Path: news.nzbot.com!not-for-mail
From: John Harshman <jharshman.diespamdie@pacbell.net>
Newsgroups: alt.fan.uncle-davey
Subject: Re: Is there a link between dominance/recessivity of genes and earlier evolutionary forms?
Date: Sat, 28 Feb 2004 21:54:43 +0000 (UTC)
Organization: SBC http://yahoo.sbc.com
Lines: 36
Sender: root@darwin.ediacara.org
Approved: robomod@ediacara.org
Message-ID: <40410F55.4080000@pacbell.net>
References: <c1r0vu$btv$0@pita.alt.net>
NNTP-Posting-Host: darwin
Mime-Version: 1.0
X-Trace: darwin.ediacara.org 1078005283 81881 128.100.83.246 (28 Feb 2004 21:54:43 GMT)
X-Complaints-To: usenet@darwin.ediacara.org
NNTP-Posting-Date: Sat, 28 Feb 2004 21:54:43 +0000 (UTC)
User-Agent: Mozilla/5.0 (Macintosh; U; PPC; en-US; rv:0.9.4) Gecko/20011130 Netscape6/6.2.1
X-Accept-Language: en-us
X-NNTP-Posting-Host: 66.158.70.254
X-UserInfo1: T[OGBZCEGZRCRPLY@BCD^VX@WB]^PCPDLXUNNHLHEQR@ETUCCNSKQFCY@TXDX_WHSVB]ZEJLSNY\^J[CUVSA_QLFC^RQHUPH[P[NRWCCMLSNPOD_ESALHUK@TDFUZHBLJ\XGKL^NXA\EVHSP[D_C^B_^JCX^W]CHBAX]POG@SSAZQ\LE[DCNMUPG_VSC@VJM
X-Spamscanner: mailbox2.ucsd.edu (v1.4 Dec 3 2003 15:07:19, 0.0/5.0 2.63)
X-Spam-Level: Level
X-MailScanner: PASSED (v1.2.8 90749 i1SLxY0B093696 mailbox2.ucsd.edu)
Xref: news.nzbot.com alt.fan.uncle-davey:2828
Uncle Davey wrote:
> Has anyone done any work on this topic?
>
> It seems to me as though the 'wild forms' of animals tend to have the
> dominant characteristics. When a wild boar mates with a pig, the offspring
> have more the shape of a wild boar, there is no fattening them up like a
> domesticated pig, and so the farmers hate when that happens.
>
> Can we see a general tendency that wild characteristics are dominant and
> ones bred in are nore recessive?
Yes, to a degree. Though I'm not sure it accounts for the phenomenon you
describe. Recessive mutations most commonly are recessive because they
create a non-functional protein, or no protein at all. So in combination
with an allele that does create a functional protein, we get a "normal"
phenotype. Since there are more ways to break a gene than to fix it,
many mutations are recessive. Breeders work with what they get, and
sometimes the phenotype produced by rendering a gene non-functional is
useful in a domestic animal. Thus many of the differences between
domestic animals and their wild ancestors are probably recessive to the
"wild type" alleles. On the other hand, many of the traits important to
breeders are polygenic and quantitative, and the domestic breed has been
assembled slowly by accumulating alleles at lots of loci that push the
phenotype all in the same direction. Mixing this with a wild type will
push the phenotype toward the mean. If, for example, some character
state, call it A in a domestic animal is influenced by 10 loci eac with
two alleles A and B, the domestic animal would have a genotype of
AAAAAAAAAA, while a wild type would be a random mix of As and Bs,
perhaps tending around 50% each, e.g. AABABBBAAB. A first generation
hybrid would have around a quarter Bs and might look like a wild type to
you.
|
|