Anatidae (2 Viewers)

[albertonykus]

Cádiz, M.I., A.N.B. Tengstedt, I.H. Sørensen, E.S. Pedersen, A.D. Fox, and M.M. Hansen (2024)
Demographic history and inbreeding in two declining sea duck species inferred from whole-genome sequence data
Evolutionary Applications 17: e70008
doi: 10.1111/eva.70008

Anthropogenic impact has transitioned from threatening already rare species to causing significant declines in once numerous organisms. Long-tailed duck (Clangula hyemalis) and velvet scoter (Melanitta fusca) were once important quarry sea duck species in NW Europe, but recent declines resulted in their reclassification as vulnerable on the IUCN Red List. We sequenced and assembled genomes for both species and resequenced 15 individuals of each. Using analyses based on site frequency spectra and sequential Markovian coalescence, we found C. hyemalis to show more historical demographic stability, whereas M. fusca was affected particularly by the Last (Weichselian) Glaciation. This likely reflects C. hyemalis breeding continuously across the Arctic, with cycles of glaciation primarily shifting breeding areas south or north without major population declines, whereas the more restricted southern range of M. fusca would lead to significant range contraction during glaciations. Both species showed evidence of declines over the past thousands of years, potentially reflecting anthropogenic pressures with the recent decline indicating an accelerated process. Analysis of runs of homozygosity (ROH) showed low but nontrivial inbreeding, with FROH from 0.012 to 0.063 in C. hyemalis and ranging from 0 to 0.047 in M. fusca. Lengths of ROH suggested that this was due to ongoing background inbreeding rather than recent declines. Overall, despite demographically important declines, this has not yet led to strong inbreeding and genetic erosion, and the most pressing conservation concern may be the risk of density-dependent (Allee) effects. We recommend monitoring of inbreeding using ROH analysis as a cost-efficient method to track future developments to support effective conservation of these species.

 

[Jim LeNomenclatoriste]

Ray M Chatterji, Tracy A Heath, Helen F James, Courtney Hofman, Michael D Sorenson, Janet C Buckner (2024). Dietary specialization drives adaptation, convergence, and integration across the cranial and appendicular skeleton in Waterfowl (Anseriformes).

https://www.biorxiv.org/content/10.1101/2024.09.21.614171v1

Abstract
Convergence provides strong evidence for adaptive evolution as it reflects shared adaptive responses to the same selection pressures. The waterfowl (order Anseriformes) are an ideal group in which to study convergent evolution as they have repeatedly evolved morphotypes putatively correlated with diet (i.e., dabbler, grazer, diver). Here, we construct the most robust evolutionary hypothesis to date for waterfowl and reveal widespread morphological convergence across the order. We quantified the shape of the skull and hindlimb elements (femur, tibiotarsus, and tarsometatarsus) of 118 species of extant waterfowl using geometric morphometrics. Multivariate generalized evolutionary models provide strong support for a relationship between dietary ecology and skull shape, and evidence for convergent evolution across lineages that share dietary niches. Foraging behavior better explained the evolution of hindlimb shape, but diet still contributed significantly. We also find preliminary evidence for integration across all three measured hindlimb elements with each other and with the skull. We demonstrate that dietary ecology drives morphological convergence within waterfowl, that this convergent evolution involves multiple integrated skeletal structures, and that morphological changes are associated with shifts in the rate of phenotypic evolution.

 

[Jim LeNomenclatoriste]

There is a strong possibility that Anas gracilis is a synonym of Anas castanea

Including A. gibberifrons and its subspecies under castanea

 

[Peter Kovalik]

Bakner, N.W., Masto, N.M., Lavretsky, P., Highway, C.J., Keever, A.C., Blake-Bradshaw, A.G., Askren, R.J., Hagy, H.M., Feddersen, J.C., Osborne, D.C. and Cohen, B.S. (2025) Mallard hybridization with domesticated lineages alters spring migration behavior and timing. Ecology and Evolution 15: e70706.
https://doi.org/10.1002/ece3.70706

