紅果蠅的減數分裂驅動因子與染色體進化的關係

The F2 offspring from the cross between
a female Drosophila albomicans from
Okinawa and a male D. nasuta are female
biased, whereas those strains have a normal
1:1 sex ratio themselves. The hybrid F1 male
is the cause for sex ratio distortion.
Therefore, we suggest that the 3-X
chromosome of the Okinawa D. albomicans
may contain both sex ratio distorter (SR) and
its suppressor, but D. nasuta has neither.
Taiwan and Thailand D. albomicans may not
have SR because no sex ratio distortion was
observed when crossed to D. nasuta . But
they don’t show sex ratio distortion when
crossed to Okinawa D. albomicans female
either. This phenomenon suggests that
although they don’t have SR, they have the
suppressor of SR.
The interaction between SR and its
suppressor may elaborate the hypothesis
“stepwise chromosome evolution of D.
albomicans” for the selfish element SR on the
3-X chromosome can make an increase the
frequency of the chromosome by meiotic
drive. Several experimental populations
were constructed to test the correlation
between SR and the increase of 3-X. The
result confirmed that the SR can indeed cause
an increase of the frequency of 3-X
chromosome.