[net.bio] Evolutionary advantages of monogamy

wmartin@brl-smoke.ARPA (Will Martin ) (02/26/86)

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?

Regards,
Will Martin

UUCP/USENET: seismo!brl-bmd!wmartin   or   ARPA/MILNET: wmartin@almsa-1.ARPA

mrh@cybvax0.UUCP (Mike Huybensz) (03/03/86)

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

jlr@we53.UUCP (JAN L. RICHARDSON) (03/05/86)

>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
....
>having evolved and continued. Are there some "standard" explanations
>for this that I just don't know?

I have not been employed in the field for several years now so I have not
kept current with all of the developments, but I do remember some very
promising research being done with primates which indicated that the
survival of the family group was actually one of the primal instincts.
The idea was that some species can survive bettee as a family unit, with
integral support.  This being true in a natural, nondisturbed environment.
This changes as man encroaches as does all of natures elements. Anyway,
since I haven't been able to keep up, I don't know what has become of this
research.  It might be a partial answer to your question however.  Perhaps
someone else has more information.

It's funny.  In all my educational background in environmental biology 
and ecology we discussed the differences between types of paring, but
no one ever offered any reasons for the differences.  A definate void 
in my education.

Jan Richardson
Richardson Consulting
147 Joel Avenue
Union,  MO  63084
314/583-4563

temporary net address:  ihnp4!we53!jlr

DISCLAIMER:   I am a subcontractor for AT&T, not an employee.  Nothing
              in this shoulb be associated in any way with AT&T.

foy@aero.ARPA (Richard Foy) (03/13/86)

In article <416@we53.UUCP> jlr@we53.UUCP (JAN L. RICHARDSON) writes:
>>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
>....
>>having evolved and continued. Are there some "standard" explanations
>>for this that I just don't know?
>

The book "The Woman that Never Evolved" by Sara Blaffer Hrdy discusses 
the mating behavior of primates in relation to human evolution. It may
give you some clues to your question. Also "The Sex Contract" by Helen
Fischer sort of relates to the subject. I found the research discussed
in them and the conclusions drawn therefrom quite interesting.


Richard Foy, Redondo Beach, CA
The opinions I have expressed are the result of many years in the school of
hard knocks. Thus they are my own.