In 2006, Watts et al. (Nature 444:1021-1022) reported the hatching of several of

Question

In 2006, Watts et al. (Nature 444:1021-1022) reported the hatching of several offspring from eggs of captive female Komodo dragons maintained at separate institutions and kept isolated from males. They confirmed by genetic fingerprinting that the eggs were produced by the dragons as the result of parthenogenesis. The fingerprinting analysis showed that the overall clutch genotype reconstructed that of the mother exactly and that each of the offspring was homozygous at all loci tested. Given that sex determination in Komodo dragons follows the ZZ/ZW system, what is the expected gender ratio in the hatched, parthenogenic Komodo dragon offspring? (Note: A clutch is the total number of eggs laid by a female at a given time.)

A. All male
B. ¾ male and ¼ female
C. ½ male and ½ female
D. ¼ male and ¾ female
E. All female

Explanation / Answer

A. All male

Given that sex determination in Komodo dragons follows the ZZ/ZW system. In case of Komodo dragons, eggs that recieve Z chromosome will become ZZ (chromosomal duplication in parthenogenesis (asexual reproduction), develops into male, and those recieve W chromosme will become WW (fail to develop). So, only males can be developed in Komodo dragons by parthenognesis.

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