African/Eurasian reed warbler (1 Viewer)

Hi everyone,

Can somebody explain me why the IOC included the subspecies ambiguus into the African reed warbler?

It clearly interbreed extensively with the nominal subspecies in Spain and the distribution is contiguous to the nominate subspecies and NOT the closest race of african.
Nowhere I can find genetic data supporting this taxonomic placement.

Only very weak morphological data.

Can someone, maybe involved in compiling the IOC list (awesome work that I am fond of), tell me the rationale, the criterion that was followed?

Thanks a lot,
Have nice time

pietrod said:

Hi everyone,

Can somebody explain me why the IOC included the subspecies ambiguus into the African reed warbler?

It clearly interbreed extensively with the nominal subspecies in Spain and the distribution is contiguous to the nominate subspecies and NOT the closest race of african.
Nowhere I can find genetic data supporting this taxonomic placement.

Only very weak morphological data.

Can someone, maybe involved in compiling the IOC list (awesome work that I am fond of), tell me the rationale, the criterion that was followed?

Thanks a lot,
Have nice time

Click to expand...

I think it has a lot to do with taxa relationships within the whole reed warbler complex being poorly known, many inhabiting remote or little-studied areas. Also, the distributions likewise are often poorly known and sample sizes are often small.

Jens Hering and colleagues are continuing to seek to untangle the relationships, and so perhaps the next few papers will shed greater light upon. It is quite possible that as-yet undescribed taxa remain to be unearthed.

At the moment, it may be that because the final extent and grouping of what comprises 'African Reed Warbler' is far from certain, taxon ambiguus is grouped for convenience until all the putative taxa in Africa are better-known.

Amongst other species, such as in the Yellow Wagtail complex, there are populations of two taxa that can interbreed in only a part of the breeding area they share, and so the mechanisms that are involved are not yet fully understood.

Perhaps Frank Gill will respond to your query with less speculative a response than mine!
MJB

pietrod said:

Hi everyone,

Can somebody explain me why the IOC included the subspecies ambiguus into the African reed warbler?

It clearly interbreed extensively with the nominal subspecies in Spain and the distribution is contiguous to the nominate subspecies and NOT the closest race of african.
Nowhere I can find genetic data supporting this taxonomic placement.

Only very weak morphological data.

Can someone, maybe involved in compiling the IOC list (awesome work that I am fond of), tell me the rationale, the criterion that was followed?

Thanks a lot,
Have nice time

Click to expand...

DD: We tentatively included ambiguous in A. baeticatus based on Olsson et al 2016. Attached.

See Figure 2 and discussion. The clade (ambiguous + minor) + (baeticatus + hallae + cinnamomeus) forms a clade sister to the Eurasian Reed Warbler clade (A. scirpaceus + fuscus + avicenniae).

Given that we chose to split African Reed Warbler from Eurasian Reed Warbler, this arrangement was consistent with one of the taxonomic alternatives suggested by Olsson et al in their concluding paragraph.

“Three alternative classifications would probably be consistent with Gill’s (2014) H02 and de Queiroz’s (2007) unified concept of species. One of
these would be to treat scirpaceus, fuscus and avicenniae as subspecies of A. scirpaceus, and cinnamomeus, hallae and baeticatus together with ambiguus and minor as subspecies of A. baeticatus, based on the basal split in the phylogeny”.

Frank Gill said:

... Olsson et al 2016. Attached.

Click to expand...

Regrettably, it isn't, or if it was, it's fallen off — can you re-attach, please?

Olsson et al. 2016 [here].

l_raty said:

Olsson et al. 2016 [here].

Click to expand...

Excellent, thanks!

Looks like I get a 'heard-only' armchair tick out of it.

pietrod said:

Hi everyone,

Can somebody explain me why the IOC included the subspecies ambiguus into the African reed warbler?

It clearly interbreed extensively with the nominal subspecies in Spain and the distribution is contiguous to the nominate subspecies and NOT the closest race of african.
Nowhere I can find genetic data supporting this taxonomic placement.

Click to expand...

have you taken a look at the paper that IOC cites as their reference for this action?:

Olson, U., H. Rguibi-Idrissi, J. L. Copete, J.L. Arroyo Matos, P. Provost, M. Amezian, P. Alströn, and F. Juguet. 2016. Mitochondrial phylogeny of the Eurasian/African reed warbler comples (Acrocephalus, Aves). Disagreement between morphological and molecular evidence and cryptic divergence: a case for resurrecting Calamoherpe ambigua Brehm 1857. Molecular Phylogenetics and Evolution 102: 30-44.

Thank you for all the replies. It was great you took the time.

I probably I was not clear enough. Before writing my previous post I read the great work of Olsson at al. 2016 and from that I concluded that the relationships are far from being clearly established.
The weakest knot in figure 2 is the basal one for the african reed warbler, with a really low support. This puts the entire clade under question and I would expect that in this case morphology, biogeography and the rest of the analysis should try to back this up.
Looking at figure 1 of the same paper we can see that there is gene flow between ambiguus and the nominal subspecies besides the contiguous range and the lack of morphological (very little) and behavioural differences.

In fact the authors write:
"The sister relationship between the Ibero- African clades (4–5) and the remainder of the African populations, to the exclusion of the northern (clades 1–3), is weakly supported and uncertain."

The authors also write, just before what Frank Gill quoted:
"We see four main taxonomic alternatives based on the present
knowledge. The most conservative approach, consistent with Gill’s (2014) H01 based on the BSC, would be to consider all taxa as sub- species of A. scirpaceus."

And after the discussion of the alternatives they conclude:
"we tentatively recommend the most conservative approach, considering all taxa as subspecies of A. scirpaceus."

Why then we should split African Reed Warbler from Eurasian Reed Warbler if the data that we have so far do not support it?
And if it was chosen to wait further data before lumping African and Eurasian why meanwhile a sub-optimal loosely supported solution was taken?

Thanks a lot for any reply.
Honestly I am just curious about the rationale behind a choice, I have no doubt that there is not a perfect answer to this dilemma.

I also admit that I am personally a little biased because I think that we went too far with splitting and we should reconsider some choices that are not backed up by solid data. However I tried to write my post in the most objective way I can.
Species is a concept that more you investigate less meaning it has but it is a useful concept and pushing it too far it is dangerous.

PS=sorry for the long post