Ecology
Island Biogeography Theory
-Larger islands have higher rates of species arrivals, resulting in a higher equilibrium # of species -Due to competitive exclusion, the more species present on an island, the harder it is for a new species to establish itself (lack of niches) -Therefore, as species accumulate, net immigration rate slows down. -For some reason as species accumulate, extinction rates go up.
Gleasonian communities
-gradual changes in species abundance along environmental gradient -transitions gradual and difficult to detect -individual occurrences based on dispersal, growth, competitive ability
Clemenstian communities
-suggest common evolution history and similar function and tolerances. -mutualism and coevolution play roles in determining species associations -converge to stable climax community as complexity increases -analogous to growth/development of an individual
Why do the tropics have a faster speciation rate than temperate or polar regions?
-uniform abiotic environment and high productivity -> faster speciation -uniform abiotic environment -> narrowing of physiology->lanscape barriers more easily restrict species ranges->faster speciation -higher ambient temperatures and more energy->higher mutation rates, shorter generation times and or faster physiological processes->faster speciation rates
What are 3 important points regarding the water cycle?
1) No net gain/loss @ global scale. Balanced through precipitation and evaporation. 2)Key processes/transformations are evaporation/precipitation and run-off 3)Only 2.5% is freshwater and only .5% of freshwater is in liquid form.
What are the 4 important factors of species diversity in an area?
1) Speciation 2) Extinction 3) Immigration 4) Emigration Diversity= Speciation-extinction+immigration-emigration
What are the latitudinal diversity gradients hypotheses?
1) Stability/Productivity (cradle) hypothesis 2)Area hypothesis 3)Museum hypothesis
Ecosystem processes: Key points
1) abotioc inorganic starts with how gets transformed. nutrients enter ecosystem through chemical breakdown of minerals in rocks via fixation of gases in the atmosphere. 2) transformations (most important are the abiotic - temperature/precipitation). Chemical and biological irons in the ecosystem alter the chemical form and supply of nutrients. 3)Controls - can be constrained by climate and chemical composition.
Energy flow and food webs
1) energy sources:energy in ecosystem originates with primary production by autotrophs 2)energy flow: food webs and pyramis describe energy flow 3)Global patterns in productivity indicate abiotic constraints 4)Net primary productivity is also constrained by biotic factors: top-down versus bottom-up control
What can increased diversity enhance?
1) productivity 2)resource conservation efficiency 3)resistance to disturbance 4)ecosystem service (direct & indirect benefits humans derive from ecosystems.
How have humans impacted the carbon cycle?
1) until industrial revolution, terrestrial & atmosphere carbon reservoirs were in balance, not anymore because more carbon goes into the atmosphere ~20% deforestation & ~80% from fossil fuel burning 2)Increases in CO2 and CH4 in atmosphere causes global warming 3)atmospheric increase in CO2 also increase ocean acidity
What are the key points of the carbon cycle?
1)Ocean reservoir holds 50x more carbon than the atmosphere; most is in deep water sediments 2)on land soil reservoir holds 2x more carbon than the vegetation reservoir 3)largest natural fluxes are between the atmosphere and terrestrial GPP (Photosysnthesis + respiration)
Global changes and conservation
1)We are in 6th mass extinction, earth's biotic increasingly homogenized 2)Major threats to biodiversity include habitat loss, invasisve species, overexploitation, pollution, disease and climate change. 3)Consequences of biodiversity loss include losses in productivity and ecosystem services. 4)Biodiversity best sustained by large reservoirs connected across the landscape and buffered from areas of intense human use.
Predator/prey assumptions
1)close population 2)constant B&D 3)continuous population growth 4)no age, stage, size structure in population 5)growth of V is limited by only predation 6) Predator is complete specialist 7)Victim and predator encounter each other each other at random according to population densities
What are the three filters to community membership?
1)immigration: Is species in regular species pool? can individual of species immigrate to local community 2)abiotic factors- given that individual species are capable of immigrating to local community. Do abiotic condition in local community allow community to persist? 3)biotic factor- given that individual can tolerate abiotic conditions, are they dependent on or restricted by certain species interactions (biotic factors)
How have humans impacted the nitrogen cycle?
