Re: Why is it macroevolution?
- From: r norman <NotMyRealEmail@xxxxxxxxxxxx>
- Date: Sat, 12 Aug 2006 20:00:03 -0400
On Sat, 12 Aug 2006 17:07:15 -0500, "Denis Loubet" <dloubet@xxxxxx>
"r norman" <NotMyRealEmail@xxxxxxxxxxxx> wrote in message
On Sat, 12 Aug 2006 17:44:42 GMT, pdunkel@xxxxxxxxxxxxxxx (Dunk)
By definition it seems. In t.o. microevolution is defined as
population - level processes, or it is defined as only changes in
allele frequencies in a single population, or it is defined as
population genetics. These are not quite the same things, but each
leaves much left over to be macroevolution. In addition,
macroevolution seems to be, per various threads with 'rev. Goetz',
sometimes not a process but the reason(s) for various processes even
though they are population-level.
Elsewhere, macroevolution is defined as including any noticeable
Sticking with the t.o. version: suppose a species subdivides into two
populations, A and B. Perhaps B is a relect group left behind as the
species' range shrinks. B's environment changes. If population B
evolves into a distinct species, that's cladogenesis, or
macroevolution, unless A (the rest of the species) dies out first.
Then the change in B is anagenesis, or microevolution. It depends on
The traditional biological definition is that microevolution is the
change in the genetic composition of a population. That is also the
technical definition of evolution, itself. Your alternative phrases,
"population level processes", "changes in allele frequencies in a
single population", or "population genetics" are not exactly the same
thing but all refer to the genetic composition (i.e. allele
frequencies) in a population.
Macroevolution refers to evolutionary changes that result in the
production of a new species or to a new taxon above the species level.
That is, microevolution refers simply to change; "descent with
modification" if you will. Macroevolution refers to branching in the
tree of descent.
That is the way most biologists describe it, although you can put in a
lot more technical details. What t.o. calls it is whatever anybody
who wants to post says.
My understanding is that it's not a biological term at all, it's a
There is no such thing a micro and macro evolution, there's only evolution.
True, there is only evolution, but it can be divided into micro and
macro categories, rather distinct subjects that can be taught in very
distinctly different courses. There is only chemistry, but still we
have organic and inorganic. Do a google search restricted to academic
sites: "macroevolution site:edu" to find almost 70,000 hits.
Searching "microevolution site:edu" finds almost 44,000.
That micro vs. macro evolution is purely a creationist construct is a
misunderstanding very common especially on t.o. And if you really
want an argument, raise the question of whether macroevolution is
nothing more than "a lot of microevolution piled high". There are
many biologists who argue that macroevolutionary processes require
mechanisms and events that surpass what microevolution considers. You
get into selection above the level of the organism and the role of
environmental change in shaping the structure of taxonomic groups and
all sorts of things.
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