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Aphelocoma jays (1 Viewer)

Richard Klim

Richard Klim

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McCormack, Heled, Delaney, Peterson & Knowles 2010. Calibrating divergence times on species trees versus gene trees: implications for speciation history of Aphelocoma jays. Evolution: in press.
http://www3.interscience.wiley.com/journal/123596996/abstract

See also:
Richard
 
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Taxonomy

The 'study taxonomy' recognises:

Mexican Jay species group:
  • A wollweberi (incl arizonae)
  • A couchii
  • A potosina
  • A ultramarina (incl colimae)
Scrub Jay species group:
  • A insularis
  • A californica (incl hypoleuca, caurina, immanis, obscura, oocleptica)
  • A woodhouseii (incl nevadae, texana, grisea, cyanotis)
  • A sumichrasti (incl remota)
  • A coerulescens
Unicolored Jay species group:
  • A guerrerensis
  • A concolor
  • A oaxacae
  • A unicolor
  • A griscomi
"Detailed taxonomic recommendations resulting from this study will be made elsewhere..."

Richard
 
Don't have access to the article, but from the abstract:

"consistent with theory that divergence times can be significantly overestimated with gene-tree based approaches that do not correct for genetic divergence that predates speciation."

Its good to see attention paid to this notion; this assumptive pitfall seems to appear in the conclusions of a great many phylogenetic studies. However, the abstract to me begs the question: How many different loci define a species? Or rather, where is the line in the sand between a gene tree and a species tree?

By the way, regarding the "study taxonomy," I wonder how badly does this paper shoot down my pet theory that A. insularis is best treated a subspecies of A. calififornica (sensu anti-woodhouseii!)
 
Island Scrub Jay

Kirk Roth said:
By the way, regarding the "study taxonomy," I wonder how badly does this paper shoot down my pet theory that A. insularis is best treated a subspecies of A. calififornica (sensu anti-woodhouseii!)
Click to expand...
Your theory's sound: the californica group seems to be more closely related to insularis than to to the woodhouseii group.

Richard
 
Kirk Roth said:
Don't have access to the article, but from the abstract:

"consistent with theory that divergence times can be significantly overestimated with gene-tree based approaches that do not correct for genetic divergence that predates speciation."
Click to expand...

This to some extent is a chicken or egg question. Is the study trying to report the time since speciation, or is the study trying to estimate the time since separation under the assumption that a long enough separation would equate speciation, even if that speciation did happen only yesterday? The second approach makes more sense to me personally, with the caveat mentioned below that DNA or time separations will never tell the whole story.

I personally think that trying to figure out how much of the divergence that happened before and how much after speciation is impossible (if for no other reason than that speciation does not happen on one given day but is a gradual process), so that the correction mentioned in the above abstract would be impossible. (all under the caveat that I have not read the actual paper either).

By the way, regarding the "study taxonomy," I wonder how badly does this paper shoot down my pet theory that A. insularis is best treated a subspecies of A. calififornica (sensu anti-woodhouseii!)
Click to expand...

If I understand what you are saying, there are two parts to it: (1) woodhouseii should be split from calififornica, but (2) insularis should not. The first part was close to getting enough votes in the AOU, so it is probably going to happen sometime in the future. The second part, I don't know the two taxons well enough to really have any opinion, but DNA sequence differences does not tell the whole story; how diverged is insularis in behavior, habitat choice, etc?

Niels
 
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njlarsen said:
but DNA sequence differences does not tell the whole story; how diverged is insularis in behavior, habitat choice, etc?
Click to expand...

With the disclaimer that I'm not a jay biologist, my understanding is that insularis looks and acts much like you would expect a large island population of californica to be. Insularis is larger with a 25% larger bill and is brighter colored with a bluish, rather than white crissum. However, both have similar, if not identical vocalizations; both are bold, not shy; both have similar pairing systems; both are chapparal and oak woodland birds.
 
Kirk Roth said:
With the disclaimer that I'm not a jay biologist, my understanding is that insularis looks and acts much like you would expect a large island population of californica to be. Insularis is larger with a 25% larger bill and is brighter colored with a bluish, rather than white crissum. However, both have similar, if not identical vocalizations; both are bold, not shy; both have similar pairing systems; both are chapparal and oak woodland birds.
Click to expand...

Don't have access to the paper, but are there any accounts of hybridization between A. californica and A. insularis? How much does the fact that insularis is an island population (which will almost certainly not encounter californica) persuade the powers that be to leave it at full species status? In other words, does the lack of a hybrid zone give insularis more leeway?
 
Kirk Roth said:
With the disclaimer that I'm not a jay biologist, my understanding is that insularis looks and acts much like you would expect a large island population of californica to be. Insularis is larger with a 25% larger bill and is brighter colored with a bluish, rather than white crissum. However, both have similar, if not identical vocalizations; both are bold, not shy; both have similar pairing systems; both are chapparal and oak woodland birds.
Click to expand...

During my visit to the island several years ago, I found the difference in voice between insularis and californica very distinct. insularis had much deeper calls with less raspiness than those of californica.


Anyone know, how divergent is californica from insularis, when brought into comparison with other Channel island endemic taxa and their mainland counterparts? eg. loggerhead shrike, island fox, island night lizard etc.
 
Island Scrub Jay

AlexC said:
...are there any accounts of hybridization between A. californica and A. insularis?
Click to expand...
It would seem that A californica hasn't been recorded on the Channel Islands:
http://www.nps.gov/chis/planyourvisit/upload/CHECKLIST OF CHIS BIRDS.pdf

And A insularis is unrecorded away from Santa Cruz Island (Alderfer 2006).

[And no scrub jay has been recorded on any of the other Channel Islands (Curry & Delaney 2002, BNA Online).]

