Parents face a trade-off between putting resources into their offspring. They use resources to enhance their chances of survival so they can have more offspring. The allocation of resources depends on age. More experienced parents are better at getting food. They can pass on more to their offspring. Resources are needed to combat ‘wear and tear’. In age less can be passed on.
This increase-decrease pattern of allocation to offspring is seen in many mammals. This includes birds and insects. Scientists found this pattern in an important disease-carrying insect which is the tsetse fly. Tsetse flies give birth to live young that are as big as their mother.
Scientists studied tsetse mothers in the laboratory for their whole lives. They have made a mathematical model. The study has been published in the journal Proceedings of the Royal Society B. The study has shown how the pattern can be explained by changes the mothers experience as they get older. Tsetse lives on blood. It is a rich food supply but hard to get.
The insects have to fly a long way to find an animal and avoid its defenses. It includes swatting tail. Tsetse gets better at acquiring food through experience. The energy they need to fly increases as their wings become worn. Tsetse mothers have evolved to respond to these effects when they pass on fat to their offspring.
The mathematical model applies to all animals which have more than one offspring during their lives. The model predicts what strategic choices animals will make depending on their ecology. Some species will allocate everything to each breeding event. Others will build up their resources and reproduce less often. This explains diversity is an aim of the project.
Scientists developed the model to include the parasites that tsetse transmit. They are hoping to better understand these important insects. It will be used to reduce the transmission of diseases like sleeping sickness.