Ecosystem Interactions Environmental Science

What Shapes Ecosystems Abiotic and Biotic Factors Habitat – physical location where an organism lives Niche – the use of the habitat by an organism (includes food, physical location, how it interacts with other organisms, etc.)

Species Interactions

Ways in Which Species Interact These categories are based on whether each species causes benefit or harm to the other species. Other types of interactions are possible. Many interactions between species are indirect, some interactions do not fit in a category clearly, and other types seem possible but are rarely found. Therefore, many interactions are neither categorized nor well studied.

Competition Competition – when different individuals or populations attempt to use the same resource Intraspecific-Within a species – food, mates, territory Interspecific-Between species – food, water Competition can occur even if the individuals never meet. Flowers competing for the same pollinators

Community Interactions - Competition When members of different species compete for the same resources, we say that their niches overlap. These species will divide up the resources either by time or space – called niche restriction Ex. Warblers in coniferous trees will live only on certain levels of the trees Ex. Diurnal v. Nocturnal insects - both need the same resources, but some are only active in the day and others at night

Community Interactions - Predation Predator/Prey Relationship Predator – organism that hunts/kills Prey – organism that is food (e.g. cat and mouse) Sometime one predator may also be another organism’s prey

Specialists v. Generalists Species that eat mostly one type of prey are called specialists Ex. Canadian Lynx and the Snowshoe Hare Generalists will eat whatever is easiest to find and capture Ex. Coyotes or Wolves

Symbiosis and Coevolution Symbiosis – two species who live closely together Overtime, species in close relationships may coevolve. These species may evolve adaptations that reduce the harm or improve the benefit of the relationship.

Mutualism Mutualism – symbiosis in which both organisms benefit – often each species depends on the other Ex. Flowers and their pollinators

Ex. Barnacles on a whale’s skin or Commensalism Commensalism – symbiosis in which one organism benefits and the other is neither helped nor harmed. Even seemingly harmless activity, however, might have an effect on another species. Ex. Barnacles on a whale’s skin or Birds nesting in trees

Parasitism Parasitism – symbiosis in which one organism is helped and one is harmed Parasite – the organism that feeds on another organism Host – the organism parasite takes its nourishment from Ex. Fleas and ticks The difference between a parasite and a predator is that a parasite does not usually kill its host.