…suggesting we need to rethink our understanding of species barriers.
Have we ever really defined species barriers? It seems to be driven more by tradition than anything else.
The vagueries of speciation has been especially exploitable by the conservatism/YIMBYism movement, where a trait common in one region but uncommon in others can be used to declare a common unthreatened animal as an endangered species, despite a lack of genetic divergence. It would be like declaring uncommonly red-haired Irish as not just an ethnicity but a separate species.
My favorite example of vagueries in species differentiation is a study that found only 13 genes that reliably differ between domestic cats and European and Near Eastern wildcats. (https://www.pnas.org/doi/full/10.1073/pnas.1410083111) It really brings into question what domestication even is, considering that housecats are perfectly capable of supporting themselves outside of areas inhabited by humans. Their lack of differentiation from wildcats means that they can easily become invasive species in areas where they are introduced by humans.
It's impossible for a species to be invasive to its native land, but Poland has managed to simultaneously consider a group of animals with a mere bakers dozen of genes differentiating them, none of which hinder their ability to interbreed, as both "currently threatened with extinction in their natural habitat" (https://pmc.ncbi.nlm.nih.gov/articles/PMC6749728/) and an "invasive alien species" (https://apnews.com/article/science-poland-wildlife-cats-bird...).
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