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Corvidae (1 Viewer)

Peter Kovalik

Well-known member
Slovakia
Gamauf, A., Däubl, B., Kryukov, A., Pinsker, W. & Haring, E., 2010. Phylogeography and synchronous diversification of the Corvus corvids of the world. Berichte des Institutes für Erdwissenschaften der Karl-Franzens-Universität Graz/Austria.

Abstract:
The genus Corvus with its approximately 40 species is world wide distributed, except S America. Highest diversity is found in Australasia and SE Asian islands. Ten species (25%) are coloured black and white/grey, the rest are completely black.
We investigated the phylogeny of the genus Corvus employing DNA sequences of the mitochondrial control region. The study was based mainly on museum material allowing the analysis of more than 30 species. Inclusion of sequences of other corvid genera as available in GenBank confirmed the monophyly of the genus Corvus. Within the Corvus clade several distinct subclades can be distinguished. Some contain only single species or species pairs (e.g., C. monedula + C. dauricus; C. frugilegus; C. palmarum) while other clades are composed of many species (e.g., the Holarctic and African clade or the SE and E Asian clade). In general, the composition of the clades reflects geographic contiguousness. The basal relationships among clades remain unresolved with this marker sequence.
It is remarkable that each clade contains black as well as white/grey coloured representatives. None of the latter are found in N America, whereas almost all African species south of the Sahara show blackwhite pattern. The most parsimonious explanation for the distribution of plumage colour in the phylogenetic tree is that the pale markings evolved at least five times independently. The assumption that the white/grey colour pattern - which is found also in other genera of the family Corvidae, e.g., Pica - is the plesiomorphic state, is less likely.
 
Hi Peter,
Is there a full article or only the same abstract as in the 25th International Ornithological Congress (22-28 August 2010) in Brazil ?
 
Haring et al

Haring, Däubl, Pinsker, Kryukov & Gamauf (in press). Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) – a first survey based on museum specimens. J Zool Syst Evol Res. [abstract] [supp info]
 
Corvus

Not sure whether this has been posted yet: http://www.biomedcentral.com/content/pdf/1471-2148-12-72.pdf

Abstract

Background
Crows and ravens (Passeriformes: Corvus) are large-brained birds with enhanced cognitive abilities relative to other birds. They are among the few non-hominid organisms on Earth to be considered intelligent and well-known examples exist of several crow species having evolved innovative strategies and even use of tools in their search for food. The 40 Corvus species have also been successful dispersers and are distributed on most continents and in remote archipelagos.

Results
This study presents the first molecular phylogeny including all species and a number of subspecies within the genus Corvus. We date the phylogeny and determine ancestral areas to investigate historical biogeographical patterns of the crows. Additionally, we use data on brain size and a large database on innovative behaviour and tool use to test whether brain size (i) explains innovative behaviour and success in applying tools when foraging and (ii) has some correlative role in the success of colonization of islands. Our results demonstrate that crows originated in the Palaearctic in the Miocene from where they dispersed to North America and the Caribbean, Africa and Australasia. We find that relative brain size alone does not explain tool use, innovative feeding strategies and dispersal success within crows.

Conclusions
Our study supports monophyly of the genus Corvus and further demonstrates the direction and timing of colonization from the area of origin in the Palaearctic to other continents and archipelagos. The Caribbean was probably colonized from North America, although some North American ancestor may have gone extinct, and the Pacific was colonized multiple times from Asia and Australia. We did not find a correlation between relative brain size, tool use, innovative feeding strategies and dispersal success. Hence, we propose that all crows and ravens have relatively large brains compared to other birds and thus the potential to be innovative if conditions and circumstances are right.
 
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Northwestern and American Crows

In case anyone hadn't noticed, there's free access to the paper: [pdf]

The caurinus/brachyrhynchos data are interesting to me. Two of the three caurinus samples are from Seattle. The conventional birding wisdom (and my own experience) is that most birds in Seattle are C. brachyrhynchos hesperis. Thus, the only noncontroversial caurinus sample in Haring et al. would be the one Vancouver sample, which is "short sequence."

It is interesting still that one of the Seattle birds is nested within brachyrhynchos - a step between two birds from Kansas, in fact.

A robust phylogeny of the American Crow is sorely needed. From a phenotypic perspective, hesperis and caurinus are just shy of identical. However, the difference between hesperis and brachyrhynchos in voice, structure, and behavior is very striking. From an Eastern U.S. point of view, the hesperis crows resemble dull-plumaged Fish Crows closer than our bulky, squawky brachyrhynchos.
 
