Transcript Ecosystems – Unit 2 - Reeths

Ecosystems – Unit 2 (cont.)
habitat vs. niche (14.1, pgs. 428 - 429)
• habitat – where an organism lives, all
the conditions (living, nonliving)
• niche – the job, role of an organism
in the habitat (food, behavior)
• school analogy
• students, teacher, principals, food service are all
niches in the same habitat
competition (14.1, pgs. 429 - 430)
• competitive exclusion – gray squirrel is better
at getting acorns; the red squirrel becomes
extinct or moves to another niche
• niche partitioning – both squirrels eat acorns,
red squirrels from the tree, gray squirrels from
the ground
• evolutionary response – gray squirrels
develop bigger teeth for larger acorns, red
squirrels have smaller teeth (seed)
competition (14.1, pgs. 429 - 430)
• competitive exclusion (example) – 2 species in
same niche; 1 does it better
EX: Michigan clams vs. zebra mussels (no predator)
(predators like carp, sheephead)
(no predator, rapid growth)
• ecological equivalents – two different species
that fill same niche in different regions
Madagascar
South America
Relationships/interactions
(14.2, pgs. 431 - 434)
Competition is good for genetics.
1. Interspecific – 2 different species
(wolf vs. wolverine over their food)
2. Intraspecific – same species
( 2 deer fighting for the best mate)
Predation – kill and eat
(snakes, gulls, cheetah)
Relationships/interactions
(14.2, pgs. 431 - 434)
symbiosis – 2 different species have a
relationship over food
• mutualism – both organisms benefit
(ex: flower gets pollinated + bee gets food)
• commensalism – one benefits, one unaffected
(ex: bird makes nest + tree doesn’t care)
• parasitism - one benefits, one is harmed
(ex: tapeworm gets food, dog loses nutrients)
Ø
Human Our eyelashes
are home to tiny mites
that feast on oil
secretions and dead skin.
Without harming us, up
to 20 mites may be living
in one eyelash follicle.
+
Ø
Organism is not affected
+
Organism benefits
Demodicids Eyelash mites
find all they need to survive
in the tiny follicles
of eyelashes. Magnified
here 225 times, these
creatures measure 0.4 mm
in length and can be seen
only with a microscope.
Predator vs. Prey
• prey impacts predator population more
hunters kill 500,000
deer/year
predators switch prey
instead of starve
Act. 1 – lynx and hare
Act. 2 – pike and perch
Population density/distribution
(14.3, pgs. 436-439)
population density – how many
organisms live in a defined area
Population density/distribution
(14.3, pgs. 436-439)
population dispersion –
how the population is
spread out
clumped – for mating,
protection, or food spot
uniform – territory and
food competition
clumped
dispersion
uniform
dispersion
random
dispersion
Population density/distribution
(14.3, pgs. 436-439)
uniform
clumped
Population density/distribution
(14.3, pgs. 436-439)
Type I – big mammals (black bear)
• few young (1-3), lots of care
Type II – small mammals, birds, rabbits
• more young (4-12), less care
Type III – insects, parasites
• thousands of young, no care
Population density/distribution
(14.3, pgs. 436-439)
Population growth patterns
(14.4, pgs. 440-444)
Factors that effect populations:
1. immigration – species moving in
2. emigration – species moving out
3. birth rate – goes up when habitat is good
4. death rate – goes down when habitat is good
Population growth patterns
(14.4, pgs. 440-444)
exponential growth – rapid population
growth due to abundant resources
J-curve
Population growth patterns
(14.4, pgs. 440-444)
S - curve
logistic growth –
slow growth, then
exponential growth,
then level off due to
resource limits
Population growth patterns
(14.4, pgs. 440-444)
carrying capacity - average # supported
by an ecosystem; environment quality can
change capacity
population crash - dramatic decline
•
•
•
•
when above carrying capacity
weather related possibly
fire
new species that messes things up
Population growth patterns
(14.4, pgs. 440-444)
limiting factors – factors that keep population down
1. density-dependent factors: are affected by the
population of individuals; when above capacity
• competition, predation, parasitism and disease,
starvation
2. density-independent factors: not related to
population; can happen anytime
• unusual weather, natural disasters, human activity