[Taxacom] 75% rule for subspecies recognition

Adam Cotton adamcot at cscoms.com
Mon Jul 4 04:08:22 CDT 2011

----- 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

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


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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