Interactions of Organisms in Ecosystems (Unit 3 – LT)

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Interactions of Organisms in Ecosystems (Unit 3 – LT). KEY CONCEPT Every organism has a habitat and a niche. . A habitat differs from a niche. . Habitat. The area or environment where an organism or ecological community normally lives or occurs: . M arine habitat. - PowerPoint PPT Presentation

Text of Interactions of Organisms in Ecosystems (Unit 3 – LT)

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Interactions of Organisms in Ecosystems (Unit 3 LT)KEY CONCEPT Every organism has a habitat and a niche. A habitat differs from a niche.

2HabitatThe area or environment where an organism or ecological community normally lives or occurs:

Marine habitat

3Niche >Rhymes with itch! The functional role of a species in its environment includes:

Clown fish living among the tentacles of a sea anemone.Food- how it fits in a food web

Behavior-interaction with other organisms and environment

Abiotic conditions it can tolerate.I think of my niche as my job!KEY CONCEPT Organisms interact as individuals and as populations.

Competition and predation are two important ways inwhich organisms interact. 5CompetitionCompetition occurs when two organisms compete for thesame resource.

Interspecific Competition involving different species

Intraspecific Competition involving the same species

6Predationoccurs when one organism captures and eat another.

7Symbiotic Relationships or SymbiosisSymbiosis is a close ecological relationshipbetween the individuals of two (or more) different species.

There are three major types of symbiotic relationships.

Mutualism:.both organisms benefit

++++Bat eats nectar.Cactus is pollinated.+Organism benefits++Organism benefits9- one organism benefits, the other is unharmed

Human Our eyelashes are home to tiny mitesthat feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle.Demodicids Eyelash mites find all they need to survive in the tiny folliclesof eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope.

+Organism benefits+Organism is not affectedCommensalismCommensalism:10Parasitism:one organism benefits, the other is harmed

Organism benefits+_Organism is affected negativelyHornworm caterpillarThe host hornworm will eventually die as its organs are consumedby wasp larvae.Braconid waspBraconid larvae feed on their host and release themselves shortly before reachingthe pupae stage of development._Parasitism++11

Parasites meet their needs as eitherEctoparasites-outside the body of hostEndoparasites- inside the body of hostLeechHookworm

KEY CONCEPT Each population has a density, a dispersion, and a reproductive strategy.

13Population density is the number of individuals that live in a defined area. Scientists can calculate population density.

Population Density 14Population dispersion refers to how a population is spread out in an area.Geographic dispersion of a population shows how individuals in a population are spaced.




15Survivorship curves help to describe the reproductive strategy of a species. A survivorship curve is a diagram showing the number of surviving members over time from a measured set of births.

Survivorship curves can be type I, II or III.

16Type I

Low level of infant mortality One to two offspring An older populationSlow to reach reproductive ageCommon to large mammals and humans

Baboon17Type II

survivorship rate is equal at all stages of lifeMultiple offspringReproductive age usually reached in one or two yearsCommon to birdsand reptiles

What ll it be berries or worms?Feed us now!Type III

Very high birth rateVery high infant mortalityUsually reach sexual maturity in one seasonCommon to invertebrates and plants

CicadaKEY CONCEPT Populations grow in predictable patterns.

20The size of a population is always changing.. Four factors affect the size of a population.Immigration (in)Emigration (out)BirthsDeaths

21Population GrowthPopulation are directly effected by the amount of resources available.

There are two distinct types of population growthExponential growth is a rapid population increase due to an abundance of resources.

Exponential GrowthAustralian farmer introduced 24 rabbits (European) in 1859 today there are ~ 300 million rabbits.23Logistic growth is due to a population facing limited resources.

Starts slowly then becomes exponential growth but levels off as resources become scarce.Logistic Growth24Carrying capacity is the maximum number of individuals in a population that the environment can support.

Carrying Capacity25A population crash is a rapid decline in the size of a population over a short period of time.

Carrying capacity Population CrashEcological factors limit population growth. A limiting factor is something that keeps the size of a population down.

Density DependentDensity Independent27Density-dependent limiting factors are affected by the number of individuals in a given area.parasitism diseasecompetitionpredation

Density-dependent28Density-independent limiting factors limit a populations growth regardless of the density.unusual weathernatural disastershuman activities