Northwestern and American Crows

Verbeek & Butler 1999. Northwestern Crow (Corvus caurinus). BNA Online.
First recognized as a distinct species by Baird (1858). Later authors have strongly agreed (e.g., Brooks 1942) or placed Northwestern Crow as a subspecies of American or Fish crows. Successive editions of the American Ornithologists' Union Check-list have listed Northwestern Crow as a full species (1910), a subspecies of American Crow (1931), and a full species (1957, 1983, 1998).
...
Northwestern and American crows are presumed closely related and may be conspecific (Johnston 1961, A. M. Rea in Phillips 1986). Northwestern Crow regarded as subspecies of Fish Crow by Hellmayer (1934), who cited the similarities of voice and habits and the suggestion of Meise (1928), who also regarded American Crow as a race of Carrion Crow (Corvus corone). Johnston (1961) studied American and Northwestern crows, paying particular attention to nw. Washington State, where the 2 species are thought to overlap in distribution or to hybridize. Since color could not be used (both taxa look alike), Johnston compared voice, habitat, nesting habits, and measurements of bill, wing, tail, and tarsus. He concluded that hybridization between the 2 taxa is common in nw. Washington State and argued in favor of making Northwestern and American crows conspecific. Ratti (1984) cautioned that Johnston's conclusion might be premature in the absence of morphological data, coupled with voice recordings, within pairs. Apparent differences in the position of nasal bristles of Northwestern and American crows (Meinertzhagen 1926, Parkes 1988) have not stood up to scrutiny (Bayer 1989b, Paulson 1989).
Verbeek & Caffrey 2002. American Crow (Corvus brachyrhynchos). BNA Online.
... Taxonomy of Rea (1986), who also recognized 4 subspecies (differing from above), indicates that many unresolved questions remain. For example, relationship of western American Crow (C. b. hesperis) may be closer to Northwestern Crow than to other races of American Crow. If these are more closely related, then the nomenclature needs clarification. As pointed out by Rea (1986), the type specimen for Northwestern Crow is from a region of potential overlap with American Crow (Fort Steilacoom, WA), and an adult paratype from Orcas I. (San Juan Co.), WA, is within size range of American Crows from s. California. This could mean that hesperis is a synonym of caurinus and the truly smaller crows from Alaska and British Columbia would require a name.
Marzluff 2009 (HBW 14):
 
I hope someone will follow soon with a phylogeny of the Philippine crows. The enca crows of Palawan are clearly different vocally from Borneo birds. And the sierramadrensis/samarensis crows are both morphologically and vocally different from them. Whether these latter 2 should be split as distinct species from each other may perhaps depend on DNA studies.
 
Northwestern and American Crows

Andrew Spencer, Earbirding.com, 30 Dec 2012: North by Northwest.
NBHC ID-FRONTIERS yesterday...
NW vs. American Crows

Listening to the collection of vocalizations and looking at the sonograms featured in Andrew Spencer's article only reinforces what most of us already believe..."Northwestern Crow" is not a species. We have some utterly miniature crows along the central Oregon coast, colloquially referred to as "Yachats" Crow (C. b. yachatensis) thanks to Alan Contreras. These birds are often counted as Northwestern Crows by visiting birders who don't realize that the "range" of Northwestern Crow doesn't include Oregon.

Dave Irons
Portland, OR
In my opinion, Corvus is one of the groups where the species concepts we tend to use do not fit reality very well, along with pink-footed gulls, Loxia, and several others. A lot of morphological differentiation among populations has occurred size and meristic characters, both in "American" Crows and in Ravens. I remember a conversation with Allan Phillips years ago in which he was disagreeing caustically (as always) with AOU classification of some neotropical thrushes with black plumage. He made the point that it is more difficult to see the evidence of divergence among populations of black birds than colored ones, and that species limits are therefore harder to determine, not less real.

Andrew Spencer's results are interesting, but I would group them with those of Johnston, and just about everyone else who has commented on "Northwestern" Crows since, in that they are not comprehensive enough to really draw hard taxonomic conclusions.

To truly understand what is going on with these crows, I suspect the sampling needed is comparable to that needed for understanding Crossbills - i.e., extensive recordings of vocalizations, and genetic data from the same individuals, for samples spanning the range of "caurinus" and south down the coast into California, and inland in "American Crow" range in western Canada, Washington, Oregon, and northern California. And as Andrew and others pointed out, the vocal sampling needs to be more comprehensive than for crossbills because crow vocalizations are so much more varied.

Several hypotheses are available to account for the information we have to date, and to my knowledge we do not have enough information to distinguish rigorously among them:

H1: caurinus is a diminutive variant of brachyrhynchos, the result of regional selection for small size.

