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Common/Northern Raven (1 Viewer)

Richard Klim said:
Webb, Marzluff & Omland 2011. Random interbreeding between cryptic lineages of the Common Raven: evidence for speciation in reverse. Mol Ecol: in press.
onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2011.05095.x/abstract
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From the abstract at least, seems like an interesting study with implications for some taxonomic decisions going on right now. I wonder how long the lineages have been "separated" before coming into contact once again - does the article lend any guesses? In other words, how long can lineages be separate and NOT speciate? (I know that theoretically, the answer is "forever," but what is the Guinness World Record?) B :)

Also, I think that "speciation in reverse" is an unfortunate term that only makes sense under the Phylogenetic Species Concept. If that.
 
Related...

 
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Kirk Roth said:
From the abstract at least, seems like an interesting study with implications for some taxonomic decisions going on right now. I wonder how long the lineages have been "separated" before coming into contact once again - does the article lend any guesses? In other words, how long can lineages be separate and NOT speciate? (I know that theoretically, the answer is "forever," but what is the Guinness World Record?) B :)

Also, I think that "speciation in reverse" is an unfortunate term that only makes sense under the Phylogenetic Species Concept. If that.
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Again, what do you call speciation? But one relevant example would be Ruddy Duck imported to Europe where there is hybridization with White-headed Duck. I found this quote "Indeed, the two species are not each other’s closest relatives and their most recent common ancestor dates to perhaps 2 million years ago (McCracken & Sorenson 2005)." in MUÑOZ-FUENTES et al Molecular Ecology (2007) 16, 629–638.
But the hybrids are fertile in both back-crosses.

Niels
 
Neils,

I suppose my cheap answer is that "speciate" means that taxonomic authorities consider them the different species. Terrible definition, I know! My question though, is how far separate can lineages be without developing morphological or reproductive differences. Your Ruddy/White-headed Duck example is a good one, despite obvious plumage differences. Thanks for bringing the quote forward.
 
Ben Marks PhD dissertation (LSU) found 8-11% differentiation in the mtDNA of phenotypically identical populations of the African Bleda syndactylus, which calibrates to a split in the Miocene (at least 5M years). Tropical birds tend to have greater intraspecific distances than temperate species, where good spp. can be as little as 1% differentiated.

"Speciation in reverse" is by definition impossible if you use the BSC.

Andy
 
Kratter said:
"Speciation in reverse" is by definition impossible if you use the BSC.
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In theory, you could have two populations develop reproductive isolation, then a "sub-population" could re-develop compatability at some time or another. In some organisms like fruit flies and several flowers at least, this would be a matter of a simple mutation.

Yet, if there were evidence of this occurring naturally, I'm not aware of it. And even so, would you call it "speciation," even under the BSC? And would it be in "reverse" or just hybridization/integration?

"Speciation in reverse" seems to be an eye-catching phrase, but not entirely useful beyond that. I suppose I should be more fair and reserve judgement until I've read the full article. Is this term defined within the article... or is it a bit of "creative journalism?"
 
RaMa said:
An interesting reading might also be:
Speciation in reverse: morphological and genetic evidence of the collapse of a three-spined stickleback (Gasterosteus aculeatus) species pair.
as well as this one
Ole Seehausen: Conservation: Losing Biodiversity by Reverse Speciation

Rainer.
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Thanks for sharing - I was unaware of the stickleback study, which seems to be a neat and contained case study in the matter.

The articles seem to have some pretty disconcerting language, at least to me. I don't feel its very scientific to say that species "collapse" into hybrid swarms or that these represent a "tremendous loss of biodiversity." Lost is the fact that in essence, a third new species is created here. Likewise lost is the hypothesis that is begging to be asked - would the two species "create themselves" again if environmental conditions reverted (for example, take the crayfish out of Lake Enos and see what happens to the fish). Perhaps hybridization and speciation are simple reactions to turbidity. Sounds like a juicy M.S. study to me.

It is well established that several species of ferns and some sunflowers have arisen through hybridization events of now-extinct taxa. There is evidence pointing to the origin of the Red Wolf as a hybrid between Coyotes and an extinct taxa of gray wolf. Yet, I've never heard anyone decrying the loss of biodiversity that these species represent.
 
Canary Islands

Rösner, Cimiotti & Brandl (in press). Two sympatric lineages of the Raven Corvus corax jordansi coexist on the Eastern Canary Islands. J Ornithol. [abstract]

Blake & Vaurie 1962 (Peters).

