Sex determination.

Bacci, Guido.

Date:: [1965]

Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Sex determination. Source: Wellcome Collection.

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HERMAPHRODITISM, BALANCE AND MODIFICATION 179 called pure males did not reach the sizes which are obtained in laboratory experiments. It is now clear that the above mechanism of sex balance reduces the fitness of the sex homozygotes which can be obtained in the sheltered laboratory conditions but fail to appear in nature. The gradually decreasing number of the progeny in the generations of arrhenogenous and thelygenous lines is also evident in Tables 3 and 4 and it can now be inteфreted on the basis of the extensive damages suffered by sexual cells as a result of selection. In this way sex homeostasis in natural populations of Ophryotrocha puerilis is ensured by its very mechanism of sex balance, despite polygenic sex determination. It is still to be seen which is the mechanism of sex balance in such un¬ balanced hermaphrodite populations like Patella caerulea or Asterina gibbosa from Lake Fusaro.