234
B. L. ASTAUROV
Equational
maturation
division
Diploid
cleavage ·
Diploid
female P,
Heatinq
|(46°C; 18 minutes^/
V
d
2/7 [zn+Zri
Equational
maturation
division
Somatic
poliploidization
Mixoploid
female P.
Diploid
oocyte I [£*■/$
FIG. 6. A schematic representation of the origin of parthenogenetic mixoploids,
tetraploid clones and bisexual tetraploid strain. To the left (2n), the origin of
mixoploid females (2n + 4n) and of tetraploid parthenoclone An; to the right
(3n), the origin of mixoploid females (3n + 6n) and their bisexual tetraploid
progeny.
rather plausible alternative hypothesis able to explain the appearance
of tetraploid descendants in $ 3 τζ X c? 2 n crosses is the nonreduction
of 3 n oocytes. Yet, in egg batches obtained by matings of 3 n parthenofemales with 2 n males, tetraploid larvae usually appear in groups, i.e.,
several or none in a given oviposition. It is not so easy to understand
why such a casual event as nonreduction during oocyte maturation
happens simultaneously in several ova of the same batch while no