lec 19

• benefits predator but hurts prey • negative postive interaction

• hurts both species • negative negative interaction

• benefits both species • positive positive interaction

• same species competing for resources, space, nutrients,etc • logistic model • as pop grows, less resource so indivisuals competes for resource

different species competing for resources

• one individual consumes a shared resource which leaves less for the other individuals

• two individuals (could be the same or different) directly interact in a negative way • direct interaction

• shows the interaction of 2 different species

• The 2 species will co exist When they reach equilibrium, both populations are still there • Species 1 outcompetes in species 2 The population size of species 1 will reach its carrying capacity and species 2 will go to 0 All we’ll see at equilibrium is species 1 and no species 2 • Species 2 outcome in species 1 Species 2 goes to carrying capacity and • The winner will depend on the size of the starting population

• populations size is not changing overtime • For a community, its at equilibrium when all the populations are not changing or the same species over time • dn/dt = 0

ability of the system to return to equilibrium following a disturbance (natural disaster)

• The lotka volterra model predicts that for 2 species coexist, competition between species must be lower than competition within species • If 2 species compete too intensely for resource, one will always win and only the winner will remain at equilibrium • They can’t overlap too much in resources • If 2 species share resources, they wont be able to co exist because they would be competing too intensely with each other

Species that are very similar and live in similar environments are going to evolve greater differences to avoid the intense competition