what is the formula for the optimal sex ratio in a hamiltonian population? What are some real organisms that show this adaptation?

The formula for the optimal sex ratio in a Hamiltonian population is known as Fisher's principle, which states that the proportion of males to females in a population should be equal to the ratio of the cost of producing a male offspring to the cost of producing a female offspring. Mathematically, the optimal sex ratio can be calculated using the following formula:

p = c(M) / [c(M) + c(F)]

where:
p = proportion of males in the population
c(M) = cost of producing a male offspring
c(F) = cost of producing a female offspring

However, it is important to note that this formula represents a theoretical prediction and may not always hold true in natural populations due to various ecological and genetic factors.

Regarding examples of real organisms that show this adaptation, one well-known example is the behavior of some parasitoid wasps. These wasps lay their eggs inside the bodies of other insects, and their offspring develop by consuming the host from the inside. Since the sex of the offspring is determined by the mother, having an equal sex ratio ensures that there is a balance between the number of females that can reproduce in the next generation and the number of males that can inseminate them.

Another example is found in some species of birds, particularly those that exhibit cooperative breeding. In these species, a dominant pair of birds form a breeding pair, and other non-breeding individuals assist in raising the offspring. The optimal sex ratio in these populations is often skewed toward more males, as the presence of additional males can provide assistance in defending territories and acquiring resources for the breeding pair.

Please note that these are just a couple of examples, and there are many other organisms that may show adaptations related to their sex ratios based on their specific ecological and evolutionary contexts.