Question

we have evolved two bacteria, e. coli and s. enterica, together in a flask for 400 generations, and are interested in whether the bacteria have co-evolved. we measured the relative fitness of ancestral s. enterica (sanc) and evolved s. enterica (sevol) when paired with ancestral e. coli (eanc) or evolved e. coli (eevol). we did similar measurements for e. coli. if we observe the following pattern, would you assert that the bacteria have co-evolved? explain your answer

Answer 1

To determine if E. coli and S. enterica have co-evolved, one would observe changes in relative fitness between evolved and ancestral strains when paired with each other. Evidence of co-evolution could be inferred if evolved strains show increased fitness together as compared to their interactions with ancestral strains.

Step-by-step explanation:

To determine if E. coli and S. enterica have co-evolved in a flask over 400 generations, one would expect certain patterns in their relative fitness when paired with both their ancestral and evolved counterparts. If evolved S. enterica (sevol) demonstrates increased fitness when paired with evolved E. coli (eevol) as compared to ancestral E. coli (eanc), and similarly evolved E. coli shows increased fitness with evolved S. enterica as opposed to ancestral S. enterica, then we can infer a degree of co-evolution. Co-evolution implies that each species has had a mutual influence on the evolutionary development of the other.

The concept is similar to the process of endosymbiosis, which has been crucial in the evolution of eukaryotic cells through gene fusion between an Archaea and a Bacteria. Additionally, the long-term co-evolution of bacteria and their host cells eventually led to the development of organelles like mitochondria and chloroplasts. Furthermore, bacteria like E. coli have been studied extensively due to their roles in both human health and disease outbreaks, highlighting the importance of understanding their evolutionary interactions with other microbes.