Week 10 Wednesday Flashcards
What are community Assembly Rules?
rules that explain why species are assembled in a certain way, which drives the change of biological communities
what factors can the community assembly rules depend on?
-historical patterns of speciation
-migration
-dispersal
-abiotic environmental factors
-biotic interactions
What is a transitive hierarchy?
when A is stronger competitor than B and B is stronger competitor than C
what happens if hierarchy is absent?
co existence is more likely
what is the centrifugal organization of species idea based on?
that core and peripheral habitats occur in landscape
describe a core habitat
has few abiotic stresses, lots of resources, and few pests or pathogens
what is the trade offs in core/peripheral areas?
if species differ in competitive abilities, core habitat is dominated by the best competitor and the weaker/more stress-tolerant competitors can exist in more peripheral areas
what is a keystone species?
The species that is largely depended on by another species in an ecosystem so much so that if it is removed, the ecosystem would change drastically
Describe the bottom-up effects
Bottom-up control is driven by the prescense or absence of the producers in an ecosystem. this approach is also called the resource-controlled (or food-limited) food web
Describe the Top-Down effects
the populations of the organisms lower trophic levels are controlled by the organisms at the top, this is also called the predator-controlled food web
describe density dependent prey preferences
- predators wills witch between prey types based on relative abundances
–handling + search times
-it allows top predators to keep medium predators in check
what are trophic cascades?
powerful indirect interactions that can control entire ecosystems.
when do trophic cascades occur?
when predators limit the density and/or behaviour of their prey and thereby enhance survival of the next lower trophic level
what is the green world hypothesis?
the idea that predators/enemies, through trophic cascades, keep herbivore populations in check so they dont consume all of the plants
