Ecology & Evolution Chpts 17, 18, 19, 20

Front 1

community

Back 1

a group of species that occupy a given area, interacting either directly or indirectly

Front 2

species richness (S)

Back 2

number of species occurring within the community

Front 3

relative abundance

Back 3

percentage each species contributes to the total number of individuals of all species

Front 4

species evenness

Back 4

distribution of species abundance

Front 5

diversity indexes

Back 5

provide a way to quantify the relationship between species number and relative abundance

Front 6

simpson's index (D)

Back 6

D={(ni/N)2
ni=number of individuals of species I
N=total number of individuals of all species

Front 7

simpsons index of diversity

Back 7

= 1 - D

Front 8

simpsons reciprocal index or simpsons diversity index

Back 8

= 1/D
*the lowest possible value is 1, representing a community containing only one species
*the maximum value =species richness: S

Front 9

Shannon (or Shannon-weiner) index

Back 9

H={(pi)(log2pi)

Front 10

numerical supremacy defines dominance
*usually in #'s (pop size), can be biomass or surface area

Back 10

when single or few species predominate within a community, these species are referred to as dominants
dominant species are usually identified separately for subsets of the community

Front 11

keystone species

Back 11

has a disproportionate impact on the community relative to its abundance
the removal of this species initiates changes in the community structure and often results I significant loss of diversity

Front 12

guilds

Back 12

groups of species that exploit a common resource in a similar fashion
ex. nectar-feeding birds, seed-eating birds, forest canopy folivores

Front 13

functional type

Back 13

group of species based on their common response to the environment
ex: plants grouped into C3, C4, and CAM
shade tolerant versus shade intolerant
iteroparity versus semelparity

Front 14

zonation (of a tidal zone)

Back 14

as one moves across the landscape, the physical and biological structure of the community changes

Front 15

how different must two adjacent areas be before we call them separate communities?

Back 15

*the answer is based on the degree of similarity or difference and can be rather subjective
*the distinction between communities is arbitrary, based on the criteria for classification

Front 16

broad-scale descriptions for defining boundaries are used for...

Back 16

larger landscape-level community structure

Front 17

two major views in the structuring of communities

Back 17

*organismic concept of communities-clements
*individualistic or continuum concept of communities-gleason

Front 18

ecological studies underestimate species interactions because such interactions are...

Back 18

diffuse, involving a number of species
ex. diffuse predator-prey interactions (lynx___hare)
diffuse mutualism (plants depend on variety of animals)

Front 19

keystone predation

Back 19

the predator enhances one or more inferior competitors by reducing the abundance of the superior competitors

Front 20

indirect commensalism

Back 20

indirect interaction is beneficial (+) to one member, does not affect the other (0)

Front 21

bottom up control

Back 21

any given trophic level is controlled (limited) by the productivity and abundance of pops in the trophic level below

Front 22

top down control

Back 22

predator pops control the abundance of prey species and the prey of the prey, etc.

Front 23

other factors influencing community structure

Back 23

*environmental conditions and tolerances of species
*basic resource/nutrient availability
*habitat complexity/hereogenetity

Front 24

succession

Back 24

the predictable series of changes in a community following a disturbance
*gradual
*directional

Front 25

primary disturbance

Back 25

exposes substrate no previously occupied by a community
-little if any: organic material, no seed bank, no/little soil bacteria

Front 26

examples of primary disturbance

Back 26

volcano, beaches, glacial retreat, landslides/cliff areas, delta/soil deposition area

Front 27

secondary disturbance

Back 27

removes all or part of existing vegetation community
-some organic material, seeds and soil bacteria are left

Front 28

example of secondary disturbance

Back 28

storms, fire`

Front 29

climax community

Back 29

end result of succession
-remains stable until another disturbance restarts succession
-may last for a short time or a long time

Front 30

early successional sp or pioneer sp

Back 30

fast growth rates, smaller size, high degree of dispersal, and high rates of pop growth

Front 31

late successional sp

Back 31

lower rates of dispersal, slower per capita growth rate, and they are larger and longer-lived

Front 32

autogenic environmental changes

Back 32

early successional sp change environment to be suitable for late successional sp
-results directly from the presence and activities of organisms within the community

Front 33

allogenic environmental changes

Back 33

ex. temp change, moisture change
caused by physical processes

Front 34

landscape

Back 34

an area of land (or water) that is composed of many different communities and ecosystems

Front 35

biomes

Back 35

geographic regions with similar geological and climatic conditions

Front 36

biosphere

Back 36

thin layer surrounding the Earth that supports all of life

Front 37

mosaic

Back 37

patchwork of different types of land cover

Front 38

patches

Back 38

distinct communities in the landscape

Front 39

landscape ecology

Back 39

study of the causes behind the formation of patches and boundaries and the effects of these spatial patterns on the landscape

Front 40

patch mosaic landscape

Back 40

-each has its own community that is different from neighboring patches
-result from differences in geology, soil, topography, climate and
-disturbances-human activity, natural:fire, grazing etc

Front 41

inherent edges

Back 41

stable and permanent

Front 42

induced edges

Back 42

subject to successional changes over time

Front 43

border

Back 43

edge of one patch meets edge of another

Front 44

equilibrium theory of island biogeography (macauthur, Wilson, simberloff)

Back 44

explains how sp come to be distributed among oceanic islands
-deals with immigration and extinction/extirpation
-predicts an island's sp richness (S) based on the island's size and distance from the mainland

Front 45

sp richness results from island size and distance from the mainland

Back 45

-fewer sp colonize an island far from the mainland
-large islands have higher immigration rates
-large islands have lower extinction rates

Front 46

large islands contain more species than small islands

Back 46

-they are easier to find and have lower extinction rates
-they possess more habitats

Front 47

simberloff says a island is...

Back 47

any patch of habitat by different relatively inhospitable terrain traversed only with difficulty by organisms of the habitat patch may be considered an island

Front 48

corridors

Back 48

can connect patches of similar habitat
-strips of habitat similar to the patches that they connect
-natural or human made

Front 49

connectivity

Back 49

extent to which a pop can move among patches within the matrix

Front 50

minimal viable pop size

Back 50

how large a pop needs to be to avoid: inbreeding and Alee effect

Front 51

Haddard and butterflies showed...

Back 51

corridors do help
-patches should be close together
-corridor needs to be "short"