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LIFE…AS WE KNOW IT!!

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• Biosphere : Biosphere : layer of Earth that supports layer of Earth that supports life roughly 13 miles thick ( 7 miles into life roughly 13 miles thick ( 7 miles into atmosphere and 7 miles down into the atmosphere and 7 miles down into the oceans !!!)oceans !!!)

• Biomes : Biomes : large regions of the globe defined large regions of the globe defined by similar by similar climateclimate (T and precipitation) and (T and precipitation) and vegetationvegetation– specific place on the mapspecific place on the map

• Ecosystems: Ecosystems: All of the living organisms and All of the living organisms and the nonliving environment in a particular the nonliving environment in a particular place place

( lg. ecosystems – small ecosystems)( lg. ecosystems – small ecosystems)

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http://www.blueplanetbiomes.org/world_biomes.htmhttp://www.blueplanetbiomes.org/world_biomes.htm

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POPULATIONSPOPULATIONS: group of organisms, : group of organisms, in same species (able to interbreed), in in same species (able to interbreed), in same area, at same time…“the 3 S’s” same area, at same time…“the 3 S’s” 5.15.1

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Population DynamicsPopulation Dynamics• Populations Populations changechange constantly in size and constantly in size and

composition…what types of things in the composition…what types of things in the environment limit the growth of a population? environment limit the growth of a population? ***ANSWER!***ANSWER!– Limited food and waterLimited food and water– Predator increase (including hunting)Predator increase (including hunting)– Climate and Weather conditions (drought, flood, Climate and Weather conditions (drought, flood,

tornado)tornado)– Diseases (immigration; close contact)Diseases (immigration; close contact)– SpaceSpace– PollutionPollution

• They experience changes in their gene pool They experience changes in their gene pool over time:over time:– births, deaths, immigration (into), emigration (out births, deaths, immigration (into), emigration (out

of)of)

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2 FACTORS THAT LIMIT POPULATION 2 FACTORS THAT LIMIT POPULATION GROWTHGROWTH• 1. Density-dependent factors = dependent on 1. Density-dependent factors = dependent on the # of organisms in a given area.the # of organisms in a given area.

**limited resourceslimited resources, predation, disease, predation, disease**intraspecificintraspecific (between members of the same species) (between members of the same species)

and and interspecific interspecific (between members of different (between members of different species) species) competitioncompetition

• 2. Density-independent factors = 2. Density-independent factors = environmental conditions that limit growth environmental conditions that limit growth

(regardless of # of organisms).(regardless of # of organisms).*weather and climate are the most impt.*weather and climate are the most impt.* “natural” disasters (flood, fire, tornado, hurricane, * “natural” disasters (flood, fire, tornado, hurricane,

etc.)etc.)

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Cover up!!!!!!

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Abiotic vs. Biotic FactorsAbiotic vs. Biotic Factors(that affect population growth/decline)(that affect population growth/decline)

• Abiotic: water, shelter, space, Abiotic: water, shelter, space, weather, climate, sunlight, nutrients weather, climate, sunlight, nutrients (soil).(soil).

• Biotic: predation, disease & Biotic: predation, disease & parasitism, food availability, mating, parasitism, food availability, mating, human impacts (disrupting habitats, human impacts (disrupting habitats, introducing diseases, introducing introducing diseases, introducing nonnative species)nonnative species)

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Growth Curves Growth Curves models that explain/depict how populations models that explain/depict how populations change over time.change over time.• 2 Types:2 Types:1.1. Exponential: “J” shaped curve Exponential: “J” shaped curve

-rate of growth stays the same…continuous-rate of growth stays the same…continuous-population -population sizesize increases steadily increases steadily-ex. bacteria-ex. bacteria

2. 2. Logistic: “S” shaped curveLogistic: “S” shaped curve-“J” shaped that is -“J” shaped that is limitedlimited by a density- by a density-dependent dependent

factorfactor-death rate = birth rate-death rate = birth rate-shows -shows carrying capacitycarrying capacity = the population size = the population size (max. #) that an environment can support.(max. #) that an environment can support.

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examplesexamples

• Exponential growth Exponential growth • Logistic growth Logistic growth

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Checking for understanding (3 Checking for understanding (3 parts)parts)

• COMPLETE THE FOLLOWING (either on your iPad---COMPLETE THE FOLLOWING (either on your iPad---then email to me; OR on a half sheet of paper):then email to me; OR on a half sheet of paper):

• Answer Answer reading check questionreading check question after after reading “Human Population” pg. 107reading “Human Population” pg. 107

• GraphingGraphing: #7 on pg. 107: #7 on pg. 107• Pg. 103 Fig. 1Pg. 103 Fig. 1: What distinguishes : What distinguishes

one zebra population from another one zebra population from another zebra population?zebra population?