Sexually - better adapt
Reproducing sexually allows for gene variation which helps in changing environments. Asexually would be the same genetically and it would be difficult to adapt
Thymine, cytosine, guanine and adenine
Answer:
Hey there!
I believe that David's prediction would be: If the amount of pollutants in the atmosphere reached an amount unhealthy for the salamanders, then the salamander population would decrease.
Let me know if this helps :)