Chapter37 Communities and Eco systems Flashcards
What is a community?
Collection of populations living close enough to each other for potential interactions
Why is community ecology important?
- Conservation and management of game, wildlife and fisheries
- Conservation of endangered species
- Helps control diseases such as malaria and flu
- Applications in agriculture
What are interspecific interactions?
Relationships with individuals of other species in the community.
How can one classify interspecific interactions?
Harmful to the population (denoted by - sign) or helpful or favorable to a population (denoted by + sign)
What are the interspecific interactions among species?
- Interspecific competition
- Mutualism
- Predation
- Herbivory
- Parasites and pathogens
What is interspecific competition?
Populations of two species compete for a scarce resource.
E.g: Squirrels and Bears compete for acorns
What is mutualism?
An interspecific interaction where both species benefit from it.
E.g: Herbivores and Cellulose digesting microbes
Digesting food for the herbivore +
Food to produce energy for the microbe +
What is predation?
One species kills the other species and eats it
What is herbivory?
Consumption of plant parts and algae by herbivores
What is the effect of interspecific interactions on species?
Interspecific competition Species 1 (-) Species 2(-)
Mutualism Species 1(+) Species 2(+)
Predation Predator (+) Prey (-)
Herbivory Herbivore (+) Plants/Algae (-)
Parasites/Pathogens Parasite/Pathogen (+) Host(-)
What is an ecological niche?
Sum of the use or consumption of abiotic and biotic factors by a species in an environment.
E.g: Nesting sites and material of a bird species
Food it eats and amount of water it consumes
How does interspecific competition occur?
When ecological niches of species intersect
What are examples of interspecific competiton?
- Desert plants compete for water
- Plants in rain forests compete for light
- Bears and squirrels compete for acorns
What will have more severe effects on a popuation? Inter specific competition or intra specific competition?
Intra specific competition because the same species has the same biological niche and therefore the resources may be consumed sooner
Give examples of mutualism?
- Corals and Dinoflagellates
a. Dinoflagellates live inside the crevices(cells) of the corals and gets security and shelter that provide access to light
b. Dinoflagellates produce sugars by photosynthesis that is used by the corals to produce energy
c, Dinoflagellates consumes corals waste materials
What are the evolutionary adaptations of prey to avoid being killed?
- Camouflage
- Mechanical defenses such as quills and hard shells
- Chemical defenses such as secretion of pungent or poisonous chemicals
Explain how predation helps adaptive evolution?
Surviving prey will pass on the allels that will result in offspring inheriting the characteristics that can successfully defend against the predator
What is coevolution?
Change in one species acts as a new selection force to another species in turn would would affect the selection of individuals in the first species
What are plants defense against herbivory?
- Thorns and spines
2. Chemical defenses such as pungent odor or bad taste or poisonous substances
Why do we have bitter tasting receptors ?
Individuals having bitter tasting receptors has a higher chance of detecting harmful or poisonous food and hence has a better chance of survival.
What is a parasite?
An organism relying on a host (the other organism) in a way harmful to the other organism without killing it.
What are the types of parasites?
- Internal parasites: Nematodes, tapeworms
2. External parasites: Mosquitoes, ticks and aphids
What is a trophic structure?
A pattern of feeding relationship in a community at several different levels
What is a food chain?
Sequence of food transfers up the different trophic levels
What is transferred up the food chain?
Chemical nutrients and energy from producers
What are the trophic levels?
- Producers - Autotrophs
- Consumers - Heterotrophs
a. Primary consumers - Herbivores
b. Secondary consumers - Eats herbivores
c. Tertiary consumers - Eats secondary consumers
d. Quaternary consumers - Eats tertiary consumers - Decomposers
Which way does the arrows point in the food chain?
Producer -> Consumer
What are producers?
Produces are autotrophs that produce their food either by photosynthesis or other chemical processes.
Give examples of produces?
Plants, Algae
What are primary consumers?
Organisms that rely only on producers (plants) for food
What are secondary consumers?
Organisms that eat primary consumers
What are detritus?
The dead material produced at all trophic levels
What are examples of some detritus?
Animal waste, plant litter and bodies of dead organisms
What is decomposition?
Breaking down of organic materials to inorganic ones
What are the ways detritus is consumed by organisms?
- Scavengers eat dead animals: E.g Vultures
- Detrivores consume decaying organic matrials: E.g Earth worms, millipedes
- Decomposes secretes enzymes that breaks down dead organic material: E,g: Fungi, Prokaroyotes
What are food webs?
A network of interconnected food chains
What are biochemical cycles?
A process by which chemical substances moves through both biotic(bioshpere) and abiotic(atmosphere, lithosphere (outer part of earth), and hydroshphere) components on earth
What provides energy to the eco systems?
Sun and the inner core of the earth
What are abiotic reservoirs?
Places where chemicals are accumulated or stockpiled outside of the living organisms (note the word living!)
What is the abiotic reservoir for carbon?
Atmosphere
What is the abiotic reservoir for phosphorous?
Soil
What is the abiotic reservoir for Nitrogen?
Atmosphere as well as soil
What is the general flow of a biochemical cycle?
- Producers incorporate chemicals from the abiotic reservoirs to organic compounds
- Consumers feed on the producers incorporating the chemicals to their own bodies
- Both producers and consumers release some of the chemicals to the abiotic reservoir as waste products.
E.g: Carbon is released to the environment as CO2 - Decomposers breaks down the detritus and releases its chemicals back to the reservoir
What are the Carbon reservoirs?
- Atmosphere with CO2
- Fossil fuels and sedimentary rocks
- CO2 Dissolved in the ocean
What are the steps of the carbon cycle?
- Photosynthesis removes CO2 from the atmosphere and incorporate in to organic matter
- The plan matter passes along the food chain and organisms replenishes the CO2 in the atmosphere by respiration
- Decomposers breaks down detritus and releases the carbon as CO2
How can burning of fossil fuels disturb the CO2 balance?
Usually the amount of CO2 removed from the atmosphere by photosynthesis is roughly equal to the amount replenished by respiration. When fossil fuels are burnt more CO2 is produced than what is taken in as photosynthesis
Why do organisms need phosphorous?
- Nucleic acid (DNA)
- ATP
- Phospolipid bylayer
What are the steps in the phosphorous cycle?
- Weathering breaks down rocks and adds the phosphorus in the rocks to the soil
- Plants absorbs the phosphorous dissolved in soil and incorporate it to organic matter
- Consumers ontain phosphorous from plants
- Decomposers releases the phosphorous in animal and plant body to the soil
- Some phosphates drain from terrestrial eco system to sea where it settles and later turns out to be rocks
- Geological processes lifts the rocks up
Why is phosphorous scarce in the environment?
It gets washed off to sea and takes a long time to get converted as rocks as geological processes can take million of years. Soil quickly absorbs phosphorous making in inaccessible for plants
Why do organisms need Nitrogen?
N is an ingredient of proteins and Nucleic acid
What is Nitrogen fixation?
Conversion of atmospheric N to compounds that can be absorbed by plants
How do plants obtain N?
Some bacteria that lives in the soil carries out Nitrogen fixation
What are the steps in the Nirogen cycle?
- Some bacteria that lives in the roots of the plants does Nitorgen fixation.
- Bacteria living in soil and water converts atmospheric N to compounds that plants can absorb
- Plants consume N
- Detritus is decomposed by organisms to give N back to soil
What type of plants have nitorgen fixing bacteria in their roots?
Legumes such as Soybeans, peanuts and alpha-alpha
