BIOL 2150 Ch. 45/46: Ecology

food webs and related definitions

a system of interconnected food chains - primary producers: autotrophs; plants producing organic compounds - primary consumers: heterotrophs; herbivores that consume the primary producers - secondary consumers: heterotrophs; carnivores/omnivores that consume the primary consumers - tertiary consumers: heterotrophs; organisms that eat the secondary consumers *carbon and other elements move through the producers and consumers before returning to the environment via decomposers and detritivores (worms, beetles, fungi, etc.)

competition and related definitions

an interaction in which the use of a mutually needed resource by one individual lowers the availability of the resource for another individual ex) food and space *these interactions can be intraspecific (within the same species - this could lead to speciation) or interspecific (between different species) competitive exclusion: when one species is prevented from occupying a particular habitat or niche by another species (this explains the realized niche concept) *the result of competitive exclusion over time can result in initially similar species that diverge in habitat use and feeding strategies via resource partitioning resource partitioning: the division of resources by different species living in the same habitat to help avoid competition - allows the two to coexist *predation influences competition!

correlation vs causation

correlation: indicates two events happening at the same time causation: indicates a relationship in which one event LEADS to another event *evidence of causation with carbon and burning of fossil fuels: different isotopes are present in the air depending on different activities involving carbon; the ratio expected with the burning of fossil fuels is what we are currently seeing in the air

the trophic pyramid

energy levels in each step of the web - this is NOT cyclic 4. predator (tertiary consumer) 1 kg 3. predatory (secondary consumer) 10 kg 2. herbivore (primary consumer) 100 kg 1. primary producer 1000 kg *from level 4-1, the number of organisms (represented by consumers) gets larger, but the amount of energy per organism gets smaller and smaller - only about 10% of biomass is passed from level 1 to 2 and so on *energy is lost at each step as heat and work

commensalisms

interactions between species in which one benefits and the other is unaffected - not harmed or helped

mutualisms (2 types)

interactions between species where both participants benefit 1. facultative: the interaction is beneficial but NOT necessary for survival 2. obligate: the interaction is absolutely necessary for survival of the organism

antagonisms (3 types)

one sided interactions where one organism benefits and the other does not - predator/prey relationship represents an extreme of this - parasitism: living in close association with another species, often gaining nutrition by consuming host tissues (typically without killing the host - this is why it is not predator prey) - herbivory: the consumption of plants (this is bad news for plants)

seasonal carbon fluctuations - why?

photosynthesis! - photosynthesis uses the sun to reduce CO2 to carbohydrates, removing it from the atmosphere - respiration does the reverse process and adds CO2 back to the atmosphere *this forms a cycle in the northern hemisphere, seasonal photosynthesis causes carbon levels to decrease in the summer but rates of respiration remain constant throughout the entire year

carbon reservoirs vs fluxes

reservoirs: places where carbon resides on earth (most - rocks > ground/water > atmosphere > organisms - least) fluxes: the rates at which carbon flows from one reservoir to another

CO2 sources and sinks

sources: any place that produces more carbon that it absorbs - fossil fuel burning, deforestation sinks: any place that absorbs more carbon than it produces - oceans, land, atmosphere

carbon cycle (basics)

the processes that shuttle carbon along rocks, soils, oceans, air and organisms CO2 added to atmosphere via: - respiration - volcanic activity and mid-ocean ridge activity - human activity like burning of fossil fuels and deforestation CO2 removed from atmosphere via: - PHOTOSYNTHESIS - geological removal (chemical weathering of rocks) the monitoring of CO2 in the atmosphere began around the 1950s (from before then, evidence of carbon can be seen in glacial ice cores) - there has been a 25% increase of carbon in the air in the past 50 years

niche (fundamental and realized)

the specific set of conditions in which a species can survive and successfully reproduce *the full extent of the niche is almost never used consists of: - the habitat (think address) - abiotic - the ecological role of the species (think profession) - biotic fundamental niche: the potential niche that could be occupied in the absence of specific biotic factors (i.e. competitors) realized niche: the actual amount of space that a population takes up

ecology and important related definitions

the study of the relationships between organisms and their physical surroundings - population: organisms in a single species occupying 1 geographical location - community: numerous populations living together - ecosystem: numerous communities and their physical environment - biome: large area with a similar climate (avg weather over long term)