Species delimitation (2 Viewers)

[Richard Klim]

Carstens et al

Most of the discussion is way beyond my limited intellectual reach! But I wonder what the authors would make of the rather simple species delimitation criteria adopted by BOU (Helbig et al 2002) and BirdLife (Tobias et al 2010) for application to avian taxa (possibly influenced by listing and conservation considerations respectively)? Anyway, it's evident that avian taxonomy is currently characterised by authors rather casually suggesting species status for particular taxa, often without even stating the species concept being applied.

 

[StevePreddy]

Most of the discussion is way beyond my limited intellectual reach!

Richard, honestly, it's not. I haven't read the whole paper yet, but the abstract says two simple things:

a) use as many of the methods that you have available to you as you can, and the more of them that give the same answer, the better your level of confidence can be in that answer

b) if you use a lot of methods and they don't agree, don't propose any changes from the status quo, no matter how badly the status quo reflects the evidence

The first is sensible and uncontroversial. The second is just a statement of the authors' political views, not a piece of science.

 

[Richard Klim]

Sangster 2013

Sangster (in press). The application of species criteria in avian taxonomy and its implications for the debate over species concepts. Biol Rev. [abstract]

V. CONCLUSIONS

(1) Contrary to widely held beliefs, avian taxonomy has not been dominated by the Biological Species Concept. The special position of the Biological Species Concept in debates over species concepts in taxonomy is therefore not warranted.

(2) Diagnosability was the most frequently applied taxonomic criterion, followed by reproductive isolation and degree of difference.

(3) In ornithology, species are recognised on the basis of several criteria that are used in at least 36 different combinations. It is argued that the Biological/Phylogenetic Species Concept distinction is a false dichotomy, which obscures how species are actually delimited.

(4) Several predictions of the Evolutionary or General Lineage Concept of Species are supported by this study: species-level taxonomy is pluralistic and eclectic; taxonomists apply different criteria as complementary rather than as rival approaches to species delimitation; and none of the taxonomic criteria are considered as defining (necessary and sufficient) for recognition as species. Taxonomic practice is more unified than is implied by the controversy over species concepts. Thus, there are good reasons to 'get over' ideological divisions between seemingly alternative concepts of species.

(5) There have been no large or sudden shifts in the use of diagnosability in the second half of the 20th century. The results of this study, therefore, do not support claims that the introduction and application of the Phylogenetic Species Concept has changed the 'nature' of species.

(6) Diagnosability was more often involved in proposals for additional species than reproductive isolation but the difference was small. Proposals based on diagnosability and reproductive isolation were equally often adopted in a mainstream taxonomic reference work. There do not seem to be major differences between these concepts in the degree by which they enhance (or threaten) taxonomic stability.

(7) Theoretically oriented debates over species concepts may benefit from empirical data on taxonomic practice.

 

[MJB]

Sangster (in press). The application of species criteria in avian taxonomy and its implications for the debate over species concepts. Biol Rev. [abstract]

There's a hefty dig in conclusion 7, methinks!:eek!:
MJB

 

[StevePreddy]

Sangster (in press). The application of species criteria in avian taxonomy and its implications for the debate over species concepts. Biol Rev. [abstract]

I found some time to read this yesterday evening, and it's well worth a look. Essentially it builds on George's 2009 paper on "taxonomic progress" with further insights. There are precious few publications out there which look at this subject empricially, rather than just being based on personal opinion, so full marks to George for what he's done. Some might see it as agenda-pushing, but the challenge to those people is to come up with data which refute George's conclusions.

 

[Richard Klim]

Kunz 2012

Kunz 2012. Do Species Exist?: Principles of Taxonomic Classification. [Wiley-Blackwell] [Amazon]

From the Amazon preview, looks quite interesting.

 

[pianoman]

Do you think it would be fair to say that organisms tend towards forming discrete species but, due to changing environments, never quite get there?

I think Darwin himself got it more or less right in Origin by saying that essentially there is one species per niche (and a niche can be very small and specific). You're either the best adapted to that niche or not - and second best eventually has to give way to the best. So all the inhabitants of a particular niche are eventually going to be closely related - in other words, a species

 

[Richard Klim]

Edwards & Knowles 2014

Edwards & Knowles 2014. Species detection and individual assignment in species delimitation: can integrative data increase efficacy? Proc R Soc B 281(1777): 20132765. [abstract] [pdf]

(Tested on a lizard species complex, but relevant to this topic.)

 

[MJB]

Edwards & Knowles 2014. Species detection and individual assignment in species delimitation: can integrative data increase efficacy? Proc R Soc B 281(1777): 20132765. [abstract] [pdf]

(Tested on a lizard species complex, but relevant to this topic.)

The core of this approach (from the abstract) is:
"Given the variety of speciation mechanisms, singular data may not adequately represent the genetic, morphological and ecological diversity relevant to species delimitation."

From the Discussion section near the end the same essential point is made (and in poor English):
"Methodological advances have brought necessary statistical rigor to species delimitation, however, the use of singular data may misrepresent diversity."

(It should read "...to species delimitation. However, the use...")

