CH 37 Communities & Ecosystems Flashcards
Define Commuinty
assemblage of all pops of organisms living close enough together for potential interaction
Define Interspecific interactions
relationships w/ individuals of other species in community (-/-)
Interspecific competition occurs when…
pops of two different species compete for same limited resource (-/-)
Define Mutualism
symbiotic relationship where both
pops benefit (+/+)
Define Predation & Herbivory
A species kills & eats another / eating plant parts or algae by an animal
Define Parasites & pathogens
A species uses a host species at its detriment.
Interactions where one organism
involved is neither harmed nor benefited but the other is harmed is…
Amensalism.
Interactions where one organism
involved is neither harmed nor benefited but the other benefits is…
Commensalism
Species that need the other to survive are known as… / Species dat don’t need other species to survive (but still benefit) are known as…
Obligates / Facultative
Define Ecological Niche
Sum of comm. use of biotic & abiotic resources in its environment
Define Coevolution
series of reciprocal evolutionary
adaptations in 2 species
What are Endoparasites? (inside)
flukes, tapeworms, etc.
What are Ectoparasites? (outside)
ticks, lice, mites, mosquitoes, etc
What are Plant parasites?
aphids and nematodes
Define Trophic Structure
Pattern of feeding relationships consisting of several diff levels
Define Tertiary & Quaternary consumers
T - carnivores that eat 2nd con & lower / Q - carnivores that eat Tert con & lower
Define Food Chain
sequence of food transfer up the trophic levels
Define Producers
autotrophic (self-feeding) organisms / Usually photosynthetic
Define Primary & Secondary consumers
P - Herbivores that eat producers / S -carnivores (including
insectivores), usually smaller organisms
Define Detritus
dead material produced at all the trophic levels.
Define Scavengers,
large animals like crows & vultures / feast on carcasses
Define Food Web
Network of interconnecting food chains.
Species diversity is defined by two components:
Species richness (# of diff species in community) / Relative abundance (representation of each species in C)
Define Decomposers
mainly prokaryotes & fungi / secrete
enzymes that digest molecules in organic material & convert to inorganic forms
Define Decomposition
Breakdown of organic materials to inorganic materials
Define Keystone species
Species whose impact on its Comm is much larger than its abundance/total biological mass would indicate
Define Disturbances
Storms, fires, floods, droughts, or human activities that change biological comm by removing organisms from it/altering availability of resources
Define Ecological succession
Disturbed area colonized by a variety of species, which gradually replaced by a
succession of other species
Define Primary & Secondary succession.
P - When Eco Succc begins in virtually lifeless area with no soil (rubble from glacier or fresh volcanic lava flows) / S - Disturbance has cleared away existing community but left soil intact (fires/floods)
Define Invasive species
New species cause environmental & economic damage by colonizing/dominating wherever they find a suitable habitat.
Define Ecosystem
All Organisms in a comm + abiotic environment
Define Energy flow
passage of energy thru components of the ecosystem,
Define Chemical Cycling
Transfer of matter within the ecosystem.
Define Primary Production
Conversion of solar energy to chemical energy (as organic compounds) by
photosynthesis..
Define Gross Primary Production
Total amt of primary production during a given time period
Define Net Primary Production
amt of new organic material added to a
ecosystem in given period (The remainder)
Define Biogeochemical cycles
Chemical cycles in an ecosystem include both biotic and abiotic
Define Abiotic reservoirs
Chemicals accumulate/are stockpiled outside of living organisms
Explain Carbon Cycle
Photosynthesis removes CO₂, / incorporates into organic matter. Consumers transfer it / respiration returns it & decomposers release CO₂ / Burning fossil fuels, increase CO₂ levels faster than photosynthesis can offset.
Explain Phosphorus Cycle
Rock weathering adds phosphate to soil / Plants absorb & consumers ingest / Decomposers return phosphates to soil from waste/dead organisms / Some phos reach ocean - new rocks / Geo uplift exposes them to weathering - restarts cycle
Explain Nitrogen Cycle (part 1)
Nit-fixing bacteria convert atmospheric nitrogen (N₂) into ammonium (NH₄⁺) - plants absorb to synthesize proteins. / Some ammonium converted into nitrate (NO₃⁻), more accessible for plants / Herbivores eat plants, break down proteins to amino acids / higher consumers obtain nitrogen from prey.
Explain Nitrogen Cycle (part 2)
Excretion & decomposition return NH₄⁺ to soil. / Denitrifying bacteria, in low-oxygen conditions, convert NO₃⁻ back to N₂, release in atmosphere & deplete soil nitrogen. / Cycle maintains nitrogen balance in ecosystems.
Define Eutrophication
Standing-water ecosystems gain nutrients from decomposition & land influx, boosts primary production over time
