Chapter 15: unusual or extreme habitats

What is Shelfords Law of tolerance

Optimal range in which fitness is greatest, as conditions devote from the optimum, fitness declines and beyond some limit the organism cannot survive and reproduce.

Why are microorganisms in extreme environment?

Because multicellular organisms generally too complex to inhabit extreme environments. Usually bacterium spealized to environment

How does temperature effect metabolic functions?

Thermotolerant enzymes have hydrophobic cores, reduced glycine content, more alpha helical conformation, high ionic interactions, reduced surface are to volume ratio, more stabilized bonds (hydrogen bonds and salt bridges), and numerous related adaptations.

•For high temperatures, lipids maintain integrity by having a greater proportion of single hydrogen bonds (saturation), increased branching, greater length and in the Archaea, ether lipids.  At low temperatures, the opposite are true.

DNA and RNA in organisms at higher temperature may have any of what?

•Higher concentrations of C & G’s

•Increased cation concentrations

•Specialized proteins

•Greater rates of DNA repair and RNA turnover

•RNA can have modified nucleotides that stabilize in high temperatures.

•mRNA and rRNA have extended regions of base pairing (A-U and C-G) to stabilize secondary and tertiary structures.

What is Diapause?

Resting stage( stops metabolism until temp goes up). Often occur during life stages of reduced biological activity, such as a egg, pupae, or cyst and can survive droughts and high temperatures

How does excessive sanity cause the water to become limiting?

t moderate levels, organisms excrete excess salts to minimize the effect.

•Only organisms that are able to tolerate high intracellular concentrations above 10% salinity can survive in high salinity environments.

•Hypersaline microbes have multiple sets of genes coding for sodium and potassium transport.

•High levels of glycerol can counteract the effects of increased salinity.

•High amounts of negatively charged amino acids on the external surface of the cell membrane can help as well.

Characteristics of Saline Lakes?

Equal amounts of water in these lakes then freshwater.

Include Great Salt Lake, Dead Sea, Caspian Sea, Aral Sea and lake ballash

Many are intermittent (usually dry up, shallow)

Concentrations 10x more in excess of the ocean

Salt Columns (Tufa Columns)

What does the statement as salinity increases diversity decreases mean?

Many organisms can not live in such salty conditions and due to the low 02 the ones that can withstand these conditions is Bacteria and Archae, Artemia (survive over 10% salt

What are Hot springs and the characteristics?

Springs associated with geothermal activity (super hot and low pH)

Low Bitotic diveristy

Can range from highly acidic (low pH) to a basic (pH 11)

Dominated by sulfates or Carbonates or silicates

What are the cold habitat characteristics?

ice, snow or polar lakes

two different groups inhabit these areas: Those found in moderate habitats and those that require cold temperatures (psychroaphilie)

Same cycles of temperate

Simple communities with no fish or invertebrates

-may have fish or microphutes if they don’t freeze to the bottom.

Characteristics of Temporary water and small ponds?

most extreme disturbance that occurs in a aquatic system

Colonization of temporary or ephemeral habitats occur fast

Most lack fishes and range form the water to pitcher plant to large prairie pothotholes

Characteristics of Hypereutroohics? (highly productive areas )

Areas with excess nutrients and are highly productive

Dominated by few species

Dominated by a few microbial species can sustain constant growth and reposition

(Human sewage ponds)

May have oxygen supersaturated during the light but because anoxic

Low oxygen demands

What are the water surface areas?

•Neustonic organisms are the microorganisms living at the surface.

•Pleustonic organisms are the macroorganisms living at the surface.

•Epineustonic live above the surface.

Hyponeustonic live below the surface.