Species Interactions and Community Structure Flashcards
community webs
a food web summarises the feeding relations in a community
dominant species
influence structure of community webs
- strong interactions
- most energy flow (major, not minor)
- large biomass (unlike keystone)
carnivores
feed at several trophic levels
- compete with lots and prey on lots
how can webs be simplified
include major energy flow and less minor
strong and weak interactions
add or remove species and see what happens
group in guilds or functional feeding groups (eat same thing)
indirect interactions
- fundamental to communities
- one species affects another through an intermediate (direct would be predation or herbivory)
- trophic cascades, apparent competition and indirect mutualism or commensalism
indirect commensalism
one species (through an intermediate) benefits another species without being helped or harmed
apparent competition
negative effects of one species on another are the result of two species sharing a predator or herbivore or by one species facilitating populations of a predator or herbivore of the second species
keystone species
the feeding activities of a few keystone species may control the structure of communities
- despite low biomass, exert strong effects on the structure of communities they inhabit
- increase diversity y decreasing competitive exclusion
mutualistic keystones
they can be keystones such as cleaner fish removing parisites from other fish which protects fish
analysis of food webs - connectance
measure of density of cross links in webs. actual/possible
analysis of food webs - linkage density
trophic links per species (how many predators/prey per species). increases with web size. actual/species
chain lengths
look at the max (usually 5)
- energy limitations (10% to next level)
- habitat size limits
- dynamic stability hypothesis - top tier are vulnerable if food changes (hard to find evidence)
