Many pathogenic bacteria species are becoming resistant to antibiotics. Explain how such adaptations can develop through the process of natural...

Evolution, natural selection, adaptation, and
survival of the fittest are all interrelated terms that this answer should explore. An evolution
of a species means that the species has gone through change over a period of time. It relies on
natural selection, and natural selection relies on adaptation. Adaptation relies on genetic
changes. Sexual reproduction creates genetic diversity, but genetic mutations can alter genetic
coding for species that reproduce asexually. Those genetic changes lead to organisms developing
various traits. Some of those changes are beneficial for a particular environment at a
particular time, and those beneficial changes result in an organism being better adapted to that
environment. Any organism that is better adapted to a situation is more likely to live and pass
on that genetic information to the next generation. The adapted organism has a higher fitness
level, and that is where we get the saying "survival of the fittest." In this way, the
fittest organisms are most likely to survive, so it looks like nature is naturally selecting
which traits get passed on from generation to generation.

You can apply those
same steps to a population of bacteria. Due to genetic changes that occur for a variety of
reasons, there are likely some bacteria that are genetically different than the billions of
other bacteria. The unique bacteria just might have a random genetic change that makes them a
tiny bit more resilient to antibiotics, and a fraction of them survive the medication designed
to wipe out the bacteria. These bacteria then reproduce asexually, and an entire population of
bacteria has now been created that are slightly more resilient than previous bacteria. The
adaptation increased bacterial fitness which then caused that group to survive through natural
selection. If this happens over and over again, the evolved bacteria are vastly different than
the ancestral bacteria that were once susceptible to antibiotics. A human response is then to
make more powerful medications, but that simply pushes the evolution of bacteria along even
more.

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