Biology midterm 9-15 Flashcards
Symbiosis
Living together
Mutualism
Benefical interaction for both species
Are mutualism and symbiosis the same thing.
No. Symbiosis can be negative.
3 types of mutualisms.
- Nutritional mutualisms: exchange for fixed C for fixed N
- Defensive mutualisms: ex: plants and ants: exchange of protection for food
- Dispersal mutualisms: Ex: Plants and seeds
Invasional meltdown
Positive feedback between mutualist tends to generate runaway population growth
What are the population dynamics of mutualism?
It leads to solution in which both populations undergo unchecked exponential growth
What are some of the limits of the population growth of mutualists.
- A third species such as a predator or a competitor can cause issues
- Diminishing returns to mutualism as the population grows
- Strong intra-specific competition
Dispersal
An individual moving from one population to another. Dispersal allows organisms to colonize new areas, escape competition, and avoid inbreeding.
Metapopulation
It’s a collection of spatially distanct population that are conntect thorugh dispersal.
What are spatially distinct populations?
A patch
Source and sink dynamics
Sinks are population in small patches that would go extinct if it wasn’t for migrants from other population.
What does global coexist require?
- Pop 1 must sometimes go exstinct in a patch OR new patches must be created from time to time
- Pop 2 must be a better disperser than pop 1.
- Pop 2 must be a species that can move around a lot.
What are some ways that population can be driven to extinction?
- Stochasticity: (the random fluctuation in population numbers)
- Competitive exclusion
- Through predator prey and host-parasite interactions
- Allee effects at low density.
Meta community
A set of local communities linked by the dispersal of one or more of their shared species.
What determines the number of species on an island?
Colonization: a species arriving to the island from somewhere else
Extinction: a species going locally extinct
In-situ speciation: when a lineage splits in two on an island (though this is a slow process )
What was the goal of island biogeography theory.
It’s meant to predict the number of species on an island based on the islands size and distance from the mainland. (it ignores insitu speciation in this case)
MacArthur and Wilsons theory of island biogeography.
As the colonization rate decreases, the extinction rate increases. When the 2 meet, the species is at equilibrium. The farther an island is from the mainland, the lower the equilibrium and the smaller the equilibrium, the faster the extinction rate.
What is a Trophic level?
A hierarchical level system (normally a triangle shape) in an ecosystem, organizing organisms that share the same function in the food chain and the same nutritional relationship.
What are some the typical roles on the trophic levels?
Primary producer= plants
Primary consumers= herbivores
Secondary consumers= predators who eat herbivores
Tertiary consumers= carnivores who eat secondary consumer
What is the difference in Food chains and food webs
A food chain is a group of organism link in ORDER of the food they eat while a food web is ALL the food chain in a single ecosystem.
Indirect Effects
One species alter the effect that another species has on the third.
Trophic Cascades (HHS)
Interactions between two trophic levels “cascade” to a third trophic level.
What is an example of a Trophic Cascade (HSS)?
When the wolf population increases causing the deer population to majorly decline. This in turn will cause the plant population to increase. The wolfs did not directly interact with the grass.
Why is the world green?
The world is green because carnivores keep down herbivores so herbivores don’t limit the plant growth.
Top down control
Abundance kept low because of predation ( Experimental test= predator removal)