14.1 Habitat And Niche KEY CONCEPT Every organism has a habitat and a niche.

14.1 Habitat And Niche

KEY CONCEPT Every organism has a habitat and a niche.


Objectives

• Differentiate between a habitat and a niche

• Differentiate between competitive exclusion and ecological equivalents


A habitat differs from a niche.

• A habitat is all aspects of the area in which an organism lives.– biotic factors– abiotic factors

• An ecological niche includes all of the factors that a species needs to survive, stay healthy, and reproduce.– food– abiotic conditions– behavior


Resource availability gives structure to a community.

• Species can share habitats and resources.• Competition occurs when two species use resources in the

same way.• Competitive exclusion keeps two species from occupying

the same niche.


• Competitive exclusion has different outcomes.– One species is better suited to the niche and the other

will either be pushed out or become extinct.– The niche will be divided.– The two species will further diverge.


• Ecological equivalents are species that occupy similar niches but live in different geographical regions.

Madagascar

South America


What are the 3 parts of an organisms ecological niche?

• Food type

• Abiotic conditions

• Behavior


What does the principle Competitive Exclusion say will happen when 2 species compete for the same resource?

• One species will be better suited to the niche, and the other species will either be pushed into another niche or become extinct


If a group of mantella frogs were transported to the ecosystem of the poison dart frogs, what might happen to the 2 species populations?

• As ecological equivalents, they share a similar niche.

• The population better suited to the niche might deprive the other of resources, causing the other to die off.

OR • One population might respond to limitted resources by

altering its niche.


A bison and an elk live in the same habitat and feed on the same grasses. Does this mean that the competitive exclusion principle does not apply? Expleain.

• The competitive exclusion principle only applies if the 2 species live in the same habitat AND occupy the same niche

• A niche includes – Food type– Abiotic conditions– Behavior

• These two species use the same food resource but occupy different niches


Considering the competitive exclusion principle, why may it be harmful to transport a species such as a rabbit, to another habitat where it currently does not exist?

• If a new species is introduced to an area, it may occupy a similar niche as a native species and be better adapted for the niche to have no natural predators.

• This could drive the native species to extinction


KEY CONCEPT Organisms interact as individuals and as populations.

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Objectives

• Compare & Contrast interspecfic and intraspecific competition

• Describe the 3 types of symbiosis

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Competition and predation are two important ways inwhich organisms interact.

• Competition occurs when two organisms fight for thesame limited resource.– Intraspecific

competition– Interspecific

competition

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• Predation occurs when one organism captures and eats another.

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• There are three major types of symbiotic relationships.– Mutualism: both organisms benefit

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– Commensalism: 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+

Ø

Ø Organism is not affected

Commensalism

• There are three major types of symbiotic relationships.

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– Parasitism: one organism benefits, the other is harmed

• There are three major types of symbiotic relationships.

Organism benefits0

_

Organism is not affected

Hornworm 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

+

0

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• There are three major types of symbiotic relationships.– Parasitism meet their needs as ectoparasites (such

as leeches) and endopaasites (such as hookworms)

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During the fall spawning of salmon, grizzly bears fight over space on the banks of a river. What type of competition is this?

• The bears are fighting amongst themselves so it is considered intraspecific competition

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Describe and give an example of the 3 types of symbiosis

• Mutualism +/+

• Commensalism +/0

• Parasitism +/-

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How are predation & parasitism similar? How do they differ?

• Predation & parasitism are both relationships in which one organism benefits while the other is harmed.

• In predation, the predator needs to kill its prey in order to benefit

• In parasitism, the parasite benefits by keeping its host alive

14.2


After a lion has made a kill birds will sometimes arrive to pick at the carcass. The birds would be considered _________(A)_________________ while the lions would be considered _________(B)_____________________

• A) Scavengers

• B) Predators

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

14.3


Objectives

• Consider density and geographic dispersal as characteristics of populations

• Describe 3 basic types of survivorship curves in relation to reproductive strategies.

14.3


Population density is the number of individuals that live in a defined area.

• Population density is a measurement of the number of individuals living in a defined space.

• Scientists can calculate population density.

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• Population dispersion refers to how a population is spread in an area.

Geographic dispersion of a population shows how individuals in a population are spaced.

Clumpeddispersion

Uniformdispersion

Randomdispersion

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• There are three types of dispersion. – clumped

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• There are three types of dispersion. – uniform

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• There are three types of dispersion. – random

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Survivorship 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.

