Organisms can sometimes hybridize. Studies have shown that these hybrids often have an increased resistance to parasites that plague each of its parents. This is most commonly seen in plants, especially those that are commercially important, but has been seen in arthropods, fish, amphibians, reptiles, and even mammals! Parasites sometimes “co-evolve” with their hosts, which is something that, until recently, most scientists ignored. This leads parasites to often have what is called a high “host-specificity” which means they can only infect few, if not one species of host. When this species hybridizes, the hybrid is like a new species, making it harder for the parasite to survive.
This combines things I've learned from both CCS 20 and Parasitology!