A tail-less Manx Cat (Tt)
Tail-lessness in Manx cats
(and other mammals) is due to a locus (T)
that affects development of the post-axial skeleton. Cats
tails are tt.
There is a
series of dominant T
alleles that lead to lesser or greater reduction of the
tail. Manx cats
often have other problems in development, such as
paralysis of the
hindquarters and prolapse of the rectum. The TT homozygote
Given the lethality of T, why does it remain
population? The skeletal phenotype is a pleiotropic
effect of another effect of the T locus, which
is segregation distortion.
heterozygotes, the T
allele is preferentially
segregated into sperm, such that the T
: t ratio may be as high as 70:30
rather than the expected 50:50.