Exam 5 Flashcards
Food chains
A linear sequence of organisms through which nutrients and energy pass.
Each organism occupies a trophic level.
Primary Producer»_space; Primary Consumer»_space; Secondary Consumer»_space; Tertiary (Apex) Consumer
Primary producer
the bottom of the food chain, usually photosynthetic organisms (plants and/or phytoplankton)
Primary consumer
consumes the primary producer.
Secondary consumers
usually carnivores that eat the primary consumers
Apex consumer
the highest-level consumer in the ecosystem
food web
a graphic representation of a holistic, nonlinear web of primary producers, primary consumers, and higher-level consumers used to describe ecosystem structure and dynamics
Photoautotrophs
plants, algae, and photosynthetic bacteria, serve as the energy source for a majority of the world’s ecosystems
Chemoautotrophs
These organisms synthesize complex organic molecules, such as glucose, for their own energy; usually they do this without sunlight and rather use other sources of energy. (Uncommon)
Heterotrophs
These organisms acquire energy from digesting living or previously living organisms
Abiotic features of an ecosystem
Energy flows, Water and nutrients cycle
Energy flows
This phrase implies that energy is not recycled in an ecosystem
Source of energy is (usually) the Sun, in the form of sunlight
Some energy is lost from the ecosystem as heat at each trophic level
Note that each trophic level also leads to detritus/detritivores
Water and nutrients cycle
This phrase implies that such chemicals are recycled in an ecosystem
Such chemicals may enter from other ecosystems, and exit to other ecosystems
Three factors for productivity within trophic levels
Gross primary productivity (GPP)
Net primary productivity(NPP)
Biomass
Gross primary productivity (GPP)
the rate at which photosynthetic primary producers incorporate energy from the sun
Net primary productivity(NPP)
the energy that remains in the primary producers after accounting for the organisms’ respiration and heat loss. The net productivity is available to the primary consumers at the next trophic level—as biomass
Biomass
the total mass, in a unit area at the time of measurement, of living or previously living organisms within a trophic level
Detritivores and decomposers
Bacteria and fungi are most prolific
Any organism that feeds on detritus (dead organic matter) is a detritivore
One influence of environment on NPP
Climate factors
Only about 10% of NPP energy becomes biomass in primary consumers—why so inefficient?
Primary consumers do not eat ALL primary producer biomass (some NPP is “left on the shelf”)
Not all NPP consumed is assimilated—what happens to energy not assimilated?
Of assimilated energy, some is used to maintain metabolic functions (respiration) and is lost as heat
Remaining energy is allocated to growth and reproduction—referred to as secondary production
Ecological efficiency between trophic levels
The measurement of energy transfer efficiency between two successive trophic levels is termed thetrophic level transfer efficiency (TLTE)and is defined by the formula:
production at present trophic level / production at previous trophic level * 100
Expressed as percent
Why isn’t energy transfer between trophic levels entirely efficient? Briefly describe some of the reasons why energy obtained by herbivores does not get passed on to the predators. What happens to energy that is not transferred from herbivores to their predators?
What compartments may carbon occur in?
Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized. Volcanic activity and, more recently, human emissions, bring this stored carbon back into the carbon cycle.
What forms may carbon take in those compartments?
Carbon dioxide gas exists in the atmosphere and is dissolved in water.
What role does photosynthesis play in the carbon cycle? What about cellular respiration?
converts carbon dioxide gas to organic carbon, and respiration cycles the organic carbon back into carbon dioxide gas
atmospheric form of nitrogen is N2 gas
unavailable to almost all forms of life, except certain nitrogen-fixing bacteria
Nitrogen fixation
causes nitrogen to leave the atmosphere and enter other compartments, such as water or soil.
Nitrogen forms are available to primary producers
ammonium or nitrate in soil and water
what is an example of organic nitrogen?
Amino acids
nutrient limitation
In practically all natural ecosystems, one nutrient required by life will be most scarce
3 types of biological diversity
Genetic diversity
Species diversity
Community/ecosystem diversity
Genetic diversity
Usually refers to allelic diversity; could also refer to genotypic diversity
Attention paid to number of alleles in a gene pool, or relative frequencies of rare and common alleles
May be indirectly estimated through examination of chemical (protein) diversity
What level of ecology is genetic diversity most relevant to?
Species diversity
May consider species richness and/or relative abundance of species
Labels such as ‘threatened species’ and ‘endangered species’ may be used
What level of ecology is species diversity most relevant to?
