Question

1A) A low rate of spontaneous mutations is beneficial in providing the genetic diversity needed for evolution, but this rate can vary among different types of microorganisms. Under what environmental conditions might an elevated rate of spontaneous mutations be selective?

B) How might the degree of genetic relatedness between two bacterial species affect the rates of genetic recombination that may occur between them?

Answer 1

1A) Spontaneous mutations are brought about by random changes independent of environmental selection in the DNA and does not always result in selective mutations that are advantageous, but rapid spontaneous mutations that are selective can occur in adverse environmental conditions like high or low temperatures, pH, restrictive nutritional condition, chemical stress due to antibiotics and in the presence of phages, where one or more spontaneous mutation can give added advantage to the bacteria over these factors

B) Recombination is more likely to occur between closely related bacterial species due to various reason

• The proximity of closely related species to live in similar ecological and geographical regions or share same type of host which is an essential causative factor for recombination through transformation, transduction or conjugation.
• Homology dependence is another factor that exponentially increase the chances of recombination of closely related bacteria. (presence of homologous DNA in closely related bacteria)
• The presence of strong environmental challenge also increases the rate of recombination among closely related bacteria as they share plasmids to ensure survival