What species a community contains and the relative abundances of those species
What is the only way a species can occur in a location?
Only if it is able to colonize and persist there
What does a community contain?
Species that are colonized those that are extinct LOCALLY
What are some reasons extinctions can occur?
Small population, exclusions (predators, pathogens, competitors), lacking of a resource, species cant tolerate the local conditions
What are factors that make species composition vary?
Environmental gradients, disturbances, and changing climate, elevation, soil type
What is atransect?
A straight line used for ecological surveys that shoes species turnover through space
What factor depends on the animals ability to get food or avoid predators?
How can species turnovers result? What are some examples?
Disturbance events; volcanic eruptions, wildfires, hurricanes, landslides, human activities.
What is succession?
The process by which species replace one another in a predictable sequence
What can happen to a community after a disturbance?
It can undergo succession which leads to a community that resembles the original one
If the original community is not reestablished after a disturbance, what happens?
It undergoes ecological transition.
What is a niche?
The environmental tolerances of a species which define WHERE it can live; and it also refers to the ways a species obtains energy and materials and to patterns of interactions with other species in the community
What are primary producers? What are they also known as?
Autotrophs. They convert solar energy into a form that can be used by the rest of the community.
What are heterotrophs?
Organisms that get energy by breaking apart organic compounds that were assembled by other organisms.
What are primary consumers?
Organisms that eat primary producers. Herbivores
What are secondary consumers?
Eat primary consumers (carnivores)
What are tertiary consumers?
Eat secondary consumers
What are quaternary consumers?
Eat tertiary consumers
What are omnivores?
Feed from multiple trophic levels
What are decomposers? What is another term?
Detritivores. Feed on waste products or dead bodies of organisms
What are decomposers responsible for?
Recycling materials and breaking down organic matter into inorganic components for primary producers to reabsorb.
How are trophic interactions shown in diagram form?
Gross product productivity. The total amount of ENERGY that primary producers convert to chemical energy
Net primary productivity. Energy contained in tissues of the primary producers and is available for consumption
What is an approximation for NPP?
Change in biomass of primary producers (dry mass) per unit of time
What is the ecological efficiency?
Why is ecological efficiency low?
Not all biomass ingested by next trophic level, some injected matter is indigestible so the animal poops it out, and organisms that use a lot of the energy they make to fuel their own metabolism
What is the per capita growth rate related to?
The sum of positive and negative contributions of species with which it interacts
What is species richness?
The number of species in the community
What is species evenness?
The distrubtion of species abundances
What aspects of diversity affect community function?
Species richness and evenness
What are communities defined by?
The species that are more abundant than the rare ones
What are important measures of community function?
GPP and NPP
What are some possible reasons that species diversity affects community function?
Sampling, niche complementarity
What is sampling?
Wen communities have many types of species, they are more likely to have some species with a very strong influence on community output
What is niche complementarity?
Communities with many species can be better able to use all the available resources
What are plant functional groups?
Plant groups that differ in traits such as ability to grow in warm vs cool weather, association with Nitrogen fixing bacteria, allocation to growth vs reproduction, etc.
Where does the greatest diversity of plants and animals take place?
Why do the tropics support more species?
Maybe because the climate is so stable and hasnt been affected by glacial cycles; they have higher abundant solar energy and productivity, environmental heterogeneity.
What does environmental heterogeneity mean?
That diversity is higher in more structurally COMPLEX habitats
Who formulated the theory of island biogeography?
Macarthur and Wilson
Why does habitat fragmentation cause loss of species?
Populations become smaller, amount of habitat decreases, average patch size decreases, patches become more isolated, human modified habitat can be a barrier to dispersal
How do you enhance colonization in fragmentation?
Cluster habitat fragments and connect them with dispersal corridors