ABSTRACT
Introgressive hybridization, the interbreeding and gene flow between different species, has become increasingly common in the Anthropocene, where human-induced ecological changes and the introduction of captively reared individuals are increasing secondary contact among closely related species, leading to gene flow between wild and domesticated lineages. As a result, domesticated-wild hybridization may potentially affect individual fitness, leading to maladaptive effects such as shifts in behavior or life-history decisions (e.g., migration patterns), which could influence population demographics. In North America, the release of captive-reared game-farm mallards (Anas platyrhynchos) for hunting has led to extensive hybridization with wild mallards, altering the genetic structure in the Atlantic and Mississippi flyways. We aimed to investigate differences in spring migratory behavior among 296 GPS-tagged mallards captured during winter in Tennessee and Arkansas with varying levels of hybridization. Despite relatively low levels of genetic introgression of game-farm genes, mallards with higher percentages of game-farm ancestry exhibited later departure and arrival times, shorter migration distances, and a tendency to establish residency at lower latitudes. Specifically, for every 10% increase in game-farm genetics, mallards departed 17.7% later, arrived 22.1% later, settled 3.3% farther south, and traveled 7.1% shorter distances during migration. These findings suggest that genetic introgression from game-farm mallards influences migratory behavior, potentially reducing fitness, and contributing to population declines in wild mallards. Our study presents a need for understanding how domestic hybridization effects fitness and behavioral change of other species.

 

[Kirk Roth]

Bakner, N.W., Masto, N.M., Lavretsky, P., Highway, C.J., Keever, A.C., Blake-Bradshaw, A.G., Askren, R.J., Hagy, H.M., Feddersen, J.C., Osborne, D.C. and Cohen, B.S. (2025) Mallard hybridization with domesticated lineages alters spring migration behavior and timing. Ecology and Evolution 15: e70706.
https://doi.org/10.1002/ece3.70706

ABSTRACT
Introgressive hybridization, the interbreeding and gene flow between different species, has become increasingly common in the Anthropocene, where human-induced ecological changes and the introduction of captively reared individuals are increasing secondary contact among closely related species, leading to gene flow between wild and domesticated lineages. As a result, domesticated-wild hybridization may potentially affect individual fitness, leading to maladaptive effects such as shifts in behavior or life-history decisions (e.g., migration patterns), which could influence population demographics. In North America, the release of captive-reared game-farm mallards (Anas platyrhynchos) for hunting has led to extensive hybridization with wild mallards, altering the genetic structure in the Atlantic and Mississippi flyways. We aimed to investigate differences in spring migratory behavior among 296 GPS-tagged mallards captured during winter in Tennessee and Arkansas with varying levels of hybridization. Despite relatively low levels of genetic introgression of game-farm genes, mallards with higher percentages of game-farm ancestry exhibited later departure and arrival times, shorter migration distances, and a tendency to establish residency at lower latitudes. Specifically, for every 10% increase in game-farm genetics, mallards departed 17.7% later, arrived 22.1% later, settled 3.3% farther south, and traveled 7.1% shorter distances during migration. These findings suggest that genetic introgression from game-farm mallards influences migratory behavior, potentially reducing fitness, and contributing to population declines in wild mallards. Our study presents a need for understanding how domestic hybridization effects fitness and behavioral change of other species.

Alert WGAC - clearly Domestic Duck is a split species under BSC.

 

[Mysticete]

Alert WGAC - clearly Domestic Duck is a split species under BSC.

I know you are joking, but honestly it's kind of weird that some of the long-domesticated species aren't treated as different species taxonomically. That is the default for mammals, where the domestic forms have there own scientific name (Canis familiaris, Felis catus, etc)

 

[Kirk Roth]

I know you are joking, but honestly it's kind of weird that some of the long-domesticated species aren't treated as different species taxonomically. That is the default for mammals, where the domestic forms have there own scientific name (Canis familiaris, Felis catus, etc)

Though notably, many of those domestic mammal examples have evolved differences in reproductive behavior and seasonality (while obviously still able to hybridize/intergrade). Mammalian BSC speciation is just different.

Even the oldest domestic birds (e.g. chickens, geese, pigeons) breed readily with "wild stock" of their own species (and many times other species!) with relatively little pre- or postzygotic price to pay.

Here is a fun fairly recent article on the messy, messy origin story of Gallus (gallus) domesticus: Origin of the domestic chicken from modern biological and zooarchaeological approaches

 

[Mysticete]

Though notably, many of those domestic mammal examples have evolved differences in reproductive behavior and seasonality (while obviously still able to hybridize/intergrade). Mammalian BSC speciation is just different.

Even the oldest domestic birds (e.g. chickens, geese, pigeons) breed readily with "wild stock" of their own species (and many times other species!) with relatively little pre- or postzygotic price to pay.

Here is a fun fairly recent article on the messy, messy origin story of Gallus (gallus) domesticus: Origin of the domestic chicken from modern biological and zooarchaeological approaches

I am not sure it has much of anything to do with species concept...domestic cats can and do readily breed with wild cats after all. and we don't know how many species would actually interact with their wild ancestors because they are extinct (Aurochs, Tarpan, wild Dromedary, possibly dog). My understanding is that this move is more something from archaeology, where obviously it is important to be able to distinguish from a wild horse vs a domestic one, since that difference is going to be incredibly important for understanding an ancient culture (or cow, or dog, etc).

 

[Kirk Roth]

I am not sure it has much of anything to do with species concept...domestic cats can and do readily breed with wild cats after all. and we don't know how many species would actually interact with their wild ancestors because they are extinct (Aurochs, Tarpan, wild Dromedary, possibly dog). My understanding is that this move is more something from archaeology, where obviously it is important to be able to distinguish from a wild horse vs a domestic one, since that difference is going to be incredibly important for understanding an ancient culture (or cow, or dog, etc).

You're certainly more of a mammologist than I am, but I know that with cats, for example the less frequent reproductive cycles and relaxed environmental cues for mating in the domestic varieties provide much more of a reproductive barrier than frankly all of the interspecific goings-on between all the ducks, all the geese, all the Gallus, etc.

Regarding archaeology, I don't think your point is unrelated to mine. If a taxon differentiates itself (e.g. due to speciation) then it is relatively easy to determine whether a bone belongs to an Aurochs or an ox, Tarpan or a horse, a dog or a wolf, etc. (without even considering its location with regard to human settlement). I'll concede that cat bones haven't changed all that much!

As the chicken paper points out, and as other studies have shown (I'm thinking Swan Goose especially), it is notoriously more difficult to determine whether bird bones are domestic or wild varieties... because they haven't changed nearly as much as the mammals have.

 

[Mysticete]

Don't disagree with you...although some of the cat differences really are recent. When I prepared a lecture on mammal domestication for my course, I was surprised to see that the various "non-wildcat coat patterns", with maybe the exception of black cats, are from a mutation that only showed up in the middle ages.

Also, random fun fact...one of the folks active in scientific research on the investigation of the origins of the chicken is actually the current crown prince of Japan, who is a PhD'd ornithologist who has published peer-reviewed papers on the topic. He actually visited the museum I was doing research at during my time I was in Tokyo, but I never got to meet him since I was over in Mammalogy.

I dunno...I always found it fascinating that the Imperial royal family has produced multiple professional biologists, versus other modern royal families whose members don't seem to do much other than appear in tabloids.

 

[Peter Kovalik]

Halligan, S.L., M.L. Schummer, A.M.V. Fournier, P. Lavretsky, J.B. Davis, C.J. Downs, and V. Musni (2025) Morphological differences between wild and game‐farm Mallards (Anas platyrhynchos) in North America. Ibis, first published 11 January 2025.

Abstract
Large-scale releases of domesticated, game-farm Mallards Anas platyrhynchos to supplement wild populations have resulted in widespread introgressive hybridization that changed the genetic constitution of wild populations in eastern North America. The resulting gene flow is well documented between game-farm and wild Mallards, but the mechanistic consequences from such interactions remain unknown in North America. We provide the first study to characterize and investigate potential differences in morphology between genetically known, wild and game-farm Mallards in North America. We used nine morphological measurements to discriminate between wild and game-farm Mallards with 96% accuracy. Compared with their wild counterparts, game-farm Mallards had longer bodies and tarsi, shorter heads and wings, and shorter, wider and taller bills. The nail on the end of the bill of game-farm Mallards was longer, and game-farm Mallard bills had a greater lamellae:bill length ratio than wild Mallards. Differences in body morphologies between wild and game-farm Mallards are consistent with an artificial, terrestrial life whereby game-farm Mallards are fed pelleted foods, resulting in artificial selection for a more ‘goose-like’ bill. We posit that: (1) game-farm Mallards have diverged from their wild ancestral traits of flying and filter feeding towards becoming optimized to run and peck for food; (2) game-farm morphological traits optimized over the last 400 years in domestic environments are likely to be maladaptive in the wild; and (3) the introgression of such traits into wild populations is likely to reduce fitness. Understanding the effects of game-farm Mallard introgression requires analysis of various game-farm × wild hybrid generations to determine how domestically derived traits persist or diminish with each generation.