Perhaps I'm misunderstanding, but I don't see how recognition of jordansi Niethammer, 1953 (Fuerteventura) for the eastern Canaries population would result in the 'dropping' of the name tingitanus Irby, 1874 (Tangier, Morocco) for the N African population.
 
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"I don't see how recognition of jordansi Niethammer, 1953 (Fuerteventura) for the eastern Canaries population would result in the 'dropping' of the name tingitanus Irby, 1874 (Tangier, Morocco) for the N African population." They are the same, see, so the old name needs an update, my God it is 2013. There also is C. canariensis from western Canaries by Hartert & Kleinschmidt. (1901) And C. leptonyx Peale (1848) from a Raven which he had shot near Funchal Madiera, but Madiera does not have any ravens?
 
mb1848 said:
There also is C. canariensis from western Canaries by Hartert & Kleinschmidt. (1901)
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Canariensis (1901) could be synonymised with tingitanus (1874), but obviously not vice versa. If tingitanus is 'dropped' then presumably it would be synonymised with corax (1758), which would logically also require geographically intermediate hispanus (1901) to be included.
mb1848 said:
And C. leptonyx Peale (1848) from a Raven which he had shot near Funchal Madiera, but Madiera does not have any ravens?
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According to Clarke 2006 (Birds of the Atlantic Islands), Common Raven is a vagrant to Madeira ("with fewer than five records in the last 50 years").
 
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White-speckled raven

Van Grouw 2014. Some black-and-white facts about the Faeroese white-speckled Common Raven Corvus corax varius. Bull BOC 134(1): 4–13.
SUMMARY.—The white-speckled raven, a colour aberration of the Faroese Raven Corvus corax varius Brünnich, 1764, has occurred in the Faroe Islands since at least the Middle Ages. It has been described in many publications, and was a desired object for collectors of curiosities, especially in the 18th and 19th centuries. Early in the 20th century (1902) the last white-speckled individual was seen in the Faeroes, leaving only about two dozen specimens in museum collections. Although often referred to as albino, the aberration causing the white feathers is not albinism but leucism.
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Johnsen, Kearns, Omland, Anmarkrud. 2017. Sequencing of the complete mitochondrial genome of the common raven Corvus corax (Aves: Corvidae) confirms mitogenome-wide deep lineages and a paraphyletic relationship with the Chihuahuan raven C. cryptoleucus. PLoS ONE.
[whole paper]
 
l_raty said:
Johnsen, Kearns, Omland, Anmarkrud. 2017. Sequencing of the complete mitochondrial genome of the common raven Corvus corax (Aves: Corvidae) confirms mitogenome-wide deep lineages and a paraphyletic relationship with the Chihuahuan raven C. cryptoleucus. PLoS ONE.
[whole paper]
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Laurent,
From the title of the paper, I had hoped for some coverage of the broader Palearctic Raven corax taxa, but I'll just have to wait.

Also, I'm somewhat uneasy that some conclusions are based on but a single sample of ruficollis. Are there grounds for my unease?:stuck:
MJB
 
Alaska Common Raven

Christin L. Pruett, Tianyu Li, and Kevin Winker (2018) Population genetics of Alaska Common Raven show dispersal and isolation in the world's largest songbird. The Auk: October 2018, Vol. 135, No. 4, pp. 868-880.

Abstract:

The Common Raven (Corvus corax) is widespread at high latitudes and a noted disperser to remote islands. We hypothesized that, given their dispersal abilities, Alaskan populations would be genetically similar and maintain genetic diversity across thousands of kilometers. We sampled 134 ravens from 9 areas in Alaska, including 6 populations we considered as mainland and 3 as island (Kodiak, Adak, and Attu islands). Using 8 microsatellite loci, we found that in most Alaskan populations gene flow is sufficient to counter population divergence due to genetic drift. Our dataset suggests that conservatively there are just 2 raven populations in Alaska (K = 2), although the second Aleutian population, from Adak Island, was significantly differentiated, too. The Attu Island population was quite different from the other sampled populations, and it was the only location that neither received immigrants nor sent emigrants to other sampled locations. In addition, a comparison of gene flow models using a Bayesian coalescent approach most strongly supported an Attu Island isolation model. Prior work suggested that the uniqueness of the Attu Island population is due to isolation in a glacial refugium during the last glacial maximum. Postglacial dispersal from the Alaskan mainland has not erased this signal, suggesting that there could be limits to the species' dispersal abilities (i.e. remote colonization is rare). The isolated Attu Island population underwent a substantial decline ∼4 Kya, which roughly coincides with the arrival of the ultimate invasive species, humans. Traditional cultural values suggest that any surmised effect of humans would likely be indirect rather than direct.
 
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