Download Ecosystems and the Biosphere

Ecosystems and the Biosphere
Energy transfer
 All organisms need energy to carry out essential functions – growth, movement,
maintenance, repair, and reproduction
 In ecosystems, energy flows from sun to autotrophs to organisms that eat autotrophs
to organisms that feed on other organisms.
 Amount of energy ecosystem receives and the amount. transferred from organism to
organism have an effect on the ecosystem’s structure.
Producers
 Autotrophs –include plants, some protists and bacteria; they all manufacture their
own food
 Most are photosynthetic - use solar energy to produce food (use abiotic factors to
obtain food)
 Some bacteria carry out chemosynthesis – they produce food by using energy from
inorganic molecules
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Biomass – measure of the total dry mass of organisms in a given area or ecosystem
Producers add biomass to an ecosystem by making organic molecules
Only energy stored as biomass is available to other organisms in ecosystem
Consumers
 All animals, most protests, all fungi, and many bacteria are heterotrophs (cannot
manufacture their own food)
 Get energy by eating other organisms or organic wastes
 Consume energy by consuming organic molecules made by other organisms
 Herbivores eat producers (deer, cows, zooplankton)
 Carnivores eat other consumers (lions, eagles, snakes, praying mantises)
 Omnivores eat both producers and consumers (bears)
 Detritivores eat “garbage” of ecosystem – organisms that have recently dies, fallen
leaves and branches, animal wastes (vulture, bacteria and fungi - decomposers)
 Decomposers – cause decay by breaking down complex molecules in dead tissue
and wastes into simpler molecules
o Some molecules released during decay are absorbed by decomposers and
some are returned to the soil or water
o Actions of decomposers makes nutrients contained within the dead bodies
and wastes of organisms available to autotrophs
o Process of decomposition recycles chemical nutrients
Community Ecology
Five types of Symbioses or interactions among species:
1. Predation – one individual captures, kills, and consumes another individual (prey)
o Influences where and how individuals live by determining their relationship
within the food web
o Effective regulator of population size
Plant – Herbivore Interaction
o Animals that eat plants are herbivores
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Plants have developed adaptations that protect then from being eaten –
sharp thorns, spines, sticky hairs, tough leaves, chemical defenses that are
poisonous, irritating, or bad tasting
2. Parasitism – one individual is harmed and the other individual benefits
o Parasite – feeds on another individual (host)
o Does not usually kill the other individual, only feeds on it
o Example – ticks, fleas, lice, mosquitoes
3. Competition – results from niche overlap (use of the same limited resource by two
or more species)
o Some plants species release toxins into the soil that prevent other species
from growing nearby, restricting the space of the other species
4. Mutualism – cooperative relationship in which both species get some benefit
o Some relationships are so close, that one cannot survive without the other
o Example: pollination – bees, butterflies, bats, and birds carry pollen to other
plants
5. Commensalism – one species benefits and the other is not affected
o Example: small insects and lizards are forced out of hiding by the movement of
buffalo and egrets (bird) nearby feed on these animals – the buffalo are just
gazing and are neither harmed nor benefit from this interaction