2nd Half - Exam Review Flashcards
Intrinsic Growth Rate
The max rate at which a population can grow under ideal conditions
- r in exponential
- Lambda geometric model
What purpose do the mathematical models serve?
- Simplify complexity
- Make (quantitative) predictions
- Explore various scenarios
- Test hypothesis and mechanisms
- Communicate between disciplines
- To criticize models and decide if assumptions are realistic
Geometric Growth
Populations grow geometrically when reproduction occurs at regular time intervals
Population Increases
- By a fixed proportion - lambda
- Constant ratio of change from one time to the next
- Over discrete, non overlapping time intervals
- The larger the population becomes, the faster it grows
- Used to model populations with discrete breeding seasons or generations.
Exponential Growth
Populations grow exponentially when reproduction occurs continuously
- at a rate proportional to its current size
- continuously
- Larger the population becomes the faster it grows
- Used to model populations that grow continuously (rather than discrete intervals)
What is the critical value for lambda?
1
What is the critical value for r?
0
What does the critical value for intrinsic growth rate mean?
No growth or change in population size
What is the differences + similarities between exponential and geometric growth? (2 and 2)
Similarities:
1. Both show rapid growth due to multiplication
2. Both involve some intrinsic rate of increase
Differences
1. Geometric growth is discrete, exponential growth is continuous
2. Different interpretation of growth rates
Liebig’s law of the minimum
The rate of biological process is limited by the factor in least amount relative to the organism’s requirements
- some factor is limiting
What are the 2 main types of limits?
1.Density dependant factors - become more important as the population size increases
- lead to carrying capacity
- often due to increased infraspecific competition at higher population
- Density independent factor - affect the population size regardless of its density
Carrying capacity
The max number of individuals of a species that can be supported by the available resources in a particular environment
What factors become more important as the population size increases (3)
- decrease in birth rate
- increase in death rate
- both
When is negative density dependance observed?
- When the relationship between r max and density is -ve
- Due to intraspecific competition
Overshoot
If population exceeds carrying capacity
- decrease in birth rates
- increase in death rate
- both
Leads die off
Positive density dependent (allee effect)
The growth rate or survival of population increases as the population density increase
Due to:
- finding mate
- cooperative behaviours
- predator satiation
- resource availallity (niche construction)
Logistic Equation Model
The common model for negative density dependence
- S-shaped
- Inflection point
- Exponential phase before inflection point
- Logistic phase after inflection
K = carrying capacoty
BIDE Model of Population Dynamics
- Births
- Immigration - individuals moving into the population
- Deaths
- Emigration - The movement of individuals out of the population to other areas
What are the 3 types of fluctuation within a population
- Regular - tied to seasonal changes in environment
- Irregular - not tied to seasonal changes
- Cyclical - Intrinsic factors, result in a regularish pattern in the species, species interactions
Monotonic Damping
A smooth approach to carrying capacity
Damped Oscillations
Regular fluctuations that that decrease overtime
Stable limit cycle
Regular fluctuations that is consistent over time
Chaos
Complex, unpredictable and irregular fluctuations
Density Independent Factors: Due to stochasticity
Due to stochasticity (conditions are changing in complex ways), typically unpredictable events
- Disease outbreaks (biotic), new disease not present (disease can be density dependant)
- Natural disasters (abiotic)
- Human disturbances
A population that is more variable is less stable: (4)
- Stability - The maintenance of a relatively constant population size over time within a given geographic area (in terms of population).
- Fluctuations can lead to periods of low population size
- Small populations are more vulnerable to environmental changes and stochastic events
- Small populations are thus at much greater risk of extinction than large populations
Resilient
Population that returns quickly after perturbation
Perturbation
Any temporary or permanent change in the conditions in an ecosystem that disrupts its normal functioning or structure
Ecological Interaction
An interaction refers to the relationship between two or more species in an ecosystem
Mutualism:
Exploitation:
- Predation
- Parasitism
- Herbivory
Competition:
Commensalism:
Amensalism:
No interaction:
Mutualism ++
Exploitation +-
- Predation
- Parasitism
- Herbivory
Competition –
Commensalism + N
Amensalism - N
No interaction NN
Exploitation
Interactions in which one one individual consumes other individuals of another species
Predation
Is biological Interaction in which one organism kills and consumes another organism
Herbivory
The consumption of plants whole or in part by animals
Parasitism
Live in or on another organism host and derive nutrients from it. Often without immediately killing the host
Carnivory
Is the predation by animals that consume other animals
Cannibalism
The predation by an organism on individual of its own species
Omnivory
The consumption of organisms from more than one trophic level.