H2a: caurinus diverged from brachyrhynchos in allopatry (presumably in ice-free areas of Alaska/BC during glacial maxima), and current contact is secondary, without much hybridization.

H2b: caurinus diverged from brachyrhynchos in allopatry (presumably in ice-free areas of Alaska/BC during glacial maxima), and current contact is secondary, with extensive hybridization.

H2c: caurinus diverged from brachyrhynchos in allopatry (presumably in ice-free areas of Alaska/BC during glacial maxima), and maintains morphological separation north of the Straits of Juan de Fuca, but dispersers south across the Straits have hybridized extensively with American Crows. etc. etc.

Now to Ravens: A decade or so ago, molecular information surfaced indicating very substantial (putatively species-level) differences among ravens from California vs northern North America. My understanding is that since then, ravens living in between have been found to be genetically intermediate, but I have not seen those results. In any case, geographically extensive sampling is necessary to understand what is going on.

And finally, a caution about using molecular genetic information in taxonomy in groups such as these: substantial genetic differences among (phenetically differentiated) populations can be indicative of no genetic interchange for long enough to conclude the populations should be treated as species. However, the converse is not always true. Likely many instances of bird speciation come from gradual differentiation of allopatric populations over time frames of hundreds of thousands to millions of years. However, it is also very possible to have more rapid speciation from strong selection in much shorter time frames, to short to leave strong signals in the traditionally used "neutral" parts of the genomes. This is clearly the case with lekking grouse, and likely is the case with crossbills, It may also be the case with northern-hemisphere geese.

Wayne Hoffman
 
Corvus

Londei 2013. Alternation of clear-cut colour patterns in Corvus crow evolution accords with learning-dependent social selection against unusual-looking conspecifics. Ibis 155(3): 632–634. [pdf]
 
Londei 2013. Alternation of clear-cut colour patterns in Corvus crow evolution accords with learning-dependent social selection against unusual-looking conspecifics. Ibis 155(3): 632–634. [pdf]

An interesting and potentially valuable thought experiment. Any thoughts on an agreed practical methodology to test these ideas across the various black/grey/pied populations?
MJB
 
Corvus

Eimes​, Townsend, Sepil, Nishiumi & Satta (in press). Species divergence, selection and polymorphism in the MHC of crows. PeerJ PrePrints 2: e621v1. [article] [pdf]
 
Corvus brachyrhynchos

Xiangfeng Li, Jiang Lu, Jing Lu, Xiaoxiao Hu, and Zhiyong Huang. The complete mitochondrial genome of the American crow, Corvus brachyrhynchos (Passeriformes, Corvidae). Mitochondrial DNA, Posted online on April 14, 2015. (doi:10.3109/19401736.2015.1022745).

Abstract

The American crow, Corvus brachyrhynchos (Passeriformes, Corvidae), is a large passerine bird species closely related to the raven. Herein, we first published the complete mitochondrial genome of American crows. The mitogenome was 16,917 bp long, and composed of 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and one putative control region. Most protein-coding genes started with a traditional ATG codon except for COI, which initiated with an infrequent start codon GTG instead, and terminated with the mitochondria stop codon (TAA/AGG/AGA) or a single T base. The mitogenome structural organization is identical to that of the other corvus species and related genera. The overall GC content is 44.25% which is lower than AT. Using the 12 protein-coding genes of Corvus brachyrhynchos in this study, together with 10 other closely species, we constructed the species phylogenetic tree to verify the accuracy and utility of new determined mitogenome sequences. We expect that using the full mitogenome to address taxonomic issues and study the related evolution events. Moreover, this is the first report of bird mitogenomes after 48 avian species genome project achievements released in December 2014.
 
Carrion & Hooded Crows

Poelstra, Vijay, Hoeppner & Wolf (in press). Transcriptomics of colour patterning and colouration shifts in crows. Mol Ecol. [abstract]

[Hooded Crow Corvus (corone) cornix is treated as a distinct species by HBW, IOC, eBird/Clements, BOURC and CSNA; but not by BirdLife, H&M4 or AERC.]
 
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Poelstra, Vijay, Hoeppner & Wolf (in press). Transcriptomics of colour patterning and colouration shifts in crows. Mol Ecol. [abstract]

" A model of evolutionary stable pre-patterns that can be exposed and masked through simple regulatory changes may explain the phylogenetically independent recurrence of colour patterns that is observed across corvids and many other vertebrate groups."

It may indeed explain why color patterns like wing bars or eye-stripes re-appear in many different birds. For example, lots of birds have pale bars along bases of flight feathers, but probably no bird has lengthwise bar through the centre of the wing.
 

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