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Nothos sex ratio manipulation
Dear Killi-List Members:
Recently, I came upon this within the text of Francisco Casado's
excellent Nothobranchius web page located at
http://ww2.hispamerica.com/gr231/index.htm . I am interested as
to whethar others have had similar results. The general gist of the
following is that if two recently hatched (Nothos) fry are isolated
prior to their sixth day and reared there is a 83.3% liklihood of
them becoming an adult pair. If two fry are isolated between day 6
to 10 there is a 71.4% liklihood. After day 10 liklihood rates go
down significantly. These, to me, are fascinating results and worthy
of scrutiny through duplicated efforts. Mr. Casado, by the way,
apologizes several times for his own english translation of his work.
(any errors on the table are mine done when converting it to .txt from
html.)
Mike Bleakley
mbleak at telepath_com
Norman OK USA
The text follows:
Occur frequently that we can have the surprise of the fact
that the repartition between males and female will be very
little balanced. I have had cases having 29 N.
aeniopygus fries and to obtain 29 females.
Without doubt influences in this case some factor that is
done not know but that it is possible to avoid with a simple
method that I discovered by chance and that then upon
commenting it with others experts have confirmed me.
The method consists of raising from very small fries for
pars, isolated in small recipient. In this way and under
some very easy conditions to fulfilling we will be obtained
in a percentage very high of cases, a male and a female.
The conditions are only that are assembled the two fries
when have not to exceed 6 or 7 given of life.
I have studied and proven this fact during several years
and I have bred fries only for this purpose.
The mechanism therefore this occurs has for me a clear
explanation, and it is to assure the descendents, priority
this that all the animals has.
Colloquially would be expressed as a position that
made the fish proving that only they two exist , and that
"or they are couple, or there finishes their Specie),
Below is described the statistics about this study.
Species (1) (2) (3) (4) (5) (6)
Orthonotus 4(1/1) - - - - -
Rachovii 8(4/0) 4(1/1) 6(2/1) 2(0/1) 6(1/2) -
Guentheri 6(3/0) - 2(1/0) - 2(0/1) -
Furzeri 4{2/0) 2(0/1) 4(1/1) - 2(0/1) -
Melanosp. 2(1/0) - - 2(1/0) - -
Symoensis 2(1/0) - 2(1/0) - 2(1/0) 2(0/1)
Neum"Manyara" 4(1/1) 2(1/0) 2(0/1) - 2(0/1) -
Kunthae 2(0/1) 2(0/1) 2(1/0) 2(1/0) 2(1/0) -
Ugandesis 4(2/0) 4(2/0) 4(2/0) - 2(0/1) 2(1/0)
Spe."Mugueta" 2(1/0) 2(0/1) 2(0/1) 2(1/0) 4(1/1) -
Spe."Abrahamu" 4(2/0) 4(1/1) 2(1/0) 2(1/0) 2(0/1) 2(0/1)
Jubby 4(2/0) 2(0/1) 2(1/0) 2(0/1) 2(0/1) -
TOTAL 48(20/4) 22(5/6) 28(10/4) 12(3/3) 26(4/9) 6(1/2)
% 83.3% 45.4% 71.4% 50% 30.7% 33.3%
Keys
(1)Separated during the period between the first and the sixth day since his birth.Isolated
(2) The same as it up but without isolating .
(3) Separated between the days 6º y 10º since his birth.Isolated
(4) Same as it up but without isolating.
(5) Separated after the 10º day.Isolated.
(6) Same as it up but without isolating.
"Isolated"=No seeing to any other fish
"No isolated"= without this condition.
EXAMPLE
N.Orthonotus. 4(1/1)......... 4 Is the Specimens number
utilized for the study(in this case on the key (1).
Into of the bracket are writed the specimens number that
they was pair (in the left), and those which they was not
pair (on the right). In this case (1/1) the results was:
From 4 specimens= 1 formed pair, and the others 2 fries
not was pair.
Repost because table came out cock-eyed sorry mb