Who gets corresponding authorship in the biological sciences and what does it mean?
The corresponding author serves as the point of access for readers to inquire about a paper. This does not imply it should be any particular author, though particularly common choices seem to be first or last author.

The corresponding author should be the author that is least likely to change institutions. Changing institutions generally implies losing your contact details where you left (including email). The corresponding author should be the one that is most likely to remain a consistent point of communication.

This is often the last author because that is the common spot for the supervising PI (typically tenured). This is not always true, for example some domains like maths and theoretical computer science organise authors alphabetically.