Hey, George, what is the evidence that hybridization has had anything to do
with speciation in the Midas cichlid? I reported that some introgressive
hybridization appears to have occurred in some populations of the Midas
cichlid, i.e., in Lakes Masaya and Xiloa (Barlow & Munsey 1976). But that
does not seemed to have produced new species or have produced
incompatibility with Midas cichlids from other lakes.
If you mean the papers by McKaye and by Meyers, they didn't get into
hybrids. And I disagree with their conclusions about the color morphs being
incipient speciation. Look for a paper I have in press in the American
Zoologist that should appear toward the end of this year.
>X-Sender: gft at mail.soton.ac.uk
>Date: Tue, 4 Feb 1997 20:01:56 GMT
>Reply-To: Cichlid Systematics Distribution List <CICHLID-L at NRM.SE>
>Sender: Cichlid Systematics Distribution List <CICHLID-L at NRM.SE>
>From: George Turner <gft at SOTON.AC.UK>
>Subject: Re: Hybrids
>Comments: To: Cichlid Systematics Distribution List <CICHLID-L at NRM.SE>
>To: Multiple recipients of list CICHLID-L <CICHLID-L at NRM.SE>
>
>In reply to Ron Coleman-
>
>>I DON'T THINK A CALL FOR WIDESPREAD HYBRIDIZATION EXPERIMENTS IS EITHER
>>WARRANTED NOR RESPONSIBLE.
>>
>>Perhaps certain crosses are of interest and value, notably particular
>>species in say Lake Malawi, but many other crosses will lead to tons
>>of dangerous fish and no useful information.
>>
>>Please reconsider.
>
>I am rather surprised at your blaze of hostility here! I am not talking
>about flooding the tropical aquarium trade with hybrids. I would however
>like to see them produced under controlled conditions and then disposed of,
>rather than traded. We're supposed to be interested in learning about our
>fish, not just in making money from them.
>
>In any case, the aquarium trade is infected with all kinds of hybrids coming
>from fish farm production. But is interesting that they seem to be quite
>limited in the species involved. In the UK, virtually all (non-wild caught)
>Aulonocaras, Pseudotropheus, and Protomelas are not recognisable by me as
>wild species. By contrast, all Melanochromis, Labeotropheus, Cynotilapia,
>Labidochromis and Nimbochromis look clearly recognisable, although the
>Labeotropheus & Cynotilapia cannot be assigned to particular geographic
>races. I suspect some species hybridise and some dont. Also that the
>particular species/race they hybridise with are not easy to predict. This
>could shed a lot of light in speciaiton processes and comparison of Malawi,
>Tanganyika, Victoria and neotropical species could be very instructive in
>understanding relative speciation rates and mechanisms.
>
>By producing these hybrids, as I suggest, the very worst that can happen is
>that some unscrupulous individuals will release these into the aquarium
>trade (not the wild!) and add to the immense numbers already circulating
>anyway. I dont think such unethical people (who surely dont subscribe to
>cichlid-l!) are going to be bothered conducting breeding for research anyway.
>
>
>>Wait a minute, George!!!! There is no evidence that hybrid infertility
>>has anything to do with speciation in the New World cichlids,
>
>Indeed there's not. There's no evidence at all about what is responsible for
>their speciation (apart from Midas cichlids & relatives and the Cuatro
>Ciengas morphs, has anyone looked at anything to do with speciation in
>neotropical cichlids?) and that's exactly the point. No-one is looking.
>
>There is a lot of anecdotal stuff in the aquarist literature complaining
>about how readily all kinds of cichlids hybridise in tanks, but virtually no
>controlled experimentation nor systematic recording of what will hybridise
>with what. Going from aquarist comments, I thought I could hybridise all
>kinds of Malawi cichlids.
>
>So far, on the basis of some very preliminary experiments, I am not getting
>this impression at all. But the message coming through is that the bland
>generalisation that all kinds of cichlids readily hybridise to produce
>viable offspring is unscientific, anecdotal and quite possibly utterly wrong.
>
>and the
>>last thing we need is all sorts of new hybrids of cichlasomines or
>>crenicichlas or geophagines floating around.
>
>As I said I dont want them floating around either.
>
>> I would even go out on a limb here and offer an answer to the
>>question for all cichlasomines: any species will hybridize with any other to
>>some extent. But say you found that C. spilurum wouldn't hybridize with
>>C. umbriferum? So what? I don't think this tells you anything more than
>>if they did hybridize since these species are vastly different in size and
>>live hundreds of miles apart with many mountains, rivers and lakes in between.
>
>I dont believe all cichlasomines will hybridise! And even if they do, it
>doesnt answer all the other important questions I asked. What circumstances?
>Viability? F2 breakdown. F1 unattractiveness to parental forms. All these
>things make a big difference to our understanding of speciation processes.
>
>Having recently dipped into the insect literature, I am shocked at how
>absolutely ignorant we are about species isolating mechanisms in cichlids.
>Indeed, its hardly possible to hold a worthwhile discussion with a serious
>student of insect speciation, because it looks like we really haven't been
>bothered doing anything much at all.
>
>
>Ron talked about flooding the place with 'tons of dangerous fish'. Just what
>is the danger? None to wild stocks or to properly maintained aquarium/lab
>populations. Most serious researchers and lot of serious hobbyists deal in
>wild-caught fish (or F1 from known & trusted sources). It's just dangerous
>to stock circulating in the 'non-specialist' end of the aquarist trade. We
>can't use these for taxonomy because of morphological plasticity. We can't
>use them for hybridisation studies if Ron has his way.
>
>So what's the point in mantaining purity? So we can say Cichlasoma xy spawn
>in a clay flowerpot at 75-78 degrees F, males are bigger and brighter than
>females and they thrive on a diet of beef heart and spinach (yawn)?
>
>So, if these stocks are not going to be used to learn something useful about
>the biology of the fish (like I have been suggesting) then why not just keep
>all the nice bright hybrids to decorate your tanks! It would make lots of
>people happy, just like all these nice Xiphophorus and Poecilia we can buy!
>That hasn't stopped serious live-bearer fans from keeping stocks of pure
>forms, nor has it stopped scientists doing fascinating research on these
>genera.
>
>George
>
>Dr G.F.Turner
>Lecturer in Ecology/ Biodiversity
>Division of Biodiversity & Ecology
>University of Southampton
>Bassett Crescent East
>SOUTHAMPTON SO16 7PX
>England, UK
>Phone- 44-(0)1703 594394
>Fax- 44- (0) 1703 594269
>e-mail gft at soton.ac.uk
>
>
George W. Barlow Ph 510/642-2947
Department of Integrative Biology FAX 510/643-6264
University of California barlowgw at garnet.berkeley.edu Berkeley, CA
94720-3140 USA
"We have to believe in free will.
We've got no choice"
Isaac Bashevis Singer