Transcript Introduction to Ecology Part II

Introduction to
Ecology Part II
Autotrophs vs Heterotrophs

What is a producer
– Autotrophs like plants, protists, and bacteria
that make their own food

What is a consumer:
– Heterotrophs that cannot make their own
food
Species Interactions

Predation
– An individual of one species eats all or part
of an individual of another species
– Predator – organism eating
– Prey – organism being eaten
Species Interactions

Predator Adaptations:
– Neutral selection favors the evolution of
predator adaptations for finding, capturing,
and consuming prey



Acute heat sensor to webs to camouflage hair to
specialized teeth
Ex 1: Rattlesnake have acute sense of smell and
heat sensitive pits below their nostrils
Ex 2: Sticky webs of spiders to flesh cutting teeth
of wolves
Species Interactions

Predator Adaptations cont.
– Natural selection also favor prey to be able to
avoid, escape, or ward off predators
– Animal prey adaptations:

Hide, camouflage, chemical defense, fake eyes
and heads, bright colors, to mimic other
dangerous animals
– Plant prey adaptations:
 Defense includes: sharp, thorns, spines, sticky
hairs, tough leaves, to being poisonous, irritating,
or bad tasting.
Competition

Interspecific competition:
– Is a type of interaction in which two or more
species use the same limited resources
– Two populations competing for the same
resource may end up reducing/eliminating one
of the competitors
Competition cont.

Competitive exclusion:
– Is where one species uses the limited
resources more efficiently than the other
species does
– Ex: Barnacles off the coast of Scottish coast between
Chthamalus stellatus and Semibalanus balanoides
 The C. stellatus could live high and low on ‘shore
rock” but due to competition S. Balanoides out
competed it restricted the C. stellas to the upper
portion of the shore rock
Symbiosis

Symbiosis is a close, long-term
relationship between two organisms
 There are three types of symbiotic
relationships:
– Parasitism
– Mutualism
– Commensalism
Symbiosis

Parasitism:
– In parasitism, the prey is called the host
– Predator is called a parasite
– One organism is harmed (host) while the
other organisms benefit (parasite)
– Usually does not result in host death

Examples: Aphids, lice, leeches, fleas, ticks, and
mosquitoes
Symbiosis

Parasitism cont.
– Ectoparasites:
 Live inside their hosts body
 Ex: Protists; tape, heart, round worms
– Parasites have a negative impact on their host’s
health
– Host defense:

Skin, tears, saliva, mucus membranes and the
immune system
Symbiosis

Mutualism:
– Relationship where both (two) species have
some benefit from each other
– Pollination is the most important mutulistic
relationship on Earth
– Termites are able to digest cellulose due to a
mutulistic protozoa called Trichonympha
Symbiosis

Commensalism:
– Is an interaction in which one species
benefits and the other is not affected
– Species that scavenges for leftover food items
are often commensal species

Best known examples are small tropical fishes in
relation to sea anemones
Species Richness:

Is the number of species or simple count of
species in the community

Each species contributes one count to the
total regardless of whether the species’
population is one in 1 million
Species Richness

Varies with latitude – the closer a community is
to the equator the greater the number of species
– Species is the greatest in the tropical rain forest

Larger areas usually contains more species than
smaller ones
 Species interaction also promotes species
richness. (Competition can keep species from
overcrowding other)
Succession

Ecological succession is a gradual
sequential growth of a community of
species in an area
Succession

Primary Succession:
– Development of a community in an area that
has not supported life in the past
– Bare rocks, sand dunes, or volcanic island
– No soil present (can take 200+ years to reach
vegetation)
Succession

Secondary Succession:
– Sequential replacement of species that
follows disruption of an existing community
– Regrowth of organisms after a severe natural
disaster (fire, tornado) or farming, logging, or
mining
– Soil already present (takes about 100 years)
Succession

Pioneer Community:
– A community that is actively undergoing
succession
– Not stable, still changing with time
Succession

Climax Community:
– A community that reaches a stable end point
(redwood forest)