Community Composition and Diversity and Community Succession

Habitat vs Niche

Habitat: Where you find the community (part of the niche)

Niche: Role that this specieis play in the community

Ex. Predator/prey relationships

How species interactions within a community affect each species niche

-Competition: negative effect on both speicies

-Amensalim: Negative effect on one species and no effect on the other

-Predation, herbivory, parasitism: Positive effect on one species and a negative affect on the other

-Mutualism: Positive effect on both species

-Commensalism: Positive effect on one species and no effect on the other

-Neutralism: No effect on either species

Resource Partioning

sharing the resource within the species

Character Displacement

Change in morphology because of coevolution (similar beak sizes)

→ Allopatrically: separate islands but same beak sizes

→Sympatically: same island but different beak sizes

Competition (Exploitation vs Interference)

Exploitation: competing but not paying attention to each other

Ex. Aphids and Caterpillars compete for common resource

Interference: Individuals come into physical contact with competition

Ex. two caterpillars fighting for milkweed

Types of prey spices defense mechanisms

1. Camouflage (cryptic coloration)

2. Warning coloration(aposematic)

3. Mimicry

   →Mullerian: two toxic species look similar

   →Batesian: one non toxic and one toxic

4. Intimidation: fighting, agility, armor, masting

5. Plant chemicals and physical defenses (alkaloids terpenoids, thorns)

Symbiotic Relationships

Parasitism: one species benefit and the other (host) is harmed, Mutualism: both species benefit and Commensalism: One species is benefited and the other (host) is unaffected

Types of parasitism

1. holoparasites: non-photosyntheitc, parasitic plant

   →Ex. Rafflesia: gains nutrients and water from surrounding plant roots

2. Hemiparisites: photosynthetic, parasitic plant

   →Ex. Mistletoe: gains water and inorganic material from others

3. Monophagos vs polyphagous

   →Mono: one species or closely related species Ex. Emerald ash

   →Poly: Diverse hosts Ex. fleas

4. Micro vs Macro parasites

   →Whole life span is inside the host ex. fleas

   →More than one species of hosts during different life stages Ex. lancelet fluke

5. Ecto vs Endo parasites

   →attacks host from the outside of the body Ex. fleas

   →attacks host from the inside of the body Ex. Bacteria, tapeworms

Types of Mutalisitic relationships

1. Trophic (feeding relationship)

   →Leaf cutter ants and fungus: they feed fungus plant material and ants eat the fungus

2. Defensive

   →Aphids and Ants: Ants provide protection for the aphids and in return the aphids secrete a sugary water that they feed on

3. Dispersive (seed dispersal)

   → pollination and seed dispersion: bird eats berry and deposits it somewhere else

Commensalism Examples

Orchid looks like a female bee: the male bee tries to mate which collects the pollen on the plant and then the bee flys to a new location pollination

Mouse carrying a seed: The seed is attached to the mouses fur which doesn’t harm it but it helps with seed dispersal

Species Richness

1. Richness increases moving from polar areas to the tropics

   -Doesn’t count the abundance (diversity does)

   -Temperatures affect on their metabolisms

   -Length of time land masses have been inhabited (age)

When does species richness increase?

1. increased time (age)

2. increased area (larger the area, the greater the richness)

3. increased productivity (energy)(producers)

→Evapotransepirate rate

→Solar radiation exposure/precipitation

4. Intermediate disturbance:moderate disturbance enhances habitat diversity and richness (microhabitats)

Primary Succession

The change in the habitat that begins with soilless terrain and no legacy of life (bare rock)

→needs pioneer species like lichens/mosses and/or cyanobacteria

Secondary Succession

The change in the habitat begins with terrain having soil and life present in the soil in the form of any or all these: bacteria, protists, fungi (usually happens after a disturbance like natural disasters)

→Pioneer species: ferns, grasses, small flowering plants (typically any producer)

→Climax community: stable community throughout time and area

Mechanisms of succession

1. Faciliation: early colonizing species sets the stage allowing another species to later colonize an area

   → Ex. Glacier Bay, Alaska

2. Inhibition: An early colonizing species preventing a later spices from moving into area (needs a disturbance to happen)

   → Ex. Intertidial zones (animals feeding on it )

3. Tolerance: Species are affected by earlier colonists in some way, but they do not require the presence of earlier colonists to change the environment (competition)

   →Ex. when a disturbance creates a light gap, succession begins with plant seeds and roots that weren’t able to grow before bc of no sunlight