[HELICONIUS] Fwd: Re: Heliconius erato x melpomene genetic distance

[Jim Mallet]

>Date: Mon, 13 Mar 2006 19:37:23 +0000
>To: Evan Braswell <wbraswel at nmsu.edu>
>From: Jim Mallet <j.mallet at ucl.ac.uk>
>Subject: Re: Heliconius erato x melpomene genetic distance
>
>Dear Evan,
>
>Please be aware that H. erato does not hybridize with H. melpomene, as you 
>suggest!  Instead, my studies were done on a pair of hybrid zones between 
>RACES of Heliconius melpomene, and RACES of H. erato.
>
>I never published these estimates, that's why you can't find them!  As you 
>will see, the results are rather boring, so didn't seem worth publishing 
>at the time. The low estimates of Nei's D (~0.001) are mentioned in my 
>chapter in the Endless Forms book (Mallet, J., Jiggins, C.D., & McMillan, 
>W.O. (1998). Mimicry and warning colour at the boundary between races and 
>species.  In  Howard, D.J. & Berlocher, S.H. (eds.) Endless Forms: Species 
>and Speciation.  Oxford University Press. pp.390-403).
>
>There are essentially no gene frequency differences between the 
>colour-pattern races, in either species, and we certainly found no fixed 
>differences.  However, we are now doing molecular analyses with 
>microsatellites and mtDNA and nuclear sequence data in the same hybrid 
>zones, and so I'll probably publish these negative estimates properly 
>soon, believe it or not (after around 20 years!).
>
>Here are the estimates based on allozymes across the Peru hybrid zones:
>
>Heliconius erato Nei's (1978) D: 0.0034 (based on 32 loci)
>Heliconius melpomene Nei's (1978) D: 0.0015 (based on 27 loci)
>
>However, most of even this tiny genetic distance is explained by real much 
>more local differentiation (Fst) between local populations. There were no 
>fixed differences, and the overall Fst (Weir Cockerham measures) among 
>local populations (i.e. over all populations on both sides of the hybrid 
>zone) are as follows:
>
>erato Fst = 0.038  (for 14 polymorphic loci)
>melpomene Fst = 0.094 (for 10 polymorphic loci)
>
>Chris Jiggins et al. (Jiggins,CD; McMillan,WO; King,P; Mallet,J (1997): 
>The maintenance of species differences across a Heliconius hybrid zone. 
>Heredity 79, 495-505) also studied a hybrid zone between Heliconius erato 
>and its "semispecies" H. himera, and this gave a higher Nei's D of around 
>0.28.  The Nei's D measured for comparison between H. erato races in that 
>paper were between non-adjacent races, so the values of interracial D in 
>that paper were slightly higher than the ones I give above, presumably due 
>to isolation by distance.
>
>You do know, don't you, that Nei's D is a particularly horrible distance 
>measure, since the more alleles you have at a locus, the lower the 
>distance, even for a given level of Fst!  This problem pointed out in 
>Swofford,DL; Olsen,GJ (1990): Phylogeny reconstruction. In: Molecular 
>Systematics. (Eds: Hillis,DM; Moritz,C) Sinauer, Sunderland, Mass, 411-501.
>
>Hope this helps!
>
>Jim
>
>At 00:58 13/03/2006, you wrote:
>>Dr. Mallet,
>>
>>Dan Howard and I are writing a review article on hybrid zones and their 
>>spatial
>>structures.  We would like to include your work on the Heliconius erato x
>>melpomene hybrid zone in this review.  One piece of data we are trying to 
>>obtain
>>for each hybrid zone is the genetic distance between the hybridizing 
>>species (or
>>sub-species).  Do you have this information easily available to you or 
>>can you
>>direct me to the paper in which the information is contained?
>>
>>Thank you in advance for you help,
>>
>>Evan
>>
>>--
>>W. Evan Braswell
>>Laboratory of Ecological
>>and Evolutionary Genetics
>>New Mexico State University
>>Las Cruces, NM 88003
>
>James Mallet
>http://www.ucl.ac.uk/taxome/jim/

James Mallet
http://www.ucl.ac.uk/taxome/jim/