[Taxacom] New lizard species

[Kim van der Linde]

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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