From: Damien Broderick (d.broderick@english.unimelb.edu.au)
Date: Sun Jul 09 2000 - 00:26:08 MDT
At 10:54 PM 8/07/00 PDT, "phil osborn" <philosborn@hotmail.com>
wrote:
>To the contrary, it is quite conceivable that a series of environmental
>fluctuations could wipe out a long-lived species, while a short-lived one
>would survive. [...]
>Let's imagine a species - of bacteria, for example - that can only reproduce
>within a narrow temperature range, although it can survive quite well over a
>much broader range. Within this species, however, there are always a few
>mutants, recessive genes, etc., for other temperature ranges scattered
>around.
[etc]
An interesting post, which led me to consider an issue I've never seen
discussed in the literature (although this is doubtless due to my
ignorance): selective differentials from secular variations in sunlight,
temperature etc and their impact on creatures with variant breeding and
mortality patterns.
I've argued elsewhere that there's evidence for moderate cycles in climate
that are possibly driven by solar energy dynamics (most notably marked by
the sunspot cycle) and long Milankovic and other oscillations in the
Earth's orbit and inclination, etc. These cycles exceed the lifespans of
many small critters, and even human generations only barely encompass the
shorter ones.
If this has any bearing upon which phenotypes are best adapted at any given
slice across the cycles, I can imagine that critters which store food might
tend to live longer than those which don't; long-distance north-south
migratory beasties might live longer than others of the same metabolic
indices; and fish, lobsters or other critters in the stabilised environment
of the sea might produce some species that escape mortality entirely (as
Joao was suggesting, I think).
Damien Broderick
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