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509 Midterm

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Terms

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Oxidation
LOSS of electrons
Reduction
GAIN of electrons- you are REDUCING what you steal the electrons from
Photoautotrophs
capture light energy and use it to drive the synthesis of organic compounds from CO2. Cyanobacteria and many other groups of prokaryotes are photoautotrophs
Chemoautotrophs
use CO2 as a carbon source. However, instead of using light for energy, they oxidize inorganic substances, such as hydrogen sulfide (H2S), ammonia (NH3), or ferrous ions (Fe2+)
Photoheterotrophs
use light for energy but obtain their carbon in organic form. A number of marine prokaryotes use this mode of nutrition
Chemoheterotrophs
consume organic molecules for both energy and carbon. This nutritional mode is found widely among prokaryotes as well as protists, fungi, animals, and even some parasitic plants.
Carbonic Acid
H2CO3
H2CO3
Carbonic Acid
Bicarbonate
HCO3
HCO3
bicarbonate
carbonate
CO3
CO3
carbonate
Ammonium
NH4
NH4
Ammonium
Nitrate
NO3
NO3
Nitrate
Nitrite
NO2
NO2
nitrite
If water is 50% saturated, will the atmosphere act as a source or sink (what it goes into) with respect to oxygen
a. The direction of oxygen exchange depends on Henry’s law, if over-saturated (supersaturated) water will lose oxygen to atmosphere and if under-saturated, water will gain oxygen from the atmosphere. Therefore, if the water is 50% saturated it will act as a sink and the atmosphere will act as a source
Henry's Law
at a constant temperature, the amount of a given atmospheric gas dissolved in a given type and volume of a liquid is directly proportional to the partial pressure that the gas in equilibrium with that liquid. b. Saturation = solubility * partial pressure c. If water is under-saturated it will gain oxygen from atmosphere. But if water is over saturated it will loose oxygen to atmosphere
3. Describe Fick's Law? Give an example sentence that illustrates how it might be useful in an ecological analysis.
⬢ While Henry's law helps to define the saturation point and direction of diffusion of a gas between the atmosphere and water, Fick's law provides a description of the rate at which these diffusive processes occur. ⬢ Diffusion Rate = K ([Saturation] - [O2]), where: o K equals a rate constant (sometimes called the diffusivity constant) ⬢ Fick's law calculates how long it takes to get to the saturation point. The rate at which you go toward saturation is determined by the difference in the current concentration [O2] and the saturation point of O2 [Saturation].
What is Alkalinity a measurement of
o Alkalinity = Acid Neutralizing Capacity= ANC o Alkalinity measures the total amount of base present and indicates a pond's ability to resist large pH changes, aka the "buffering capacity". The most important components of alkalinity are carbonates and bicarbonates.
How does photosynthesis affect pH in aquatic environment?
a. Plants in aquatic ecosystems utilize HCO3 and CO3 as well as dissolved CO2 as inorganic carbon sources for photosynthesis. They convert the carbonates to CO2 and liberate hydroxide ions This induces strong pH fluctuations - As aquatic plants shift pH up to use carbonates  Free CO2 declines, and calcite precipitates - changes of 1-3 pH units are not uncommon where photosynthesis rates are high.
Is marl production associated with high rates of respiration or high rates of photosynthesis?
a. Marl is a freshwater form of CaCO3 – photosynthesis, bc lots of O2 available b. When you have photosynthesis, CO2 is taken up by plant and reaction will go to left hand direction (see calcite/marl deposition and carbon storage). So marl production is associated with high rates of photosynthesis. c. Respiration causes marl to dissolve
Why is carbonic acid ubiquitous in terrestrial and aquatic ecosystems?
b. Because there is always carbon dioxide available in the atmosphere. CO2 is easy to dissolve into water. Carbonic acid is an ion, so it must dissolve in water and therefore it will get into the water in the terrestrial ecosystem. c. Carbonic acid is very important because it keeps pH in balance by buffering acid inputs. Respiration is an acidifying process. In ecosystems, natural tendency toward acidification, which is buffered by carbonates.
