Strange tales of mating flies

Scientists at UNSW have studied Nereiid flies, above, and discovered a new form of non-genetic inheritance, showing for the first time that offspring can resemble a mother's previous sexual partner.
Russell Bonduriansky

A mothers offspring can resemble her previous sexual partner – at least if she is a fly.

University of New South Wales scientists discovered this form of non-genetic inheritance after manipulating the size of male flies and then measuring their offspring.

Angela Crean, Russell Bonduriansky and Anna Kopps found that the size of the young was determined by the first male the mother had mated with, rather than the size of their father.

Just as we think we have things figured out, nature throws us a curve ball, said Crean, the lead author.

In their study, published in Ecology Letters, the researchers propose the seminal fluid of the first mate was absorbed by the females immature eggs, influencing the growth of her offspring in subsequent matings.

The team manipulated the size of the male flies by feeding them diets that were high or low in nutrients when they were maggots. Immature females were mated with a large or small male, and then mated with a different sized male when they matured. The researchers do not know if the results of the fly experiment would apply to other species.

We know that features that run in families are not just influenced by the genes that are passed down from parents, said Crean.

In the same vein a Canadian study, Project Ice Storm, has been examining the long-term effects of a storm in January 1988 that kept more than three million people in Quebec without power for up to 45 days.

Researchers have found that the number of days pregnant women were deprived of electricity influenced the DNA profile of their child, an effect known as epigenetics.

Women who were pregnant during the storm were recruited for the study and assessed for the degree of stress and hardship they endured.

Scientists from the Douglas Mental Health University Institute and McGill University have detected a distinctive signature in the DNA of children born in the aftermath of the storm. The results of the study were published in the online journal PLOS ONE.

They have concluded that maternal hardship – as opposed to emotional distress – causes long-lasting changes in the epigenome of their babies, specifically the degree of methylation of DNA in their T cells.

The health impacts remain unclear, but the changes may put these teenagers at greater risk of asthma, diabetes or obesity.

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