Principles of Ecology Ecology: Scientific study of how organisms and their surrounding environments interact

Abiotic vs. biotic factors – presence/absence of these define levels of organization Abiotic – nonliving parts of an orgs surrounding environment Ex. Soil, moisture, light, temperature (though nonliving, abiotic factors are an important part of an organism’s life…) Biotic – all of the living organisms that live in a particular area under consideration. Ex. Goldfish in a bowl, other goldfish, plants, algae

Levels of Organization Individual organism Ex. One frog Species Ex. Bullfrogs group of organisms so similar to one another that they can breed and produce FERTILE offspring. Population Ex. Bullfrogs in a pond group of organisms of ONE species that interbreed and live in the same area at the same time. Community Ex. Bullfrogs, fish, insects, algae in that pond made up of several populations that interact in the same area Ecosystem Ex. Pond ecosystem collection of ALL the living things that live in a particular place together with their physical environment Biome Ex. Tropical rainforest group of ecosystems with the same climate and similar dominant communities Biosphere: Ex. Earth and atmosphere above it Consists of the portion of Earth that supports life. (includes land, water, atmosphere)

Organisms in Ecosystems Habitat – place where an org lives its day- to-day life. (habitats can change dramatically due to natural or man-made effects: Ex. fire because of lightning or careless campers... Niche – the role and position a species occupies in its habitat or location. HOW it lives in the habitat…This includes all of the org’s interactions with the living and nonliving parts of the habitat. Ex. Earthworms act as decomposers

Interactions in Ecosystems

Resource Availability and competitive exclusion Gives structure to a community Many species can share similar habitats and use some of the same resources… BUT, when two species use the same resources in the same ways, Competitive exclusion comes in to play: DEF: when 2 species are competing for the same resources, one species will be better suited to the niche and the other species will be pushed into another niche or become extinct Ex. NA Gray squirrel vs. Red squirrel in Great Britain Gray is larger, more aggressive

Other outcomes of competitive exclusion…. Niche partitioning: Natural division of resources based on competitive advantages Ex. One squirrel eats nuts from top of tree, one squirrel eats nuts from the ground Evolutionary response: Divergent evolution (body forms change over time) Ex. Large teeth for large nuts, small teeth for small nuts

What happens in different communities: Ecological equivalents: Species that occupy similar niches but live in different geographical regions Ex. Poison dart frog of SA and Mantella frog of Madagascar

Community Interactions Competition Predation Symbiosis *for tomorrow’s lab, we will deal with the symbiosis considerations….

Living Together – species interactions Symbiosis – relationship where there are close and long-lasting associations between orgs of different species Types of symbiotic relationships: a. parasitism b. commensalism c. mutualism

Parasitism Symbiotic relationship where one organism benefits and another organism is harmed. Ex. Ticks on a dog -- tick gets food source, dog gets hole in protective skin layer and possible infection Ex. Tapeworms in intestine -- tapeworm absorbs nutrients in pre-digested form, host loses weight, and host never gets the nutrition that it needs (malnutrition)

Each section of a tapeworm’s body is called a PROGLOTTID and contains a full set of reproductive organs…

Commensalism Symbiotic relationship where one species benefits and another is neither harmed nor helped Ex. Barnacles attached to a whale -barnacles get a free ride to areas where food is available

Mutualism Symbiotic relationship where both species involved benefit from the association. Ex. Ants and acacia trees – ants get shelter and nectar from plant as food, plants get protection from predators Ex. sponges attached to crab shell -- sponges get moved to new area to filter food from water, crab gets portable camouflage