List authors (scientists) by various attribute
I don't think that you can do this systematically in Web of Science but you can do it in an exploratory way.

Initial search: Topic - "population genetics" + Address - UK

sort by Times cited is probably more useful than the default (newest to oldest)

open Authors in sidebar - this is a list of the top 100 names
can refine to the top 10, or whatever

For example consider Brian Charlesworth:


Open an item with his name in the author list (he has some single author items)
Click on the link of his name to see his papers
Click on Create citation report to see charts of published items per year and citations per year


It may be that you know all this.