exam 4 Flashcards
Community
a group of interacting plants and animals inhabiting a given area
Dominance
if a species if found to predominate (or have a large proportion of the total number of individuals) it is defined as a dominate species
Species richness
number of species
Species evenness
relative abundance of individuals among the species
Simpson’s index
(number of individuls of a species/number of inidivudals of all species) which ranges between 0(as richness and evenness increase, value approaches ) in comparison to 1(no diversity)
Shanon Index
no diversity (one only species) is 0! Max diversity is ln (total number of species)
Rank-abundance curves
graph that has rank abundance (species rank from most to least abundant) on x axis and relative abundance on y axis… THUS THIS GRAPH CANNOT EVEN INCREASE AT ANY POINT…
Keystone species
species that has dispoorportionately large effect on its environment reltive to its abundance. They maintain a critical role in the ecological community EVEN when in small abundance
Basal species
Basal species – species that feed on no other species! Typically plants
Intermediate species
Intermediate species – species that are both predator and prey
Top predator
Top predator – it is eaten by no other species… usually is a cannibal as well?
Food web connectance
(number of links/maximum possible number of links or speciescount^2)
linkage density
links/species
chain length
length from basal to top predator
compartmentalization in food webs
extent to which a food web contains relatively islolated subwebs
Diffuse interactions
when the abundance of the species is influenced by a number of competing species, the removal of single species may have minimal or insignificant effect on the chain
Indirect interactions (interpretation from analysis of food webs)
effects have big effects on whole communities! Direct interactions occur when anything is eaten or eats. Indirect interactions occur between organisms that don’t eat or be eaten directly by eachother but are impacted through other organisms… like how grass will help the top predatoor
Apparent competition
A form of competition between species or group of organisms indirectly competing with another species or group of organisms, which both of them serve as prey of a predator…. For example if food source for an organism(1) goes up, so that organism’s predator goes up, thus hurting another species(2) that that predator usually eats… competition between the two consumers(1 AND 2)!
Trophic cascade
species interactions lead to changes in pop sizes of various species?? CHANGE IN TOP PREDATOR
Zonation
spatial changes in community structure as one moves across the landscape…different zones
Role of resource availability on plant community species diversity- species interactions on a large scale
competition leads to changes in seedling survival, mean growth rate, and flowers produced per plant… THERES A TRADEOFF BETWEEN TOLERANCE TO LOW RESOURCE AND CMPETITIVE ABILITY
Relationship between habitat diversity and species diversity in animal communities
(e.g., Foliage height diversity and bird species diversity)
greater habitat diversity leads to more species diversity. WITH MORE FOLIAGE HEIGHT DIVERSITY (more vertical layers of vegetation) THERE IS MORE BIRD SPECIES DIVERSITY
Succession
Succession - temporal changes in community structure…changes in dominance
Primary vs secondary succession
Primary – succession on a previously unoccupied site
Secondary - succession following disturbance that has removed previous vegetation