[Taxacom] New lizard species

Sat Jun 5 22:19:16 CDT 2010

That is very well possible. It could be a population on the verge of 
splitting, they might even have developed mating barriers and be real 
cryptic species to be distinguished by bar-coding like two Zaprionus 
species of the same region: Yassin, A., Capy, P., Madi-Ravazzi, L., 
Ogereau, D. & David, J. R. (2008). DNA barcode discovers two cryptic 
species and two geographical radiations in the invasive drosophilid 
Zaprionus indianus. Molecular Ecology Resources 8, 491-501.

Or it is a solid case of oversplitting that has nothing to do with 
speciation and everything to do with isolated populations, insufficient 
sample sizes etc.

Who knows?

Kim

On 6/5/2010 7:01 PM, Robin Leech wrote:
> Or, it could be that they just have not looked carefully enough for
> morphological characters. My suggestion is to give the specimens,
> several from each DNA group, to a lizard taxonomist.
> On several occasions I have looked at collections of spiders and at
> first glance figured that they were all representatives of the same
> species.
> but, when I sorted according to locality, then looked again, I did find all
> the morphological characters I needed. I am sure that most morphological
> taxonomists have had this experience.
> And I will acknowledge that these lizards might represent a population that
> is on the verge of splitting - has done so with DNA, but has not done so
> yet
> with morphology.
> Robin
>
> ----- Original Message ----- From: "Kim van der Linde" <kim at kimvdlinde.com>
> To: "Robin Leech" <releech at telusplanet.net>
> Cc: "TAXACOM" <taxacom at mailman.nhm.ku.edu>
> Sent: Saturday, June 05, 2010 2:55 PM
> Subject: Re: [Taxacom] New lizard species
>
>
>> Yes, that would be a way out of it, but they state explicitly that there
>> are no morphological or ecological difference. So, we have four lineages
>> described as species.
>>
>> Kim
>>
>> On 6/5/2010 4:40 PM, Robin Leech wrote:
>>> Why don't we take the individuals that have solid DNA differences,
>>> then when these are sorted, start looking for external morphological
>>> characters that confirm the DNA?
>>> Robin
>>> ----- Original Message -----
>>> From: "Kim van der Linde"<kim at kimvdlinde.com>
>>> To: "TAXACOM"<taxacom at mailman.nhm.ku.edu>
>>> Sent: Saturday, June 05, 2010 12:26 PM
>>> Subject: Re: [Taxacom] New lizard species
>>>
>>>
>>>> I just read the article, and I have mixed feeling about the article.
>>>>
>>>> 1. The central idea is that we can determine species limits by
>>>> estimating where solid differences in the DNA can be found, as
>>>> estimated
>>>> using specific Bayesian methods.
>>>>
>>>> 2. The species concept used here is a strict phylogenetic species
>>>> concept. Whether or not this corresponds with species using the
>>>> biological species concept is unclear.
>>>>
>>>> 3. The number of individuals used for some populations is as low as
>>>> one.
>>>> if you have a single outlier. Humm, so much for an estimate of
>>>> population variance, which is at the heart of the idea.
>>>>
>>>> 4. The use of guid trees is problematic at least. Why 4 species, and
>>>> not
>>>> 5, 6 or 3. If you a priori start with 4, you of course can find
>>>> four. As
>>>> long as you have well-supported nodes with a posterior probability
>>>> of 1,
>>>> you can determine species. The fact that the 10-species guide tree
>>>> provides FIVE species should have resulted in major alarm bells.
>>>>
>>>> 5. They use the SAME data to first estimate the species, and then to
>>>> estimate the probability of those species. This is a circular process.
>>>> You need two separate data sets to do this. This sounds way to much to
>>>> self-conformation.
>>>>
>>>> Overall, I am not buying this article. Maybe when it is done properly,
>>>> with sufficient number of individuals per population, independent data
>>>> sets and a search algorithm that determines what number of species is
>>>> actually explaining the data the best, I might be persuaded to accept
>>>> these phylogenetic species, in the context of phylocode.
>>>>
>>>> Kim
>>>>
>>>>
>>>> On 6/4/2010 8:19 PM, Bob Mesibov wrote:
>>>>> If you haven't seen it, do read
>>>>>
>>>>> Leache, A.D. and Fujita, M.K. 2010. Bayesian species delimitation in
>>>>> West African forest geckos (Hemidactylus fasciatus). Proceedings of
>>>>> the Royal Society B. Published online as doi:10.1098/rspb.2010.0662
>>>>>
>>>>> In a well-argued and very clear paper, the authors plump for
>>>>> probabilistic determination of species, and name four *Linnean*
>>>>> species on probabilistic grounds. They say '...we are not aware of
>>>>> any morphological or ecological characteristics that differentiate
>>>>> these lineages,' and therefore diagnose their species as follows (one
>>>>> example):
>>>>>
>>>>> 'Diagnosis. This species includes all populations that cluster with
>>>>> those from the southern portion of the Congolian rainforest included
>>>>> in this study (southern Cameroon, Gabon and Congo), with strong
>>>>> support in the Bayesian species delimitation model.'
>>>>>
>>>>> I don't actually have a problem with the methods used or the
>>>>> argument. My concern is that the authors confuse Linnean species with
>>>>> lineages. Lineages can be diagnosed within a probabilistic framework.
>>>>> They give us an insight into how evolution might possibly have
>>>>> happened. Linnean species are those nice, easily recognised things
>>>>> that enable us to retrieve biodiversity information, write field
>>>>> guides and feel that we have a handle on natural history.
>>>>>
>>>>> It's been obvious for a long time that Linnean taxonomy and molecular
>>>>> taxonomy were headed in different directions, but this paper (IMO) is
>>>>> a clumsy attempt to yoke them back together.
>>>>
>>>> --
>>>> http://www.kimvdlinde.com
>>>>
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>>>
>>>
>>>
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>>
>> --
>> http://www.kimvdlinde.com
>>
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