Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?

The numbers of eggs produced by an oviparous mother will be more than the young ones produced by a viviparous mother. This is because in oviparous animals, the development of young ones takes place outside the mother’s body. Their eggs are more prone to environmental conditions and predators. Therefore, to overcome the loss, more eggs areproduced by mothers so that even under harsh environmental conditions, some eggs might be able to survive and produce young ones. On the other hand, in viviparous organisms, the development of young ones takes place in safe conditions inside the body of the mother. They are less exposed to environmental conditions and predators. Therefore, there are more chances of their survival and hence, less number of young ones is produced compared to the number of eggs.

In case of oviparous animals, eggs are exposed to the vagaries of nature and also face the danger of predators. Hence, a larger number of eggs needs to be laid to ensure survival of the species. 

In case of viviparous animals, the foetus develops to a size that it can have better chances of survival after birth. Moreover, development of foetus requires more resources from the female’s body. Hence, a smaller number of offsprings are produced by viviparous animals.

Usually number of eggs produced by oviparous mothers is greater than number of young ones produced by viviparous mothers. The main reason for this is the need of resources required for development of the embryo. In oviparous the major part of development of the embryo takes place outside the uterus. This makes lesser burden on the mother.

On the other hand in viviparous animals the development takes place inside the uterus so lesser number of young ones can be successfully incubated. Moreover, once eggs are outside they are at risk of getting eaten by some predator because of their immobility, so need of more eggs is there to ensure continuity of progeny.