Community Ecology Flashcards
What is community ecology
a population of different species within defined areas
species may compete with one another over limited resources
interspecific competition
affects competition is not within a species.
intraspecific competition
affects competition WITHIN a species
competitive exclusion
one species excludes another from utilizing resources or inhabiting area entirely
( invasive zebra mussels outcompeted native mussels in great lake in the 90s. recently invasive quagga mussels out competing zebra mussels)
species coexistence
species continue to live in the same area and population density remains constant
- adjust behaviors to decrease competition with competitors
What is Niche Partitioning?
divide up resources by specializing in different ways
Some birds with long beaks eat small insects and sap, others eat big insects, seeds, flowers and bark
Predation
paired cycles : increase predator population –> decreasing prey population and visa versa
(lynx and hare are classic example, essentially a ten year cycle)
Parasitism
one species exploits another, weakening but not killing it
doesn’t like to kill host because parasite needs to stay alive.
Example : TAPEWORMS. They live in geldas. Don’t watch YouTube videos on this. They are bastards.
Herbivory
some plants have evolved defenses to protect against herbivory
(Acacia trees produce thorn nests and extrafloral nectaries for ants, who protect tree from herbivorous insects)
Trophic levels
energy passes among trophic levels
1) producers: get energy directly from the sun via p/s (plants, algae) and accounts for greatest biomass in an ecosystem . only about 10-15% of energy is transferred from 1 tropic level to the nest. Nearly 90% of energy is lost at each trophic level.
2) consumers: herbivores, consumers, parasites, and other disease-causing organisms
3) detritivores: feed on wastes and decomposes dead plant and animal tissue (bacteria) , resulting n chemicals taken up by producers for growth
food webs
depict feeding relationships between species
food guilds
species at same trophic level that eat similar foods are part of a guild of competing species
Example : multiple species of guenons (monkeys) in the same forest that eat fruit and insects
Apex predators
often keystone species
eliminate them –> trophic cascade –> herbivore populations explode –> big changes to veg + possible great loss in biodiversity
ecosystem engineers
species that physically modify the environment around them
(prairie dogs in great plains - aerate the soil that grazers pack down, tunnels provide homes for other animals, channel rainwater into the water table, preventing runoff and erosion)
(beavers - build dams, streams –> ponds, create habitat for other animals, create wetlands and decrease droughts, decrease floods, decreased erosion, decrease water loss, and purify water)
disturbance
natural or anthropogenic disturbance on a community. If disturbance is severe it will lead to succession (predictable series of ecological changes over time) . if no further disturbance = climax community .
Forest = herb layer (pioneer species) then shrubs come along, then fast growing light demanding trees. Climax community
Coral reef: overfishing causes the decline in algae eating fish which creates a a domination of algae . Climate change is causing acidification and warming of the ocean which is leading to coral reef bleaching because the reefs are stressed due to so manny changes in the environment.
succession
predictable series of ecological changes over time
early stages dominated by pioneer species (forest: herb layer –> shrubs–> fast-growing light-demanding trees)
extreme disturbance
phase shift –> cannot recover
the overall character of the community is fundamentally changed
(coral reef communities= overfished –> decreased algae eating fish and turtles –> dominated by algae)
(acidification and warming of oceans –> coral bleaching–> corals expel symbiotic algae living in their tissues causing them to turn white–> may never shift back to being dominated by coral )
invasive species
non-native organisms that spread widely and become dominant in the community. Threaten community stability.
- introduced deliberately or accidentally
- growth = limiting factors (predators, disease, competitiors, etc.) are absent
- have major ecological effects (Asian chestnuts blight fungus wiped out American chestnut ) (many of CA grasslands dominated by few exotic grass species, with few native grasses and herbs left) (Eurasian zebra and quagga mussels in Great Lakes)
Macqarie Island
Most successful pest eradication program on a large island though cost $25 million. Sole breeding ground for royal penguin.
Using invasive species to control other invasive species backfired
- rats and mice jumped onto island from ships of seal hunters and ate grain stores
- cats introduced, then rabbits (food for sailors and easy prey for cats)
- Myxomatosis disease introduced to kill rabbits (6 fold decrease in rabbits in 10 years)
- with fewer rabbits to eat cats turned to native birds
- cats eradicated to save birds from 1985 to 2000. rabbit population exploded (myxo declined)
- $25 million spent to position rabbits and hunt them with dogs, by 2014 island was rabbit free and much of the vegetation damage remains
Restoration ecology
restoring altered areas to condition before industrialized civilization changed them.
