quiz #8 1.draw the idh curve. when and why is species diversity highest according to idh? 2.explain...
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QUIZ #8
1. Draw the IDH curve. When and why is species diversity highest according to IDH?
2. Explain how anthropogenic disturbance can be either beneficial or detrimental.
3. How can wetlands function as a transitional community (zone) between open lakes and upland terrestrial forest habitats?
4. What is the difference between (or define, up to you) allogenic and autogenic succession.
5. Give an example of both primary and secondary succession.
Forces leading to adaptation
1. Anoxia: lack of oxygen
2. Salinity: fluctuating or high salinity
3. Soil toxins: sulfide, methane, etc.
4. Nutrient stress: low nitrogen or phosphorus
availability
5. Submergence: anchorage, locomotion, change in C
source, wave energy, light
6. Herbivory/Predation
Responses to anoxia at different levels of complexity
Bacteria• alternative respiratory pathways• utilize energy in reduced compounds (e.g. NH4
+, CH4, S-)
Plants• arenchymous tissue (ethylene production), lenticels, adventitious roots, stem elongation, shallow rooting, hypertrophy, carbohydrate storage structures• pressurized gas flow, radial oxygen loss• Alcohol dehydrogenase(ADH) accumulation
Animals• specialized respiratory structures (gills, parapodia, etc.)• pigments• various other physiological and behavioral modifications
Responses salt stress atdifferent levels of complexity
Bacteria• accumulation of “non-lethal” ions (e.g. K+ relative to Na+)• compatible (organic) solutes
Plants• salt exclusion• salt excretion• storage in vacuoles or senescent tissues• C4 instead of C3 photosynthetic pathway
Animals• osmoregulate• osmoconform
Mangrove Adaptations
waxy leaves andviviparous seedlings
lenticelsspecialized root
structures
salt exclusion vs. salt excretion
low tide
High tide
Spatial Gradients
decreasing soil redox
increasing soil salinity, and sulfide concentrations
Definitions
tolerator (conformer): an organism that has functional modifications allowing it to survive and often function in the presence of stress.
regulator: organisms that actively avoid stress or modify it to minimize its effects (e.g. thermoregulator, osmoregulator, etc.)
Quiz # 8
1. Why is nitrogen fixation inhibited by aerobic conditions?
2. Describe one way in which bacteria deal with anoxia.
3. Describe a mechanism that allows hydrophytes to deal with salinity stress.
4. What is the source of inorganic carbon for plants photosynthesizing under water (i.e., SAV)?
5. What microbial process gives rise to reduced inorganic nitrogen?