Inbred sperm fertilise fewer eggs

June 16th, 2010 - 6:49 pm ICT by IANS  

London, June 16 (IANS) Males with genetically-related parents have been found to have sperm that fertilise fewer eggs when compared with non-inbred males, according to a latest research.
Inbreeding is the reproduction from the mating of two genetically-related parents, which can increase the chances of offspring being affected by recessive or deleterious traits.

Research into the breeding habits of the red flour beetle shows that the reduced fitness of inbred beetles, known as ‘inbreeding depression’, reveals itself in competitive scenarios.

Inbreeding is a potentially important problem in declining species across the world, and conserving genetic variation is now recognised as a priority by the International Union for Conservation of Nature.

When population depletes or fragments, relatives can be forced into reproduction, often leading to inbreeding depression.

Led by Matt Gage of the University of East Anglia (UofEA), the new research into the promiscuous red flour beetle (Tribolium castaneum) measured how male reproduction responded to forced inbreeding.

After mating brothers with sisters for eight generations, the research found no changes in male fertility or mating behaviour.

However, inbred male sperm fertilised fewer eggs when in competition with another non-inbred male, and sperm became more variable in size, said an UofEA release.

Gage said: “The experiment was designed to make comparisons with non-inbred control lines. Using multiple inbred lines, we measured the effects of inbreeding on pre- and post-mating success, in the absence and presence of male-male competition.”

The results showed no differences between inbred and non-inbred males in terms of mating success, latency, duration, the number of mounts or persistency in a non-competitive setting.

However inbred males suffered significantly reduced sperm competitiveness, fathering an average of 15 percent fewer offspring than non-inbred males across 330 sperm competition comparisons.

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