In phylogenetics, reticulation is when genes from multiple branches end up in the same daughter lineage. Thinking of it as a family tree, this means that instead of the branches only splitting over time, occasionally they make a network. For example, my ancestors 100K years ago include Homo neaderthalensis as well as Homo sapiens, and possibly also Homo denisova.
This is certainly similar to the Linnaean concept of hybridization, and often results from sexual hybridization, but can also result from less familiar forms of recombination between viruses or bacteria, and even other means of genetic materials moving between relatively unrelated organisms. The endosymbiosis between archaea and bacteria that resulted in eukaryotes is a good example of a very deep reticulation. The reported uptake by tardigrades of genetic material from their food suggests another.
What I’m wonder is if there are any cases, other than present day hybridization, where past reticulations complicate the branching Linnean taxonomy that iNat uses. To give a theoretical example, there is no hard reason except custom why a single genus couldn’t belong in two separate families, if past members of these families (before they had diverged so much) bred and gave rise to the new genus. In practice most taxonomists would likely elevate this hybrid genus to a family along side the other two, or collapse the whole mess into a single family.
But I’m curious if there are any case where taxonomist have seen fit to recognize reticulation, at the generic level or higher, in ways that iNat either has to treat or purposefully sidestep? And are there groups (viruses, perhaps) where reticulation happens so often that the assumption of a tree-like taxonomy has to be largely abandoned? Thank you.