Transcript Community Interactions - Welcome to Cherokee High School

Community
Interactions
AP Biology - 2005
Community
 A division of an ecosystem that
describes all of the organisms that live
in an area
 Focuses on interactions within the
community
 Establishes a niche – a set of
conditions under which an organism
exists
Interactions
 Focus on resources available in the community
Food
Water
Space
Mates
Nesting sites
Hiding places
Light
Macro and micronutrients
Limiting Resources
 There are only so many resources in a
community for all of the organisms
 This limits the growth of populations
of organisms within this community
 It leads to specialized interactions
within the members of this community
 ( population dynamics)
Interactions
 Interspecific – Between different
species
 Intraspecific – Within the same
species
Interaction links and
Examples
 http://eebweb.arizona.edu/Animal_Be
havior/lycaenids/lycaen2.htm
Ecological relations( 1)
 One organism benefits in a relationship
the other is harmed or is eaten
Example – predator – prey and parasite =
host
Rating +/Lynx and hare – predator and prey
Malaria, red blood cell, and human –
parasite and hosts
Cyclic predator-prey relationships
Experiment
Experiment( con)
Ecological relations( 2)
 Two organisms compete for the same
resources. This is known as competition.
 Rating -/- or +/Examples
Competition for mates – intraspecific
Competition for space – plants – allelopathy
Competition for nutrients and space – fungi
and bacteria - antibiotics
Mutualism






Both organisms benefit
Rating +/+
Zooxanthellae and coral polyp
Legumes and Rhizobium
Leaf cutter ant and fungal garden
Ant and acacia
Leaf cutter ants and fungal gardens
http://www.blueboard.com/leafcutters/what.htm
http://cas.bellarmine.edu/tietjen/Ecology/fungus.htm
Ant and the Acacia
Commensalism
 One organism benefits – the other is
neither harmed or benefits
 +/0
 Examples – Pinnepidia crab and tube
worm
Amensalism
 Animals can have a negative effect on
the environment
 0/ Animals trampling the grass on the way
to the water hole
Contradictions
 Not all organisms fit the description
exactly
 The definition for symbiosis is
changing to include only those
interactions between organisms of two
different species whose metabolism is
altered by the interaction
Competition- Interspecific
 Allelopathy – How plants guard their
space by releasing molecules into the
environment that deters other plants
from occupying their space
 http://www.units.muohio.edu/dragonfly
/itc/index.htmlx
Intraspecific Competition
Interspecific Competition
 Barnacle species on
a rocky shore
 Establishes zonation
of organisms
 Niche determined
by ability to
barnacles to
tolerate
dehydration
 Competition may restrict species’ ranges.
 Two species of barnacles live on North Atlantic
seashores, but as adults, one species lives higher in
the intertidal zone than the other, with little
overlap between the two (a phenomenon called
intertidal zonation).
 If one of the species is removed experimentally, the
vertical range of the other species becomes
greater.
 The higher-zone barnacle outcompetes the other
because it is more hardy when exposed to air; in the
lower zone, the other barnacle is able to smother or
crush higher-zone intruders.
Barnacle Competition
Batesian Mimicry
 Two different species
resemble each other.
One is unpalatable. The
palatable receives the
benefit of birds not
wishing to eat it
because they have
eaten the unpalatable
one with bad results.
It pays to advertise
Keystone Species
 http://www.prairiedogs.org/
keystone.html
 A keystone species is a
species whose very presence
contributes to a diversity of
life and whose extinction
would consequently lead to
the extinction of other
forms of life. Keystone
species help to support the
ecosystem (entire
community of life) of which
they are a part.
Succession
 Succession begin when an area is made
partially or completely devoid of
vegetation because of a disturbance.
Some common mechanisms of
disturbance are fires, wind storms,
volcanic eruptions, logging, climate
change, severe flooding, disease, and
pest infestation.
Plant Succession
Succession in a Glacial
Moraine
Degradative succession
 The dead body of an organism is
reduced to basic molecules by
decomposers
 Plants may produce litter
 Deciduous trees may produce layer of
litter - compost
Coevolution
 The changes in one species may affect
the changes in another species over
time
 Adaptations may occur
 The organisms can develop a close
association
 Pollinators and flowers a key example
of coevolution
Yucca Moth
http://waynesword.palomar.edu/ww0902a.htm
Yucca and moth
 Female yucca moths only lay their eggs
in the ovules of yucca flowers. A
female Tegeticula( Yucca moth) lays no
more than 5 eggs in the ovules.
 After she has laid the eggs she
scrapes the pollen from the flower’s
anthers and flies to another Yucca
where she transfers the pollen and
lays 5 more eggs
Island Biogeography
 Immigration of mainland species to island –
birds flying – other animals and plants and
animals drifting on trees or floating on rafts
of vegetation in the currents in the ocean
( new plants and animals) Seeds also carried
by birds
 Isolation of species after immigration
 Novel adaptations
 New species develop – allopatric speciation
 New genetic species
Galapagos
Darwin’s finches and the
Galapagos Islands
 http://www.rit.edu/~rhrsbi/Galapagos
Pages/DarwinFinch.html