Inbreeding bad


“Inbred male sperm have been found to fertilise fewer eggs when in competition with non-inbred males according to a new study by the University of East Anglia,” says a press release from the same university. This caught my eye: male sperm? Can there be female sperm? Inbred sperm? Sperm “breed”? Where is East Anglia? And, why would anyone doubt the inefficiency of inbred anything?

First things first, the University is highly regarded and located in London. I really do need to get out more.

Also, it’s really not inbred male sperm. More correctly it could be worded sperm from inbred males (and no, there is no female sperm). The research is actually quite fascinating and is rooted in real world trouble. As populations diminish or become more isolated, for whatever reason, the breeding pool is reduced and inbreeding becomes a reality. Conserving genetic variation is a priority recognized even by the International Union for Conservation of Nature.

For this research, promiscuous red flour beetles were studied to see how they would react to forced inbreeding. After mating brothers and sisters for eight generations, Dr. Matt Gage, team leader, found no changes in male fertility or mating behavior. However, the inbred males fertilized fewer eggs compared to other non-inbred males. They father an average of 15% fewer offspring. Apparently the sperm of the inbred males also comes in an unusual variety of sizes.

However, you can only extend a comparison to humans so far with this study. As Dr. Gage explains, “One limitation to this study is that the ancestral laboratory stock we have used is likely to carry relatively reduced genetic diversity. Also insect sperm do not generally manifest cellular abnormalities akin to those commonly found in more complex mammalian sperm.”

This is just the first part of a three year study. The ultimate goals are to identify when inbreeding becomes a problem, how it progresses and how to best manage or reverse it. Any implications for humans will be interesting, but in the meantime, it seems clear that that inbreeding is not recommended - for red flour beetles or for you.

Source: University of East Anglia, Medical News Today


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