed

What are typical ecological conversion efficiencies? Why are they so low?

in most conversions, 90% of energy is lost - lost in metabolic processes, waste, heat

apparent competition

indirect negative influence/competition; ex. native bunchgrass will grow in high density next to invasive black mustard unless herbivores are present - then bunchgrass is low density next to black mustard

competition

interaction where both individuals are negatively affected. interspecific = between species, like galapagos finches. intraspecific = within species ex. David Tillman experiment in praries - at high densities, even extra N would not make plants grow larger. means they are competing for nitrogen

Define and describe some keystone species, top-down & bottom-up trophic cascades.

keystone species: a predatory species in small abundance that is at the top of the food chain - food chain would be destroyed without it important to the food web but not in high numbers ex. orca in pelagic food chain, starfish in tide pools (Robert Paine), snails in tide pools (Jane Lubchenko), fish in streams (Mary Power) top-down: if number of individuals at the top is changed, levels below will be affected ex. when more rainbow trout were placed in section of river, affected all the way down bottom -up: when nutrient addition/subtraction affects lowest level of web/chain ex. lake erie w/ algae blooms

nutrient sink

long-term storage of a nutrient ex. fossil fuel deposits

phosphorous cycle

main source is weathering of rocks - plants uptake through roots/mycorrhizae. often most limiting nutrient. not in atmosphere. largest pool is minerals - limestone and guano. any P found in sedimentary rock has already passed through cycle at least once bc it has gotten in an organism and was released/trapped when it died

net PP (NPP)

mass of carbon fixed in excess of respiratory loss

gross PP (GPP)

mass of carbon fixed including losses to respiration

what is the role of natural disturbances on H'? human caused disturbances?

moderate disturbance gives opportunities for new niches to be filled but too much can destroy diversity

nutrient flux

movement of a nutrient from one pool to another - largely driven by decomposers

carbon cycle

moves between atmosphere and organisms via photosynthesis and respiration (includes decomposition); soil contains 2x more carbon than atmosphere - CaCO3 in rocks and ocean are large pools

Why is competition important in evolution, community structure, and species distributions?

niches are self-regulated by interspecific competition and population size. coexistence is allowed by the slight overlap of niche breadths - here is where species interact and where communities are defined bs that's where competition occurs

competitive exclusion principle

no two species can occupy the same niche

species richness (S)

number of species

predator

organism that eats other organisms/prey

prey

organism that is eaten by other organisms/predators

generation

photosynthesis

What are the two processes that move carbon between organisms and the atmosphere?

photosynthesis and respiration

lotka volterra model

predicts populations of two species that are competing. when alpha is greater than 1, species with larger K wins. if alpha greater than one and same Ks, initial numerical advantage wins. if alpha less than 1, equilibriun will occur. ex. paramecia. A has higher K than C, so A outcompetes C when grown together

role of modeling + pros and cons

pros: predictive, practical way to show data, identifies patterns. cons: have to make assumptions about complex environments, based on existing therefore incomplete data

pros and cons of biocontrol

pros: should only affect targeted species, self-sustaining, cheap to maintain. cons: specificity may fail, takes time to work, expensive to start, may not completely work

equilibrium

relatively stable ecosystem condition where population sizes are in sustainable, "regulated" amounts

Know the history of the Endangered Species Act (when signed? Who was president? Why then and not earlier or later? Etc)

signed into law by President Nixon in 1973 was not signed earlier bc environmental consciousness was not mainstream until the 50s/60s and it takes many years for a law to come into effect after a problem has been identified.

What factors control rates of PP?

solar energy input, temperature and moisture levels, carbon dioxide levels, nutrient availability, and community interactions (e.g., grazing by herbivores)

how do human activities influence nutrient cycling

speed up flux and deplete pools

What variables influence the rate of decomposition?

temperature, aeration, pH, chemicals, moisture

intermediate disturbance hypothesis

the hypothesis that ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels; reduces competition and opens niches bc it prevents community from reaching climax stage

ecosystem ecology

the integrated study of living (biotic) and non-living (abiotic) components of ecosystems and their interactions within an ecosystem framework

predator satiation

time where there are high densities of prey that reduces the chances of an individual being eaten

oxidation

transforming organic molecules to inorganic molecules. ex. consuming hemoglobin and using inorganic Fe+ ions

indirect commensalism

when the actions of one organism do not directly interact with another but benefit the second organism ex. beaver, beetle, cottonwood - beaver eats tree, promoted new shoot growth which beetle prefers to eat

mutualism + 2 types

when two species benefit directly from each other; facultative = could live without each other ex. bees and flowers. obligate = could not live without each other ex. coral and zooxanthellae

Can organisms influence nutrient cycling? Support answer with specific examples.

yes; death, pooping, migration, respiration - this is called bioturbation. ex. prarie dogs, salmon in streams, aquatic insects like caddisflies

Can consumers influence PP? Provide examples.

yes; ex. humans, grazers, promote growth

Does human hunting have an effect on ecosystems? Please describe and support your answer.

yes; humans hunt for the best looking, most healthy prey. means that only weakest prey is left for other hunters that are more impactful on the prey. adding an apex predator will always impact ecological relationships. also may leave less prey for natural predators, affecting those populations. also bullets leave foreign minerals/chemicals in the earth.