So they now appear to be totally isolated, and there are unlikely to be any accounts of hybridisation in the wild.

Richard
 
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calibird said:
During my visit to the island several years ago, I found the difference in voice between insularis and californica very distinct. insularis had much deeper calls with less raspiness than those of californica.
.
Click to expand...

A deeper voice would be expected of a larger bird, cf. Common Ravens across the northern hemisphere, or all of the crow species and subspecies in America for a couple of good examples.

There are many things that cause raspiness in bird voices, including (secondarily) speciation, so I guess I don't have anything intelligent to say about that!
 
Kirk Roth said:
A deeper voice would be expected of a larger bird, cf. Common Ravens across the northern hemisphere, or all of the crow species and subspecies in America for a couple of good examples.

There are many things that cause raspiness in bird voices, including (secondarily) speciation, so I guess I don't have anything intelligent to say about that!
Click to expand...


The western subspecies of American crow has a lower pitched call than the eastern race, and is the smaller of the 2.
Tamaulipas crow has an even deeper voice, and is considerably smaller than the American.

Not saying that differences in the jays voices is conclusive proof of their speciation, but that there are definitely consiistent differences in their voices, in addition to differences morphology and phylogeny.
 
calibird said:
The western subspecies of American crow has a lower pitched call than the eastern race, and is the smaller of the 2.
Tamaulipas crow has an even deeper voice, and is considerably smaller than the American.QUOTE]

True, I didn't consider the Tamaulipas, which has an interesting and unique voice development itself. See this article for a comparison of Fish and Tamaulipas Crow voice development:

http://www.fosbirds.org/FFN/PDFs/FFNv18n4p74-80Hardy.pdf

And I was just flat-out mixed up about hesperis crows. That's what I get for trying to over-simplify. Thanks for keeping me straight!
Click to expand...
 
Kirk Roth said:
With the disclaimer that I'm not a jay biologist, my understanding is that insularis looks and acts much like you would expect a large island population of californica to be. Insularis is larger with a 25% larger bill and is brighter colored with a bluish, rather than white crissum. However, both have similar, if not identical vocalizations; both are bold, not shy; both have similar pairing systems; both are chapparal and oak woodland birds.
Click to expand...

Just came across the species account in Sibley online: the size difference seems to be about 40% by weight, I would call that pretty substantial!

Niels
 
I can't speak for all the other island endemics, but the Island Fox is probably of Holocene origin, and was brought over by early Native Americans. I believe it is paraphyletic in respect to the mainland foxes, but have never heard of anyone suggesting to subsume it within Gray Fox. The size difference is pretty substantial.

Speaking of Channel Island endemics, does anyone have any info in regards to the endemic forms of Orange-crowned Warbler or Allen's Hummingbird?
 
Channel Islands races

Mysticete said:
Speaking of Channel Island endemics, does anyone have any info in regards to the endemic forms of Orange-crowned Warbler or Allen's Hummingbird?
Click to expand...
Although Selasphorus sasin sedentarius 'Channel Islands Hummingbird' was until recently an island endemic, its range expanded to coastal S California in the 20th century. As the ssp name implies, unlike nominate sasin it's resident rather than migratory.

Likewise, Oreothlypis celata sordida 'Dusky Orange-crowned Warbler' also breeds on the mainland as well as on the Channel Islands (and was once more widespread).

An interesting endemic breeder is Empidonax difficilis insulicola 'Channel Islands Flycatcher', which has been suggested as a possible species (eg, Monroe & Sibley 1993).

Lowther 2000 (BNA Online):
"Although not presently recognized as a separate species by Am. Ornithol. Union (1998), birds breeding on Channel Is. off s. California genetically distinct. These populations, currently regarded as a subspecies under Pacific-slope Flycatcher (E. d. insulicola), exhibit substantial differences from mainland Pacific-slope Flycatchers in morphology, coloration, voice, and habitat preference; this population shows extremely reduced gene exchange with mainland populations of Pacific-slope Flycatcher, with which insulicola is otherwise most closely related (Johnson and Martin 1988)."

Farnsworth & Lebbin 2004 (HBW9):
"Channel Is race insulicola possibly a separate species, differs from mainland populations in morphology, voice, habitat use and genetics."
​
Richard
 
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As I understand, the hummingbird and warbler "rode" the islands until they became part of the mainland. The Palo Verde penisula is a "remnant" of what once was an island.

Never heard of the flycatcher before, so thanks
 
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Channel Islands Hummingbird

Mysticete said:
As I understand, the hummingbird "rode" the islands until they became part of the mainland. The Palo Verde penisula is a "remnant" of what once was an island.
Click to expand...
This from Mitchell 2000 (BNA Online):

  • "Historical Changes

    The range of nonmigratory race sedentarius expanded this century to the Palos Verdes Peninsula, Los Angeles Co., CA, probably from Santa Catalina I., the closest island (32 km) to the peninsula (Johnson 1972, Wells and Baptista 1979a). Apparently, sedentarius has since spread north from the peninsula to Malibu (Small 1994) and extreme north coastal Los Angeles Co. (K. Garrett pers. comm.), and south from the peninsula to coastal Orange Co. (Gallagher 1997) and perhaps to extreme n. San Diego Co. (P. Unitt pers. comm.). S. s. sedentarius has also recently expanded its breeding range to include areas inland away from the immediate coast in Los Angeles Co., including locations within the San Fernando Valley to the north and San Gabriel Valley to the east (L. Allen pers. comm.). S. s. sedentarius colonized San Miguel I. sometime between 1939 and 1968 (Jones and Collins in press). This may actually be a recolonization after habitat degradation caused by introduced grazing animals in the early part of the century eliminated a possible breeding population (P. Collins pers. comm.)."

Richard
 
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