QUIZ BIO 160

• community


  The group of species that occupy a given area, interacting either directly or indirectly
• food, light, space, or moisture


  shared resource
• species composition (set of species present and their relative abundances)


  biological structure of a community is defined by...
• rank- abundance diagram


  the most abundant species is plotted first along the x-axis, with the corresponding value on the y-axis being its value of relative abundance
• Species richness


  a count of the number of species occurring within the community
• Species richness


  What is typically denoted by the symbol S?
• Species evenness


  What refers to the equitability in the distribution of individuals among the species?
• index of species richness


  The simplest quantitative measure of community structure
• species diversity


  which consider both the number and relative abundance of species within the community?
• Simpson's index (D)


  What is one of the simplest and most widely used indices of species diversity?
• Simpson's index (D)


  measures the probability that two individuals randomly selected from a sample will belong to the same species (category)
• Shannon index


  The maximum value of the index, which occurs when all species are present in equal numbers
• dominants


  When a single or few species predominate within a community, those species
• Dominance


  the converse of diversity
• Simpson's index


  What is often used as a measure of dominance?
• relative abundance


  percentage of total individuals in community
• relative biomass


  percentage of total biomass in community
• keystone species


  A species that has a disproportionate impact on the community relative to its abundance
• keystone species


  Their removal initiates changes in community structure and often results in a significant loss of diversity.
• keystone species


  Their role in the community may be to create or modify habitats or to influence the interactions among other species.
• food chain


  a descriptive diagram—a series of arrows, each pointing from one species to another, representing the flow of food energy from prey (the consumed) to predator (the consumer)
• food web


  highly interwoven, with linkages representing the complex interactions of predator and prey.
• links


  the arrows from the consumed to the consumer
• basal species, intermediate species, or top predators


  The species in the webs are distinguished by whether they are?
• Basal species


  feed on no other species but are fed on by others
• Intermediate species


  feed on other species and they are prey of other species
• Top predators


  not subject to predators; they prey on intermediate and basal species.
• S^2


  the maximum number of links for a food web consisting of S species
• L


  actual number of observed links in a food web
• food web connectance (C)


  actual number of observed links in a food web (L) expressed as a proportion of the maximum possible number of links (S^2)
• Linkage density (LD)


  measure of the average number of links per species in the food web
• mean chain length (ChLen)


  arithmetic average of the lengths of all chains in a food web
• decreases


  connectance _________ with species richness
• increase


  linkage density and mean chain length ________ as the number of species in the community increases
• increases


  As species richness _________, the structure of food webs become more complex and often food webs become compartmentalized
• autotrophs


  organisms that derive energy from sunlight
• heterotrophs


  Organisms that derive energy from consuming plant and animal tissue
• trophic levels


  feeding groups
• trophikos; nourishment


  trophic came from the greek word "" which means ?
• guilds


  trophic level groups of species that exploit a common resource in a similar fashion