37.8-37.12 Flashcards
Define “Trophic Structure”
A Trophic Structure is a pattern of feeding relationships on several different levels.
Define “food chain”
The process of going up the Trophic Structure.
What organism is at the bottom of the food chain?
producers/autotrophs/photosynthesizers. Marine: phytoplankton, terrestrial: plants. Hydrothermal vents: chemosynthetic prokaryotes. (??)
What is the first level of the food chain/trophic structure called?
Primary consumers/herbivores. Directly dependent on producers. Terrestrial: grasshoppers, insects, snails, grazing animals, birds. Aquatic: zooplankton
What are the higher levels of a food chain?
primary, secondary, tertiary and quaternary consumers. They each eat the lower one.
What are examples of secondary consumers?
terrestrial: mice, birds, frogs, spiders. However, lions that eat grazers can be here too! Aquatic: small fishes that eat zooplankton
What are examples of tertiary consumers?
Terrestrial: snakes. Aquatic: tuna Most ecosystems have secondary and tertiary consumers.
What are example of quaternary consumers?
Terrestrial: Hawk Aquatic: Killer whale. Not super common.
Where can you find animals that derive their energy from detritus?
all trophic levels: they all produce waste.
What is detritus, and what are some examples?
animal wastes, plant litter, body of dead organisms.
What are scavengers?
Crows and vultures: eat carcasses that are usually fresher.
What are examples of detritivores, and what do they eat?
Millipedes, earthworms. They usually eat detritus that has been decomposing for longer.
What are the role of decomposers in the Trophic levels?
They connect the Trophic levels. As they convert detritus to inorganic materials which plants and phytoplankton can use, they convert it into a cycle.
If you eat pizza, what trophic level are you on?
Primary.
In 37.8, the Trophic structure is described as linear. What is a more accurate description of a trophic structure?
A food web.
Can you be more than more than one level of consumer?
Yes. See example in 37.9.
What is species diversity defined by?
Singular species abundance and species richness (diversity)
If a certain species is dependent on a certain tree, what would happen in an environment that has high species diversity/richness and abundance that is not that tree?
They would struggle significantly if the woods where they lived had the tree that they needed, but was dominated by a different tree. This would also send waves throughout the food web.
How do species diversity and pathogens intersect?
More rich species in environment have less of a consequence because of pathogens, as pathogens often can only affect certain hosts.
What is monoculture?
Low species diversity. A characteristic of modern agriculture; fields with only one singular specie. Plants are often bred to have desirable traits; there is little genetic diversity within the singular species. They are especially prone to attacks by pathogens. Caused the Irish potato famine!
What was the solution to the pathogens and monoculture issue?
Chemical methods; however they became genetically resistant and continued to infect. This situation caused the Corn Leaf Blight.
What are farmers and scientists exploring to replace monoculture?
Polyculture.
Would you expect a well-maintained or a poorly-maintained lawn to have more species diversity?
A poorly-maintained lawn would have higher species diversity. Well-maintained would have weeds plucked away, etc.
What causes species diversity to vary among different communities? (37.11)
The ability of predators to prevent any one species from monopolizing resources. This interspecific interaction determines species diversity. See Paine Experiment.
What is the name for the predator that stops the monopolization and decrease in species diversity?
A keystone species.
Removing saguaro cacti from the Sonoran desert community would have a drastic impact, and yet saguaro is not considered a keystone species. Why?
Saguaro is abundant, but its effect is not disproportionate to its biomass or abundance. Keystone species have a large effect relative to their representation in the community just as a keystone is a small but vital piece of the arch.
In ecosystems, what are disturbances?
storms, fires, floods, droughts or human activities that damage biological communities and alter the availability of sources. Severity and frequency varies.
Can disturbances be positive?
Yes, small-scale one can create new communities.
What is ecological succession?
After a major disturbance, how the new ecosystem grows back, often colonized by new species.
What is primary succession?
Ecosystems that start from something that is virtually lifeless. No soil, like the melting of a glacier. Usually starts with autotrophic bacteria, then lichen, then plants, then animals. Can take thousands of years.
What is secondary succession?
Where there is soil intact, but its resources are depleted, from forest clearing, etc.
what species are the most successful in secondary succession.
Those with low survivorship curves.
In early stages of (secondary?) succession, what species dominates?
Weeds. Not much interspecific competition in the early years, however.
Define perennial
enduring, continually recurring
What happens in succession from 5-15 years.
It becomes a pine forest.
Post-15 years, what trees begin to replace pines?
As pines need much sun to grow, and seedlings to do not receive it when the canopy becomes denser. Deciduous trees, such as maple and oak, which can survive better in shade, replace.
How is the new ecosystem after succession finally determined?
it depends on geography and topography, climate. What is settles as determines the consumers in the area.
