Resource acquisition by societies part 3 Flashcards
How do we evaluate the diversity and patterns of resource acquisition and its consequences?
- Defining what species eat.
- Establishing how much species eat.
- Direct and indirect ecological impacts of what species eat.
defining what species eat - define trophic level
Different points on the feeding chain of consumer-resource feeding relationships
defining what species eat - define primary producers
The plants and other autotrophs (self-feeding, photosynthetic organisms) that form the base of the feeding chain.
defining what species eat - define primary consumers
Consumers of primary producers - herbivores
defining what species eat - define secondary consumers
Consumers of primary consumers - carnivores
defining what species eat - define top predator
- A predator residing at the top of a food chain, upon which no other species preys
- trophic role dominated by societies.
social primary consumer examples
- Leaf-cutter ants
- Many mammal societies (like the mole rats)
social top predators examples
- wolves
- social cats (cheetah, lion)
How do we determine trophic level?
- direct observations
- waste products
- tissue in organisms
- stable isotope analysis
how do we determine trophic level? - direct observations
For simple trophic levels, direct observations can be useful but are often misleading.
how do we determine trophic level? - waste products
can look at waste products (feces, etc.), but this is only a “snapshot”
how do we determine trophic level? - tissue in organisms
Foods leave detectable traces in the tissues of the organisms that feed on them.
how do we determine trophic levels? - stable isotope analysis
Stable isotope analysis is a powerful tool for studying trophic levels of organisms
stable isotope analysis - ratio of different isotopes can tell us what?
The ratio of a different isotopes in the tissues of an organism can therefore tell us at which trophic level they have been feeding
stable isotope analysis - nitrogen and carbon ratios
- Nitrogen (15N vs. 14N) and carbon (13C vs. 12C) ratios are particularly informative
- heavier isotopes (extra neutron) are known to increase predictably with increasing trophic level.
stable isotope analysis in ants
- lower ratio = herbivory
- higher ratio = predation/scavenging
Examples of complexities in trophic interactions that stable isotopes can address
- Variability in diet of species within a species
- Geographical variations
- Contrasts between recovering and mature habitat.
- Contrasts across urban and natural environments
Examples of complexities in trophic interactions that stable isotopes can address - variability in diet of species
stable isotopes can address differentiating trophic differences in cryptic feeders.
Examples of complexities in trophic interactions that stable isotopes can address - geographical variation
stable isotopes can link the differences in diet to patterns of environmental shifts.
Stable isotope example
Variation in diet across habitats in Chimpanzees
stable isotope example - variation in diet across habitats in Chimpanzees
- Stable isotopes reveal substantial differences in diet across sites
- explained by complex interactions between habitat, and access to different ratios of food types.
establishing how much species eat - what is the only way to determine precise biomass consumption
Direct measurements of feeding are the only way to determine precise biomass consumption.
establishing how much species eat - what is the focus typically on?
the focus is on feeding rates within some logistically feasible observation window
establishing how much species eat - Rate data can then be combined with other data types to calculate total biomass consumption. e.g. using:
- Daily foraging period.
- Annual activity pattern.
- Size of society.
- Size of population.
