How allopatric and sympatric speciation work to produce new species?

A variety of mechanisms have been proposed to describe how speciation can occur. The two most important mechanisms are undoubtedly allopatric and sympatric speciation. How do these two processes work to produce new species?

Chemical Evolution Causing Life

For life to occur on europa what stages of chemical evolution must occur and the chemical and physical factors these require, if life is to emerge from europa.

Help with questions

Why do crystals (like quartz for example) have such amazing shapes? Why are researchers so hopeful about the uses of stem cells in finding cures for disease? Why does the fossil record contain more sea animals than land animals?

Hardy Weinberg

Please do following problems attached and please SHOW ALL WORK: 2. B, C 3. B 4. B 5. B

What kind of selection is demonstrated in this example? Is the equilibrium point under this type of selection stable or unstable? What is the long-term fate of A and a alleles in this population?

Please see attached file for full problem description. What kind of selection is demonstrated in this example? Is the equilibrium point under this type of selection stable or unstable? What is the long-term fate of A and a alleles in this population?