[Taxacom] New lizard species
Robin Leech
releech at telusplanet.net
Sat Jun 5 18:01:23 CDT 2010
2010
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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> The Taxacom archive going back to 1992 may be searched with either of
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>
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>
> Or (2) a Google search specified as:
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