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Hi friends, in this video let us
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understand two confusing terms.
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Genetics, sex influence trait and sex
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limited trait. Sex influence trait. Let
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us focus on this word influenced.
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Influenced means the trait the
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expression of this trait is influenced
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by the gender whether it is male or
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female. The severity or intensity of
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expression is influenced by the sex that
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is male or female. Whereas sex limited
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means that particular trait is limited
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to a particular sex in male or in
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female. Let us understand with some
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examples. The classical example in
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humans is the baldness. So this is the
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genotype of baldness.
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It's a dominant gene in males capital B
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capital B. Whereas in females capital B
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capital B often lead to thinning not
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complete hair loss. Whereas in
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heteroscygus condition as this gene is
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dominant in males baldness in males
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whereas not bald in females. So the
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expression of this gene is not directly
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dependent on genotype alone. It is also
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dependent on the sex whether it is male
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or female. This gene is autotosomal. So
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the expression of this trait the
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baldness is influenced by the sex
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especially the hormonal environment. The
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reason is high testosterone is the
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reason for this baldness in male and
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that makes this gene dominant whereas
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low testosterone in females makes it
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recessive or in hetereroygous condition
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there won't be no expression. So the
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severity of the expression of this
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particular gene differs and that is
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dependent on the sex. That is why this
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is called as sex influenced trait.
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The second condition is a sex limited
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trait that is it is present only in one
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of the sexes. Classical example is in
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bull and cow both have this the gene for
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milk production. In bull there is no
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milk production because there is no
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memorary glands or associated hormonal
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assistance or hormonal expression.
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Whereas in cow there is anatomy and
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physiology that is presence of memory
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glands and hormones that induces milk
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production. This gene is also
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autotosomal but the expression of this
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trait is limited to one sex due to
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anatomy or physiological difference. So
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this is called as sex limited trait. So
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let me summarize. The key difference is
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sex influence traits appear in both
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sexes but with different severity or
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frequencies whereas sex limited traits
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are exclusive to one sex despite both
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carrying the gene. Let us quickly
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summarize the differences. Sex influence
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trait is a trait that is expressed in
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both sexes. But the dominance of the
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alil differs between males and females.
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Whereas sex limited trait is expressed
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in only one sex even though both sex
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carries the gene. Sex influence trait is
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heavily influenced by sex hormones like
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testosterone and estrogen. Whereas sex
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limited trait it is heavily dependent on
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sex specific anatomy and also hormonal
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Sex influence traits. Both sexes shows
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the trait but expression intensity
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differs whereas sex limited trait is
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exclusive in one sex and completely
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absent in another. And finally both
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these traits sex influenced and sex
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limited traits are usually autotosomal.
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Hope you are clear. Take care. Stay
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blessed. Thank you so much. You are with
