unit 15a habitat niche interactions and growth patterns

14.1 Habitat And Niche

KEY CONCEPT Every organism has a habitat and a niche.


A habitat differs from a niche. How would you describe a habitat? • 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.

• What big predator lives in California?

• What big predator lives near the North Pole?

• How about Africa?• Why do we rarely see more than 1-2 big predators in

one area?

• Competitive exclusion keeps two species from occupying the same niche.


• Competitive exclusion has different outcomes. What is one possible outcome?– 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.

14.2 Community Interactions

KEY CONCEPT Organisms interact as individuals and as populations.


Competition and predation are two important ways inwhich organisms interact. • Competition occurs when two organisms fight for the

same limited resource.– Intraspecific

competition– Interspecific

competition

Where else have we used “intra” and “inter”In Biology this year?


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


– 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.


– Parasitism: one organism benefits, the other is harmed. Give one example.

• There are three major types of symbiotic relationships.

Organism benefits0

_

Organism is harmed

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


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

as leeches) and endoparasites (such as hookworms)

“Ecto” means…

“Endo” means…

What does that tell you about these parasites?


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

as leeches) and endoparasites (such as hookworms)

“Ecto” means Outside, such as leeches, ticks, fleas, and mosquitoes

“Endo” means Inside, such as malaria, roundworms, and tapeworms

14.4 Population and Growth Patterns

KEY CONCEPT Populations grow in predictable patterns.


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

• The size of a population is always changing. Why?

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


Population growth is based on available resources.

• Exponential growth is a rapid population increase due to an abundance of resources. What would you expect to happen after exponential growth?


• Logistic growth is due to a population facing limited resources. What do you suppose the carrying capacity is?


• 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.


Ecological factors limit population growth. Give an example. • 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.


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

– parasitism and disease

– predation– competition


• Density-independent limiting factors limit a population’s growth regardless of the density.

– unusual weather– natural disasters– human activities


What does the term ecological equivalents describe? • A. species that occupy the same niche in the same community • B. species that occupy similar niches in different geographical

regions • C. species that occupy different niches in the same habitat • D. species that occupy different niches in different geographical

regions




regions • Correct Answer = B

What is the habitat of a zebra? • A. African savannah • B. tropical rain forest • C. wetland • D. mountainside




regions • Correct Answer = B

What is the habitat of a zebra? • A. African savannah • B. tropical rain forest • C. wetland • D. mountainside• Correct Answer = A


Review

• A habitat defines the biotic and abiotic factors in an organism’s surroundings

• A niche includes the habitat and all other factors a species needs to survive, be healthy, and reproduce

• Competition over resources structures a community.• Symbiotic relationships include mutualism,

commensalism, and parasitism. • Changes in population sizes arise from immigration,

births, emigration, and deaths.• Population growth is typically limited by resource

availability.

unit 15a habitat niche interactions and growth patterns

Documents

ecological niche

organism lives

biotic factorsabiotic

key concept

abiotic conditions