1)industrial fixation Nitrogen into fertilizer 2)Biofixation of nitrogen for agriculture 1+2 EXCEED natural rates of nitrogen fixation on land 3)burning fossil fuels releases nitric oxide 4)fertilization can create dead zones in aquatic ecosystems causing algal blooms which deplete oxygen content of the water killing many species (Eutrophocation). 5)fertilization decreases biodiversity while increasing productivity 6)atmospheric deposition of reactive nitrogen is a big problem
What are the best types of reserves?
1)large is better than small 2) One large is better than several equal to same total area 3) several reserves close together better than far away 4)several connected by habitat corridors better than unconnected 5) compact shapes better for minimizing boundary length 6) reserve surround by a buffer zone better than one without
Species interaction models
1)many factors influence outcome/strength of species interactions including abiotic conditions, other species interactions and evolution 2)species interactions can be modeled with simple modifications to single species growth equation 3)models predict outcomes of dynamics of species interactions
What are the three largest pools of carbon ranked from largest to smallest?
1)ocean 2)fossils & sediments 3)soil
What are the three largest fluxes of carbon ranked from largest to smallest?
1)photosynthesis or atmosphere to terrestrial plants 2)plant & microbial respiration or from terrestrial system to atmosphere 3)Ocean photosynthesis or atmosphere to ocean
How have humans impacted the water cycle?
1)reduced percolation and increased run-off via barriers (asphalt) to percolation 2)Depletion of water in agricultural use and Industry ~40% of global population currently has sufficient water resources.
What is habitat fragmentation?
1)reduces habitats to size too small to support some species. 2) reduces ability of individuals to disperse, lending to genetic inbreeding. 3) creates large amounts of poor-quality "edge" habitat When habitats fragmented,quality and quantity of habitat decreases with drastic consequences for diversity and abundance
Given what you know about energy transfer efficiencies approximately how many kg of carnivore (secondary consumer) biomass can be supported by a grassland containing 200,000 kg of plant material?
200
What is the Shannon-Weiner information theory index?
A more complicated way to measure and compare species diversity that accounts for evenness in the equation. To calculate the index: Divide the number of individuals of species #1 you found in your sample by the total number of individuals of all species. ... Multiply the fraction by its natural log (P1 * ln P1) Repeat this for all of the different species that you have. ... Sum all the - (Pi * ln Pi) products to get the value of H.
Relative abundance
Abundance of species divided by total abundance
Do tropical bivalve species have higher or lower extinction rates?
An all tropics lineage went extinct: 30 cases Non-tropical lineages went extinct: 107 case Supports museum hypoth
communities
Association of population of different species living in the same area -many metrics exist for describing community structure -communities change through time (succession) Those changes may be predictable among communities or might not -variation in local community structure can be caused by abiotic stresses, disturbances and species interactions as well as by stochastic process
How do the distributions of species patterns vary?
At the global, regional and local scales
Whittaker's Beta Diversity Index
Beta = Gamma/Mean alpha or Beta = Regional/mean local
Where is the largest bio fixation supplies?
Bio fixation nitrogen supplies ~ 12% of the natural bio demand, 88% comes from decomposition.
Succession is
Change in species composition over time and at a specific place
Beta diversity
Difference or turn over in species diversity from 1 habitat to another. It relates to both alpha and gamma diversity. It measures how much diversity change is among local patches
facilitation and inhibition
Early successional colonists can facilitate or inhibit growth and establishment of successional species Secondary succession Fire-pioneer species 0-4 years-intermediate species 5-150 years - Climax community 150+ years
What did Wallace discover by overlaying the distribution of animals on the continents?
Earth's land mass can be divided into 6 biogeographic regions that differ greatly in species composition and diversity. There is a latitudinal gradient of species diversity, where it's greatest in the tropics and decreases toward the poles.
Where is species richness greatest?
Equator
Stability/Productivity hypoth
Example: What was first appearance in fossil record of modern bivariates? Of 163 clades studied, 117 of them originated in what was then the tropics
What are invasive species?
Exotic species- non-native species introduces to a new area. If it grows to large population size & disrupts native species, it becomes an invasive species. Globally 4-44% of species in local community non-native. ~50K exotic species in the US cause major damage & losses totaling~$137 bill per year
True or false: Temperate biomes have highest species diversity
False - Tropics have highest species diversity
True or false: Heterotrophs are responsible high marine productivity along coast lines.
False - it is autotrophs
True or false: Terrestrial ecosystems contain the largest pool of nirtogen.
False - it is the atmosphere
True or false: A keystone predator only affects trophic level below it
False. Affects all trophic levels below
In an experiment two species of barnicles C. stellatus (barnacle) is competitively excluded from the lower intertidal zone B. balonoides but C. stellatus has no effect on distribution of B. balonoides. What could be concluded about the two species niches?
Funamental niche B. balonoides indentical to its realized niche B. balonoides but fundamental niche C. stellatus different from realized niche C. stellatus
What factors can influence outcome and strengths of species interactions?
"context dependent" 1)abiotic context:environmental conditions (temp/precipitation) 2)Biotioc context: other types of sepcies interactions 3)disturbance 4)evolution
Key points Island biogeography
-"immigration" - species establishes itself on island -"extinction" elimination of species on an island -major force is dispersal of individuals to initiate colonization and establishment on an island. -islands nearer continent receive higher rates of species arrivals = higher equilibrium of number of species. -larger islands receive higher rates of species arrivals resulting in higher equilibrium of number of species. -competitive exclusion - more species present, harder it is for new species to establish -result of species accumulation , net immigration slows down -same reason extinction goes up (run out of resources)
How do we measure and compare species diversity?
Simple: estimate of the total number of species (species richness). This is just a list. More complicated takes into account the evenness (how many of 1 species is living in an area).
Biogeography
Study of the variation of species distribution patterns
What is the largest resevoir of the nitrogen cycle?
The atmosphere
Which of following factors best explains why NPP is highest in wet tropics?
The climate is warmer and wetter in the tropics
Why is atmospheric carbon concentration increasing more slowly than the rate at which anthropogenic carbon emissions are increasing?
The land and ocean sinks take up roughly / of annual antropogenic emissions
What is the biogeochemical cycle?
The path an element takes as it moves from abiotic pools through producers and consumers and back to abiotic pools. Decomposition limits overall rate of nutrient recycling. Increase temp, increase water = faster decomposition
In his experiment with different pairs of paramecium species Gause found sometimes both species persisted and sometimes only one species did and the other went extinct. Which hypothesis did Gause propose to explain case in which both species persisted?
The two species tended to use different resources
What is ecosystem ecology?
Trace nutrients through a system using food webs
Museum hpyoth
Tropic have slower extinction rates than temperate and polar regions because of historical perturbations such as glaciation in temperate regions. Uniform abiotic environment = more individuals = larger ranges = slower extinction
Area hypoth
Tropics have more land area than the temperate and polar regions. Larger area means larger range size which increases speciation rates. Larger areas have larger population sizes decreases the risk of extinction.
True or false: NPP is constrained by species composition & nutrients
True
Which species has a higher capture efficiency (alpha)? dv/dt=rV-aphaVP Whale eating many fish or spider eating one fly
Whale eating many fish average effect of one predator on per capita growth of victim
Do different parts of the planet have different numbers of species?
Yes. Tropical rain forests have 4100 species of trees, Temperate rain forest have 12 species of trees while Tundra has only 2.
Beta diversity will be highest when:
abiotic conditions are highly variable between patches
Spatial scales
alpha, beta an gamma diversity Species richness increases with the area sampled. Global patterns of diversity and composition are controlled by geography, area and isolation, evolutionary history and the global climate.
What are the largest natural fluxes of nitrogen cycle?
between the atmosphere and the biota (nitrogen fixation and dentrification).
sucession
change in species composition overtime as a result of abiotic and biotic agents of change
Study closely related predatory insects, two-spot and three-spot avenger beetles. Notice each seeks prey at dawn in areas without the other. Rangers overlap. Two-spot hunts at night and three-spot in the morning. When bring individuals from both populations that overlap into lab & keep separate. Find two-spot is nocturnal but three-spot in the morning. This is an example of:
character displacement
What are the goals of conservation biology?
conservation of: larger intact, functioning ecostystems, areas with high biological diversity, species or groups of species of special interests (poor local lineage), significant natural communities, important ecosystem services
species richness
count of number of species
Primary succession
establish and development plant communities in newly formed habitats (lava flows, sand dunes, bare rock)
Niche partioning
evolution change in resource use and partioning between two or more species
In Lotka-Volterra predator-prey model, prey exhibit what type of growth in absence of predators?
exponential
secondary primary production
generated through consumption of organic matter by hetertrophs mostly detritivores
Keystone species
have a much greater effect on community structure than their abundance (biomass) would suggest Ex: Pisaster in rocky intertidal removed pisaster from 1 area 8 invertebrates left adjacent area alone (control) 15 invertebrates starfish (predator) increases invertebrate diversity
In Island biogeography theory distance from mainland controls the?
