chapter 57 and 58

competition, predation and parasitism, mutualism, commensalism

between individuals of same species

between individuals of different species

organisms compete indirectly through the consumption of a limited resource

individuals interact directly with one another by physical force or intimidation

- no two species can share same vital resource for long
- one will always outcompete other
* resulting in local extinction of the loser

- dividing up of scarce resources among species with similar requirements
- facilitates coexistence

one organism feeding on parts or all of a second organism
- prey can include all forms of life

classified according to
- how lethal they are for the prey
- length of association between consumer and prey

type of predation in which predator feeds on prey but does not kill it (and may never kill it)

feed on one or two closely related hosts

feed on many hosts

multiply within hosts, usually within cells (bacteria and viruses)

live in host but release juvenile stages outside host's body

live on the outside of the host body (fleas and ticks)

live inside the host body (bacteria and tapeworms)

- predator-prey populations can move up and down together
- but generally only one of several forms of environmental resistance

bombardier beetle ejects hot spray

- advertises unpalatable taste, stinger, etc.
- common in tropical frogs with poisonous skin

- camouflage
- stick insects mimic branches
- sea horses - body coloration to mimic habitat

- resemblance of mimic to another organism (model)
- Mullerian mimicry - noxious species converge to reinforce warning
- Batesian mimicry - palatable mimic resembles unpalatable model

- porcupine fish inflates itself
- deceive predator about ease of eating

horns and antlers can be used in defense

ex: grasshopper jumping

ex: turtle shells, exoskeletons

- synchronous production of progeny
- satiate predators, allowing some young to survive
- ex: seed herbivory, periodical cicadas

array of unusual and powerful chemicals
- also mechanical defenses like thorns and spines

not part of primary energy generating metabolic pathway
- alkaloids
- phenolics
- terpenoids

beneficial for both species
- most common: plant root-fungi interactions
*plants get water and minerals
* fungi get photosynthetic products (food)

- one member benefits while the other neither benefits nor is harmed
* epiphytes growing in trees do not harm the trees
* cattle egrets benefit from cattle stirring up insects
- phoresy - one organism uses another for transportation
* flower-inhabiting mites use hummingbird nostrils

- grass-pink orchid produces no nectar, but mimics the rose pogonia, so still visited by bees
- plants mimic female bees, wasps, etc
- plants cheat seed-dispersal agent out of meal with barbs or hooks on seeds

- number of species in each community
- number of species of generally varies according to geographic range
* increasing from polar to temperate to maximum in tropical areas
* increases by topographical variation

- shannon diversity index - measures the diversity in a community
* considers species richness and evenness
~ richness - simple count of species
~ evenness - how equal the abundances are

- species diversity tends to enhance community and productivity
* amount of solar energy captured by photosynthesizes and transformed into biomass
*why?
~ each community member can exploit different portion of available resources

- parcels of land or water abandoned by humans or devastated physical forces will be reclaimed by nature
- succession - series of replacements of community members at a given location
* until stable final state reached

- vegetation changes through time
* one type of growth succeeds another
* general movement toward more and larger greenery through time

from original state of little or no life and soil that lacks nutrients

final state of habitat is first disturbed by some outside force, but life remains, and the soil has nutrients
- ex: abandoned farm land

- final community of succession
- stable