Biodiversity Flashcards
What is biodiversity?
The variety of all life at all levels in a given area
What is a community?
Populations of interacting species and the abiotic factors in the given area
What is an ecosystem?
Sum of communities and abiotic factors in a given area, often determined by climate. E.g. biome, landscape
Is every species important?
The loss of any species can prevent the natural mechanisms of an ecosystem due to its fragility. The higher the biodiversity the more stable it is.
Is extinction natural?
Yes, but the rate of extinction has been greatly increased by human interaction
What are the 3 measurements of diversity?
What are the two combining factors?
Alpha, Beta and Gamma
Species Richness and Species Evenness
Where is diversity highest?
Tropics where there is a high amount of environmental complexity (produces diversity), which are intermediately disturbed
What is alpha diversity?
Within habitat diversity- species richness + species evenness (relative abundance)
What is beta diversity?
Between habitat diversity / difference between habitats
What is gamma diversity?
Total landscape diversity ( alpha * beta = gamma)
What is species richness (R) ?
Total number of species in a given area, doesnt have to be species (can use higher rate of taxon).
Can compromise phylogenetic diversity (how similar are the species there)
What is species evenness?
How abundant is each species in a given area. An area where one species dominates is less diverse than one where the species are equally abundant.
What is the purpose of biodiversity indices and what are two examples?
To summarize the information collected about species richness and evenness.
Simpsons and Shannons
How does Simpsons index work?
0 (highest) - 1 (lowest) diversity scores
Sum of (Proportion of each species in an area^2)
How does Shannons index work?
0 (no diversity) upwards
Sum of( MINUS - proportion of species*( ln proportion of species)
What is the problem with biodiversity indices?
Counter-intuitive results at extreme ends of the scale
Special forms of a general measure
What is effective species number?
Equivalent number of species at maximum evenness.
Makes biodiversity indices comparable
How do you get effective species number from biodiversity indicies
Simpsons: 1/ final result
Shannons: exponent( final result
Describe some of the changes in biodiversity over time
Burst in diversification due to adaptations to environment Overall increase in diversity over time Succession events Seasonal variation within species - migration - hibernation
Describe some the spatial patterns of biodiversity
Greater habitat variety –> greater species variety
Increased complexity –>greater species diversity
Species-Area Curve (larger area = more species)
High levels of endemism in isolated areas (islands)
Tropics more diverse than higher latitudes
Intermediate levels of disturbance promotes highest biodiversity.
Why does intermediate disturbance lead to the highest rates of biodiversity?
Low disturbance- competition reduces diversity
Intermediate- time to colonize an area but not out-compete
High - little time for colonization due to random elimination
Describe some other patterns in biodiversity?
Diversity declines as trophic level increase (food web cannot support many high end predators / few omnivores)
Most species are moderately abundant, not very or rare.
What are biodiversity surveys and what is the point?
Build up knowledge of environment –> conservation
Requires: taxonomic knowledge, good observation, checklists, data collection, satellite images, GIS locations,
E.g. Bioblitz
How do you estimate population size?
Mark and recapture
N1 (number caught in first bout)
N2 (number of individuals in second bout)
M2 (number of marked individuals in second bout)
(N1 x N2) / M2
