Taxonomy, Cladistics, and iNaturalist

[upupa-epops]

If anyone cares to read even more discussion of this topic, there are these threads from the past to refer to. :P

• Genetics to replace morphological examination?
• Should New Disruptive Technologies be Used for Classification in Ancient Linnaean Rankings

Some relevant quotes from those threads:

@earthknight

The interbreeding/unable to interbreed distinction isn’t all that relevant any more. There are far too many cases of hybridization between species, including some widely divergent. An extreme example of this is with American Paddlefish and Russian Sturgeon that have been separated for 184 million years, yet can still hybridize.

The current summary when it comes to species definitions is basically, “Well, it’s complicated.” As a result there are a number of different classifications schemes being used, not all of which include reproductive isolation as the primary distinguishing marker.

• A brief overview of 26 different ways to define a species - not paywalled
• Zachos 2016 An Annotated List of Species Concepts - paywalled

@upupa-epops

I’m most [familiar] with the general species concept with birds where there are overarching taxonomic authorities that have a fairly consistent method. Just from following North American bird taxonomy (overseen by the American Ornithological Society) for a bit over a decade I’ve seen enough edge cases discussed to know where the line is and generally it makes sense to me. … [list of examples cut for brevity] …

The most important factor seems to have been detailed analysis of hybridization; how large the overlap zone is, how successful hybrid offspring are, etc. But because birds use vision and sound to communicate with each other, their appearance and sound tends to be correlated with reproductive isolation as well so identifiability is also a factor. Birds are relatively “large” animals too so subtle differences are easy to see.

I have no idea how you are supposed to determine those things when you’re studying insects or plants because they don’t necessarily distinguish among themselves using the same features we use to distinguish them

A number of those hybrid swarms have been lumped and resolved now, but the one with Western Gull and Glaucous-winged Gull in the Pacific Northwest will probably never be because they aren’t even each others’ closest relatives (unless all Larus gulls get lumped into “seagull”, but that’s unlikely with Herring Gull just being split up even more this year…).