Community Ecology

Question 1

What is community ecology

Answer 1

a population of different species within defined areas

species may compete with one another over limited resources

Question 2

interspecific competition

Answer 2

affects competition is not within a species.

Question 3

intraspecific competition

Answer 3

affects competition WITHIN a species

Question 4

competitive exclusion

Answer 4

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)

Question 5

species coexistence

Answer 5

species continue to live in the same area and population density remains constant

• adjust behaviors to decrease competition with competitors

Question 6

What is Niche Partitioning?

Answer 6

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

Question 7

Predation

Answer 7

paired cycles : increase predator population –> decreasing prey population and visa versa

(lynx and hare are classic example, essentially a ten year cycle)

Question 8

Parasitism

Answer 8

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.

Question 9

Herbivory

Answer 9

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)

Question 10

Trophic levels

Answer 10

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

Question 11

food webs

Answer 11

depict feeding relationships between species

Question 12

food guilds

Answer 12

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

Question 13

Apex predators

Answer 13

often keystone species

eliminate them –> trophic cascade –> herbivore populations explode –> big changes to veg + possible great loss in biodiversity

Question 14

ecosystem engineers

Answer 14

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)

Question 15

disturbance

Answer 15

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.

Question 16

succession

Answer 16

predictable series of ecological changes over time

early stages dominated by pioneer species (forest: herb layer –> shrubs–> fast-growing light-demanding trees)

Question 17

extreme disturbance

Answer 17

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 )

Question 18

invasive species

Answer 18

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)

Question 19

Macqarie Island

Answer 19

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

Question 20

Restoration ecology

Answer 20

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.

Question 21

Tallgrass prairie benefits

Answer 21

decreases flooding, increases species diversity, increases animal habitats, and offer people a scenic panorama of grasses and wildflowers.

Question 22

Florida everglades restoration

Answer 22

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)

Question 23

NYC central Parks North Woods

Answer 23

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.

Question 24

Biome

Answer 24

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

Question 25

chaparral

Answer 25

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

Question 26

Tundra

Answer 26

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

Question 27

Tropical Rainforest

Answer 27

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

Question 28

Latitudinal patterns

Answer 28

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

Question 29

Aquatic systems are shaped by

Answer 29

water temperature, salinity, and dissolved nutrients, wave action, currents, depth, light levels,

Question 30

Aquatic systems communities

Answer 30

coastlines, continental shelves, open ocean, deep sea, coral reefs, kelp forests

Question 31

Sea Otters as a keystone species

Answer 31

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

Question 32

What are two ways that interspecific competition can affect the composition of a community?

Answer 32

• 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)

Question 33

Keystone species

Answer 33

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.

Question 34

Evidence of figs as a keystone species?

Answer 34

Figs feed many mammals (apes) and birds (toucans) in the rainforest year around since they produce fruit year around

Question 35

Small scale restoration ecology

Answer 35

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.

Question 36

Why do similar latitudes feature similar biomes?

Answer 36

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

Question 37

Compare and contrast abiotic and biotic characteristics of any two biomes of your choice

Answer 37

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,