FAQ Friday - How do you define "species"? Why can some species still hybridize? : askscience
https://www.reddit.com/r/askscience/comments/1wndb1/faq_friday_how_do_you_define_species_why_can_some/Genes | Free Full-Text | Hybridization of Russian Sturgeon (Acipenser gueldenstaedtii, Brandt and Ratzeberg, 1833) and American Paddlefish (Polyodon spathula, Walbaum 1792) and Evaluation of Their Progeny
https://www.mdpi.com/2073-4425/11/7/753How many early human species existed on Earth?
https://www.livescience.com/how-many-human-species.htmlResearchers discover hybrid fungus involved in lung infections
https://phys.org/news/2020-07-hybrid-fungus-involved-lung-infections.htmlSpecies concept - Wikipedia
https://en.wikipedia.org/wiki/Species_conceptThere are no ring species – Why Evolution Is True
https://whyevolutionistrue.com/2014/07/16/there-are-no-ring-species/