Community/ecosystem diversity
Refers to diversity of (healthy) habitats upon the landscape
Probably most overlooked type of diversity, but has potential to influence other types of diversity described above
Species richness
refers to the total number of species that belong to a community
Relative abundance
refers to the frequency of each species in a community
Adaptive radiation
Rapid divergence of an ancestral lineage in response to new habitat availability
Regarded as a pattern of macroevolution associated most closely with the process of speciation
New habitat may become available for different reasons
Mass extinction
A period of history in which elevated extinction rate occurs, compared to the background rate
Regarded as a pattern of macroevolution associated most closely with the process of extinction
There are five mass extinctions known from Earth’s geologic record (see next slide)
Explain why extinction may be regarded as a process of evolution, but mass extinction is a pattern.
Threats to biological diversity
Habitat loss
Overharvesting
Exotic/ invasive species
Global change/climate change
Habitat loss
When humans occupy and develop land for their own uses, the habitat that was previously present probably suffers disruption of some kind
Species-Area relationship
Studies have shown that the number of species present increases with the size of the habitat
Habitat conservation concerns
Impacted habitats may be regarded as fragments
The ratio of edge to interior space increases when a habitat becomes fragmented
This means the habitat is more likely to be influenced by conditions outside of the habitat—edge effects
Overharvesting
Implies harvesting at an unsustainable rate
What wild species do humans rely upon for food or other products?
Invasive Species
Exotic species are those introduced into a new habitat from somewhere else
Potential for invasiveness is high in such introductions
Why are invasive species most likely also exotic, or introduced, species?
Global change
Refers to disruption of some feature of climate, biogeochemical cycle, or other chemical constitution of the biosphere
Global change can take many forms
Nutrient pollution
By-product of industrial agriculture
May be toxic in high concentration (but this is not the main concern)
Nutrient enrichment of aquatic habitats may lead to the following:
- Prolific growth of micro-organisms/algae that rapidly absorb dissolved oxygen
- Anoxic (oxygen-depleted) conditions unable to support multicellular life
- As a result, ‘dead zones’ may occur (see next slide—heat map indicates intensity of nutrient enrichment/dead zone on the Gulf Coast of North America)
Biodiversity and politics
Governing bodies recognize conservation databases intended to prioritize conservation efforts
Global change is one category of threats to biological diversity; in practice, it can refer to a variety of threats including:
Pollutants like:
Acids
Chemical nutrients (nitrogen, potassium, phosphorus, etc.)
Chemical toxins (PCBs, dioxin, mercury, etc.)
Ozone
Ozone-depleting chemicals
Carbon
Three areas of Global climate change study:
current and past global climate change
causes of past and present-day global climate change
ancient and current results of climate change
greenhouse gases and greenhouse effect
an important feature of Earthly conditions that makes life possible—causes radiant heat to be trapped in the atmosphere, rather than dissipate into space
While Mars cannot support life because it lacks a greenhouse effect, Venus has an enriched atmosphere that causes extreme greenhouse effect which is detrimental to life
Historical climate change
Ice cores contain air bubbles and biological substances that provide important information for researchers.
Contemporary climate change
While greenhouse gas concentrations may fluctuate due to natural processes, their concentrations have steadily increased since industrialization of global human population began
As atmospheric concentration of CO2 has increased, a correlative increase in atmospheric temperature has also occurred
Glacial retreat
The effect of global warming can be seen in the continuing retreat of Grinnel Glacier. The mean annual temperature in the park has increased 1.33 °C since 1900. The loss of a glacier results in the loss of summer meltwaters, sharply reducing seasonal water supplies and severely affecting local ecosystems
Compare and contrast historical climate change with contemporary climate change. How are they similar? How are they different? What role do humans play in each?
Environmental toxicology
Refers to the study of movement and fate of toxins in environmental compartments
POPs
Persistent organic pollutants’ and other toxins that exhibit biological persistence (such as mercury)
persistent toxin enters the body of an organism and stays (is not metabolized)
Biological accumulation
refers to the tendency of POP concentrations to increase in individuals as they age
Biological magnification
refers to the tendency of POP concentrations to increase greatly in each successive trophic level
Intrinsic value
refers to the value something has just for existing
Instrumental value
refers to the value something has, based on its functionality (to humans)
Ambiguous cases involving ecosystem services
Ecosystem services are services provided by an organism that contribute to the health and function of the natural habitat it occupies
Ecosystem services may be assigned instrumental value by some authors, but not by others
Suppose a friend tells you, “It no longer matters if species go extinct, as long as we are able to sequence the genome of each species before it goes extinct.” Carefully explain why an ecologist would regard this argument as problematic and potentially dangerous.
