C34 Advanced Biology
Ecology = study of interactions b/w organisms and their environment
Biosphere = earth and it’s atmosphere (all of Earth that sustains life)
(note: life exists in inhospitable areas – deep sea vents – chemoautotrophs – bacteria
oxidize hydrogen sulfide gas (H2S).
Biotic Factors = living components of the environment
Abiotic Factors = nonliving components of the environment
(ex: temperature, water, nutrients, etc.)
Ecosystem = includes both biotic & abiotic components of the environment (ex: forest)
Community = all of the biotic factors in an environment (ex: all of the bacteria, frogs,
turtles, fish, protists, etc. in a pond)
Population = all of the members of a single species residing in an area (ex: deer
population in Greenup Co.)
Organism = living thing
Environmental awareness – widespread use of DDT and other pesticides led to Rachel
Carson publishing book – Silent Spring. 70’s began era of legislation addressing
environmental concerns.
Physical/Chemical Factors that Influence Life:
1) Energy Source (In dark environments, bacteria that extract energy from inorganic
chemicals power ecosystems – ex: sulfur bacteria use H2S to produce energy.
Organisms feed on these bacteria or take nutrition form bacteria w/in their bodies
– p. 684)
2) Temperature – affects metabolism (amphibians and reptiles absorb heat from
surroundings)
3) Water – essential to life (animals maintain fluid balance by variety of
mechanisms)
4) Nutrients (plants and other photosynthetic organisms – algae and photosynthetic
bacteria depend on inorganic nutrients such as N and P Plants obtain these
nutrients from the soil. In aquatic ecosystems, low levels of N and P limit growth
of algae & photosynthetic bacteria)
5) Aquatic Factors (ex: dissolved oxygen, salinity, current, tide)
6) Terrestrial Factors (ex: wind increases an organism’s rate of water loss by
evaporation – resulting increase in evaporative cooling would be advantageous on
a hot day but causes dangerous wind chill in the winter).
Organisms are adapted to abiotic and biotic factors by natural selection.
What is the role of the environment in adaptive evolution?
The individual whose phenotypes are best suited to the environment (including both
abiotic and biotic factors) will pass their alleles to the next generation. But individuals
with other phenotypes may not. For example, if the biotic environment includes wolves,
a pronghorn that is not able to run as long as the rest of the herd will probably not survive
to reproduce.
Aquatic Biomes:
 Marine
 Freshwater
Marine Ecosystem:
 Pelagic Ream = all open water
 Benthic Realm = seafloor
 Photic Zone = depth of light penetration (max of 200 m)
 Continental Shelve = submerged parts of continents
Photic zone:
 photosynthetic photoplankton (microscopic algae and cyanobacteria) &
photosynthetic multicellular algae provide food source for sponges, burrowing
worms, clams, sea anemones, crabs, and echinoderm (inhabitants of benthic realm
of photic zone)
 Zooplankton (small drifting animals), fish, and marine mammals inhabit pelagic
photic zone.
Coral Reefs = biologically diverse biome. Scattered throughout photic zones in tropical
waters above continental shelves. Built up by coral animals – cnidarians that secrete hard
outer skeleton and by multicellular algae encrusted w/ limestone. Single celled algae live
within the corals, providing the coral with food. Coral reefs abundant in invertebrates &
fishes.
Aphotic zone
 Lies below photic zone
 Some light reaches these depths. Not enough light for photosynthesis.
 Referred to as twilight zone. Dominated by small fish and crustaceans.
 Food sinking from photic zone provides some nourishment. Also, many of these
organisms migrate to surface at night to feed.
 Enlarged eyes in organisms help to adapt to dim light & luminescent organs
attract mate and prey.
No light below 1000 m. Scarcity of food. Ex: Angler fish. Crustaceans, sea anemones,
echinoderms such as sea cucumber, sea star, sea urchin. Most bentic organisms are
deposit feeders – consume detritus.
Intertidal zone = where ocean meets land
 rocky area


shore is pounded by waves at high tide & exposed to sun & drying winds at low
tide
home to sedentary organisms such as algae, barnacles, and mussels (attach to
rocks)
Estuary = occurs where freshwater merges w/ the ocean
 very productive biomes
 oysters, crabs, and fish
 nesting and feeding areas for waterfowl
Wetlands = transitional biome b/w aquatic & terrestrial ecosystem
 covered w/ water either permanently or periodically
 mudflats and salt marshes
Freshwater ecosystems = lakes and ponds (standing water), rivers and streams (running
water), and a variety of wetlands (marshes, swamps, and bogs)
 current, sunlight, & nutrients are important abiotic factors
Terrestrial Biomes:
1) Tropical Forest = occur along equator. Tropical rainforest = greatest biodiversity
2) Savanna = grasslands w/ scattered trees (Africa & Australia)
3) Desert – driest biomes
4) Chaparral = shrub land w/ cool rainy winters and dry, hot summers (largest
chaparral surrounds Mediterranean Sea). In US – Southern California.
5) Temperate Grasslands = found where winters are cold (In US, prairies)
6) Temperate Broadleaf Forests = where we are (deciduous trees, Eastern US)
7) Coniferous Forests (Taiga) = short summers and long, snowy winters
8) Tundra (arctic – treeless biome characterized by extreme cold, wind, &
permafrost. Alpine – occurs above the treeline on high mountains) permafrost =
permanently frozen subsoil.