Community Ecology
Campbell and Reece - Chapter 53
(above the level of the population) - interaction

SPECIES
(MANY) - 1.6 million (actually few are known - maybe there are several million more)
and maybe 100 x as many in the past
recall mass extinctions, most past species are gone
Recall a species is defined in terms of reproduction to produce fertile offspring (only apply to sexually reproducing species)

Of course, species interact with eachother (in lots of ways). Any changes can have broad ranging consequences (like a row of dominoes), and that is the reason to file an "ecological impact statement."

INTERACTIONS

Coevolution -
Earlier example: Angiosperm Pollination, Bees, (UV ultraviolet) Hummingbirds, (red) Bats, honey possom, Orchid

Defenses
Plant defenses (opium, nicotine, etc)
Predator-prey
cryptic coloration (camouflage) (again the examples vary) canyon tree frog (Fig. 53.5), caterpillars
Warning (aposematic) coloration poison arrow frog (Fig. 53.6)
Mimicry
Batesian (Fig. 53.7 - hawkmoth looks like snake)
Mullerian (Fig. 53.8) - cuckoo bee looks like yellow jacket
Example (not from book) Monarch, milk weed, digitalis 1 trial learning

Niche - needs of species - all get filled
Adaptive radiation e.g. of Darwin's finches
because the Galopagos were new volcanic islands
1934 - Gausse - no 2 species share niche at one time
(2 species together - competitive exclusion)
e.g. diff time of day, etc
PARTS OF A NICHE:
Habitat - physical environment - much damage is from "loss of habitat" or "fragmentation"
microhabitat - e.g. rotting log
Interaction with other species
Climate: Temp., light, wind, etc.
Food, water, nest site
Fundamental Niche - theoretical, Realized Niche - actual
TRANSPARENCY - Fig. 53.2 Barnacle example

HOW DO NICHES GET FULL?
Divergent evolution - e.g. Darwin's finches Figs. 1.17 & 22.6
Character displacement TRANSPARENCY Fig. 53.4 - resource partitioning

Important whether species are sympatric or allopatric

Problem with introduction of new species, especially in island habitats. Zebra mussels cam in in balast water of ships.

Symbiosis (living together)
Parasitism vs. Mutualism (for mutual benefit ant and acacia Fig. 53.9)
(Commensalism - one benefits, the other unaffected hard to prove- egret and cape buffalo)
Bacteria in gut, E. coli - vitamin K, superinfection after
broad-spectrum antibiotic
Nitrogen fixation - Rhizobium in root nodules
Microorganisms in termite (and ruminant) gut - cellulose
Lichens-fungi and algae or blue green algae
Oxpecker on giraffe
Raven on African bufallo
Cleaner wrass, red snapper, sabre toothed blenny
mimicry
Estrilded finch & brood parasite long tailed paradise
willow bird (mimicry) (shown earlier)

Ecological succession - primary, after glacial retreat
TRANSPARENCY (Fig. 53.19)
also secondary
after chestnut blight, after 1988 Yellowstone fire
pioneers like lichens, annual plants
climax community with stable relationships

geography in divergent evolution and speciation
interaction of sympatric vs allopatric species
Cline - variations in diversity or characteristics with eg latitude

Islands are particularly interesting places for is biogeography

About half of SLU Biology's faculty are dedicated to "Ecology, Evolution and Systematics," and you can check out the home page index for EES

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this page was last updated 4/16/03