What are the three primary forms of inorganic carbon used by aquatic autotrophs?
a. CO2, HCO2 and CO3 b. Autotroph is an organism that makes its own food from chemical or light energy
What does the term nitrogen fixation refer to? What major group of organisms are important nitrogen fixers in aquatic environments?
a. When N2 is turned into organic N with the help of biological energy (or sometimes non-biological, i.e. lightning) b. Blue-green algae (cyanobacteria) and other bacteria c. Aerobic environments
What organisms are important in fixing nitrogen in terrestrial environments?
a. When N2 is turned into organic N with help of biological energy (or sometimes non-biological, i.e. lightning) i. Nitrogen fixing bacteria ii. Rhizobium 1. Live in legumes (beans)
What is the significance of having different colored pigments in plants?
a. A pigment is a protein that absorb particular wavelengths b. Allows plants to absorb energy from wavelengths c. Ultimately, light that isn’t matched to the absorption spectrum of an individual plant’s available pigments can’t be used for photosynthesis d. Chlorophyll absorbs red and blue, REFLECTS green wavelengths
What is meant by phylogenetic chromatic adaptation?
a. Chromatic adaptation- find algae at diff depths in the oceans i. Green algae in shallow water bc they thrive on red wavelength 1. Red wavelength dissipates in water faster b. Evolution sets some limits on what pigment are available can influence what species dominate a particular area i. e.g. on many ocean coasts red algae occupy in deeper water while green algae occupy shallower sites ii. e.g. blue-green algae dominate eutrophic lakes where self shading by algae absorbs most available blue and green light
ontogenetic chromatic adaptation
many plants can physiologically adapt to light regimes by altering production ratios of the pigments they have.
What is the most easily utilized form of phosphorus that occurs in aqueous solutions?
Soluble orthophosphate. Phosphorus cycle: Weathering rocks – soil – plants – aquatic food chain – sedimentary rock or back into phosphorus cycle. b. If its in an aqueous solution, it has to be soluble by definition c. Phosphorus usually exists as phosphate (PO3 or PO4) d. Oxygen is an oxidizer  likes to pull electrons from things e. Find phosphorus in biological molecules- nucleic acids (DNA and RNA) and sometimes in proteins f. When an animal or something dies and decomposes, it releases phosphates g. Orthophosphate- soluble form of organic phosphate i. Organic- part of carbon based molecule
What is conductivity a measure of? What useful information does it provide?
a. Measure of dissolved content (TDS) in water i. which enhance ability of substance, such as water, to conduct electricity b. Provides info on how easy electricity can pass through something i. way of measuring salt ions in water
Under what conditions would you expect large diel/daily fluctuations in oxygen concentration of an aquatic ecosystem?
a. A lot of plants or algae- only have photosynthesis during the day  at night it stops so oxygen stops, so fluctuates
What is an autotrophic ecosystem? What is an autotrophic organism
a. Auto (own) trophic (food)- produces its own food b. Autotrophic ecosystem: Ecosystem where rate of photosynthesis is > the rate of respiration. i. A system driven by photosynthesis where P is bigger then R c. Autotrophic organism: produces complex organic compounds from simple inorganic molecules and an external source of energy. i. Plants, photosynthetic algae, cynobacteria, blue-green algae (really bacteria)
What would a large accumulation of organic muck soil (i.e., peat) signify about carbon balance in an ecosystem.
o Signify that this is an autotrophic ecosystem. This is a system that the carbon inputs are > carbon outputs. Most likely plants are decaying anaerobically. o Peat forms when plant matter decays in acidic and anaerobic conditions, such as bogs and marshlands. o When organic matter is prevented from decaying aerobically, the result is that carbon is stored in the organic muck (peat) because it is not released as CO2 (a byproduct of aerobic respiration).
What is the compensation plane in a lake
a. Compensation POINT- the level of light intensity at which photosynthetic assimilation of energy balances plant respiration i. Above the compensation point, the energy balance is positive; below the energy balance is negative b. The depth at which there is no longer any net photosynthetic gain. Point where photosynthesis and respiration are equal, and creates the border between the trophogenic and tropholytic zones
What is the difference between a trophogenic and a tropholytic zone in an ecosystem?
