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From: mrh@cybvax0.UUCP (Mike Huybensz)
Newsgroups: net.bio
Subject: Re: Evolutionary advantages of monogamy
Message-ID: <964@cybvax0.UUCP>
Date: Mon, 3-Mar-86 11:38:38 EST
Article-I.D.: cybvax0.964
Posted: Mon Mar  3 11:38:38 1986
Date-Received: Wed, 5-Mar-86 04:12:00 EST
References: <1334@brl-smoke.ARPA>
Reply-To: mrh@cybvax0.UUCP (Mike Huybensz)
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Organization: Cybermation, Inc., Cambridge, MA
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In article <1334@brl-smoke.ARPA> wmartin@brl-smoke.ARPA (Will Martin ) writes:
> Inspired by an overindulgence in watching animal and nature progams on PBS,
> I've been trying to think of why some species would evolve (or maintain)
> a pattern of monogamous mating. I can think of evolutionary advantages
> to having new matings each season, for example based on competition
> between males so that the strongest fertilizes as many females as he can
> dominate or defend from other males. When it comes to species that are
> monogamous (mating for life, or, I suppose, until one of the pair dies),
> like some varieties of geese, eagles, beavers, etc., though, I find it
> hard to think of equivalently-good arguments to support this behavior
> having evolved and continued. Are there some "standard" explanations
> for this that I just don't know?

There are really two questions here: fidelity to one mate at a time,
and fidelity to the same mate for life.

Theoretically, both can be explained in terms of resources needed to
rear offspring.  If there is a prisoner's dilemma payoff scale (payoff in
offspring) based on parental care, then infidelity doesn't pay.  Thus
mechanisms would evolve for ensuring fidelity by requiring expenditure
of resources (time, materials, site) that could only be provided to one
mate at a time.

Lifelong fidelity is a quick heuristic from there: why bother with the
risky and expensive process of attracting and establishing fidelity with
a new mate when the old mate with a proven record is still available?
-- 

Mike Huybensz		...decvax!genrad!mit-eddie!cybvax0!mrh