"Anon."  wrote in message
news:...
> Name And Address Supplied wrote:
> > "Representative Trantis"  wrote in
message news:...
> > 
> >>On the whole males are larger than females. The only
exceptions are those
> >>animals which live close together and therefore have increased
competition
> >>between males for females.
> >>
> > 
> > 
> > Strong competition between males for females is a major factor
> > *promoting* large males.
> > 
> > 
> >>Humans are a good example of this, so much so that we tend to
think of all
> >>males being bigger.
> >>
> >>Humans (And various primates)
> >>Bulls
> >>Dogs?
> >>
> >>Does anyone know the complete list of species which have
larger males, and
> >>if it's a big list then a summary of many commonly known animals?
> > 
> > 
> > I don't know of a list, but I do know that the elephant seal has the
> > greatest sexual size dimorphism of the mammals.
> > 
> > Because of a fundamental asymmetry between males and females, stemming
> > from the initial asymmetry in gamete size (anisogamy), females are a
> > limiting resource and males are exploiters of this resource.  
> 
> I can't see how this stems from anisogamy - at best I would guess that 
> they are both due to the female carrying the offspring.  Pregnancy is 
> the limiting factor, and this will affect mate competition, and also 
> which sex has the larger gametes in an anisogamous system.
> 

Trivers showed that the initial asymmetry due to anisogamy selects for
females to be the primary carers in general.  In the mammals, part of
this care takes the form of 'pregnancy'.  Yes, there are parental
investments in which the female makes the larger contribution other
than anisogamy, and yes, these all increase the sense in which the
female is a resource to competed over, but the reason that it is the
female which makes these additional investments stems from the intial
asymmetry of anisogamy.
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