14.2 Community Interactions
KEY CONCEPT Organisms interact as individuals and as populations.
14.2 Community Interactions
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
14.2 Community Interactions
• Predation occurs when one organism captures and eats another.
14.2 Community Interactions
• There are three major types of symbiotic relationships.– Mutualism: both organisms benefit
14.2 Community Interactions
– 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
14.2 Community Interactions
– 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_
14.2 Community Interactions
• 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)
14.2 Community Interactions
KEY CONCEPTKEY CONCEPT Populations grow in predictable patterns.
14.2 Community Interactions
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
14.2 Community Interactions
• 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.
14.2 Community Interactions
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
14.2 Community Interactions
14.2 Community Interactions
14.2 Community Interactions
KEY CONCEPTKEY CONCEPT Ecological succession is a process of change in the species that make up a community.
14.2 Community Interactions
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
14.2 Community Interactions
• There are two types of succession.– primary succession — started by pioneer species
14.2 Community Interactions
• There are two types of succession.– secondary succession — started by remaining species
14.2 Community Interactions