a. Trophogenic: above compensation point- photosynthesis is possible b. Tropholytic: below compensation point- respiration is dominant
If the water levels in an imaginary in a lake were controlled only by a river flowing into it, rain, and evaporation; draw a box and arrow diagram of the system, and write the continuity constraint in as much detail as you can
o Change in anything is the diff between what is going in and out o Sum of inputs-sum of outputs o With just water, sources coming in are rain and river (inputs) o Outputs- evaporation and river and photosynthesis o Continuity constraint
Under aerobic conditions which of the following forms of phosphorus is likely to be insoluble: orthophosphate or inorganic metaphosphates.
a. Inorganic metaphosphates i. Not biologically useful b. Orthophosphates dissolve in water i. Form of phosphates used in plants
Is 10 ppm a high or low alkalinity, what, if anything, does it tell you about rates of primary production?
o 10 ppm is a low alkalinity. Accordingly, certain nutrients are unavailable to aquatic plant life, and thus insufficient to sustain primary production so it decreases.
nitrification
bacterial process of oxidizing NH4+ into NO2 and NO3, in the presence of O2
denitrification
bacterial process of reducing NO2 and NO3 to N2 in the absence of O2.
assimilation
process that plants use to convert NH4+ and NO3 into plant matter. It occurs in the presence of O2.
Why does light in the ocean become progressively bluer the deeper it travels?
a. Due to differential absorption of various wave lengths by water itself. b. Long wavelengths penetrate the most (blues), short wavelengths the least (reds). c. In deeper waters, blues penetrate the most do that is the color that can be reflected in the water and the color that appears to the eye d. Longest wavelength has the lowest energy e. So highest energy light makes it farther into the water then the lower energy light (short wavelength –roy part of spectrum)
Why are “blackwater rivers” tea-colored
a. Tannins are leached from the decaying leaves of adjoining vegetation. Dissolved organic matter, which “blackwater” rivers are full of affects light absorption characteristics. Dissolved organic matter absorbs strongly in the 400 -500 NM range. Blackwater has even higher levels of dissolved organic matter so it absorbs the even longer dark wavelengths. o Blackwater rivers are rivers with waters colored like black tea to coffee. A blackwater river is one with a deep, slow-moving channel that flows through forested swamps and wetlands. The color results from the leaching of tannins from the decaying leaves of adjoining vegetation. o Answer: The spectral characteristics of light vary with depth of water due to differential absorption of the various wavelengths by water itself. Long wavelengths (blue) absorb the most, so reds (short wave) penetrate the least. The dissolved load, particularly the amount of dissolved organic matter, greatly affects the absorption characteristics. Dissolved organic matter absorbs strongly in the 400-500 nm [blue] range. Blackwater rivers carry a high load of dissolved organic matter, which absorbs the longer wavelengths and imparts a dark tea color to the water.
What does “turbidity” refer to?
a. Turbidity is a cloudiness or haziness of a fluid, or of air, caused by individual particles (suspended solids) that are generally invisible to the naked eye, similar to smoke in the air
Why are ecological transfers of energy and mass (up a food chain) inherently inefficient?
a. Bio-energetics requires inputs to sustain functions such as Exploitation (acquiring or making food), Assimilation (digesting food, making feces and urine), and Growth (incorporating energy into tissue and respiring). b. Autotrophs (food producers- plants) only require exploitation and growth functions, and not the assimilation function. c. Species have different bio-energetic profiles. i. Animals like a Daddy Long Legs spider spend a lot of energy actively hunting for prey- that energy is not invested back into their tissue. Small beings and homeothermic (warm blooded) beings have high energy costs. d. Organisms spend a lot of energy gathering & digesting food, so organisms are not getting the full energy value of their inputs. i. More tissue you have, the more energy you require
What would incipient lethal level of a limiting input mean in the context of bioenergtics? How is it related to metabolic scope?
a. An organism reaches its incipient lethal level when the amount of energy it can get today from consumption and synthesis is equal to the amount of energy it needs for maintenance and critical repair. Occurs when energy is a limiting input. If metabolic scope = 0, there is no energy for growth or activity. At this level, you are going to die because you only have the minimum maintenance requirement
What is the function of ventilation in relation to oxygen uptake for respiration?
a. Ventilation decreases the distance between the organism and the next batch of oxygen it needs for respiration. It controls deterioration of diffusing distance and decreases the time it takes to replenish the zone of depletion.
As organisms get larger does their total maintenance metabolism increase or decrease?
