From: Glenn Morton (glennmorton@entouch.net)
Date: Sat Jul 19 2003 - 14:56:39 EDT
Hi David,
You wrote:
>-----Original Message-----
>From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]On
>Behalf Of bivalve
>Sent: Saturday, July 19, 2003 12:32 PM
>To: Asa
>Subject: new light on the Cambrian
>
>
>> The claim isn't that there aren't any nocturnal animals, just
>fewer of them than the day-jobbers. I would be interested in any
>contrary data to Parker's claim.<
>
>Birds are the only major group that I know are principally
>diurnal. The majority of mammals are nocturnal. I don't know
>relative numbers for all insects, but certainly the primarily
>nocturnal moths far outnumber the primarily diurnal butterflies.
>The insect diversity around the porch light at night seems to
>exceed the diversity at flowers during the day. I believe most
>marine invertebrates that show a preference are more active at
>night. This is much of the appeal of night diving and night shell
>collecting. Likewise, there is the abundant plankton that forms
>the scattering layers, hanging out in deep water with little light
>during the day and coming shallow at night. I think the nocturnal
>species probably outnumber the diurnal ones, though a lot would
>depend on whether beetles show an inordinate fondness for one or
>the other. Being diurnal ourselves, we detect and observe the
>diurnal ones much more easily.
>
>Ironically, this may acually support his main thesis, in that an
>advantage of being nocturnal is to hide from visual predators or
>visually wary prey. On land, it may also help avoid dessication
>or overheating.
interesting. I went back to check what he says about nocturnal animals to be
sure that I hadn't messed it up in reading him. He says what I said he
said:
"It is interesting that on land the same physical environment exists at
night as it does during the day. Trees and rocks continue to provide nooks
and crannies.but no longer areas of brightness and shade. And the
evolutionary outcome? There are considerably fewer species active at night
compared with the day. There really are fewer niches-'ways of life
'-available at night." Andrew Parker, In the Blink of an Eye, (Cambridge:
Perseus Publishing Co., 2003), p. 119
**
"So the food web becomes stretched and offers less opportunity for tangling,
or for evolution to cross lines. Evolution maintains a comparably low
diversity at night.
"Heat is partly responsible for this. It is warmer during the day than at
night, and many animals are adapted to warmth. But animals from most phyla
can be adapted to the cold. This is not an evolutionary impossibility So we
can consider at least part of the day-night biodiversity difference as
evidence towards the power of light as a stimulus affecting life on Earth.
Begin to remove this stimulus and evolution becomes much less complicated. I
say 'begin' because night-time on land is only a step towards total
darkness." Andrew Parker, In the Blink of an Eye, (Cambridge: Perseus
Publishing Co., 2003), p. 119
You have now got me thinking about counting the dirunal and nocturnal
species to see what the actual case is. You are correct that most mammals
are nocturnal (at least from my first check on mammals in India where 60%
are.
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