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Re: Croc's care



Jack Kane wrote:

> On July 2 John Bois wrote:
>
> >Crocs, while they do defend the nest, do not help the eggs in any other
> >way after oviposition.  This style is of lay-'em-and-leave-'em is more
> >typical of basal reptiles.
>
> Actually many mom crocs hand around and listen for the chirps of the
> hatching babies. She then digs them out and meticulously carrys them to the
> water in her mouth. Not much help after that but it is not "lay 'em and
> leave 'em"
>
> Also some snakes will hang out with their little one for awhile as well. I
> don't know how this fits in but couldn't some "primitive"dinos done the croc
> thing and worked up from there in regards to their parental involvement.
>
> I have a question related to this: As parental involment increases wouldn't
> the number of offspring decrease and the size increase. Instead of having a
> bunch of little ones and hoping they make it, having fewer, bigger, stronger
> ones and working harder at caring for them longer? Is this seen in the
> fossil record or do we just not have enough material for any statistical
> evaluations? Or the third possability is I have no clue and should go back
> to lurking and dreaming of playing with the big boys someday;-)
>
>                 Be kind,   Jennifer R. Kane

I don't know about the fossil record, but that is the general pattern
among
living animals.  In fact, it logically has to work that way:  if a
species has
the same birthrate but better mortality (assuming parental involvement
does any
good), the population has to increase until it puts pressure on the
environment.  This in turn will cause something to happen to reduce the
population to what the environment will support.

In this particular case, if a parent's offspring are more likely survive
(once
born), what's the advantage to having more?  The environment can
(usually) only
support a (long-term) average of 1 offspring per parent surviving to
breed.
Thus care-givers can improve their own energy expenditure either by
reducing
care given or by reducing the number of offspring born.  This gives them
a
differential advantage over the others of the same species.

-- Jon