~MarciaH
Wed, Jul 25, 2001 (15:37)
seed
population dynamics and systematics - Marshall, this one is yours!
~marshallsmyth2
Wed, Jul 25, 2001 (16:00)
#1
This forum is about how evolutionary biology has been known to work, and how the results of studies are expressed. Phylogenetics and cladistics both have some essential work to make improvements in the forms. This is because we can now understand how important population dynamics are. (More when I am well rested).
~MarciaH
Wed, Jul 25, 2001 (18:43)
#2
Welcome, Marshall, and warm Hugs for taking on this most daunting subject. I am not enough aware of the developments since I left college to pose even a reasonable question. I have, however, reserved a seat at your feet, front and center, so I might learn more. After all, we have talked about extinct people, ones that pollute and so on, but not any living beings and how we got to be the way we are. My curiosity is boundless and my is admiration, too. I await the moments when you have time to spare to post here. Again, Aloha and E Komo Mai.
~MarciaH
Thu, Aug 16, 2001 (19:00)
#3
I don't know where to put this so Genetic research is going to go here till Marshall takes over. From Liam the Resoureceful, ever ready to baffle me with new goodies:
Wistar Study Offers New Support For A "Histone Code" Theory Of Gene Regulation
PHILADELPHIA - A new study by researchers at The Wistar Institute
provides important experimental data to support a novel theory of gene
regulation. The theory holds that coordinated patterns of modifications to
DNA-packaging proteins called histones may be a key factor in turning
specific genes on or off.
The proposed system of gene control has been termed a kind of "histone
code" by one researcher and may govern most gene activity. Understanding
the system could well prove crucial to researchers exploring cancer,
developmental disorders, and other disease processes that hinge on gene
control gone awry.
more... http://www.sciencedaily.com/releases/2001/08/010810065922.htm
~MarciaH
Fri, Apr 19, 2002 (17:44)
#4
From the mind of the man for whom this topic was created, a very clever demonstration:
The simplest, (and tastiest), experiment for evolution that anyone
can do is to start off with 2 large bags of assorted M & M's. First,
open the 2 bags and pour them all into a large bowl. Next, put 1
handful of totally random pieces on the far left side of a good sized
coffee table, then another random handful a few inches to the right
of the first handful. Continue this until you have a bunch of
handfuls all the way across your coffee table. Consider that each
pile of M&M's represents a population, and that all those M&M's
together represent an entire biological species. The colors of the
candies for this simplest experiment can represent PHENOTYPES.
Phenotypes are subject to evolutionary pressures of all kinds, the
easiest to understand of which is NATURAL SELECTION. But, there are
other things, concepts, involved! The randomness of colors in each
pile creates FOUNDER EFFECT. Now, in the far left pile, remove ALL
the GREEN M&M's. The greens got selected out. Eat those green ones.
Your mouth represents something that selected against those green
ones in the environment that that population lives in. Do the same
thing to ALL the BROWN M&M's in the far right pile. Next, remove 5
RED M&M's from every single pile except for one randomly chosen pile,
in fact, take that pile, and put it onto a different table, and leave
it there. Removing those 5 red ones represents a concept called
GENETIC DRIFT. Sometimes this happens! A trait comes or goes for NO
SELECTIVE reason or cause. The DNA molecules simply find a set
combination to get FIXED on. This is a form of DIRECT GENE FREQUENCY
ALTERATIONS. Next, break one M&M in half in any randomly selected
pile. Chose and pick which one at random. That represents a MUTATION.
Now eat both halves. SELECTION got that one, and removed it. Next,
push any 2 of the piles, (but not the far left nor the far right
piles), up and away from the other piles, and place them near one
another. Now, with these 2 piles, take half the brown M&M's out of
one of them, and put them into the other pile. Then, take half the
red M&M's out of the now larger pile, and place them into the other
pile. This represents GENE FLOW. These 2 piles represent together a
POPULATION CLUSTER. In this concept, GENE FREQUENCIES get altered
because they get mixed, and then those new gene frequencies can
become further altered by selection pressures. For example, with your
new population cluster up there, remove all the green ones and eat
them. Go ahead and do some more playing like this. Find a way to
create a new species and tell us about it! There are also other more
advanced games where heterozygosity and homozygosity of genes can be
played with.
The point here is that NATURAL SELECTION is not everything. There is
a relationship of many concepts that yield EVOLUTION. Simply put,
Natural selection + Genetic drift + Mutation + Gene flow YIELD Gene
frequency changes, and when this happens in populations GENETICALLY
ISOLATED from one another, eventually SPECIATION can happen.
Marshall Hugh Smyth
http://groups.yahoo.com/group/evolutionarybiologybasics
~MarciaH
Fri, Apr 19, 2002 (17:45)
#5
Marshall, we miss you!
He is back in college finishing his degree, so I will be patient. But that does not mean I don't still miss him!
~MarciaH
Sat, Apr 27, 2002 (01:14)
#6
EVOLUTION & PALEONTOLOGY
* Scientists Push Back Primate Origins From 65 Million to 85 Million
Years Ago
* Mummy Trove Found in Peru
* Early Cowboys Herded Cattle in Africa
* How Life Originated in Space
References
1. http://www.sciquest.com/cgi-bin/ncommerce3/ExecMacro/sci_level3.d2w/report?nav_banner=bio&resource=articles&gateway=B-evolut
~CherylB
Wed, Mar 24, 2004 (14:06)
#7
Early humans swapped bite for brain
Humans owe their big brains and sophisticated culture to a single genetic mutation that weakened our jaw muscles about 2.4 million years ago, a new study suggests.
The slack muscles relaxed their hold on the human skull, giving the brain room to grow. Other primates remained stuck with mighty muscles that squeezed the skull in a vice-like grip.
The finding is "pretty amazing", says Peter Currie, an expert on skeletal muscle development at the Victor Chang Cardiac Research Institute in Darlinghurst, Australia: "Changes in muscle anatomy are well known to alter the bones to which they attach. The exciting part of this is the mutation in the gene dates to exactly when this transition occurs in the fossil record."
Over the past 2.5 million years, human brains have grown enormous compared to those of other primates. Human brains are now roughly three times the size of those of chimps or gorillas.
http://www.newscientist.com/news/news.jsp?id=ns99994817
~terry
Thu, Mar 25, 2004 (08:10)
#8
Early humans swapped bite for brain
Humans owe their big brains and sophisticated culture to a single
genetic mutation that weakened our jaw muscles about 2.4 million
years ago, a new study suggests.
The slack muscles relaxed their hold on the human skull, giving the
brain room to grow. Other primates remained stuck with mighty muscles
that squeezed the skull in a vice-like grip.
The finding is "pretty amazing", says Peter Currie, an expert on
skeletal muscle development at the Victor Chang Cardiac Research
Institute in Darlinghurst, Australia: "Changes in muscle anatomy are
well known to alter the bones to which they attach. The exciting part
of this is the mutation in the gene dates to exactly when this
transition occurs in the fossil record."
Over the past 2.5 million years, human brains have grown enormous
compared to those of other primates. Human brains are now roughly
three times the size of those of chimps or gorillas.
http://www.newscientist.com/news/news.jsp?id=ns99994817
Less bite, more brain.
~MarciaH
Thu, Apr 8, 2004 (07:20)
#9
Hmmmm we're seeing double! I beat Terry by a few hours in posting that.
Btw, Terry, I got a trojan horse virus from your spring email address (admin@apring.net if I recall correctly.) Not due to your sending it, I'm sure.