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Autotroph
An organism capable of developing organic molecules from simple inorganic molecules using either chemical or light energy
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Heterotroph
An organism that cannot fix carbon and therefore must obtain organic molecules from other eating organisms
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Photosynthesis
a chemical process that converts carbon dioxide and water into organic compounds, especially sugars, using light energy
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Respiration
metabolic assimilation of oxygen, accompanied by breakdown of organic compounds, release of energy, and production of carbon dioxide and water
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Net Photosynthesis
photosynthesis – respiration; units are moles CO2 per unit leaf area per unit time
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Light Compensation Point
light level (value of PAR) at which photosynthesis and respiration balance each other
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Light Saturation Point
light level at which maximum photosynthesis is achieved
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Stomata
pores in the leaf or stem of a plant that allow gaseous exchange between the internal tissues and the environment
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Water Use Efficiency
ratio of carbon fixed (photosynthesis) per unit of water lost (transpiration); Has important implications for where different types of plants are found
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Light reactions
the capture of light energy during photosynthesis; results in the synthesis of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate)
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Dark reactions
the biochemical incorporation of CO2 into simple sugars; do not require the presence of sunlight, but are dependent on the products of the light reactions (ATP and NADPH)
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Temperature
a measure of the quantity of thermal energy in an object
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Heat
thermal energy in transit from a high-temperature object to a low-temperature object
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Radiation
transfer of heat by electromagnetic waves
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Conduction
transfer of heat from molecules of one substance to another
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Convection
transfer of heat by the movement of a liquid or gas
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Evaporation/Condensation
transfer of energy required to initiate phase change from a liquid to a gas or a gas to a liquid
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Why are leaves green?
The combination of visible light wavelengths absorbed by the combination of pigments present in the leaf (i.e. chlorophyll) allow for the overall reflection of green light
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C3 Photosynthesis
- CO2 is captured by rubisco and converted into a three-carbon molecule (phosphoglycerate; 3PGA)
- -Rubisco has low affinity for CO2 and favors oxygenation over carboxylation at low CO2 concentrations and warm temperatures
- -most common where temperatures are cooler or water availability is high
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C4 Photosynthesis
- CO2 is captured by PEP carboxylase and converted into a four-carbon acid (oxaloacetate; OAA)
- -Unlike rubisco, PEP carboxylase has high affinity for CO2 and does not catalyze photorespiration
- -Depends on specialized leaf anatomy; rubisco is found only in cells that are spatially segregated from external air
- -favored under warmer and drier conditions
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Crassulacean Acid Metabolism (CAM)
- uses essentially the same biochemistry as C4 photosynthesis to overcome the limitations of rubisco and eliminate photorespiration
- -Instead of using spatial separation, capture of light energy and uptake of CO2 is separated temporally
- -most closely associated with highly arid temperate regions
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How and why does photosynthetic rate vary with light availability?
The less light, the less photosynthesis. The light level must be above the Light Compensation Point (LCP) for the carbon uptake to exceed the carbon loss in respiration. But it is also possible for photosynthesis to become light saturated, at values of PAR above the Light Saturation Point, whereupon it maxes out. However some plants extremely adapted to shady environments may experience photoinhibition, where overbearing light causes photosynthetic rates to decline as well.
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Describe the movement of water between soils, plants, and air and the common mechanism driving this movement
- Water moves from larger to smaller values of water potential.
- Water loss through transpiration continues as long as (1) the amount of energy striking the leaves is enough to promote evaporation; (2) moisture is available for roots in the soil, and (3) roots are capable of maintaining a more negative water potential than that of the soil.
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Water potential (ψ)
- the difference in potential energy between pure
- water (which is defined as having a water potential of zero) and the water in some system, such as in a plant cell or in the soil
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Osmotic potential (ψπ)
due to differences in concentration of dissolved solutes (zero or negative)
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Pressure potential (ψp)
- due to differential hydrostatic or pneumatic pressure in the system
- (positive or negative)
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Matric potential (ψm)
due to the cohesive force that binds water to physical objects (negative)
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Gravitational potential (ψm)
due to the pull of gravity on water (negative)
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The trade-offs associated with each of the three types of photosynthesis and how climate change might influence global patterns of photosynthesis as a consequence
- At temperatures below 25 °C rubisco operates quite well; the C4 system operates best at ~45 °C
- C4 plants must expend energy to regenerate PEP, a disadvantage at low light levels
- Photosynthesis evolved under high levels of CO2 where the advantages of the C4 pathway would be reduced
- While temporal separation of C3 and C4 reactions in CAM plants limits maximum photosynthetic rates, water use efficiency is maximized
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Herbivore
animals feeding exclusively on plant tissue
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Homeotherm
organisms who maintain relatively stable body temperatures (an example of homeostasis); warm-blooded; generally endothermic
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Carnivore
animals who feed exclusively on animal tissue
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Poikilotherm
organisms whose body temperature changes in concert with external conditions (cold-blooded); generally ectothermic
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Omnivore
animals feeding on both plants and animal tissues
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Heterotherm
An organism whose ability to regulate its body temperature is intermediate between an endotherm and an ectotherm. Some small birds and mammals – generally endothermic (‘warm-blooded’) groups – may reduce their metabolic rate during a particular season or even a certain time of day, allowing their body temperature to fall and entering a state of torpor. At the opposite end of the spectrum, certain animals that are generally regarded as ectothermic (‘cold-blooded’) have the ability to generate heat internally for limited periods.
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Detritivore
animals that feed on dead plant and animal matter
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Torpor
a temporary state of reduced metabolic rate
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Nutrient
substance an organism requires for normal growth and activity
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Thermoneutral Zone
range of environmental temperatures within which metabolic rates are minimal
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Essential Nutrient
a nutrient which cannot be synthesized by a given organisms; must be supplied by the diet
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Countercurrent Exchange
an anatomical and physiological arrangement by which exchange of energy or matter takes place between arterial and veneous blood moving in opposite directions
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Homeostasis
An organisms regulation of internal conditions such that a balance of said conditions is always maintained within a normal range
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Endotherm
organisms who rely on internal (metabolic) heat production to maintain relatively high body temperatures
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Ectotherm
organisms whose body temperatures are determined primarily by external thermal conditions (variable)
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The difference between isometric and allometric scaling
Relationships between length and surface area or volume are constant as size changes in isometric scaling whereas in allometric scaling the relationships change.
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How surface area/volume ratios change with increasing size of an object and why that might matter for living organisms
- When an object increases in size, its surface area increases, however it decreases with respect to volume. This relationship places a critical constraint on the evolution of animals; for example, as most every animal (Loriciferans being exceptions) depends on oxygen to survive, this causes the diffusion of oxygen from the external environment through to the interior tissues to increase in difficulty with an increase in body size. Animals could not get very large at all by way of diffusion alone for oxygen transport. This has allowed for the development of wrinkled surfaces on organisms to increase surface area, and/or elaborate active transport systems for oxygen into the body's interior.
- Especially concerned is the relative heat loss which increases with decreasing size for endotherms; this must be offset by increased metabolic activity. Ectotherms have decreasing relative heat gain from their environments with increasing size; therefore large ectotherms are restricted to warmer environments
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Herbivory
Developed specialized digestive systems with which they may digest their diets rich in cellulose. Many depend on the presence of microorganisms bacteria/protozoa in their DT for the digestion of cellulose. Some even eat what they regurgitate or defecate for additional digestive purposes.
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Grazers feed on
leafy material
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Browsers feed on
woody material
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Nectivores feed on
nectar
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Carnivory
simple stomachs and short intestines; eating animals (herbivores)
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Omnivory
feeding on both plants and animals
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Detritivory
feeding on dead plant and animal matter
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The major pathways through which organisms gain and lose heat
- Changes in metabolic rate
- Heat exchange
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The potential adaptive advantages of acclimatization
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How homeothermic ectotherms are able to regulate their body temperature
They might sun themselves when it is cool, seek shade and moisture, and be more still when it is warm
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How organismal performance typically relates to temperature and what happens physiologically
at extreme temperatures
- Poikilotherms respond to increasing temperature with a standard performance curve that increases to a maximum before declining sharply
- Cannot be active at extreme temperature
- Homeotherms may shiver when cold or sweat when warm.
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How width of the thermal neutral zone among species varies with latitude and why
The width of the thermal neutral zone is greater for species closer to the poles due to the fact that they are subjected to much lower temperatures and have evolved such that they maintain their constant metabolic rate over a broader ranger. If Arctic animals were going to shiver in the cold, they wouldn't live in the Arctic!
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Trade-offs between endothermy and ectothermy
- Endothermy
- -Animals can remain active regardless of environmental temperatures
- -Energetic demands are very high; limits allocation of resources to growth and reproduction
- Ectothermy
- -Energetic demands are often low; increases allocation of resources to growth and reproduction
- -Animals are often inactive due to environmental temperatures
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How a countercurrent exchange system works
An anatomical and physiological arrangement by which exchange of energy or matter takes place between arterial and veneous blood moving in opposite directions, a countercurrent exchange system may work by surrounding cooler veins with warmer arteries in the extremities to warm the blood being returned to the body and minimize heat loss.
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Life History
an organism’s lifetime pattern of growth, development, and reproduction
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Hermaphrodite (Animal)
an individual that posses both male and female sexual organs (testes and ovaries)
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Simultaneous Hermaphrodite
individuals that posses both male and female sexual organs at the same time in its life cycle
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Sequential Hermaphrodite:
individuals that change sex at some point during its life cycle
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Principle of Allocation
if organisms use energy for one function such as growth, the amount of energy available for other functions is reduced
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Mating System
describes the pattern of mating between males and females in a population
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Monogamy
males and females form a lasting pair bond, mating with only one member of the opposite sex
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Promiscuity
individuals form no pair bond and mate with more than one member of the opposite sex
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Polygamy
acquisition by an individual of tow or more mates; a pair bond exists between the individual and each mate
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Asexual reproduction
any form of reproduction that does not involve the fusion of gametes
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Sexual Selection
differential mating success among individuals as a result of competition for access to mates; male-male combat (intrasexual) and female choice (intersexual)
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Parthenogenesis
development of an individual from an egg that did not undergo fertilization
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Sexual reproduction
any form of reproduction that involves the fusion of haploid gametes (egg and sperm) into a diploid zygote
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Dioecious
plants with male and female reproductive organs on separate individuals
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Hermaphrodite (Plant)
plants with both male and female reproductive organs within the same floral structure
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Monoecious
plants with male and female reproductive organs in separate floral structures on the same individual
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Advantages and disadvantages to asexual reproduction
- Advantages – local adaptation and high population growth rate
- Disadvantages– low genetic variability and consequent inability to respond effectively to natural selection
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Common life history trade-offs relating to reproduction
- Individuals produce either many small eggs or few large eggs
- Smaller individuals produce fewer eggs
- Larger seeds often lead to fewer seeds but greater seedling success
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How individual energy budgets typically change after organisms meet sexual maturity
- Before – energy goes to maintenance or growth
- After – energy goes to maintenance, growth, and reproduction
- Individuals delaying reproduction should grow faster and reach a larger size, resulting in increased fecundity
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Intrinsic rate of increase, rmax; r versus K selected species
- r selection: High
- K selection: Low
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Competitive ability; r versus K selected species
- r selection: Not strongly favored
- K selection: Highly favored
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Development; r versus K selected species
- r selection: Rapid
- K selection: Slow
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Body size; r versus K selected species
- r selection: Small
- K selection: Large
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Reproduction; r versus K selected species
- r selection: Early; single, semelparity
- K selection: Late; Repeated, iteroparity
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Offspring; r versus K selected species
- r selection: Many, small
- K selection: Few, large
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Population
a group of individuals of the same species living in a given area at a given time
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Random
- distribution lacking pattern or order; placement of each individual is independent of all other individuals
- -Uniform distribution of resources
- -Neutral interactions among individuals
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Genet
a genetic individual that arises from a single fertilized egg
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Regular
- distribution in which individuals are more uniformly placed than would be expected by chance
- -Local depletion of resources
- -Negative interactions among individuals
