14.2 Community Interactions Community Interactions Succession occurs following a disturbance in anSuccession occurs following a disturbance in an ecosystem. • Succession regenerates

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• Competition occurs when two organisms fight for the

same limited resource.– Intraspecificp

competition– Interspecific

competitioncompetition


• Predation occurs when one organism captures and eats another.


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


– Commensalism: one organism benefits, the other is unharmed

• There are three major types of symbiotic relationships.

unharmed

Human Our eyelashesØ CommensalismHuman Our eyelashes are home to tiny mitesthat feast on oil secretions and dead skin. Without harming us up to 20 mites may

Demodicids Eyelash mites find all they need to+

Ø Commensalism

us, up to 20 mites may be living in one eyelash follicle.

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 bemm in length and can be seen only with a microscope.

Organism benefits+Ø Organism is not affected


– Parasitism: one organism benefits, the other is harmed• There are three major types of symbiotic relationships.

Braconid waspBraconid larvae

Parasitism+0

_Hornworm caterpillarThe host hornworm will eventually die as

feed on their host and release themselves shortly before

+

yits organs are consumedby wasp larvae.

shortly before reachingthe pupae stage of development.

Organism benefits0Organism is not affected_


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

as leeches) and endopaasites (such as hookworms)as leeches) and endopaasites (such as hookworms)


KEY CONCEPTKEY CONCEPT Populations grow in predictable patterns.


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

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

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

bi th– births– emigration

deaths– deaths


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


What’s Behind Human Population Growth

Industrial Revolution• Three Factors – Fertility

• Industrial Revolution– Growth of Cities and

Infrastructure– Infant Mortality– Longevity

InfrastructureWaterEnergyT t ti

• Animal Domestication and Agriculture

Transportation

– Increased Productivity– Nutritionand Agriculture

– Provided for a few to feed many

Nutrition– Sanitation– Medicine




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


Succession occurs following a disturbance in anSuccession occurs following a disturbance in an ecosystem.

• Succession regenerates or creates a community after a• Succession regenerates or creates a community after a disturbance.– a sequence of biotic changesg– damaged communities are regenerated


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


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


Documents

14.2 Community Interactions Community Interactions Succession occurs following a disturbance in anSuccession occurs following a disturbance in an ecosystem. • Succession regenerates