Final answer:
The question about Andersson and Hughes' study of Muller's ratchet in bacteria cannot be answered as it is not detailed in the provided references. However, Muller's ratchet refers to the accumulation of deleterious mutations in asexual organisms and can be mitigated by horizontal gene transfer in bacteria.
Step-by-step explanation:
The study by Andersson and Hughes regarding Muller's ratchet in bacteria is not explicitly detailed in the provided references. However, Muller's ratchet is a biological phenomenon that explains how populations of asexual organisms, including bacteria, accumulate deleterious mutations over time. This process occurs because, without sexual reproduction, the genomes of asexual populations can only get worse or maintain their current state, as there is no way to recombine genes and thereby 'ratchet' down the load of bad mutations. One of the ways bacteria can combat the effects of Muller's ratchet is through horizontal gene transfer, as it allows them to incorporate beneficial DNA from other cells, which can potentially counteract the accumulation of harmful mutations.
While the references do not discuss Andersson and Hughes' study directly, they do highlight important research related to bacterial genetics and the impact of DNA on heredity and transformation, as well as the potential benefits of horizontal gene transfer for prokaryotes struggling against Muller's ratchet.