Mesopredator
A mid sized predator within an ecosystem that occupies an intermediate position in the food chain.
Optimal forage theory
- How organisms make decisions about their foraging behavior
- Assumes that organisms have limited time and energy to spend on foraging
Top Down regulation
Consumers regulate the abundance of prey species
- In turn can influence the abundance of lower trophic levels and the structure of the community
Bottom-up regulation
The availability of resources influence the abundance of consumers
- in turn can affect the structure and dynamics of the community
Search Image
Refers to a mental representation or template formed by predators to recognize and effectively locate a specific type of prey within their environment.
Functional Response
A relationship between the density of the prey and an indig=vidual predators rate of food consumption
Type I functional Response
Linear increase with prey density. Sometimes saturates at high prey densities. Predators are not constrained and can consume prey at a constant rate.
Type II Functional Response and Handling Time
Rate increases with density. Starts to slow down at higher prey densities. Plateaus at high prey density. Predators have limited handling capacity encounter prey defenses
- Handling Time: the duration of time required for a predator to capture, subdue and consume its prey after successfully locating and capturing
Type III Functional Response (most common) , Search time, and Refuge
Low prey consumption under low prey density. Rapid increase at moderate prey densities. Plateaus at high prey densities. Predators: switch between prey types or when prey have complex anti-predator defenses uses refuge. Spend time searching for prey or learning to capture prey.
- Search time: the duration of time spent by a predator actively searching for its prey within a given habitat area
- A Refuge: a location or habitat that provides protection or shelter to individuals or populations of organisms
Type I: Shows…
Type II: shows…
Type III: shows…
Type I: Shows a constant linear increase
Type II: shows a plateauing effect
Type III: shows a delayed increase followed by a plateau
Numerical Response
A change in the number of predators through population growth or population movement due to immigration or emigration.
The Lotka-Volterra Model
Used to understand dynamics of predator-prey relationship
Capture rate of predator on prey = … = …
= Functional response = consumption rate
Conversion efficiency of predator x capture rate of predator on prey = …
Numerical Response
Isoclines
Lines on a graph that indicate where the population growth rate is 0 for one or more species
- represent equilibrium conditions in population dynamics model
- particularly in predator-prey interactions or competition between species
The principal of interaction strength
- As a consumer-resource interaction strength increases, consumer-resource interacitions tend to become:
- More top heavy
- less stable and therefore more prone to extinction
- Energy flow between a consumer and its resource, the interaction becomes more oscillatory
The Weak Interaction Effect
- Weak interactions mute strong excitable interactions by..
- deflecting away from them and inhibiting population cycles
- Weakening generalist interaction strength on any one prey due to trade offs
Interspecific competition
The interaction between two species where the increased abundance of any one species the population growth of the other species to decrease
- between individuals or populations of different species
Intraspecific Competition
- Between individuals of the same species
- competition can occur through exploitation or interference
Exploitative Competition
Competition between organisms where individuals compete indirectly through the consumption of a limited resource.
- Indirect
Interference Competition
Competition between organisms where individuals directly interact with one another to access or control resources.
- Direct ex. Aggression, territorial defense, occupying space
Competitive Exclusion
One species outcompetes the other species, causing extirpation or local extinction
- on species may be better adapted to a particular resource
Competitive Exclusion Principal
Two species competing for the same limited resource cannot coexist indefinitely
Resource Partitioning
Exploitative different resources in some way such that each specialized on a different resource or in a different location
- both survive
Character displacement
Competition between similar species can lead to the evolution of distinct differences reducing competition
Niche Overlap
The extant to which ecological niches of two or more species in a community share similar resources
Niche/ resource partitioning
Different species with a community adapt to use different subsets of resources or occupy different ecological niches to reduce competition and co-exist in the same habitat
- when this leads to evolutionary changes becomes character displacement
Competition coefficients
Quantify the intensity of competition between species for a shared limiting resource
- Quantifies the effect of one species on another
- Describe how the growth of one species is affected by the abundance of another species
- Converts the number of individuals of one species into the number of individuals of the other
Mutualism
A reciprocal relationship between two species where both species benefit
Symbiosis
A type of mutalism in which individuals live within or on the other organism
Obligate Mutualism
Essential for survival of one or both interacting species
Facultative Mutualism
Are not essential for the survival of either species
Trophic mutualisms
- trade food for nutrients
- trade food for food
Defense Mutualisms
trade defense for energy
Transport mutualism
Trade transport for energy
Mutualism can change with changing conditions
- Strengths of mutualism depends on the conditions that motivate the trade
- mutualisms can biome parasidi
Indirect Inderactions
Refers to the relationships that are mediated or influenced by the presence or activities of one or more additional species
- trophic cascades
- apparent competition
- facilitation
Apparent competition
