Mostly when I read about things like this happening, it's happening to a formerly intractable problem in mathematics. Do you have examples outside of math?
Theoretical ecology is a bit more old-school answer. Many mathematicians have been involved in that field.
I take that back. One can never forget the brilliance of HiC by Erez. But other than that TBH all other “mathematical” or computational breakthroughs I’ve seen are just at best meticulous application of obvious math and computational algorithms to biological problems (and may I say poorly? Thinking back to the microarray nightmare years).
Pretty much everything in genomics depends on shotgun sequencing, which in turn depends on CS. The algorithms used for assembling something useful out of the sequence reads are highly non-obvious. In fact, most developments in string algorithms since the 80s have been driven by the needs of DNA sequencing. (Information retrieval used to be another contender, but word tokens turned out to be a better tool for that field.)