That’s a reasonable assumption, given the sexual conflicts that rage in other insects – many species produce sperm that harm females or even shorten their lives.But Andy Gardner and Laura Ross from the University of Oxford think that there’s more to the evolution of the scale insect’s sex life than males versus females.At some time, there would have been a tipping point when conflict gave way to collaboration.
The rare pure males look very different.) How did this bizarre sexual system evolve?In 2009, Benjamin Normark suggested that it’s the result of a battle of the sexes.They developed a mathematical model to simulate these sexual conflicts among ancestral scale insects where the sexes were still separate.The model accounts for the fact that daughters aren’t infected with any old parasitic tissue – it comes from their “father”, and carries many of the same genes that they have.He envisioned a time when males and females were separate entities.
When males gained the ability to infect their daughters with “parasitic” sperm, they could fertilise the eggs of multiple generations.
These bacteria can often be found in tight clusters around the infectious tissue, and if they are killed with antibiotics, females are more likely to produce sons.
To Gardner and Ross, this suggests that the bacteria could help to protect the infectious tissue from being destroyed. Because the bacteria are passed down from mother to daughter. In this regard, their “interests” are the same as those of the infectious tissue. The evolution of hermaphroditism by an infectious male-derived cell lineage: an inclusive-fitness analysis.
The life of the cottony cushion scale insect reads like something from the most ridiculous of tabloid newspapers.
Dad leaves parasitic body parts in his own daughter, which produce sperm that fertilise her eggs.
With the exception of the odd pure male, almost every individual is both male and female.