Ch.16&19- Species diversity Flashcards
How many species are on Earth?
about 2 million described
- 4%vertebrates
- 75 inverebrates
- 18 plants
- 3 other
-estimated there are actually 5-30 million species on earth
Biodiversity
A term used to describe the diversity of important ecological entities that span multiple spatial scales (genes, species, and communities)
species richness and composition by latitude
-Lower latitudes have more species and more variation in composition
Sampling effort
- Should start to see a plateau
- where researchers want to get because they don’t want to have to sample more
How much should we sample?
Until we start to see a plateau
Who should we sample?
An easy to find group or indicator taxa
How do we collect our data?
standardized sampling: Can determine relative abundance
lognormal distribution
rare->subordinate-> Dominant
3 ways to measure community diversity
1) species richness
2) Species Evenness
3) Species diversity
species richness
the number of species found in the community = S
Species Evenness
- provides information on the commonness or rarity of species
- includes abundance of each species in the area
Species diversity
-Measure combining both number of species and relative abundance (evenness)
-Lost of different indices of species diversity
~most common is the Shannon Index
~greater H’ value means greater diversity
-scientist use diversity indices to compare communities
H’
-[sum (pi ln Pi)]
Environmental Complexity
More environmental complexity = more species
-can include: vegetation, elevation, nutrient availability, hydrology, and more!
Stability
the tendency of a community to remain the same in structure and function
Resilience
the rate of recovery after a disturbance
What are the consequences of biodiversity?
Diverse communities are more stable and more resilient
Generally, more diverse communities perform more functions
Community functions include: nutrient cycling, carbon sequestration, purification of water, purification of air, pollination
Complementarity Hypothesis:
as species richness increases, there will be a linear increases in community function (graph: increase linear )
Redundancy hypothesis
There is an upper limit on the effect of richness on community function (starts to get redundant) (graph: levels off like a K and evens out no matter if yo add)
Driver and passenger hypothesis
Strength of effect varies dramatically with species ( graph: like stair cases)
D& P with overlap:
drivers and passengers will over lap in their functions (graph: stair case and starts to level off)