37. As organisms get larger does their total maintenance metabolism increase or decrease? a. Other factors constant: maintenance metabolism increases linearly w/ size. Other factors affecting metabolism are physical activity, activity temp, and physiological state.
Which is more important to photoautotrophs, photosynthesis or respiration, why?
a. Photosynthesis is more important than resp because photo gives plant energy to live and allows the plant to create organic substances from inorganic ones, which leads to respiration. Resp. can’t happen without photosynthesis.
What is required for an organism to grow? Explain in terms of a general input output paradigm.
a. More inputs than outputs are required for an organism to grow. Growth trajectory & size is a matter of energy balance. Energy In Energy Energy Out. Difference between inputs and outputs is what’s available to be used from growth
What is (approximately) the maximum annual rate of carbon production by ecosystems on this planet?
a. 2 kg of organic carbon / m^2 is most possible per year
How many domains are there in the universal tree of life and what are they called? On what evidence is the universal tree of life based?
3 Domains 1. Bacteria 2. Eucarya 3. Archaea Based on ribosomal RNA sequences.
In one or two sentences, what is the problem with Protists?
Don’t know how to classify them- as Eukaryotes or Prokaryotes
What were the constituents of the earth’s early atmosphere and how would you describe its redox potential?
⬢ Atmosphere of nitrogen and N-oxides, CO2, methane, ammonia, hydrogen, hydrogen sulfide ⬢ Redox- reduction oxygen reaction o Because of the strong presence of Ammonia (NH3) and Methane (CH4) it would have been strongly reducing to create organic molecules o OR- there might not have been enough ammonia or methane in the atmosphere, so the reducing was happening around deep sea vents and organic molecules were formed there
How old is the earth, about what proportion of the earth’s history is “Pre-Cambrian” and how long ago did Homo sapiens show up?
• Earth is 4.6 billion years old • Precambrian makes up about 4 billion years, or 87% or earth’s history • Homo Sapiens showed up about 5.3 million years ago
Name the three major groups of land plants and in a sentence or two, described their most significant traits.
⬢ Bryophytes- liverworts, hornworts and mosses o Lack vascular tissue which transports water and nutrients, therefore are restricted to a very small size ⬢ Seedless Vascular Plants- lycophytes and pterophytes o Reproduce sexually via spores ⬢ Seed Plants- gymnosperms and angiosperms o Plants that have an embryo (2N) packaged in a projective coat with nutrients
What are stromatolites, when did they appear, and why do we care about them?
⬢ Stromatolites are among the first fossilized prokaryotes, and still occur in shallow salty bays ⬢ Appeared about 3.5 billion years ago ⬢ Major constituent of the fossil records of early earth
Name and briefly describe two fundamental processes carried out by some cyanobacteria that are critical to life on earth as we know it today.
• Nitrogen Fixation- “fix” inorganic atmospheric nitrogen (N2) into ammonia (NH3) o The fixed nitrogen can then be incorporated into amino acids and nucleic acids (organic) • Oxygenic photosynthesis- liberates oxygen into the atmosphere
What internal features characterize eukaryotic cells and how did they appear
⬢ Appeared about 2.1 billion years ago ⬢ Their cells include a variety of organelles, some of which are of prokaryotic origin o HAS a NUCLEUS Nucleus created by infolding of cell membrane, internal structures (chloroplast & mitochondrion) were prokaryotic cells engulfed by eukaryotic cell
What were the contributions of MacArthur & Wilson (1967) and Grime (1974) to the study of life-history evolution?
- r and k selection (environmental variability is selective force for evolution of life history) - Applied r & K selection to plants – ruderals (high disturbance, low severity), competitive (low, low), tolerators (low, high)
Describe the typical characteristics associated with r-selected and K-selected species. What ecological factor is meant to be the primary driving force behind the evolution of these traits?
Describe the typical characteristics associated with r-selected and K-selected species. What ecological factor is meant to be the primary driving force behind the evolution of these traits?
What is genetic drift and what effect does it have on genetic variation within populations?
- When a population is very small, the random loss of a single individual can cause dramatic change in genotype ratios - As populations get steadily larger, random events become less likely to influence genotype frequencies - Alleles can become fixed in the gene pool as a simple result of genetic drift in small populations
In what three ways does sexual reproduction increase the genetic diversity of organisms
Crossing over random assortment fertilization/outcrossing
Describe in a couple of sentences the Red Queen Hypothesis and describe one piece of evidence in support of it.
