FCAT Biology

FCAT BiologyS.C.G.2.4.2Ecological SuccessionDo all ecosystems stay the same all the time?What are some things that cause changes to ecosystems?Natural and unnaturalQuickly and slowly

2Ecosystems are constantly changing in response to human and natural disturbances. As an ecosystem changes, older habitants die out and new organisms move in, causing more change3Ecological SuccessionSeries of predictable changes that occur in a community over timePhysical environmentNatural disturbanceHuman disturbance

4Primary SuccessionSuccession on land that occurs on surfaces where no soil exists Volcanic eruptionsGlaciers melting

5

6

7Stages of Primary SuccessionStart with no soil, just ash and rockFirst species to populate this areapioneer speciesFor example, pioneer species on volcanic rock are lichens (LY-kunz)Lichens made up of fungus and algae that can grow on bare rockWhen lichens die, they for organic material that becomes soilnow plants can grow

8Secondary SuccessionSuccession following a disturbance that destroys a community without destroying the soilNatural hurricanefiresHuman disturbancesFarmingForest clearing9

10

11

12

13

14

Population Ecology15What is population?Group of individuals of the same species that live in the same area

A Population is a group of individuals of the same species living in an area.16Does population change?Sea otters, kelp, and sea urchins

17Kelp forests offer a habitat for sea ottersSea urchins feed on kelpSea otters feed on sea urchins18

Then come the hunters...19What do you think happens when sea otters are hunted?Sea urchins increase or decrease?Kelp forest increase or decrease?Sea otters are then placed on the endangered species listSo now what happens to the population of sea otter?Starts to increaseHow does this affect the kelp and the sea urchins?Sea urchins start to get eaten again=decrease in #Kelp increases b/c less sea urchins to eat them

20But now we have a new hunter.

21What happens to the sea otter, kelp, and sea urchins?

22What does this tell us about population?Population changesThere are many factors that influence a populationNatural UnnaturalPopulation density has a great impact on ecosystems

233 Factors that affect population size# of births# of deaths# of individuals that enter or leave populationPopulation will increase or decrease depending on # of individuals added or removed24What happens to the population when we.Have more births than deaths?Population increasesHave more deaths than births?Population decreases Have equal amounts of births and deaths?Population remains constant25

26Immigrationim= inMigrate= to move from one place to anotherImmigration is the individual movement into an areaAnimals in search of mates and food in new areas27

28

29

30

31EmigrationE means outMigrate means to move from one place to anotherEmigrate means individuals moving out of one place and into anotherYoung wolves and bears leaving as they matureShortage of food32Two types of growthExponential growthIndividuals reproduce at a constant ratePopulation multiplies by constant FACTOR over constant time intervalLogistic growthOccurs when a populations growth slows or stops after a period of exponential growthAs population approaches carrying capacity, BR may decrease, DR may increase or both, until equal33Exponential GrowthOccurs under ideal conditions with unlimited resourcesThink about exponents in math.Starts slowly then sky rockets to infinityOur graph will look like a JBacteria

34Lets look at bacteriaBacteria reproduce by splitting in halfBacteria have a doubling time of 30 minutesIf you start will one bacterium, how many bacteria will there be after the first 30 minutes?2After an hour?4After an hour and a half?8After two hours?16After 15 hours?Over a billion

35

36Logistic GrowthAs resources become less available, the growth of the population slows or stopsS-shape curveNo net increase or decrease in populationWhat we usually see in nature: except for humans37

Carrying Capacity38Carrying CapacityThe largest number of individuals that a given environment can supportThe flattened part of the logistic graph after the exponential growthThe point at which this flat line reaches the y-axis is the size of the population when the growth rate reaches zeroThis doesnt mean the population stops growingMany factors slow the growth of plants and animals

39

Limiting FactorCondition that can restrict a populations growthCould be:SpaceDiseaseAvailability of food

Factors Affecting Population GrowthDensity Dependent FactorsDensity Independent FactorsFactor that limits population as population density increases

Factors that affect population but are not related to population density; affect population regardless of sizeInsects are mainly vulnerable to theseCompetition for foodWeather / Natural disasters:HurricanesTornadoesDroughtPredation (being hunted)Disease (can be passed on)ParasitismHuman Activities: Fires Deforestation

Crowding and StressBoom and Bust Growth CyclesIncrease rapidly for a period of time followed by a sharp decrease in population for a brief period of timeStill not completely understoodHypothesis:Changes in food supplyStress from overcrowdingOther organisms influence on populationBoom-and Bust Population Cycles-Involves more than one population-Rapid increase and decrease in populations