How is biodiversity used as a measure for the health of an ecosystem?

The more diverse an ecosystem is, the better the health of an environment. For example, a rainforest. One can tell that the animals are thriving with all the different species. If the health of an ecosystem was poor, then there would be fewer animals.

Since a female is both xx chromosome and the male passes down the x chromosome, than the offspring would be female since a female is xx.