New Zealand dotterels

[Ian Southey]

This one's a surprise to me so it will be interesting to see how it stacks with future work.

http://www.plosone.org/article/info%3Ad ... ne.0078068

Ian

[Michael Szabo]

Thanks for posting the link, Ian. It gives "a Middle to Late Pleistocene divergence of the two New Zealand Dotterel subspecies" which would presumbly be somewhere between 1.25 mya and the end of the Pleistocene c12,000 years ago - ie, in a time period within which some of the NZ kakariki speciated. As you say, Ian, this is definitely one to watch as a potential candidate for splitting.

Michael

[Ian Southey]

The younger end given for the date on the divergence of the NZ Dotterel subspecies is only 3000 years which is well post Pleistocene.

The big eye opener for me was the fact that New Zealand Dotterels, Banded Dotterels and Wrybills all derive from a single common ancestor as the morphology and calls seem quite different. The mid Miocene origin for this group comes soon after the start of the recent mountain building period so it is plausible and it shows significant local evolution. It also means likely that Anarhynchus will no longer be a valid genus name for Wrybill.

Ian

[Michael Szabo]

Yes, that's very interesting. Previously, Thomas et al (2004) said: "The distinctive Wrybill (Anarhynchus frontalis) is the sole member of an endemic NZ genus, which is sister to an Australian species (Peltahyas australis = Charadrius australis or Inland Dotterel). Despite current taxonomic distinction, the Anarhynchus⁄Peltahyas clade originated as recently as the mid-Pliocene."

Thomas, G.H., Wills, M.A. & Szekely, T. 2004. A supertree approach to shorebird phylogeny. BMC Evol. Biol. 4: p. 28.
http://www.biomedcentral.com/1471-2148/4/28

This study also placed diademed plover, Eurasian dotterel, NZ shore plover and hooded plover close to wrybill.

Michael

[Ian Southey]

The super tree does not have such fine resolution at species level. Also the way they line up the names on the right does not indicate relationship it is shown by the branching pattern. Many of the species come off the same base line with a pattern that looks like a comb. These indicate unresolved nodes. The ideal level of resolution is a simple split into two branches. The placement of Wrybill thus is not resolved in this tree beyond a very general grouping and some of the species vary. The next thing to look for is consistency as different strips of DNA and different methods of analysis can give different results unless they are well founded. The last thing you can do is just look at the birds and consider what else you know and try the believability test.

While I'm always keen to see more results the first paper is the more convincing to me because they found a similar pattern of relationships indicated by the behavioural data in an earlier study. Ironically I did not take those results seriously then as I have always thought of these as three very different birds.

Although these results showing substantial radiations within New Zealand over this time period are not really surprising now, I was raised on Charles Fleming's biogeography so I find these studies indicating a deeper history to our birds to be fascinating.

Ian

[Michael Szabo]

Yes, it will be interesting to see what the relationship was between the common ancestor and Australian wader species.

Michael

[Ian Southey]

A quick and dirty biogeographic summary has two main groups.

The earliest branches of the first group are some odd South American species with the Eurasian Dotterel as an offshoot and then a group of mainly North American species with coloured bills but including Ringed Plover and from them come the Shore Plover, Black-fronted Dotterel and Hooded Plover so that's a little radiation across the Tasman Sea. They put the Little Ringed Plover in this group too but that surely must be misplaced. Incidentally if the these three are a good group then a name change will be required - either all in Thinornis or another genus for the hoodies.

The second group has all of the lapwings and all of the rest of the dotterels in separate groups. The oldest branch among the dotterels is Red-kneed, which some regard as a lapwing, then the Australian Inland Dotterel, next some Asian migrant species, then the New Zealanders, then the Kentish Plover group, then a bunch of mainly North and South American species which includes the Australian Red-capped Dotterel and the African Kittlitz's Plover.

North and South America pop up a lot especially in the oldest splits in the first group so it looks like many of the groups have spread from there - maybe along the shores of Antarctica in kinder times. On the other hand in the second group the oldest lapwing in the tree is the Australian Spur-winged Plover and the earliest splits among the other plovers are Red-kneed and Inland Dotterels so Australia could have been important to the early radiation of this group but leaving few modern species behind.

It's a bit of a guessing game and don't forget there are species not included in the tree which might change the story and some of the data may be misleading but the groupings seem to be more or less sensible to me - whatever that means!

Ian

[Murray Lord]

Here the split is being formally proposed: http://www.birdlife.org/globally-threat ... hreatened/

[Ian Southey]

Interesting consequences if the local checklist committee follow this lead. There would seem to be several groups of subspecies that are at least as well defined as these birds - tomtits and fantails would be two of them. This could mean that eventually we are going to consider most, if not all of our birds as species.

Not that I can't see good reasons for regarding the two dotterels as different birds but the description, as I remember it, seems to hang on the tone of colouring above and below, different mid toe length, alpine vs coastal breeding and a few other natural history traits that might just reflect how incredibly soggy the tops on Stewart Island are.

Ian

[Ian Southey]

Here's another DNA study of the plovers found on Birdforum- scroll to page 114 for the tree.

http://api.viglink.com/api/click?format ... e%20thesis

There is some good agreement with Barth et al regarding the grouping of the Wrybill, Banded and New Zealand Dotterels - we may have to take that one seriously. This means it is an interesting endemic adaptive radiation as these birds seem quite different in some ways.

The placement of Shore Plover also has some similarities but this bit of the tree is not so clear. It makes more sense if you cut out the Eurasian Dotterel (morinellus) and if forbesi had gone next to tricollaris - both African species that look the same. Doing that you get some African and Asian species (including Little Ringed Plover) as ancestors to Shore Plover, Hooded Dotterel and presumably also Black-fronted Dotterel which doesn't appear to be included.

Another interesting one is the Australian Red-capped Plover which does not seem to belong to the Kentish Plover group in either tree but still looking for a good home.

There is quite a bit of consistency in species groupings in these two studies but we're not there yet.

Ian