Scottish Crossbill - Yes? No? Never? (1 Viewer)

[mjh73]

An interesting thread, as a result I've just deleted Scottish CB off my life list

Was in Abernethy volunteering with RSPB early 90s and wardens called Scottish but from memory it was on chunkier than normal bill rather than call (birds in a tree , not in hand so in hindsight was perhaps always wishful thinking!)

Has sat there in my list for 30 years without a second thought til today....

 

[phototroph]

I once posted an mtDNA tree here, if there is interest.

Thanks, do you know if anyone's done WGS on Scottish/Common/Parrot or is all the genetic analysis restricted to mtDNA?

 

[l_raty]

Thanks, do you know if anyone's done WGS on Scottish/Common/Parrot or is all the genetic analysis restricted to mtDNA?

For American birds (Red/Cassia), there is this. I'm not aware of anything similar using Eurasian birds.

 

[Tiraya]

Basically everyone I know over here will disown you and pretend they don't know you if you consider Cassia a separate species, or by any means "worth" going for.

 

[jurek]

Both studies show that if you try to treat Cassia, Scottish or Parrot Crossbills as a separate species, the Red Crossbill becomes paraphyletic.

A wish to split species is so strong that main principles of taxonomy get ignored.

 

[raymie]

Both studies show that if you try to treat Cassia, Scottish or Parrot Crossbills as a separate species, the Red Crossbill becomes paraphyletic.

A wish to split species is so strong that main principles of taxonomy get ignored.

The splits were made with the desire to further split Red Crossbill in the future, it's just that we don't have enough info to fully understand the diversity within it yet.

 

[Kirk Roth]

Both studies show that if you try to treat Cassia, Scottish or Parrot Crossbills as a separate species, the Red Crossbill becomes paraphyletic.

A wish to split species is so strong that main principles of taxonomy get ignored.

I'm not sure that's true in any of the three cases based on the phylogenies that have been posted here anyway.

The parrot and the scotsbill mTDNA were interspersed among (other?) Red Crossbill lineages. A paraphyletic group is one in which a lineage divides other groups - so if there were a group of basal Red Crossbills, then a more derived group of Parrot Crossbills, and then even further divided birds we called "Red Crossbills" that would by paraphyletic. What we see instead are the Scottish and Parrot crossbills (at least in this very limited British-heavy dataset) are sprinkled in with all the other lineages. The term for that is "polyphyletic" (meaning no discreet common ancestor) and so the Parrot and Scottish Crossbills are polyphyletic within Red Crossbill.

In the American situation, Red Crossbills would be paraphyletic in the strictest sense that the group includes some, but not all of its descendants - however, this is typically not an issue for "main principles of taxonomy," because that frankly happens in any group as it buds off of a phylogeny. We don't classify birds as reptiles, even though reptiles are paraphylitic in this sense, but birds are a discreet lineage (ie they aren't in the middle of a reptile "sandwich" similar to my hypothetical example above with the crossbills). Cassia Crossbills are the same way - a discreet lineage that buds off of the Red Crossbill line at some point and remains discreet. The link in Laurent's post #63 shows this very well - the Cassias are all in one lineage (and interestingly, the same is true for the Strickland's/Mexican large-billed crossbills). All the other call types are polyphyletic.

Ornithology has historically used the Biological Species definition of animals which have no barriers to breeding, rather than the Phylogenetic Species Concept that defines species on diagnosable lineages. In the former, paraphylogeny is only of subsidiary importance. In the latter, the Cassia case exhibits one of the interesting philosophical questions with the PSC - what do you do when a diagnosable taxon is nested within lineages which are undiagnosable from one another? In common practice, the solution seems to be to treat them exactly the way the Cassia is treated. In other words, budding speciation does not seem to be a problem for the main taxonomic concepts that we discuss in ornithology.