Diversity and Abundance Flashcards
(30 cards)
Machia Seal Island
tons of different types of warblers landed here because they were exhausted from migration and the diversity was insane
Species abundance curve
- most species are moderately abundant
- very few are super rare or super common
Relative abundance
- proportion each species represents of all individuals in the community
- consistent between habitats and taxonomic groups
Species diversity (definition and parts)
- variety of organisms that make up a community
- determined by species richness and relative abundance
species richness
of different species in a community
What happens to diversity if your sample size is too small? What happens to diversity when you increase the sample size area?
- you underrepresent rare species and overrepresent common ones
- you find more species so diversity goes up
Shannon-Weaver Index
H = sum of pilnpi
where pi is the relative abundance
Abundance
how many individuals of a certain species
density
number of individuals per unit area
Relationship between nutrients and plant/algae diversity
- negative relationship
- reduces number of limiting nutrients
- causes competitive exclusion
Soons et al. experiments
- adding nitrogen reduced plant richness by 16%
- adding phosphorus did nothing
Two major biogeographical factors that affect species diversity
- lattitude (tropics are more diverse than poles)
- area (bigger area means more diversity)
Tree species per hactre
- Michigan = 10-15
- S.E. U.S. = 30
- Tropical Peru = 300
hot spots
- very diverse due to high number of endemic species
- Tropical areas near equator
- islands
- Mediterranean ecosystems
Why does latitude affect diversity (weather)
- dif latitudes have dif levels of sunlight and precipitation
- higher levels of evapotranspiration = more diversity
evapotranspiration
- evaporation of water from soil plus the transpiration of water from plants
- potential evaoptranspiration = potential water loss, assuming the presence of water
Why does latitude affect diversity (time)
- Tropical areas have had more time for speciation to occur (also more extinction)
- polar regions have had to restart due to glaciation
What kind of environments are good for diversity and how do phytoplankton/algae/diatoms reject this?
- complex environments = high diversity
- algae can live in simple communities if they have different trophic niches and have different ratios of nutritional needs
open ocean hot spots
- usually close to land
- only kinda follow the equator rule
What forms of life contribute the most to diversity?
-arthropods (especially insects)
-flowering plants
(prokaryote diversity is mostly unknown)
Biogeography
the study of the geographical distribution of species
- provides evidence for evolution
- an understanding of continental movement and modern species helps us know when and where these species evolved
Species Area Effect
- all other factors being equal, bigger area = more species
- S = cA^z
- S = # of species
- c = constant
- A = area
- z = how many species should be found as area increases
-in log-log plot of S vs A, z is the slope of the line through the data
Island equilibrium model
- richness = balance of immigration and extinction
- more S = less I + more E
- less A = less I + more E
- close to land = more I + less E
Wilson and Simberlof experiment
- Tested diversity of mangrove tree islands in Florida keys
- counted species
- fumigated island
- tracked increase of species over time
- equilibrium number returns to normal