Refers to indirect interaction between two or more species mediated by a common predator
Trophic Cascade
The indirect effects in which a change in the abundance or behavior of one species cascades through food web, influencing the abundance or behavior of other species at different trophic levels
- change in abundance at one trophic level can be refleced in changes in abundance of organisms at other trophic levels
Top-down cascade
- The effects originate from changes in the top trophic level and cascade downward through the food chain
- Consumers regulate the abundance of prey species
- In turn influence the abundance of lower trophic levels
Bottom-up Cascade
- The effects start from the changes in the primary producers or lower trophic levels and cascade upward through the food chain
- The availability of resources influence the abundance of consumer
- In turn affect higher trophic levels
Keystone Species
A disproportionately large impacts on its environment relative to its abundance
Dominant Species
An abundant species that exerts a significant within that community or the structure and function of an ecosystem
Ecosystem Engineer
Significantly modifies or creates habitat, thereby directly or indirectly affecting the ability of resource for other species
- Type of keystone species
- can reek havoc in areas where they are not
Foundation Species
Provide the physical foundation or infrastructure for a community or ecosystem
- often dominant species (corals, mangrooves)
Facilitation
One species positively influences another species
- in terms of growth, survival, reproduction
Invasive Meltdown
Phenomenon in which the invasion of non-native species facilitates the invasion of additional non-native species
Conductance
The proportion of possible links or interactions between species that are actually realized in a food web
- # actual links/ # possible links
Compartments
Relatively isolated food web subsystem that are richly connected within the subsystem but are loosley connected between subsystems
- strong interactions within a compartment
- Weak interactions between compartments
Module/ Motifs
A subset species within a larger food web that are interconnected by their feeding relationships
- more common than expected by chance
Generalist
- A consumer that can make use of a variety of different resources
- Flexibility is useful when facing variable environmental conditions
Habitat Coupling
- Linking of discrete habitats are connected through the movement and foraging of mobile consumers
- Flexability is useful when moving between habitats
Food web rewiring
Fundamental changes in the structure of a food web that alter the pathways of nutrients and or energy in an ecosystem.
What are the two types of rewiring?
- Topological rewiring - changes in who eats whom. Results from species introductions and/or losses
- Interaction Strength Rewiring - Changes in how much. Results from changes in the consumptive demands of consumers
- these two types can co-occur
Primary Productivity
The rate at which energy is captured and concerted into organic compounds by photosynthesis or chemisyntheis
- preformed by primary producers
Primary producers: (3)
- provide energy for all ecosystems
- Most commonly sun used (photosynthesis)
- Chemosynthesis - convert carbon containing molecules into organic matter using the oxidation in organic compounds or ferrous ions as a source of energy
Productivity
The rate at which energy is converted onto organic matter
Production
The biomass produced by organisms in an ecosystem over a given period of of time
The standing crop
The biomass of producers at a particular moment in time
Gross primary productivity (GPP)
The rate at which energy is captured and assimilates by producers in a given area
Net Primary Productivity (NPP)
The rate at which energy is assimilated by producers and converted into biomass in a given area
Primary productivity varies with (4)
- latitude
- Region
- Ecosystem type
- Season
Consumers
Obtain their energy by “eating” primary producers and or other consumers/heterotroughs
- or by decomposing dead organic matter
Food chain
A linear sequance of energy flow between organisms
Tropic Level
A position in the food chanin that represents a group of organisms sharing the same primary source of nutrient and energy
- named in order from primary producers to various levels of consumers
Secondary Production
Biomass accumulation in an area
- consumers assimilate some energy and egest some energy
- Consumers respire some of their enrgy for metabolism
- The rest contributes to secondary production
Ecological Efficiency
The percentage of the net primary production from one trophic level compared to the next trophic level
- only a fraction of the energy and biomass at each trophic level are transferred to the next level
- Some enrgy is always lost
- Most trophic pyramids are wide at the bottom and narrow at the top
Trophic pyramid
A chart composed of stacked rectagles representing the amount of energy or biomass in each trophic group
- pyramid of numbers
pyramid of biomass
- pyramid of energy
Consumption efficiency
The percentage of energy or biomass in a trophic level that is consumed by the next higher trophic level
Assimilation efficiency
The percentage of consumed energy that is assimilated
Top Heaviness in a biomass pyramid
A relatively high concentration of biomass or numbers at higher trophic levels compared to lower trophic levels
- more biomass at higher trophic levels than at lower trophic levels means the pyramid is inverted
Local Guild
A group of species that share a common resource and occur in the same community
A community
A group of interacting species that occur together in the same place and time
- boundarie scan be distinct or gradual
An ecotone
a transition area between two biological communities
- can be well blended or very small leading to gradual or abrupt change
- often the two communities are intermixed
Succession
Process by which a community changes overtime
- occurs in a community as species replace each other overtime
- different species are present in different stages of succession
R selected species are associated with what kind of successional stages?
