Introduction to Introduction to Ecology Part IIEcology Part II

Autotrophs vs HeterotrophsAutotrophs 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 InteractionsSpecies 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 InteractionsSpecies 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 InteractionsSpecies 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.

CompetitionCompetition

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.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

SymbiosisSymbiosis

Symbiosis is a close, long-term relationship between two organisms

There are three types of symbiotic relationships:– Parasitism– Mutualism– Commensalism

SymbiosisSymbiosis

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

SymbiosisSymbiosis

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

SymbiosisSymbiosis

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

SymbiosisSymbiosis

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: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 RichnessSpecies 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)

SuccessionSuccession

Ecological succession is a gradual sequential growth of a community of species in an area

SuccessionSuccession

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)

SuccessionSuccession

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)

SuccessionSuccession

Pioneer Community:– A community that is actively undergoing

succession

– Not stable, still changing with time

SuccessionSuccession

Climax Community:– A community that reaches a stable end point

(redwood forest)