Chapter 16

Question 1

Communities

Answer 1

groups of interacting species that occur together at the same place and time

Question 2

A community can be defined by

Answer 2

the physical characteristics of the environment (streams or deserts) or species associated (kelps or corals)

Question 3

Species subsets ecologists consider when defining and studying communities

Answer 3

Taxonomic affinity, Guilds, Functional Groups, or Trophic interactions

Question 4

Taxonomic affinity

Answer 4

groups classified based on the evolutionary lineage (forest community can be limited to all bird species in that community)

Question 5

Guild

Answer 5

group of species that use the same resources, even though it may be taxonomically distant (birds and bees feed on pollen)

Question 6

Functional group

Answer 6

subset that includes species that function in like ways, but may not use the same resources (nitrogen fixing plants are in the same functional group)

Question 7

Food web

Answer 7

shows the trophic connections between species of a community

Question 8

Trophic levels

Answer 8

primary producers(autotrophs)>primary consumers(herbivores)>secondary consumers(carnivores)>tertiary consumers(carnivores)

Question 9

Nontrophic interactions

Answer 9

horizontal interactions which include competition and positive interactions

Question 10

community structure

Answer 10

made up of species diversity and composition

Question 10

Interaction Web

Answer 10

depicts both trophic and nontrophic interactions among species

Question 11

Species diversity

Answer 11

a measure that combines the number of species and their abundances compared with those of the other species within the community

Question 12

Species richness

Answer 12

the number of species in the community

Question 13

Species evenness

Answer 13

the rarity of species, which requires the ability to know the abundance of each species relative to those of other species within the community

Question 14

Shannon index

Answer 14

describe species diversity quantitatively

Question 15

Shannon Index Equation

Answer 15

H = s∑piln(pi)

Question 16

H

Answer 16

Shannon index value

Question 17

Pi

Answer 17

proportion of individuals found in the ith species

Question 18

Ln

Answer 18

natural logarithm

Question 19

s

Answer 19

number of species in the community

Question 20

Value of H

Answer 20

The higher the H value, the more diversity (lowest it can be is 0)

Question 21

Species diversity

Answer 21

describes the number of species in a community

Question 22

Biodiversity

Answer 22

used to describe the diversity of important entities that span multiple spatial scales including, genes, species, and communities

Question 23

Genetic diversity affects population viability…

Answer 23

… which affects species diversity within a community

Question 24

Rank abundance curves

Answer 24

plot proportional abundance of each species relative to the others in rank order from most abundant to least abundant

Question 25

Species accumulation curve

Answer 25

depict the point of no significant return for finding additional species (Plotted by calculating species richness as a function of sampling effort)

Question 26

Hughes and collegues calculated species accumulation curves for what five communities

Answer 26

Human mouth
Tropical moth community
Tropical bird community
Bacteria from tropical soils
Forest plant community

Question 27

Results of Hughes species accumulation curve studies

Answer 27

species richness of forest plant and bird communities were well represented
Human mouth bacteria and moth communities never completely leveled off
Indicated a higher need for sampling effort of these communities
Soil bacteria richness was high, each sample had new species

Question 28

Species composition

Answer 28

identity of each species in a community (two communities can have similar diversity but different members )

Question 29

Direct interactions

Answer 29

occur between two species and incude trophic and non-trophic interactions

Question 30

Indirect interactions

Answer 30

occur when the relationship between two species Is mediated by a third species

Question 31

Example of indirect interaction

Answer 31

bees hives are feasted on by mice which are then eaten by felines-increasing felines can allow for more flower pollination by bees

Question 32

Trophic cascade

Answer 32

occurs when rate of consumption results in change in species abundance or composition at lower trophic levels

Question 33

Example of trophic cascade

Answer 33

Indirect regulation of kelp forests by sea otters. Sea otters feed on sea urchins, decreasing abundance of them, and in turn causing less consumption on kelp, increasing abundance of kelp
More kelp means more urchins which is more food for the sea otters

Question 34

Trophic facilitation

Answer 34

when a consumer is indirectly helped by a positive interaction between prey and another species

Question 35

Trophic facilitation Example

Answer 35

Sally Hacker and Mark Bertness studied a salt marsh where a rush and shrub had a commensal interaction. Removing rush decreased shrub growth, but removing shrub had no effect on rush. Rush reduced soil salinity and increased oxygen, benefiting shrub growth. Aphids struggled in rush presence but thrived when finding shrubs. Without rush, aphids faced local extinction in the salt marsh.

Question 36

Competitive networks

Answer 36

competitive interactions among multiple species where every species has a negative effect on every other species (networks buffer strong direct competition)

Question 37

Buss and Jackson Competitive Network

Answer 37

Buss and Jackson tested invertebrates and algae, finding that each species both overgrew and was overgrown by another, leading to a network rather than a hierarchy. No single species emerged as a clear winner in the results.

Question 38

Interaction Strength

Answer 38

Interaction strength
The effect of one species on the abundance of another,
can be measured through removal of species (interactor species) from community and observing effect on other species (target species)

Question 39

Foundation species

Answer 39

have large effects on other species, and as a result, diversity of communities, by virtue of considerable size and abundance

Question 40

Ecosystem engineers

Answer 40

can create modify or maintain physical habitat for themselves and other species

Question 41

Keystone species

Answer 41

have large effects not because of their abundance, but rather the vital roles they play
(For example sea otters since by preying on sea urchins, they indirectly enhance presence of kelp)

Question 42

Beavers are both keystone species and ecosystem engineers

Answer 42

Dam streams with cut trees and woody debris, flooding allows for sediment and changing the structure by having flood resistant plants have higher survivability

Question 43

Redundant species

Answer 43

have the same function as other species within a larger functional group, their loss may have little effect as long as other species in the functional group are present