Aldo Leopold is considered the founder of restoration ecology. Tallgrass prairie restoration.
Florida Everglades - began drying during the 20th century because water was diverted for flood control, irrigation, and development. This affected wading birds , and fisheries were collapsing. Led to restoration project to restore natural water flow by undoing dams and diversions.
Tallgrass prairie benefits
decreases flooding, increases species diversity, increases animal habitats, and offer people a scenic panorama of grasses and wildflowers.
Florida everglades restoration
marshes and seasonal flooded grasslands
water is diverted for flood control, irrigation, and development. The project will restore natural water flow by undoing dams, diversion, and levees. Expensive and difficult (11 billion over 35+ years)
NYC central Parks North Woods
corner of park restored to natural forest typical of Manhattan before colonization
- habitat for native insects, birds, and small mammals
- critique : too small to restore many lost ecosystem services
- response : education and inspire city dwellers.
Biome
a distinctive complex of communities found in multiple regions that are similar in plant and animal types, and vegetation structure.
depends on abiotic factors
- temperature, precipitaion, soil type, atmospheric circulation, etc. similar latitudes feature similar biomes
chaparral
small patches around the globe
- CA, Mediterranean, Chile, South Australia, South Africa
- Highly seasonal biome
- mild, wet winters
- warm, dry summers
- densely thickened, evergreen shrubs
- frequent fires
- animals: mountain lion, coyote, jackrabbit, many hummingbirds
Tundra
Alaska, Canada, Greenland, Russia, Scandinavia
- low precipitation, very cold winters, permafrost = permanently frozen soil + dead matter (melting due to climate change, releasing methane)
- low vegetation, few trees
- few animals: polar bears, musk oxen, caribou, migratory birds
Tropical Rainforest
Central and South America, C&W Africa, SE Asia
- rain and warm temperature year around
- lush vegetation = tall trees, many climbers
- closed canopy = little light filters to forest floor
- poor , acidic soils
- > 50% of earths terrestrial biodiversity on <6% of earths surface
- most mammals, birds, and invertebrates
- increased habitat loss due to logging + slash and burn agriculture
Latitudinal patterns
vegetative communities rapidly change along mountain slopes
-increase in altitude= decrease in temperature, decrease in oxygen= increase in UV
Eastern Africa 1000m = Savannah 2000m = forest 3000m= grassland 5000m = glacier
Aquatic systems are shaped by
water temperature, salinity, and dissolved nutrients, wave action, currents, depth, light levels,
Aquatic systems communities
coastlines, continental shelves, open ocean, deep sea, coral reefs, kelp forests
Sea Otters as a keystone species
sea otters feed on sea urchins, which feed on kelp
- otters abundant –> urchins rare and kelp forests well developed
- in the last 25 years, killer whales have begun eating otters
- a decrease in sea otters in North Pacific –> increase in sea urchins
- destruction of kelp forests
- a decline in fish species that inhabit them
What are two ways that interspecific competition can affect the composition of a community?
- competitive exclusion : one species excludes another from utilizing resources (zebra mussels)
- species coexistence: species continue to live in the same area and population density remains constant (birds eating bugs from different areas of tree trunk as an example)
Keystone species
Has disproportionate impact on community - holds community together
Apex predators are often keystone species - top of the food web
Tropic cascade - eliminating apex predators leads to ecosystem collapse issues.
Evidence of figs as a keystone species?
Figs feed many mammals (apes) and birds (toucans) in the rainforest year around since they produce fruit year around
Small scale restoration ecology
Can improve life in urban areas by bringing back drinking water, increasing tourism, and making people happy by giving them a natural place to be outside and explore.
Why do similar latitudes feature similar biomes?
Because of abiotic factors that are the same at that latitude (temp, precipitation, soil type, atmospheric circulation)
Ex: chaparral in CA and Mediterranean Sea : same latitudinal line - mild wet winters and dry summers, densely thickened , evergreen shrubs, frequent fires, mountain lion/coyotes
Compare and contrast abiotic and biotic characteristics of any two biomes of your choice
Tundra- low precp and cold winters - permafrost (permanently frozen soil and dead matter) because summers get to 50 F - few animals (polar bears, moose, caribou) , low vegetation and free trees
Rainforest - high precipitation , lots of animals and vegetation,
