factor regulation U.5 L.5

  • density-independant facotr : an abiotic event that affects population growth in the same way regardless of population density

    • ex, food/nutrient limitation

    • environmental polluntants

    • climate extremes including seasonal cycles

    • catastrophic events (ex, fires, hurricanes)

  • density-dependant factor : a biotic interaction that varies in its effect on population growth depending on population density

    • ex, stress

    • disease

    • food shortages

    • invasive species

    • competition

    • predation

  • intraspecific compatition : members of the same species compete for resources, they compete when resources are limited, birth rate decreases/death rate increases and population growth slows

  • interspecific competition : two or more species comete for limited resources, they have to outcompete each other

  • competition is one of the driving orces for evolutionary change

    • individuals that are most different from their comeptitors will be able to avoid competitive interactions

  • primary producers have a direct relationship w the primary consumers that eat them

  • primary consumers have a direct relationship with their predators (the secondary consumers)

  • producers and orey use defensive strategies and “weapons” against their consumers and predators

  • producer-consumer & predator-prey relationships put selective pressure on both parties

  • population cycle : alternating periods of large/small population sizes (sinusoidal growth)

  • protective colouration : adaptations that help individuals avoid predations )ex. camofluage, mimicry, body colouration)

  • sybiosis : an ecological relationship between two species living in direct contact includes parasitism, mutualism and commensalism

  • parasitism : a symbiotic relationship where a parasite (symbiont) benefits and the host is harmed

  • parasite-host cycles are similar to preator-prey cycles and show a direct relationship to population density

  • increase in host population leads to increase in parasites, which decrease host, and a general decrease in everything else

  • mutualism : a symbiotic relationship where both species benefit

  • they both co-evolve resulting in growth in both populaations, if one increases the other one will, vice versa, ex. accacia ants

  • commensalism : a symbiotic relationship where one benefits one is neutral

  • some ecologists argue that there are few cases of this and they both typically benefit, but it has been proven incorrect ex. lemon shark and remora fish