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• Survivorship curves can be type I, II or III.– Type I—low level of infant mortality and an older

population– common to large mammals and humans– Type II—survivorship rate is equal at all stages of life– common to birds

and reptiles– Type III—very

high birth rate, very high infant mortality

– common to invertebrates and plants

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An Organism has 10 offspring. Two of these offspring die each year over a 5 year period. Is this organism more likely to be a bird or insect? Explain.

• The organism is a bird because the mortality pattern described is closest to type II.

• Insects tend to be type III, with many offspring and high mortality early in life stages

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KEY CONCEPT Populations grow in predictable patterns.

14.4


Objectives

• Describe 4 characteristics that affect population size

• Compare exponential and logistic population growth

• Identify factors that limit population growth

14.4


Changes in a population’s size are determined by immigration, births, emigration, and deaths.

• The size of a population is always changing.

• Four factors affect the size of a population.– immigration– births– emigration– deaths

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Population growth is based on available resources.

• Exponential growth is a rapid population increase due to an abundance of resources.

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• Logistic growth is due to a population facing limited resources.

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• Carrying capacity is the maximum number of individuals in a population that the environment can support.

• A population crash is a dramatic decline in the size of a population over a short period of time.

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Ecological factors limit population growth.

• A limiting factor is something that keeps the size of a population down.

• Density-dependent limiting factors are affected by the number of individuals in a given area.

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• Density-dependent limiting factors are affected by the number of individuals in a given area.

– parasitism and disease

– predation– competition

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• Density-independent limiting factors limit a population’s growth regardless of the density.– unusual weather– natural disasters– human activities

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What 4 factors determine the growth rate of a population?

• Immigration

• Births

• Deaths

• Emigration

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How does carrying capacity affect the size of a population?

• Carrying capacity limits the size of a population

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14.1 Habitat And NicheWhat is the main difference between a density-dependant limiting factor and a density-independent limiting factor? Give an example of each.

Density-Dependant

• A density dependant limiting fact is affected by the number of individuals in a given area– These are usually BIOTIC

limiting facto=rs such as Predation

Competition

Disease

Density-Independant

• A density independent limiting factor is not affected by population size/density– These are usually ABIOTIC

limiting factors such as Weather

Forrest fires

Natural disasters

Human activities

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What might cause exponential growth to occur only for a short period when a new species is introduced to a resource filled environment.

• Eventually, the growing population will consume all the resources, and the species may experience a population crash.

14.4


Give an example of how a symbiotic relationship could cause a population to crash.

• If a parasite or disease spreads in a dense population, it could cause a population to decline dramatically over a short period of time.

14.4


KEY CONCEPT Ecological succession is a process of change in the species that make up a community.

14.5


Objectives

• Describe the process of primary succession

• Explain the difference between primary and secondary seuccession

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Succession occurs following a disturbance in an ecosystem.

• Succession regenerates or creates a community after a disturbance.– a sequence of biotic changes– damaged communities are regenerated– new communities arise in previously uninhabited areas

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• There are two types of succession.– primary succession — started by pioneer species

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• There are two types of succession.– secondary succession — started by remaining species

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How is primary succession different from secondary succession?

• Primary succession begins with barren rock, worn down and colonized with a pioneer species

• Secondary succession begins with established soil in which many different plants can grow

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Why are pioneer species so important for primary succession?

• Pioneer species such as mosses and lichens can break down rock into smaller pieces.

• When they die, their remains may mix with the pieces of rock forming a thin layer of soil

• They change the ecosystem in ways that enable the support of more diverse species

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Does the process of primary succession take longer in the tropical or arctic areas? Explain.

• Primary succession takes longer in arctic areas because – rock is covered in snow part of the year– the growing season is shorter– and cold temperatures slow growth and decomposition

• Soil takes much longer to form.

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Which reaches a climax community 1st, an area undergoing primary or secondary succession? Explain

• Secondary succession takes less time to reach a stable climax community because the soil is already there

• In primary succession there is no soil and so it will take longer to reach a climax community

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During succession, what might be the limiting factor for sun-loving mosses as taller plants begin to grow?

• The amount of sunlight that reaches them

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At what point during primary succession does an ecosystem provide the fewest habitats for an organism? Explain.

• There are no habitable areas in the earliest stages of succession because there is no soil to support producers..

• Land becomes habitable once rock has weathered enough to support mosses and lichens

• Over time mosses and lichens will provide the resources needed to support other organisms

14.5

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14.1 Habitat And Niche KEY CONCEPT Every organism has a habitat and a niche.

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