[acn-l] Re: Hybrids (fwd)

peter.unmack at asu.edu
Wed, 05 Feb 1997 11:46:37 -0700 (MST)

---------- Forwarded message ----------
Date: Tue, 04 Feb 1997 10:11:00 -0800
From: Ron Coleman <colemanr at GARNET.BERKELEY.EDU>
To: Multiple recipients of list CICHLID-L <CICHLID-L at NRM.SE>
Subject: Re: Hybrids

On Tue, 4 Feb 1997, George Turner wrote:

> I am interested in the evolution of cichlid species. The key stage in this
> process is the establishment of reproductive isolation between populations.
> One way to find out about this is to know what is presently preventing/not
> preventing introgressive hybridisation between existing species. So I want
> to know about hybridisation in the aquarium.
>
> A lot of cichlid aquarists talk about hybridisation, but most of it is
> anecdotal information. I would like to encourage all cichlid aquarists to
> start to record instances of hybridisation in a systematic fashion and
> perhaps to deliberately set up conditions to see under what circumstances it
> can happen. Obviously I agree with the commonly-expressed opinion that
> hybrid progeny should not be release onto the aquarium trade so that
> innocent enthusiasts end up with hybrids when they dont know it.

Wait a minute, George!!!! There is no evidence that hybrid infertility
has anything to do with speciation in the New World cichlids, and the
last thing we need is all sorts of new hybrids of cichlasomines or
crenicichlas or geophagines floating around.
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 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.

-- Ron Coleman
University of California, Berkeley
colemanr at garnet.berkeley.edu

> Here's what I'd like to know.
>
> 1. What species are involved?
>
> 2. How many adult males and females of each species were present in the tank
> when hybridisation occurred?
>
> 3. Did the eggs hatch? (actual % hatch would be nice)
>
> 4. Did fry survive to sexual maturity?
>
> 5. What did adult hybrid males and females look like (colour especially)?
> What was sex ratio?
>
> 6. Did hybrid progeny reproduce with each other to produce F2 offspring?
>
> 7. Were the F2 viable and fertile?
>
> 8. Would hybrid offspring mate with either parental species and if so which
> sex was involved and were parentals/hybrids given a chance to mate with own
> type?
>
> If anyone (especially enthusiastic aquarists) would be interested in trying
> out a systematic set of experiments to investigate this with any kind of
> cichlids, I'd be glad to advise on how to set it up, analyse and interpret
> data and publish results.
>
> 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
>