Path: utzoo!attcan!uunet!mcsun!ukc!newcastle.ac.uk!turing!q1ygq
From: J.M.Spencer@newcastle.ac.uk (J.M. Spencer)
Newsgroups: sci.bio
Subject: FISH:  sex ratio of 1 male : 100 females, why?
Message-ID: <1990Sep27.142437.21755@newcastle.ac.uk>
Date: 27 Sep 90 14:24:37 GMT
Sender: news@newcastle.ac.uk
Organization: Computing Laboratory, U of Newcastle upon Tyne, UK NE1 7RU.
Lines: 20

A recent TV program showed a species of fish which was yellow
and lives in the Red Sea, but I've forgotten the name.  The odd
thing about this species is that they maintain a sex ratio of 1
male to every 100 females.  When the male dies, the *largest*
female turns into a male.

Questions:

1.	How do the fish know when they have the correct ratio?
	i.e. how do they discriminate between 1:90 and 1:100?

2.	What survival advantage does the species gain from this?

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