lecture 24 Flashcards
biological community
a group of populations of different species that co occur in a geographic area
species composition
mix of species in the community
community structure
which species, how many, and how abundant
spatial turnover
the change of species across space often occurs along environmental gradients, such as elevation or soil
what determines the habitat structure
plant community
habitat structure
3 dimensional distribution of objects that you have in a habitat
what is the temporal composition
extinction and colonization
disturbance
abrupt environmental change (fires, volcano, hurricane)
succession
after a disturbance and some animals were killed, succession is the predictable sequence of changes in community composition over time
temporal turnover
change in biodiversity over time in species composition due to global change
species diversity has two components
species richness and species evenness
species richness
total number of species
species evenness
relative abundance of each species
theres more diversity in what part of the world
equator
what are the four hypothesis for latitudinal diversity gradient
- species-energy hypothesis 2. geographic area 3. evolutionary rate 4. historical perturbation
species energy hypothesis
solar energy and water availability increases productivity
geographic area hypothesis
the tropics are the largest biome and that tropical areas therefore can support more species and species with larger ranges are less likely to go extinct
evolutionary rate hypothesis
higher evolutionary rate means that you have higher speciation rates and thats going to lead to increased diversity (higher temps causes increased mutation rates)
historical perturbation hypothesis
at higher latitudes there hasnt been enough sufficient time to colonize or recolonize these areas because of historical perturbations like ice age
theory of biogeography
species richness on islands is a function of immigration (colonization) and extinction and will level off at dynamic equilibrium point
islands can only gain species from
near by islands or the mainland
as the island fills up, youre going to see the
colonization rate decline
what increases as island fills up
rate of extinction
larger islands will have higher
equilibrium points
how are the colonization rate in farther islands
are lower compared to closer islands
fragmentation causes species loss due to 3 reasons
- total amount of habitat decreases 2. size of habitat patches decrease 3. patches become more isolated
when we take care of our ecosystems we get
goods and services like sweetwater park that helps filter water or the dung beetles that help decompose the cows poop
