Please enable JavaScript.

Coggle requires JavaScript to display documents.

Community Ecology (Metapopulations in Patchy Environments image…

- - - - some patches are occupied by the species whereas other suitable patches are not
      - empty patches will become colonized by migration from occupied patches
      - a region of the environment is composed of many discrete patches in which species can live
      - populations within individual patches have a probability of going extinct within that patch
  - - - low quality patch is a sink habitat :star:
  - - - must have adequate resources otherwise its will not be used :no_entry:
      - natural corridors are more preferred than artificial ones :+1:
  - - - can cause equatorial latitudes to be too hot for some species and northern latitudes to be more tolerable :warning:
    - - huge risk as we do not know which regions will create preferable patches for colonization :!?:
      - seeds of plants are transferred to new, suitable grounds
      - are artificially introducing a foreign species :red_cross: :check:
- - - - other communities can remain the same for many years
  - - - works for both plant and animal species in reestablishing old ecosystems and community stability
      - must be done gradually so ecosystem is not overwhelmed and can adapt appropriately :warning:
- - - - less attention to herbivores and little to plants, and it has been discovered that invertebrates make up to 50% of biomass in community :red_flag:
    - - difficult to trust food webs because they are so incomplete
  - - - this in turn means that the populations of a particular resource (type of plant) can indirectly depend on the presence of spiders
- - - - mathematical models have been developed to study interspecies competition
        
        cont. than it has on the per capita growth rate of its competitor :green_cross:
        
        two species can coexist if one or the other can increase from low density even in the presence of the other :star:
        
        2 competing species can coexist if each species has a greater negative effect on its own per capita growth rate :green_cross:
    - - abiotic resources include light, water, etc.
      - biotic resources are pollinators, seed dispersers. etc.
      - many cases happen in which one species grows better when resource is limited bt poorly when resource is abundant :star:
      - factors like temperature and atmosphere do not count as they are not technically consumed
  - - - predator feeding rate, refers to how quickly a predator can find new prey individual :check:
      - handling time, refers to time needed to consume prey :alarm_clock:
        
        both together constitute predator's functional response :star:
        
        feeding rate will be faster with abundance of prey so predators functional response is dependent on prey density called prey-dependent :red_flag:
    - - r is the intrinsic rate of increase for the prey species
      - N is the number of individuals of prey species in the community
      - dN/dt is the rate of change with time of the prey population
      - a is the predators per capita attack rate
        
        units of a are the number of prey eaten per prey per predator per unit of time, is prey dependent :star:
      - the equation for the net rate of change of predator numbers is ; dP/dt = faNP- qP :star:
        
        q is the predator's per capita mortality rate (independent of population density)
        
        f is a constant indicating the predator's efficiency at converting the prey it has eaten into new predators
        
        dP/dt is the rate of change with time of the predator population
        
        The population of prey will be stable, neither increasing nor decreasing when dN/dt= 0, expressed as :star:
        
        r/a=P
        
        prey population is stable when the density of the predator equals r/a. population of predators is stable when dP/dt=0 :star:
        
        N=q/fa
        
        predator population will be stable when the density of prey equals q'fa
        
        The line indicating population stability is called a zero growth isocline :check:
        
        when two zero growths isocline intersect indicates the population size of predators and prey can coexist stably :star:
        
        if one factor causes a population to change, then it will also affect the other population :red_flag:
      - P is the number of predator individuals present
      - The Lotka-Volterra model has been criticized for being too simplistic :warning:
        
        The Rosenzeig-MacArthur model adds more factors that affect both predators and prey in real communities :star:
        
        is a little more complex than the L-V model
        
        presents a realistic model where zero growth isoclines are curves instead of lines
        
        relationships between stable and unstable populations are more complicated
        
        main value is its ability to simplify complex interactions while teaching the fundamentals of predator-prey relationships :check:
    - - can create predator-one prey model and is helpful for humans to understand how we should harvest prey
      - is a direct relation in population size for both prey and predator, if prey is low then predator numbers will drop
      - in most natural communities, plants are attacked by multiple predators and almost every herbivore attacks several plant species :check:
    - - called the paradox of enrichment :star:
      - may be an important factor in the loss of species diversity when a habitat is improved :forbidden:
    - - inflection point is the populations maximum per capita productivity at which growth rate changes from positive to negative :check:
      - an alternative is fixed effort harvesting :star:
        