immigration rate
How does area influence species richness?
larger areas have more species than smaller areas SAR - Species - area relationship Species richness increases with area island size log# species = log (c) + (z)log(area)
Energy
most basic requirements all organisms organisms obtain from sunlight, inorganic chemical compounds or through consumption of organic compounds all these sources of energy are resources
There is evidence from some ecological studies some grasses benefit from being grazed by animals. Which term best describes such plany-herbivore interaction?
mutalism
Which of the following measure productivity accounts for respiration by heterotrophs?
net ecosystem production
Species richness depends on
number of existing species, island size, remoteness of island
In Lotka-Volterra predator-prey model, the zero population growth solution for predators is in terms of?
number of prey required to maintain zero population growth
Primary succession is succession that:
occurs on newly exposed geological substrate, not organic soil
autotrophs
organisms that get energy from sunlight (photosynthesis) or from inorganic compounds energy converted into chemical energy stored in carbon-carbon bonds autotrophs do not create energy, they transform it
coevolution
reciprocal evolution change in two species 1)reciprocity 2)evolution occurs in response to another species 3)specific sequences of events Arms race one possible consequence of coevolution
Secondary succession
regeneration climax community following disturbance (forest fire)
What's best way to directly test hypothesis that C. stellatus (barnacle) is competitvely excluded from lower intertidal zone by B. balonoides (another barnacle)?
remove all B. balonoides from the lower intertidal zone
At a predator isocline will V (#victims) be larger for wolf eating a moose or a sparrow eating a seed?
sparrow eating a seed predator isocline: # victims (prey) will maintain predator at zero groth rate (dP/dt =0)
Agents of selection
species are important agents of selection through their interactions Predators select for mimicry among prey. Predator can effect prey evolution consumption and coevolution arms race caterpillar on plant~1 plant cahnges color, makes caterpillar stand out, all plants change color, 1 caterpillar changes color to blend, all caterpillars change color... reciprocity
Local diversity (alpha)
species diversity in a small area of homogeneous habitat
At a victim isocline, will P (#predator) be larger for the prey of a baleen whale or web spider?
spider victim isocline:# predator will maintain prey (victims) at zero growth rate (dv/dt=0)
Food chains
tertiary consumers - carnivores secondary consumers - carnivores primary consumers - herbivores primary producers - phosynthesis - plants
Total abundance of commmunity
total #individuals of all species (Sometimes called community size)
Net primary production
total chemical potential energy input into ecosystem (growth, storage of carbon)
Regional diversity (gamma)
total species diversity observed across all habitats with in a geographic area
Resource niche partinioning
use of a limiting resource by different species in different ways reducing interspecific competition and allowing for coexistence
Ecosystem diversity
variety of biotic communities in a region, along with abiotic components~soil, water, nutrients measured as array of biotic communities and variation of physical conditions in region
Regional vs local diversity
when local and regional species diversity values = slope 1, then species within the region found in all communities of the region.
How does energy enter an ecosystem?
with primary production - autotrophs
Which species has a higher conversion efficiency (beta)? dP/Dt=Beta VP-qP Bird eating seed or wolf eating moose
wolf eating moose average ability of a predator to convert one prey into own per capita growth
How fast are species going extinct?
Methods to estimate: fossil record, species area curves, rates of population decline & range contraction, changes in conservation status. Extinction risk evaluated <5% world's described species. Use area of habitat lost to estimate how many species eventually will be lost.
What are Wallace's 6 biogeographical regions?
North America, Eurasian plate, Oriental, South America, African plate, Australian Each of these bigoegraphic realms house the regional (gamma) diversity. These regions reflect evolution isolation an correspond to tectonic plates.
What is the largest reservoir for the global water cycle
Ocean 97.5%
How to plot normal vs log scales of species area relationships
Plot # species of partic taxon(trees, insects, mammals) Y-axis against the island area X-axis.
Zero population isoclines
Population does not increase or decrease in size for any combo of V & P that lies on these lines Why calculate? Zero growth isoclines determines conditions under which each species will increase or decrease
Latitudinal Gradients in Diversity
Regional differences in species diversity that are controlled in part by area and distance due to the balance between immigration and extinction (Island Biogeography Theory).
