NIS - BIOLOGY

Lecture 8Organisms and Their Relationships

Ozgur Unal

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EcologyScientists can gain valuable insight about the interactions between organisms by observing them in their natural environment.What are some of these interactions?

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Examples: Plants provide a source of

food for many organisms as well as a place to live

Plants require butterflies and bees for pollination

There is an interdependence between organisms in nature.

EcologyEcology is the scientific discipline in which the relationships among living organisms and the interaction the organisms have with their environments are studied.Scientists who study ecology are called ecologists.

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What tools and methods do ecologists use?Why is it important to study ecology?

The BiosphereEcologists study in the biosphere.Biosphere is the portion of Earth that supports life.If Earth were the size of an apple, what part of the apple would represent the biosphere?

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The figure shows the color coded satellite photo of the biosphere.Green plants are a good indicator of the distribution of living organisms in an area.Even the frozen polar regions, desert etc. is a part of biosphere

Biotic and Abiotic FactorsThe living factors in an organism’s environment are called biotic factors.The interactions among organisms are necessary for the health of all species in the same geographic location.

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Biotic and Abiotic FactorsThe nonliving factors in an organism’s environment are called abiotic factors.Organisms are adapted to surviving in the abiotic factors that are present in their natural environments.

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Biotic and Abiotic FactorsIdentify the biotic and abiotic factors in the photo below.

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Levels of OrganizationBiosphere is too complex for most ecological studies.Ecologists study the smaller pieces of the biosphere (or different levels of organization).The levels of organization are:

OrganismPopulationBiological CommunityEcosystemBiomeBiosphere

The lowest level of organization is the individual organism itself. 8

Levels of OrganizationPopulation: Individual organisms of a single species that share the same geographic location at the same time make up a population.

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Biological Community: A biological community is a group of interacting populations that occupy the same geographic area at the same time.

Levels of OrganizationEcosystem: An ecosystem is a biological community and all of the abiotic factors that affect it.

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Biome: A biome is a large group of ecosystems that share the same climate and have similar types of communities.

NIS - BIOLOGY

Lecture 9Ecosystem and Community Interactions

Ozgur Unal

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Ecosystem InteractionsTake a closer look at the tree shown.It is a shelter for birds and it has different resources in terms of food.

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The trees shown are habitat for birds and possibly other organisms.A habitat is an area where an organism lives.What is the habitat of the organism shown in the picture?

Ecosystem InteractionsOrganisms also have niche.A niche is the role or the position that an organism has in its environment.An organism’s niche is how it meets its needs for food, shelter, and reproduction.

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What are the habitat and niche of the fungus shown in the picture?

Community InteractionsOrganisms that live together in a biological community constantly interact.These interactions include competition for basic needs (food, shelter mates etc) and relationships in which organisms depend on each other.

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Competition: Competition occurs when more than one organism uses a resource at the same time.Resources include, food, water, space and light.Usually the strong survive and the weak die.

Community InteractionsPredation:Many species get their food by eating other organisms.The act of one organism consuming another organism for food is predation.Organisms that pursue another organism is the predator, and the organism that is pursued is the prey.Some insects also prey on other insects.Animals are not the only predators: Venus Flytrap

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Community InteractionsSymbiotic Relationships:The clsoe relationship that exists when two or more species live together is symbiosis.There are three kinds of symbiosis: mutualism, commensalism and parasitism

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The relationship between two or more organisms that live closely together and benefit from each other is mutualism.Example: Lichens (fungi + algae)

Community InteractionsCommensalism is a relationship in which one organism benefits and the other organism is neither helped nor harmed.Example: Sea anemones + clownfish

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A symbiotic relationship in which one organism benefits at the expense of another organism is parasitism.Parasites can be external or internal.Example: heartworm + dog