- In Nature, organisms must continuously “run” (≈evolve) to prevent co-adapted parasites and pathogens with much shorter generation times from driving them to extinction. Meiosis helps them “run” faster by constantly generating genetic novelty. - Asexual lineages of vertebrates don’t last long
What is meant by the term gene flow, why is it sometimes limited, and what consequences might that have for the conservation of species?
- movement of genes from immigration/emigration - Limited by habitat fragmentation - Low genetic diversity = less adaptable, more susceptible to disease
Name four ways that organisms can become vulnerable to the effects of low genetic diversity. Which ones apply to hymenopteran pollinators?
a. Asexual reproduction b. fragmented habitats c. habitat loss d. low populations. e. First three are for bees
Would you expect r-selected or K-selected organisms to be more vulnerable to regional extinction? Explain your answer
- K – more susceptible to negative effects of genetic drift; more vulnerable to random events, which leads to reduced genotype variation
Provide an example of an organism that has gone through a genetic bottleneck. How is the bottleneck expressed in the organism today?
- Northern elephant seal – Allele tests prove lack of genetic variation
In two or three sentences, describe the particular difficulties that we face in the conservation of the Florida Panther. Name one conservation solution that you might recommend and explain why you favor it.
- K-selected species, low birth rate, hunting, cars, fragmented habitat, reduced gene flow - Hybridize Florida panther w/ Louisiana/Texas panther to increase gene flow.
Darwin stood on the shoulders of giants. Name four of those giants and what they contributed to our understanding of evolution
• Linnaeus – developed a nested classification of species by their similarity to one another – Phylum, Order, Class, Genus, Species – Recognized that some looked/didn’t look alike à grouped them • Hutton – Scottish geologist – promoted gradualism – the idea that small changes occurring over long periods of time can accumulate to cause large transformation of the earth – Can only think this way if earth is 4.6 billion years old à big change • Malthus – populations have the potential to grow exponentially and will therefore compete for resources with mortality of excess individuals – Resource limitation à competition for resources • Important for Darwin’s theory • Lamarck promoted the idea of “transmutation” whereby physical change in organisms occurred over time
Linneaus
developed a nested classification of species by their similarity to one another – Phylum, Order, Class, Genus, Species – Recognized that some looked/didn’t look alike à grouped them
Hutton
Scottish geologist – promoted gradualism – the idea that small changes occurring over long periods of time can accumulate to cause large transformation of the earth – Can only think this way if earth is 4.6 billion years old à big change
Malthus
populations have the potential to grow exponentially and will therefore compete for resources with mortality of excess individuals – Resource limitation à competition for resources • Important for Darwin’s theory
Lamarck
promoted the idea of “transmutation” whereby physical change in organisms occurred over time
Define evolution and name three mechanisms by which it can occur.
• change in genotype frequencies within a population • Mechanisms: – 1. Genetic Drift – Movement of organisms – Artificial selection – Natural selection – Genetic engineering
Define fitness in words, and then provide a simple mathematical expression for fitness, defining carefully each term in the equation. Repeat this for inclusive fitness and Hamilton’s inequality.
- the ability to reach reproductive age and to reproduce - l = proportion surviving to adult stage - m = fecundity at adult stage (fertility) - Fitness (W) = l x m - Hamilton’s inequality: o Has led to much of the development of modern behavioral ecology o An altruistic behavior will evolve if: o rb-c > 0 o Where r is relatedness, b is benefit of the altruistic behavior to the recipient, and c is the cost to the provider
In a couple of sentences, provide an example (a real one, from class) that demonstrates rapid evolution of organisms by the mechanism of natural selection.
- Darwin’s Finch’s - Drought on island led to plants producing larger seeds. Small beaked birds had greater mortality than large-beaked birds. Beak sized increased throughout remaining population
Name four factors that place limitations on the evolution of life-history strategies
- All factors of environmental variability: temperature variation, moisture content, existence & prevalence of predators, availability of food
Name four ways that organisms can become vulnerable to the effects of low genetic diversity. Which ones apply to hymenopteran pollinators
a. Asexual reproduction b. fragmented habitats c. habitat loss d. low populations. e. First three are for bees
What is the hydrologic continuity equation
o Context: Individual organisms are self-regulating, self-replicating, input-output systems. Input-output modeling is an important type of systems analysis that appears frequently in ecology, hydrology, and environmental chemistry. o The change in the amount of water is the sum of the inputs minus the sum of the outputs. Where: • Storage represents amount of water (units are “amounts”) • Arrows represent rates of movement (units are “amounts per unit time”) o Why It Is Useful: Rewrite equation to predict what will happen in the system (i.e. storage tomorrow is the storage today plus the change in input minus the change in outputs).