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Ramet
clone; a module produced asexually and a potentially physiologically independent unit
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Clumped
- distribution in which individuals have a much higher probability of being found in some places than in others
- -Patchy resource distribution
- -Positive interactions among individuals
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Metapopulation
a population composed of subpopulations held together by movements of individuals among them
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Dispersal
leaving an area of birth or activity for another area
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Abundance
- the number of individuals in a population (N)
- Determined by:
- the area over which the population is distributed
- & the population density
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Migration
intentional, directional, usually seasonal movement of animals between two regions or habitats; involves departure and return of the same individual
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Density
number of individuals per unit area
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How the concepts of genet and ramet relate to counting individuals in a population
though genets and ramets exist as two distinct levels of population structures, for practical purposes, ramets are counted as (and function as) individual members of a population
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The relationship between body size and population density for animals and plants
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Three patterns of spatial distribution of organisms at small scales and the ecological factors that might generate such patterns
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Intrinsic Rate of Increase (r)
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Finite Rate of Increase (λ)
- the proportional change in population size from one year to the next (λ = Nt+1/Nt);
- the average number of offspring produced by an individual per generation
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Life Table (Cohort and Time-Specific)
tabulation of age-specific mortality and survival
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Net Reproductive Rate
average number of female offspring produced by a female during her lifetime
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Stable Age Distribution
constant proportion of individuals of various age classes within a population through time
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Carrying Capacity (K)
population density where b = d and population growth is zero
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Density-Dependent effects
- – population growth slows due to interactions among organisms (e.g., competition, aggression, disease) in proportion to population size; implies feedbacks
- Mortality rate increases (density-dependent mortality)
- Fecundity rate decreases (density-dependent fecundity)
- -implies feedbacks
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Independent Population Growth
- population growth limited by environmental factors (e.g., temperature, fire, wind) regardless of population size
- -no feedbacks
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Allee Effect
when reproduction and/or survival decrease with decreasing population density, in contrast to the general expectation
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Competition
any interaction that leads to reduced survival, growth or reproduction due to shared requirements for limited resources; an interaction that is mutually detrimental to both participants (-/-)
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Scramble Competition
when limited resources are shared to the point that no individual survives
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Contest Competition
when limited resources are shared only by dominant individuals; a relatively constant number of individuals survive
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Exploitative Competition
operates indirectly by the depletion of some shared resource
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Interference Competition
involves direct interactions among competitors
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Metapopulation
set of (local) subpopulations held together by dispersal or movements of individuals among them
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Habitat Patch
discrete area of suitable habitat (place where an organism lives) within a larger landscape of unsuitable habitat
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Environmental Stochasticity
random variations in the environment that directly affect birth and death rates
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Rescue Effect
increase in population size (and decrease in extinction risk) that occurs with an increasing rate of immigration
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Mainland-Island Metapopulation Model
a single habitat patch (the mainland) is the dominant source of individuals to island populations
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What are the four conditions necessary to have a metapopulation?
- Suitable habitat occurs in discrete patches that may be occupied by local breeding populations
- Even largest populations have a substantial risk of extinction
- Habitat patches must not be too isolated to prevent recolonization after local extinction
- Dynamics of local populations are not synchronized
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How is patch occupancy in a metapopulation elated to local extinction and recolonization rates?
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How are local extinction and recolonization rates related to patch size and isolation (interpatch distance)?
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How does habitat heterogeneity influence metapopulation persistence?
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What is the difference between source and sink habitats and the potential implications of that difference for conservation?
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How might local population dynamics become synchronized and what are the potential effects on
metapopulation persistence?
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