[Taxacom] 75% rule for subspecies recognition

[bckcdb at istar.ca]

Quoting Adam Cotton <adamcot at cscoms.com>:

> ----- Original Message -----
> From: "Oliver Hawlitschek" <oliver.hawlitschek at gmx.de>
> To: <taxacom at mailman.nhm.ku.edu>
> Sent: Monday, July 04, 2011 3:30 PM
> Subject: [Taxacom] 75% rule for subspecies recognition

>>
>> I have a question concerning the 75% rule for subspecies recognition.

* hasn't the "75% subspecies" been extinct since Wilson and Brown  
debunked it in 1954? And didn't multivariate morphometrics in the  
1970s show that generally, with a moderate number of characters,  
*populations* could generally be distinguished at the 75% level? I'm  
in the field now, and won't have time to reply extensively, but I'd  
say that the subspecies concept is useful only when there's evidence  
that proposed subspecies are real entities, as evidenced by a  
multivariate break in variation, or increased variation due to  
hybridization, where they come into contact.

fred schueler
=========================================================

>> It
>> says that a subspecies should be considered valid if 75% or more of a
>> certain sample of individuals (a potential subspecies or operational
>> taxonomic unit) can be distinguished from 99% of all other individuals of
>> the same species according to the characters examined (Amadon 1949, Mayr
>> et al. 1953, Patten and Unitt 2002).
>>
>> How could I handle a case of sexually dimorphic species in which only
>> males can be recognized at subspecies level, but not females? Does that
>> mean that <50% of the species can be recognized and the subspecies should
>> be dismissed (<75%), or could I restrict the 75% rule to the
>> distinguishable sex (males)? I would be happy to read of any examples of
>> similar cases.
>>
>> Thanks
>>
>> Oliver Hawlitschek
>> Bavarian State Collection of Zoology
>> Muenchhausenstr. 21
>> 81247 Munich
>> Germany
>> +49-89-8107-115
>>
>>
>
> Oliver,
>
> This is an interesting question, since I also work on taxa with sexual
> polymorphism. However, I do not think there is a binding 75% rule anywhere,
> rather it is a guideline for good practice in defining subspecies.
>
> Certainly if most or all males of one population clearly differ from those
> of another locality there are good grounds for regarding them as distinct
> subspecies, but acceptance is as always in the purview of the users of the
> name and it could be synonymized by the next person who works on these taxa
> if they disagree.
>
> Adam Cotton.
>
>
>
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