The value of the Edwards and Knowles approach, assuming its principles remain valid when tested with other organisms such as birds, is well-expressed:
"Our integrative method narrows the parameter space where species are undetected in species groups differentially diverging along multiple axes, by allowing a statistically integrative approach to species detection and individual assignment that can be validated using statistical species delimitation. The use of integrative data also provides cohesiveness between species detection and description in an integrative taxonomy. Furthermore, our method requires the user to carefully consider sampling design and which data-types are used by considering the axes of divergence within the group being assessed, therefore allowing for variance in the potential mechanisms driving speciation."

Perhaps the main problem that twitchers and birders generally may have as a consequence, is that they might have to take a course in understanding the origins of the techniques employed, and pass the exam at the end before they can decide what to 'tick'!:eek!:
MJB

 

[Richard Klim]

Watson 2005

Watson 2005. Diagnosable versus distinct: evaluating species limits in birds. BioScience 55(1): 60–68. [pdf]

[via BOU (IBIS_journal) on Twitter]

 

[l_raty]

Watson 2005. Diagnosable versus distinct: evaluating species limits in birds. BioScience 55(1): 60–68. [pdf]

In case anyone would want to see it: the online material referenced in the paper (two .xls files, on the website of the author's institution) cannot be accessed via the published url anymore, but is now at http://www.csu.edu.au/ses/staff/profiles/academic-staff/david-watson (click on the "Publication" tab).

Related:
Collar NJ, Spottiswoode CN (2005) : Species Limits in Birds: A Response to Watson. BioScience 55 (5): 388-389. [Free access here.]
Watson DM (2005) : Response from Watson. BioScience 55 (5): 389. [Free access here.]

(BioScience was recently transferred to OUP, and is currently freely accessible on the new website of the journal.)

 

[Richard Klim]

Sangster 2014

Sangster (in press). The application of species criteria in avian taxonomy and its implications for the debate over species concepts. Biol Rev. [abstract]

Now open access: Biol Rev 89(1): 199–214. [pdf]

 

[MJB]

Now open access: Biol Rev 89(1): 199–214. [pdf]

All I get is a blank page headed 'Wiley' when trying that link, Richard.
MJB

 

[l_raty]

Mike,

All I get is a blank page headed 'Wiley' when trying that link, Richard.

I don't know what you use to browse the web, but this likely means that your program is configured to save pdf files in a default directory. You should find the file there. (It will be named brv12051.pdf)
Wiley does not allow direct linking to the pdfs themselves, you have to go through this page if you want to save the file on your disk. Alternatively you can read an html version of the paper at: http://onlinelibrary.wiley.com/doi/10.1111/brv.12051/full

 

[MJB]

Mike, I don't know what you use to browse the web, but this likely means that your program is configured to save pdf files in a default directory. You should find the file there. (It will be named brv12051.pdf). Wiley does not allow direct linking to the pdfs themselves, you have to go through this page if you want to save the file on your disk. Alternatively you can read an html version of the paper at: http://onlinelibrary.wiley.com/doi/10.1111/brv.12051/full

Laurent,
Many thanks for this info. As it happens (and I tried about six times before I wrote the above message), I tried about five hours later and everything worked fine instantly!
MJB:king:

 

[Richard Klim]

Wiley Online Library

Over the years, the Wiley Online Library website has been prone to frequent periods of very slow response, verging on unusable – which I've reported to them (moaned about) on a couple of occasions. I tend to go away and try an hour or so later. It's often been very slow in recent weeks – probably not helped by the fact that its journals are now being encouraged to include multiple sexy graphical images for each paper in the contents summary (We can, so we will!). Progress?

 

[Richard Klim]

Löbl 2014

Löbl 2014. Overestimation of molecular and modelling methods and underestimation of traditional taxonomy leads to real problems in assessing and handling of the world's biodiversity. Zootaxa 3768(4): 497–500. [preview]

 

[aegithalos]

Over the years, the Wiley Online Library website has been prone to frequent periods of very slow response, verging on unusable – which I've reported to them (moaned about) on a couple of occasions. I tend to go away and try an hour or so later. It's often been very slow in recent weeks – probably not helped by the fact that its journals are now being encouraged to include multiple sexy graphical images for each paper in the contents summary (We can, so we will!). Progress?

You may have a point there. Earlier today, I experienced what I thought was a very slow download of an article from a Wiley Online journal. When I finally got it, it turned out to be 18MB for a very ordinary 13 pages! The download wasn't slow - the file size was huge, which can only have been due to, as you put it, 'sexy graphical images'.

There is a reason online supplementary material was invented.

Cheers,

Keith

 

[Richard Klim]

Gill 2014

Gill 2014. Species taxonomy of birds: Which null hypothesis? Auk 131(2): 150–161. [abstract]

 

[Peter Kovalik]

Gill 2014. Species taxonomy of birds: Which null hypothesis? Auk 131(2): 150–161. [abstract]

"Many thanks to the following colleagues who greatly
improved this manuscript: David Donsker, Douglas Futuyma,
Douglas Gill, Peter Grant, Richard Klim, Scott Lanyon, Town
Peterson, Douglas Pratt, Pamela Rasmussen, Robert Zink, and
two anonymous reviewers."
:t: