Ecology: Chapter 4 Flashcards
Biotic Factors
- the biological influences on organisms within an ecosystem
- includes all of the living things that an organism may interact with: the ecological community
- example: food; parasites; competitors for food/space/mates
Abiotic Factors
- the physical or nonliving factors that shape an ecosystem
- example: pH, soil, terrain, H2O, oxygen, CO2, temperature/weather/climate, minerals (N,P,K), salinity
The Niche
- the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions
- the role the organism plays in the environment
Fundamental Niche
the total niche that an organism could potentially use within an ecosystem
Realized Niche
the part of a fundamental niche that an organism actually occupies as a result of competition
The Competitive Exclusion Principle
no two species can share/occupy the same niche in the same habitat at the same time; however, different species can occupy niches that are very similar
Resource Sharing
- phenomenon characterized by different species of a community dividing similar resources instead of competing for them
- different niches will be occupied; feeding may occur at different times or in different areas
Keystone Species
single species that are not actually abundant in a community, yet exerts strong control
Competition
- occurs when organisms of the same or different species attempt to use an ecological resource at the same place at the same time
- example: food, water, shelter, mates
Predation
- interaction in which on organism captures and feeds on another organism
- example: amoeba –> paramecium –> jumping spider –> captured moth
Symbiosis
- an intimate relationship in which 2 species live closely together
- an excellent example of coevolution
Mutualism
- both species benefit from the relationship; in many cases neither one could survive without the other
- example: a) lichens: fungal component absorbs minerals and algal component produces food
Commensalism
- one member benefits and the other is neither helped nor harmed
- example: a) epiphytes: (orchid) plants that grow on some trees
Parasitism
-one organism lives in or on another organism and harms it
Ecological Succession
- the regular progression of species replacement in a developing ecosystem
- the gradual change in the structure of a community over time
Primary Succession
takes place on land where no soil and no vegetation exists
-example: on the surface formed as volcanic eruptions build new islands; on the dunes of a beach
Pioneer Organisms
- early settlers specialized for life in harsh conditions, such as bare rock
- example: lichens and mosses
Secondary Succession
- the return of an area to its original condition after it has been disturbed; takes place on land where soil is already in place
- example: abandoned fields or forest clearings after major fires
Climax Community
- a community of organisms that will remain stable in an area as long as the area is undisturbed
- a community that has reached the end of succession
Biome
a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals
Tropical Rainforest
most biodiverse; nutrient poor; thin topsoil; fragile
Epiphytes
- plant that non parasitically grows upon another plant or object
- since the soil is thin and nutrient poor, if destroyed rainforest plants will not grow well
Savannas
tropical grasslands; seasonal rainfall; scattered trees (low density); warm; found in East Africa; South Brazil; India; North Australia
Deserts
all with <25 cm annual rainfall and variable temperatures; plants and animals can tolerate arid conditions
-example: insects, lizards and other reptiles, birds, cacti
Xerophytes
plants that have adapted to and tolerate dey and arid conditions
Temperate Grasslands
much of Midwestern US; seasonal changes in temperature; fertile soil; Pampas of South America; Steppes of Russia
Temperate Woodland
example: Chaparral where we live; life forms similar to desert
Temperate Deciduous Forest
most trees are deciduous
deciduous = looses their leaves in the fall
Taiga (Boreal Forest)
dominated by evergreen conifers; none in the Southern Hemisphere
Tundra
not much precipitation; permafrost; low growing plants and lichens
First Two Links in Aquatic Food Webs
phyoplankton and zooplankton
Aphotic Zone
permanently dark region below the photic zone; the onnly producers are chemosynthetic autotrophs
Photic Zone
well lit upper layer (up to about 200m/600ft); photosynthetic producers cannot grow below this zone
Benthos
bottom dweller
Nekton
actively swimming aquatic organism in a lake or ocean
Interdial or Littoral Zone
underwater during high tide; exposed to air/sunlight/temperature changes during low tide (the organisms that live here have adapted tothe changes)
Freshwater Ecosystems
- lakes and ponds
- rivers
- wetlands (swamps = trees present; marshes = no trees present)
Coastal Ocean or Neritic Zone
- extends from low tide mark to the outer edge of the continental shelf (the relatively shallow border, up to 200 m, that surrounds the continents)
- mainly in the photic zone, thus rich in plankton and many other organisms
Open Ocean (Oceanic/Pelagic Zone)
- begins at the edge of the continental shelf and extends outward
- largest marine zone: depth from 500m-11,000m
Benthic Zone
- the ocean floor from coastal ocean through open ocean
- organisms living here are collectively referred to as benthos
- example: sea stars, anemones, marine worms, crabs, flounder, etc.