Describe the "laws" of Leibig and Monod. Write a brief (1-2 sentence) statement about the relevance of each to the growth rate individual organisms
a. Leibig: yield or growth of an organisms is determined by the abundance of that substance which, in relationship to the needs of the organism, is least abundant in the environment i.e.,at a minimum i. Growth is controlled by the scarcest resource b. Monod: A simple 3 parameter model for rate-constrained growth. i. Commonly used to describe the relationship between availability of a limiting resource and the resulting rate of cell uptake, growth or photosynthesis. ii. Biological processes respond in a non-linear fashion to changes in essential but limiting inputs 1. I.e. doubling sunlight does not double photosynthesis
What does “molar ratio” mean?
b. The ration of how many moles of elements you need for an element or an equation, like co2 is 1 carbon to 2 oxygen c. The molar ratio is the coefficient for a balanced (chemical) equation. Ex. 2H2 + O2 becomes 2H2O. Molar ration between H2 and O2 is 2
What is the density anomaly of water, and why is it ecologically significant?
o It is usual for liquids to contract on freezing and expand on melting. However, water expands and is less dense when it freezes than very cold water. This is ecologically significant because o ice seals help water bodies store heat and keep both oceans and lakes livable o density variations lead to thermal stratification of oceans and lakes o thermal stratification leads to chemical stratification of oceans and lakes o variations in density drive fluid movement (convective currents
List and explain the principal chemical transformations of the nitrogen cycle. Which require the presence of oxygen? Which are mediated by organisms
o Fixation: occurs when bacteria take atmospheric Nitrogen (N2) and convert it into organic forms of nitrogen in the presence of oxygen o Ammonification: bacterial process of converting organic nitrogen into NH4+. This process occurs with or without O2. o Assimilation: process that plants use to convert NH4+ and NO3 into plant matter. It occurs in the presence of O2. o Nitrification: bacterial process of oxidizing NH4+ into NO2 and NO3, in the presence of O2. o Denitrification: bacterial process of reducing NO2 and NO3 to N2 in the absence of O2.
simple population model
N(t)= (λ^t)N(time 0) population at time t = lamda to the t power times the population at time zero
λ
per capita geometric rate of increase population at time t divided by population at time t-1
r and λ when a population is GROWING
r > 0 λ > 1
r and λ when a population is remaining constant
r = 0 λ = 1
r and λ when a population is decreasing
r < 0 λ is a fraction
what controls population growth?
negative feedbacks density dependence- as population goes up, rate of growth goes down
K in terms of population
the number of organisms an environment can support above K - r < 0 below K - r > 0
logistic growth equation
its the population growth with the carrying capacity included in the equation dN N ---- = rN(1- ---) dt K
stable age structure
when proportion of of each age class remains the same, regardless of size develop under CONSTANT environmental constraints
Alkalinity
Measure of the ability of a solution to neutralize acids to the equivalence of carbonate or bicarbonate
Monod's Law (equation)
Max * (S/(S+k)) S=input concentration Max = maximum rate K = 1/2 saturation concentration
Life history strategy
growth, differentiation, storage, movement, reproduction, and senescence
Provide an equation that defines r in terms of four vital rates of population change.
• r = (b + i) – (d + e)
How (mathematically) is r related to λ?
⬢ r=loge λ ⬢ λ=e^r
discrete time logistic growth
Nt+1= Nte^[r(1-(nt/k))] as r increases, becomes more chaotic bc of time lag
When it comes to predicting changes in the size of a population that we wish to manage, why does age structure matter?
Because age influences reproduction. We need to make sure that we manage the age of the population so that they can reach the age where they can reproduce in order to continue to grow the population. There are age specific fecundities and mortalities we need to factor into population management.
What do we mean by stable age structure and under what conditions do populations achieve it?
