Ecology

Question of the Day Create a brief sketch including you and your community (randolph, your home(s), where you are during a normal week). Then explain why you think it is important to know about populations. Create a T chart for things in your environment that are alive versus things that are not alive.

Ecology Ecology Interaction among organisms Interactions between organisms and their environment

Populations Population The number of individuals of a species in a specific habitat Lagos, Nigeria

Factors that change population size Birth: leads to an increase Death: leads to a decrease Needs to be balanced for population size to remain constant Immigration: leads to an increase Coming into a habitat Emmigration: leads to a decrease Leaving a habitat

Changes in Pop. Size and Biodiversity Speciation and Extinction are influenced by: Natural causes (mutations, evolution) Changes in climate (adaptations needed) Human activity (deforestation, pollution) Introduction of invasive species Non-native species that move into a habitat and has devastating effects http://nbii-nin.ciesin.columbia.edu/ipane/ipanespecies/ipanespeciesmapper.htm

Example of Invasive Species Kudza Vine Introduced from Japan for erosion control (1876) and has been growing uncontrollably ever since Has no competitors for resources or predators Grows (in summer) almost a foot a day

Australia and Its Rabbits Rabbits were brought to Australia in for hunting and food ~ 1880s No natural predators Plenty of resources Within 6 years, there hundreds of thousands There are now about 300 million Destroying habitats Digs up root systems Developing deserts

Rabbit Solutions Hunting Rewards Fumigation (spraying poisons) Dynamite Plowed 2000 mile fence All Failed

Rabbit Solutions Introduced virus in 1951 (2nd invasive species) Killed millions But some were naturally resistant They survived and reproduced Bunnies are also resistant to virus (genetics) 1991, 1996: Introduced new viruses and killed many but same as above Decision to release a new virus every two years to lessen the population (or at least keep it in check)

Australian Rabbits Besides acting as an invasive species, the rabbits serve to demonstrate a second point: Co-evolution Two species that evolve in response to each other Rabbits obtain immunity to virus (through genetics) Virus evolves and begins killing again Rabbits again obtain immunity to virus (through genetics) This continues…

Food Web

Food Web

Food Webs Divided into levels known as trophic levels (feeding levels) Composed of: Producers Make their own food (autotrophs) Consumers Must consume food (heterotroph) Decomposers Breaks down waste (dentritivore)

Producers

Consumers

Decomposers

Food Webs What is your food web? Take 5 minutes to list and then map or web your food web.

Energy Exchange Energy is not transmitted evenly from our food Usually only 10% of the lower trophic level makes it to the next level (most is used by the organism)

Complex Food Webs Relationships between organisms are greatly intertwined Many organisms are dependent on others for survival

Relationships in the Food Web Symbiotic relationships: “living together” Predation Species hunt other species Parasitism one species benefits, one is harmed Competition Species “fight”/ “use” the same resources Commensalism one species benefit, one is unbothered Mutualism Both species benefit

Predation

Parasitism

Competition

Commensalism

Mutualism

Resources and Ecology Living parts of the habitat are called biotic Any nonliving part of a habitat is known as abiotic Rain, soil, nitrogen, carbon Water, carbon, and nitrogen are very important for the stability of a habitat Each is cycled through the habitat and reused

Nitrogen Cycle

Oxygen and Carbon Dioxide Cycles Photosynthesis and cellular respiration help cycle O2 and CO2 in a habitat Plants take in CO2 and release O2 Animals take in O2 and release CO2 Repeat, repeat, repeat

Carbon Cycle

Water Cycles

Biotic material is also cycled Decomposers break down decaying organisms and add this to the soil for plant growth Plants are then eaten by herbivores Herbivores are eaten by carnivores Carnivores die and decomposers consume them The Circle of Life Why are we the exception?