Early successional stages
- they quickly colonize and exploit disturbed habitats
K selected species are more prevalent with what kind of successional stage?
Later stages
- they outcompete other species and dominate stable environment
Primary succession
When communities develop in habitats that are initially devoid of plants and organic soil
Secondary Succession
When communities develop in habitats that have been distributed and include no plants but still contain organic soil
Disturbance
Any event or process that disrupts the normal structure or functioning of an ecosystem
Priority Effect
The arrival of one species at a site affects the subsequant colonization of another species
Mechanisms of Succession (3)
- Facitiation - one species increases the probability of another species being present/ established
- Inhibition - one species decreases the probability that a second species will become established
- Dependant on priority effect and disturbance - Tolerance - when the probability that a species becomes established depends on its
a. Dispersal ability
b. Ability to survive under the conditions of the environment
Are the mechanisms of succession exlusive?
No, they can happen at the same time.
Paradox of Enrichment (kinds)
Increasingly the available of resources can lead to the decline or instability of a consumers population
1. increased resources
2. consumer response
3. overexploitation
4. boom and burst
Two parallel food webs (green and brown)
Green food web
- how producers obtain energy from primary production
- how this energy moves up the food web when producers are consumed
Brown food web
- how scavengers, detrivores, and decomposers obtain energy from dead organic matter
- how this energy moves up the food web when they are consumed
- dead organic matter
Biogeochemical Cycle
The movement and transformation of chemical elements and compounds between living organisms and gaseous/solids/liquid forms in the atmosphere, and rocks, soils, and sediment
Pools
The total amount of a particular substance or element within a specific compartment or reservoir in an ecosystem
- can include living organisms as well as non-living components
- can vary greatly in size
- can be relatively stable or dynamic
- measurement units: mass
Fluxes
The movement or transfer of matter, energy, or other substances between different pools within an ecosystem
- rate of exchange between pools
- can include photosynthesis, respiration, decomposition, predation, nutrient uptake
- measurement units
Residence Time
The average amount of time energy or biomass remains within a specific compartment or trophic level
- Before it is either transferred to another pool or removed altogther
Uptake
Decomposition
Mieralizarion
Leaching
Runoff
Volatilization
Weathering
Sedimentation
Uptake - nutrients are taken up by organisms from the environment
Decomposition - dead organic are broken down by decomposers
Mieralizarion - The conversion of organic nutrients into inorganic forms that can be taken up by plants and other organisms
Leaching - nutrients can be lost from an ecosystem through leaching where water carries dissolved nutrients downward into bodies of water
Runoff - nutrients can be washed away from the land surface into bodies of water
Volatilization - Nutrients are released into the atmosphere
Weathering - physical/ chemical breakdown of rocks
Sedimentation - the movement of elements back into sediments
What role do microorganisms play on nutrient cycling
They transform organic form s of nutrients into inorganic forms that can be taken up and assimilated by primary producers
Stoichiometry
In ecology refers to the study of the balance of elements and compounds in biological systems and their role in regulating ecological processes
- The elemental composition of organisms and ecosystems
- Relative proportions of different chemical elements: often expressed as ratios of one element to another.
- Provide insights into: nutrient limitation, growth and productivity, ecological interactions.
Dark Diversity
Is the set of species that are absent from a study site but in the surrounding region and potentially able to inhabit particular ecological conditions
Extinction
the future extinction of species due to events in the past
- Extinction takes time
Biodiversity hotspot
Refers to a biogeographic region that is characterized by a high level of species richness and endemism
- Are under threat from human activities
Species-area Relationship (SAR)
well established pattern in ecology
The specific mechanisms vary depending on context.
The Equilibrium Theory of Island Biogeography
- Incorporates habitat area and isolation
- The mainland is a species pool
1. New species colonize islands from nearby sources
2. As more species colonize fewer species are left to disperse to the island
3. Colonization rates slow
Over time species will go extinct
As species go extinct
- Fewer competitors for resources
- Less niche overlap
- Larger populations for remaining species
- Extinction rate slows
Alpha Diversity
The species richness in a defined habitat/ area
Beta Diversity
In some measurments of species differences or turnover of species between habitats
Value of biodiversity
- Cultural spiritual significance
- economic value
- inspiration for innovation
- aesthetic value
