Sally Conyne
Active member
Check out the documentation regarding the restoration of the Mexican Duck to species level at the website - homepage and updates - http://www.worldbirdnames.org/updates.html
Sally
Sally
hah...If I didn't know better I would say someone involved in IOC reads this forum
FYI I never doubted the validity of the Mexican Duck, just for consistency's sake I usually hold off on counting strictly NA species until AOU decides to evaluate them.
Carboneras 1992 (HBW1) and BLI consider oustaleti to have been a hybrid of platyrhynchos and superciliosa ('unstable' according to HBW); and Dickinson 2003 and Drilling et al 2002 (BNA Online) don't even recognise it as a subspecies.If A. diazi is a distinct species wouldn't that mean that Anas oustaleti (the extinct Marianas Mallard) is a distinct species too (and not a subspecies as stated in many current sources)?
Page 30, Mallard Anas platyrhynchos
Beginning with the 5th edition of Clements Checklist, there has been an entry for an extinct subspecies, oustaletti, formerly found on the Marianas Islands. This entry is incorrect, in two different ways. The correct spelling of the name of the subspecies is oustaleti (with only a single 't' in '-leti'). More importantly, this population probably was not a valid subspecies, but instead was a variable hybrid swarm between Mallard and Gray Duck (Anas superciliosa) (see Y. Ysamashina, 1948, Notes on the Marianas Mallard. Pacific Science 2: 121-124). Therefore, this subspecies no longer is recognized, and is deleted from the Clements Checklist.
Okay. But you have to give them credit for drawing aside the curtain and letting us mere mortals into their thought processes. More evidence that the open process of the SACC is going viral?
Speciation is a continuous and dynamic process. Early in speciation, the genomes of incipient taxa are manipulated by evolutionary forces, and identifying their heterogeneous composition can reveal potentially important processes influencing species composition. We conducted genomic scans across the mitochondrial DNA (mtDNA) control region, 3563 autosomal loci, and 172 Z-chromosome loci in the mallard (Anas platyrhynchos; N = 17 individuals) and Mexican duck (A. [p.] diazi; N = 105 individuals from six Mexican and two US states) to disentangle their incipient evolutionary relationship. Between mallards and Mexican ducks, we found discordance in divergence estimates among autosomal (mean ΦST = 0.018), sex-linked (mean ΦST = 0.086), and mtDNA (ΦST = 0.14) markers, and five Z loci and one autosomal locus were more divergent than expected given background levels of divergence. In contrast, divergence in autosomal (mean ΦST = 0.012) and Z-linked markers (mean ΦST = 0.018) were tightly correlated within Mexican ducks, and divergence at only two autosomal loci strongly deviated from background levels. We conclude that speciation between mallards and Mexican ducks is likely proceeding via selection on a few sex-linked markers with large effects, whereas divergence at the remaining genome is the result of genetic drift. These results suggest post-zygotic isolating mechanisms. In contrast, divergence among Mexican duck populations is consistent with isolation-by-distance and large role for genetic drift. These results demonstrate that a large number of loci are necessary to better understand the speciation process between recently diverged taxa and provides a compelling example of the differential roles of selection and genetic drift across genomic regions.
This surprised me!we identified that only four of the 14 specimens originally classified as phenotypic hybrids were truly hybrids.