Lecture 8 Organisms and Their Relationships Ozgur Unal 1

 Scientists can gain valuable insight about the interactions between organisms by observing them in their natural environment.  What are some of these interactions? 2  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.

 Ecology 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. 3  What tools and methods do ecologists use?  Why is it important to study ecology?

 Ecologists 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? 4  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

 The 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. 5

 The 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. 6

 Identify the biotic and abiotic factors in the photo below. 7

 Biosphere 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:  Organism  Population  Biological Community  Ecosystem  Biome  Biosphere  The lowest level of organization is the individual organism itself. 8

 Population: Individual organisms of a single species that share the same geographic location at the same time make up a population. 9  Biological Community: A biological community is a group of interacting populations that occupy the same geographic area at the same time.

 Ecosystem: An ecosystem is a biological community and all of the abiotic factors that affect it. 10  Biome: A biome is a large group of ecosystems that share the same climate and have similar types of communities.

Lecture 9 Ecosystem and Community Interactions Ozgur Unal 11

 Take a closer look at the tree shown.  It is a shelter for birds and it has different resources in terms of food. 12  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?

 Organisms 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. 13  What are the habitat and niche of the fungus shown in the picture?

 Organisms 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. 14 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.

Predation:  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 15

Symbiotic 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 16  The relationship between two or more organisms that live closely together and benefit from each other is mutualism.  Example: Lichens (fungi + algae)

 Commensalism is a relationship in which one organism benefits and the other organism is neither helped nor harmed.  Example: Sea anemones + clownfish 17  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