⬢ When the proportion of the population in the age structure remains constant, regardless of the population size ⬢ Achieve it under constant environmental conditions o Constant age specific fecundities and mortalities
Px
age specific survival =lxt/lxt-1
fx
fertility Px*Mx
# of offspring
lx*Mx
Define Gause’s Principle and explain its relevance to the study of competition between species.
• One species per niche • Species which use resources in an identical fashion cannot coexist – the dominant competitor will always exclude the weaker • Principle of competitive exclusion
Does the overlap of resource utilization spectra provide an adequate indication of competition between species? Explain your answer.
⬢ first step in analyzing competition in the past but it does not equal competition ⬢ Although species may overlap in one dimension, such as seed size, they may not overlap in others, such as one lives on the ground and the other lives in trees). Therefore, they do not compete ⬢ Overlap is irrelevant if the resource is not limiting
What is an interspecific competition coefficient and how is it used in population models?
• The competition coefficient “converts” individuals of species 2 into equivalents of species 1 • When the coefficient = 1, then an individual of species 2 has the same effect on per capita growth rate as an individual of species 1 • When the coefficient = 0, then species 2 has no effect on the per capita growth rate of species 1 • If 0 < coefficient < 1, then intraspecific competition is stronger than interspecific competition • If the coefficient is > 1, then interspecific competition is greater than intraspecific competition
Draw the zero growth isoclines for two species that coexist while competing according to Lotka Volterra competition theory. Label the axes carefully, and label the points where the isoclines intersect the axes.
• Zero growth isoclines equation: o N1 = K1 – α12N2 o N2 = K2 – α21N1 X axis- N1 Y axis- N2
What are the mathematical conditions required for the coexistence of species under Lotka Volterra competition theory? What do those mathematical conditions mean ecologically?
⬢ That the carrying capacities are less than ⬢ Species 1 inhibits its own population growth before it gets to a density where it could exclude species 2 ⬢ Overall, intraspecific competition must be greater than interspecific competition ⬢ Product of alphas has to be <1
What did Hutchinson’s view of the niche contribute to our understanding of competition among species?
⬢ According to Hutchinson, the realized niche is smaller than the fundamental niche, ⬢ A species may frequently be absent from portions of its fundamental niche because of competition with other species.
What kind of dynamics occur in simple 2-species models of mutualism that don’t have self-limitation acting on either species? Explain your answer.
⬢ Both partners benefit from the relationship ⬢ Fitness is higher with the mutualist present ⬢ This may translate into higher rates of population growth and higher carrying capacity
⬢ Both partners benefit from the relationship ⬢ Fitness is higher with the mutualist present ⬢ This may translate into higher rates of population growth and higher carrying capacity
⬢ Intraorganismal mutualists are more tightly coevolved because one of the mutualists lives within the body of the other which requires significant adaptation by both parties. ⬢ Intraorganismal mutualists: Flagellate protozoa or bacteria in the guts of termites ⬢ Free-living mutualists: pollinators and flowering plants.
What are ant plants? Describe three kinds of rewards that they might offer their mutualistic partners.
⬢ Acacia provide food for ants (Beltian Bodies rich in protein, extrafloral nectarines that are rich in sugar. ⬢ Acacia provide domatia in which ants can live ⬢ Ants protect plants from herbivores ⬢ Plant gives ant home ⬢ Ant can prunes the vegetation around o Can protect from herbivores
Why can mutualisms be considered as “mutual exploitation”? Draw a graph that illustrates the fine line between mutualism and parasitism.
⬢ Mutualisms are not always peace and harmony. In the example of ants and ant plants, the ants often prune seedlings around their host trees which can reduce competition but may also kill offspring. ⬢ If the costs and benefits change, the relationship could easily become parasitism.
Draw a graph that combines an Allee effect with an inverse-density dependent death rate such that the two lines cross. Label your axes carefully. Show the equilibrium on your graph, determine whether or not the equilibrium is stable, and explain your an
draw
Draw a graph of continuous-time logistic population growth. Label your axes carefully. Does this population exhibit an equilibrium? Explain your answer.
draw
Draw a graph that illustrates the relationship between per capita growth rate and population density that is required to generate an equilibrium. Label your axes carefully. Show the equilibrium point on the graph.
draw
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