Re: Temp and sex ratios

[Mike & Diane Wise <apistowise@bewellnet.com>]

Jonathan,

I for one would like to read your thesis. Keep us informed.

Mike Wise

jonathan wrote:

> I am currently working on a thesis titled
> Investigation of behaviour and environmentla sex determination in
> Apistogramma borellii (Cichlidae)
>
> and I shall publish it when it is complete. General trend in most
> (not all) developing Apistogramma spp. broods appears to yield more
> females at higher pH (near 7.2) and more males at lower pH (near 6).
> Temperature appear to have an effect where higher temperatures (near
> 29 C) yield more males while lower temperatures (near 23 C) yeild more
> females. However, I suspect that the relationship between temperature and
> sex determination may be indirect. Perhaps it is related to rate of growth
> or embryonic development as Apistogramma borellii fry grow painfully slow
> (for my thesis) at 23 C.
>
> Published sources on environmental sex determination so far include
>
> Romer, U. and W. Beisenherz. 1996. Environmental determination of sex in
>      Apistogramma (Cichlidae) and two other freshwater fishes (Teleotei).
>      J. Fish. Biol. 48: 714-725.
>
> Rubin, D.A. 1985. Effect of pH on sex ratio in Cichlids and a Poecillid
>      (Teleostei). Copeia. 1: 233-235.
>
> -------------------------------------------
> Jonathan Fung... Reef Geek
> Dalhousie University Honours Marine Biology
> Aqua Creations Inc. Assistant Manager
> writer for Marine Fish Monthly
> -------------------------------------------
>
> On Thu, 8 Feb 2001, David Sanchez wrote:
>
> > Could anyone tell me where, on-line if possible, I could find the the paper
> > done on Apistos and the relationship Temperature has on their sex ratios?
> >
> > Thanks in advance
> >
> > David Sanchez
> >
> >
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