Newsgroups: comp.ai.genetic
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!howland.reston.ans.net!vixen.cso.uiuc.edu!uwm.edu!msunews!harbinger.cc.monash.edu.au!newsroom.utas.edu.au!pacit.tas.gov.au!prpc43.dpi.tas.gov.au!bhorton
From: bhorton@aries.dpi.tas.gov.au
Subject: Re: Question from an AI weenie
Organization: Department of Primary Industry and Fisheries
Date: Sat, 20 May 1995 00:53:02 GMT
Message-ID: <bhorton.14.000AE2A5@aries.dpi.tas.gov.au>
Lines: 28
X-Newsreader: Trumpet for Windows [Version 1.0 Rev A]
References: <Pine.OSF.3.91.950512001035.25176A-100000@odin.cbu.edu> <3p4e0i$avm@deadmin.ucsd.edu> <1995May16.071812.16985@pat.uwe.ac.uk> <1995May16.154602.21314@pat.uwe.ac.uk>
Keywords: inbreeding depression
Sender: usenet@pacit.tas.gov.au (News User)

In article <1995May16.154602.21314@pat.uwe.ac.uk> pa-ross@pat.uwe.ac.uk (PA Ross) writes:
>From: pa-ross@pat.uwe.ac.uk (PA Ross)
>Subject: Re: Question from an AI weenie

>....  I have observed that the Fitness
>of the colony steadily increases until it reaches peak fitness. It then hovers
>around this for a while before it starts to come crashing down and behaving
>unpredictably. Is this a natural phenomina or a bug ? This sort of thing 
>definately happens in nature, if two animals breed with similar genes then the
>resulting offspring do tend to be weaker.
>Paul

Inbreeding Depression is common in nature, but is generally believed to be due 
to an excess of homozygous genes (both members of each pair identical) 
particularly if some of these are deleterious recessives.  It should only 
apply to diploid organisms (two copies of every gene). 

GA users sometimes avoid inbreeding, but this is to avoid early random loss of 
useful genes rather than to prevent inbreeding depression.  Most GAs are 
haploid, with only one copy of gene per 'organism'.  Unless you have a diploid 
system with dominant and recessive genes then inbreeding depression is 
unlikely.

Do you have multiple peaks?  If you specifically disallow inbreeding, then in 
the later stages most matings might be between parents from different peaks, 
with the offspring falling in the valleys between.

Brian Horton
