Species Interactions & Species Diversity Cont.

Question 1

Species diversity

Answer 1

Variety of organisms that make up a community

Question 2

Trophic structure

Answer 2

Feeding relationships between species

Question 3

Species richness

Answer 3

number of diff. species in a community

Question 4

Relative abundance

Answer 4

the proportion each species represents of all individuals in a community

Question 5

Shannon density index (H)

Answer 5

An index that is commonly used to characterize species diversity in a community; H=-(pAlnpA + pBlnpB + pClnC+ …)

Question 6

Why is it important to characterize the species diversity of communities?

Answer 6

Diverse communities are more productive and more stable in their productivity, better able to withstand and recover from environmental stresses, and more resistant to invasive species

Question 7

Species area curve

Answer 7

The relationship between the area of a habitat and the # of species found within that habitat; larger area=more species; S=cA^z (S=# of species, A=area, z=how many more species should be found as area increases; the far away the species is from the mainland the less there are

Question 8

When can an equilibrium be reached?

Answer 8

It is reached when the rate of immigration is equal to the rate of extinction

Question 9

Latitudinal diversity gradient

Answer 9

Species richness is especially great in the topics and generally declines in a gradient towards the polls; affected by evolutionary history and climate

Question 10

“Tropics as cradle” model

Answer 10

Tropical environments may have greater species richness because there has been more time for speciation to occur; - parabola

Question 11

“Tropics as museums” model

Answer 11

Temperate and polar communities may have less species richness because they have “started over” repeatedly following glaciations; + parabola

Question 12

Evapotranspiration

Answer 12

Evaporation of water from soil plus transpiration of water from plants (sunlight + precipitation); tends to be greater in tropics; correlated w/ species richness

Question 13

Pathogens

Answer 13

Disease causing microorganisms that alter community structure locally and globally

Question 14

Disturbance

Answer 14

An event, such as a storm or fire, flood, drought, or human activity that changes a community by removing organisms from it or altering resource availability

Question 15

What do you think: Communities can maintain the highest species diversity when disturbance is:

Answer 15

Medium

Question 16

Intermediate disturbance hypothesis

Answer 16

Idea that local species diversity is maximized when ecological disturbance is neither too rare nor too common

Question 17

Ecological succession

Answer 17

Process by which the mix of species in an area changes over time

Question 18

Primary succession

Answer 18

Happens when a new patch of land is created or exposed for the first time; Ex: lava cools and creates new rocks, or a glacier retreat

Question 19

Secondary succession

Answer 19

A previously occupied area is re-colonized following a disturbance that kills much of all of its community; Ex: after a fire