This episode of This Podcast Will Kill You actually goes into that: https://player.fm/series/series-2359894/ep-31-giardia-gerardia
There is also a transcript if you just want to read about it: https://thispodcastwillkillyou.com/wp-content/uploads/2021/07/TPWKY-Episode-31-Giardia.pdf
(Warning: they make an alcoholic beverage towards the beginning of each episode in case anyone is in recovery)
https://news.ucsc.edu/2013/03/polar-bear-genomics.html
Polar bear brown bear hybridization