 All living things interact with their environment, both biotic and abiotic  Most living things produce more offspring than can survive

 Most living things produce more offspring than can survive  Populations cannot grow indefinitely  The population can only be as big as the resources will allow  The environment contains a finite amount of food, water, living space  These factors are limiting factors because any one of these factors can limit the size of the population

 The largest population that can be supported in a given environment  When a population grows larger than its carrying capacity, limiting factors in the environment cause the population to decrease.

 Four main ways that species interact with one another  Competition  Coevolution  Predator/Prey  Symbiosis

 Can occur within populations and within communities  Organisms try to use the same resources

 Long-term change that takes place in two species because of their interactions with one another.

 Prey - organism that gets eaten  Predator – organism that eats the prey  Both predators and prey evolve in response to one another in order to survive

 Close long-term relationship between different species in which at least one species benefits  3 types mutualism – both species benefits – ex coral and algae commensalism – one species benefits, the other is unaffected – ex sharks and remoras Parasitism – one species benefits, the other is harmed Parasite – the organism that benefits Host – the organism that is harmed Ex- deer tick is parasite, deer is host