[HELICONIUS] K.S. Brown and C. Jiggins on gene flow between spp

[Jim Mallet]

Hello everyone.  This was bounced from the Heliconius mailing list -- I am 
not quite sure why.  As it contained rather a complex email conversation, I 
have edited it to provide better clues for clarity and authorship.  Please 
try to keep emails simple, and if necessary edit them for clarity yourself. 
Email quotation marks often get garbled in ASCII records of the emails.

Jim M
_______________________________
Hi All,
I hope I am not filling your inbox with unwanted email, but I thought this 
message from Keith Brown, which he suggested I forward to the list, might 
be of interest - some history and biology of Brazilian species.  Also below 
is my response to his comment on the gene flow papers.

Following up on Jim's posting about his interaction with Jerry Coyne 
regarding our Heliconius heurippa paper, I recently had a brief chat with 
Jerry about this at the speciation meeting in Vancouver.  He said that he 
remains sceptical about the genetic data and in particular the gene 
networks as being evidence for hybrid origin (we would agree that this is 
the area where more data is needed), but the mating studies look sound.  So 
his views are not as damning as they seemed earlier (or perhaps he was 
being polite, but that maybe that is unlikely!).

Cheers
Chris Jiggins


From: "Keith Spalding Brown Jr" <ksbrown at unicamp.br>
Date: 28 July 2006 19:07:37 BDT
To: "'Chris Jiggins'" <chris.jiggins at ed.ac.uk>
Subject: RES: RES: [HELICONIUS] Evolution cover

Hi Chris,
I admit that I enjoyed your strong response to my complaints.
Perhaps I am still stuck back in Simla where Jocelyn Crane started
monkeying around with these species, their boundaries, and their babies
in the 50s.  Since I was persuaded by her to start looking at Brazilian
species in cages, I set up the second butterfly house in Rio de Janeiro;
Luis Otero, who sadly died last month after a lifetime of captive
breeding experiments including many butterflies and moths, was already
working on this at that time.  He discovered some amazing natural
crosses and sibling species and all the other things that make us
mortals trip along the rocky way, but published very little.  I believe
that he found our "cydno" (H. besckei, hard to rear in captivity,
montane habitats) somewhat compatible with melpomene (that is very rare
here and almost never co-occurs with besckei) and both with silvaniforms
- where is the next step?  H. nattereri is too wild and rare to try to
tame and work with (we attempted a few times, and Luis Otero also tried
with all his detailed training in Japan; adults may need to pollinate
certain treetop bromeliad flowers in order to survive, and I don't know
where this character fits into our matrices and phylogenies).  H.
ethilla and numata have made their peace by habitat use factors
including flight level, but there are two more silvaniforms in some
sites.  H. luciana also seems to wedge into this mess from an unexpected
direction (Amazon wet-field obligate), and what do you do with atthis?

On another front, I had very little difficulty in crossing swallowtails,
even across tribal barriers!!  Want to blow a computer fuse someday? -
map out the genes for the interaction of behavior and morphology in some
of these misbehaved bugs.  They will still make all of us feel
vanquished on several fronts, I fear.

Best wishes (send this along if you wish),
Quitibrão


-----Mensagem original-----
De: Chris Jiggins [mailto:chris.jiggins at ed.ac.uk]
Enviada em: sexta-feira, 28 de julho de 2006 13:03
Para: Keith Spalding Brown Jr
Assunto: Re: RES: [HELICONIUS] Evolution cover

KB: Thanks for keeping me up on new results.  I have only one
important objection, which is that the field hybridization between
melpomene and cydno already persuaded most of us in the 50s that they
were in sister lineages. Gene by gene, Larry Gilbert and his students
have been pretty successful in demonstrating this leaky boundary under
many different conditions and in many different places; something we
used to attribute, at least, to sister species status.

CJ: Hi Keith,

I quite agree that this data from Larry, yourself and others makes it
very unsurprising that genetic information is exchanged between
Heliconius species such as melpomene and cydno.  Indeed, most Heliconius
biologists would probably be far less surprised about this than other
evolutionary biologists precisely because we have been able to see the
wild and lab hybrids.  However these results are novel because the
existence of hybrids does not necessarily imply that substantial genetic
information is exchanged as a result of this process (it might be that
hybrid sterility and other forms of incompatibility actually prevent
gene exchange even though backcross hybrids are occasionally produced).

The fact that we can observe significant and recent gene exchange just
by sequencing a tiny fraction of the genome (a few thousand base pairs
out of 300 million bases or so in the genome) means that it is actually
a massively significant force presumably across a very large fraction of
the genome.  Given the large ecological, behavioural and morphological
differences between melpomene and cydno, I actually think that even for
Heliconius biologists this is quite surprising! (maybe you dont agree?).

Incidentally, the reason for the 'non-sibling species' title of our
paper was to emphasise that melpomene and cydno show so many ecological
and morphological differences - they are much more differentiated than
some other recent studies of gene flow between morphologically identical
'sibling' species of Drosophila and Anopheles.

So the hybridisation has been known about for a long time, but the
question of the extent of its impact on the genome really does depend on
the molecular seqeunce data.

KB: I would not be so picky about this question if this same phenomenon
did not happen also between many well-defined sister species in lots of
animals (I will not even mention that with plants even of distant genera
this is even more common both in nature and in the garden).

CJ: Well you are right about plants thats for sure, and maybe animal
biologists should have taken notice of this a long time ago.  But this
stuff is still controversial in animals - hence the appearance in Nature
of papers on hybridisation between human/chimp lineages and on hybrid
speciation etc. rather than in more mundane journals.  So I think
actually the molecular data which is coming out for many different
animal groups is only now persuading more people that inter-species gene
exchange is common.  This is obviously something that Heliconius
biologists find unsurprising - as usual, you and Larry were ahead of the
game.

KB: Perhaps some of us should go back to studying the genetic mechanisms
that avoid hybridization, rather than those that are more proximal.  Or
is this just considered kid stuff nowadays?

CJ: I think this is what we are doing?!  I have published about hybrid
sterility and mate preferences in melpomene and cydno - actually the
coolest thing to come out recently was Marcus and Larry's paper showing
genetic linkage of mate preference and colour pattern in pachinus x
cydno hybrids.  Quite surprising I think.

KB: Who will be the first volunteer to follow (or participate in)
the system Homo x Gorilla x Pan to the fourth generation of
backcrosses? (Don't tell anybody I am suggesting this be done.....)

Cheers,
Quitibrão

CJ: Think I might give that experiment a miss, thanks

Cheers
Crees


-----Mensagem original-----
De: heliconius-bounces at ucl.ac.uk [mailto:heliconius-bounces at ucl.ac.uk]
Em nome de Chris Jiggins
Enviada em: sexta-feira, 28 de julho de 2006 11:23
Para: Heliconius List
Assunto: [HELICONIUS] Evolution cover
...


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