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Subject: Re: [DNA-R1B1C7] DNA-R1B1C7 Digest, Vol 2, Issue 101
Date: Fri, 26 Sep 2008 07:49:30 EDT
In a message dated 9/26/2008 2:00:50 A.M. Central Standard Time,
writes:
There are no "proclivities" of Y-DNA haplogroups. The markers that determine
haplogroups and haplotypes find NO EXPRESSION in the phenotype, they do not
code for proteins, they do not mark ethnic groups, and they do not support
crack-pot theories of the Israelites settling Britain. Give it a rest.
David Ewing
Yair
David is correct If you are only preaching on a scientific platform . But
most of us are more interested in a real life story of our genetic continuity
and if in reality and we can only be identified by a haplogroup. And in the
future our tribal surname may not have as much significance and does not have
continuity,and we only represent a random sexual event that can be only
traced by DNA
Gene Ashley
Genotype-phenotype distinction
>From Wikipedia, the free encyclopedia
Jump to: _navigation_
(http://en.wikipedia.org/wiki/Genotype-phenotype_distinction#column-one) , _search_
(http://en.wikipedia.org/wiki/Genotype-phenotype_distinction#searchInput)
The genotype-phenotype distinction is drawn in _genetics_
(http://en.wikipedia.org/wiki/Genetics) . "_Genotype_ (http://en.wikipedia.org/wiki/Genotype) "
is an organism's full _hereditary_ (http://en.wikipedia.org/wiki/Hereditary)
information, even if not expressed. "_Phenotype_
(http://en.wikipedia.org/wiki/Phenotype) " is an organism's actual observed properties, such as
_morphology_ (http://en.wikipedia.org/wiki/Morphology_(biology)) , _development_
(http://en.wikipedia.org/wiki/Development) , or _behavior_
(http://en.wikipedia.org/wiki/Behavior) . This distinction is fundamental in the study of
_inheritance_ (http://en.wikipedia.org/wiki/Biological_inheritance) of _traits_
(http://en.wikipedia.org/wiki/Trait_(biology)) and their _evolution_
(http://en.wikipedia.org/wiki/Evolution) .
The genotype represents its exact genetic makeup — the particular set of
_genes_ (http://en.wikipedia.org/wiki/Gene) it possesses. Two organisms whose
genes differ at even one _locus_
(http://en.wikipedia.org/wiki/Locus_(genetics)) (position in their _genome_ (http://en.wikipedia.org/wiki/Genome) ) are
said to have different genotypes. The transmission of genes from parents to
offspring is under the control of precise molecular mechanisms. The discovery of
these mechanisms and their manifestations began with _Mendel_
(http://en.wikipedia.org/wiki/Mendel) and comprises the field of _genetics_
(http://en.wikipedia.org/wiki/Genetics) .
It is the organism's physical properties that directly determine its chances
of survival and reproductive output, while the inheritance of physical
properties occurs only as a secondary consequence of the inheritance of genes
Therefore, to properly understand the theory of evolution via _natural selection_
(http://en.wikipedia.org/wiki/Natural_selection) , one must understand the
genotype-phenotype distinction.
The _mapping_ (http://en.wikipedia.org/wiki/Mapping) of a set of genotypes
to a set of phenotypes is sometimes referred to as the genotype-phenotype
map.
An organism's genotype is a major (the largest by far for _morphology_
(http://en.wikipedia.org/wiki/Morphology_(biology)) ) influencing factor in the
development of its phenotype, but it is not the only one. Even two organisms
with identical genotypes normally differ in their phenotypes. One experiences
this in everyday life with _monozygous (i.e. identical) twins_
(http://en.wikipedia.org/wiki/Identical_twins) . Identical twins share the same genotype,
since their genomes are identical; but they never have the same phenotype,
although their phenotypes may be very similar. This is apparent in the fact that
their mothers and close friends can always tell them apart, even though others
might not be able to see the subtle differences. Further, identical twins can
be distinguished by their _fingerprints_
(http://en.wikipedia.org/wiki/Fingerprint) , which are never completely identical.
The concept of _phenotypic plasticity_
(http://en.wikipedia.org/wiki/Phenotypic_plasticity) describes the degree to which an organism's phenotype is
determined by its genotype. A high level of plasticity means that _environmental
factors_ (http://en.wikipedia.org/wiki/Environmental_factor) have a strong
influence on the particular phenotype that develops. If there is little
plasticity, the phenotype of an organism can be reliably predicted from knowledge
of the genotype, regardless of _environmental_
(http://en.wikipedia.org/wiki/Environment_(biophysical)) peculiarities during development. An example of
high plasticity can be observed in _larval_ (http://en.wikipedia.org/wiki/Larva)
_newts_ (http://en.wikipedia.org/wiki/Newt) 1: when these larvae sense the
presence of _predators_ (http://en.wikipedia.org/wiki/Predator) such as
_dragonflies_ (http://en.wikipedia.org/wiki/Dragonfly) , they develop larger heads
and tails relative to their body size and display darker _pigmentation_
(http://en.wikipedia.org/wiki/Pigmentation) . Larvae with these traits have a
higher chance of _survival_ (http://en.wikipedia.org/wiki/Survival_skills) when
exposed to the predators, but grow more slowly than other phenotypes.
In contrast to phenotypic plasticity, the concept of _genetic canalization_
(http://en.wikipedia.org/wiki/Canalisation_(genetics)) addresses the extent
to which an organism's phenotype allows conclusions about its genotype. A
phenotype is said to be canalized if _mutations_
(http://en.wikipedia.org/wiki/Mutation) (changes in the genome) do not noticeably affect the physical
properties of the organism. This means that a canalized phenotype may form from a
large variety of different genotypes, in which case it is not possible to
exactly predict the genotype from knowledge of the phenotype (i.e. the
genotype-phenotype map is not invertible). If canalization is not present, small changes
in the genome have an immediate effect on the phenotype that develops.
The terms "genotype" and "phenotype" were created by _Wilhelm Johannsen_
(http://en.wikipedia.org/wiki/Wilhelm_Johannsen) in 1911.
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