Question

Environmental factors such as exogenous hormones and temperature-dependent sex determination can cause sex ratios to diverge from 1:1.

Research a scenario that causes a sex ratio to diverge from 1:1?

Answer 1

Ans) sex of animals is also determined by exogenous hormones environmental factors such as temperature PH social interactions and seasonality. In various species sex is determined by the temperature at which the egg incubation take place during the temperature sensitive period and cannot be predicted by genotype of zygote. Temperature dependent sex determination has been observed in in all crocodiles species majority of turtle species and a very few species of lizard. In this reptiles the temperature at which fertilsed eggs are incubated during a specific period of developmentis the main deciding factor in sex determination and small changes in temperature can cause drastic changes in the sex ratio which diverged from 1:1

For eg, in turtle if eggs are in temperature above 34°C during sensitive period this  produces male while below34°C produces female. This causes divergence of sex ratio. This happens because enzyme aromatase is essential in temp dependent sex determination in turtle. Aromatase is an enzyme which convert testosterone inti estrogen.Y

The activity of aromatase is temp sensitive and at female producing temperature its activity  is higher which leads fertilized egg into female turtle .