From: Glenn Morton (glennmorton@entouch.net)
Date: Mon Sep 29 2003 - 06:57:16 EDT
Bill Wrote:
>-----Original Message-----
>From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]On
>Behalf Of bpayne15@juno.com
>Sent: Sunday, September 28, 2003 9:28 PM
>The development of sexual reproduction is an interesting case to ponder.
>What step-by-step process would produce an egg and sperm, and all the
>other equipment that goes along with being male and female? Is this
>irreducibly complex (IC)? What good is half an egg and half a sperm, or
>half a penis and half a vigina, or a fertilized egg with no uterus or no
>unbilical cord, or a baby that doesn't know how to suck, or a mother with
>no mammary glands?
All one has to do is go look in the literature rather than merely pose
questions.
some of the simpler Volvoceans use somatic cells for reproduction. But with
the *Volvox*
In *Volvox*, almost all the cells are somatic, and very few of the cells
are able to produce new individuals. In some species of Volvox,
reproductive cells, as in Pleodorina, are derived from cells that originally
look and function like somatic cells before the enlarge and divide to form
new progeny. However, in other members of the genus, such as V. carteri,
there is a complete division of labor; the reproductive cells that will
create the next generation are set aside during the division of the
reproductive cells that are forming the new individual. The reproductive
cells never develop functional flagella and never contribute to motility or
other somatic functions of the individual; they are entirely specialized for
reproduction. Thus, although the simpler Volvocaceans may be thought of as
colonial organisms (because each cell is capable of independent existence
and of perpetuating the species), in V. carteri we have a truly
multicellular organism with two distinct and independent cell types (somatic
and reproductive), both of which are required for the perpetuation of the
species. Although not all animals set aside the reproductive cells from the
somatic cells (plants hardly ever do), this separation of germ
(reproductive) cells from somatic cells early in development is
characteristic of many animal phyla and will be discussed in more detail in
Chapter 7."~Scott F. Gilbert, Developmental Biology (Sunderland: Sinauer
Assoc. Inc., 1991), p. 18
But this illustrates how sex originated.
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