RE: Re: A New Rainbow Species?

Harro Hieronimus (Harro.Hieronimus at t-online.de)
Sun, 25 Aug 96 06:39 +0100

Hi Carry,

<Just a theoretical question - if one of these crosses escaped into the
<wild and became a viable population, would it eventually be recognised
<as a species?

Your question isn't easy to answer. This is a case we didn't have very
often before. In livebearers there have be some cases of natural
hybrids though introduction of foreign species.

If a cross would escape into the wild there are a few questions which
had to be answered before:
1. Is there any related species in the water where the cross is released?
If so, you can be rather sure that it will cross with it - if it survives, not all
aquarium fish introduced into the wild will do so - and that the whole
stock will take up the foreign genes and remain as slightly changed
population. Normally after several generations it will be rather similar
as the original stock - presumably, you never can't be sure.
2. If there's no related species in the water and the fish will survive
(what means, they have found a suitable habitat) there are a few
possibilities.
In a cross you normally (there are exceptions, but not in rainbowfish)
find the Mendelian rules to be followed. That means, that in the first
generation you may have very similar fish according to the first Mendelian
rule (unformity rule). In the second generation you will have a split
(second Mendelian rule). As a fact, you never will have the original fish
again (except in some very rare cases). Also if the fish look totally like
one of the parental species, you will find through genetic fingerprinting
that it is different.

In the first case the population will have changes (which you may not
recognize), in the second case a genetically uniform population will
result after several generations (if the population survives), which may
be similar to one of the parental species and not to be distinguished
except with genetical methods or it may become a new species (we will
not live long enough normally to wait for it) which may look different
than the parental generation. This is just a short story of what could
happen.

But let me make you sure: Whoever releases crosses into the wild
should be hung up on his (her) fingertips for a few weeks or so. In Germany
it's strictly forbidden to release foreign species and as far as I know in
Australia it's the same (?). By the way, basically it's no difference
between releasing a cross or a pure species. We have to protect
environment, to "enrich" (that the term people used 100 years
ago when they introduced new species into German waters) nature
is none of our aims.

Harro

harro.hieronimus at t-online.de