        this is where a populations health is determined by the amount of fish/deer that can be harvested with a particular amount of effort :check:
        
        if a population is healthy, then many organisms will be harvested and the opposite is true for scarce populations
        
        an alternative to this is fixed quota harvesting :star:
        
        this is when fishermen/hunters are allowed to harvest a particular amount no matter time or effort required :red_flag:
        
        both require government to set regulations and have increasing pressure from independent parties who want higher harvesting numbers despite risk of species :star:
        
        can be witnessed internationally with marine life as Japan and Norway continue to harvest endangered whales or multiple countries trying to strip Antarctica of its resources
  - - - probability that a particular prey individual will be encountered
      - is the prey plant poisonous or spiny
      - probability the attacked prey item will be successfully eaten
      - optimal foraging theory examine the interaction between these factors in an attempt to understand why certain plants are eaten or ignored :star:
        
        optimal diet model was produced in response to optimal foraging theory and makes 4 predictions :<3:
        
        if high yield prey become sufficiently scarce, the predator will be more successful broadening its diet to include low energy prey
        
        important when considering omnivore predators as plants are considered less valuable than other animals :star:
        
        some prey items will always be eaten even if they are encountered, others will not even if they are easy to obtain
        
        predators should prefer whichever prey yields the most energy per unit of handling time
        
        the probability that a particular plant will be eaten depends partially on abundance of other plants that are easy to handle and have higher value
- - - - lava and glaciers from new substrates after their destruction of the previous one
      - pioneer plants become prevalent and suffer the poor conditions to help make it favorable for new plants :check:
  - - - cost of production of nectar in flowers and loss of pollen eaten
      - plants supplying carbohydrates to nitrogen-fixing bacteria
      - pollinators must work to obtain nectar and pollen
      - natural selection favors organisms that can reduce costs, aka cheating that can evolve :star:
        
        cheating refers to obtaining benefits without paying costs :forbidden:
        
        is prevalent in many cases of mycorrhizal associations and nitrogen-fixing bacteria
        
        not technically cheating as plants can break off if soil composition is desirable
- - - - S is number of species, A is area, c and z are constants that must be discovered by studying individual communities :check:
      - three means by which to measure diversity by Robert Whittaker :<3:
        
        Beta diversity compares differences between several small sites within a larger region. :star:
        
        region should be the larger community being studied; comparison is between various plots within a forest
        
        Gamma diversity is the number of species within a region :star:
        
        Alpha diversity is the number of species or growth forms that occur at a local, small site :star:
    - - no community will have equal numbers of individual species :check:
      - abundant number of individuals in a species= common. rare is when the is only a few members of a species present
      - a plot of number of species in each abundance class will produce a species abundance distribution :check:
        
        has been shown not to describe most communities accurately
        
        will give inaccurate data on amounts of species and rarity and can be due to numerous factors
    - - this is due to large areas have more variation of types of soil, topography, geology etc.
      - more diverse habitats = more types of species that have adapted to their specific environment :check:
      - large areas also have an increased population size and are able to survive major disturbances such as fires :red_flag:
  - - - checklist are usually incomplete since not all microscopic life needs to be recorded
      - checklists can also help keep track of species count as in presence and absence and abundance of key species :check:
  - - - in higher latitudes, hard to find areas with no ice which can result in a very limiting amount of plant life, lowering diversity :red_cross:
      - the opposite is true for equatorial latitudes which contain optimum growing environments
    - - indicates the changing climate of earth and conditions at various latitudes
      - indicates earths tropical period and cooling period in which the northern latitudes began to freeze
      - This knowledge allows hypothesis on how plants were able to adapt to their new environments so well :check:
        
        produced the ability for tropical plants to become more temperate and develop necessary advantages
    - - places in northern latitudes tend to have fewer species and equatorial latitudes even with the same amount of area :warning:
      - believe this is due to equatorial latitudes have benign environments and higher latitudes have more severe ones :red_cross:
      - latitudes :sunny: can affect the amount of light received and in turn affect the environmental make up