The life expectancy of male seed beetles is extended by inbreeding.
Reading Inbreeding extends the life expectancy of male seed beetles and shortens the females. However, the reproductive success is decreasing for both sexes alike, Swedish researchers have found around Trine Bilde from the University of Uppsala. Their observations provide clues as to why life expectancy of males and females is significantly different in many species. In most insects and mammals, as well as in humans, the females live longer on average than the males. There are different explanations for this phenomenon. One theory is that the second X chromosome of females can compensate for genetic defects on the first X chromosome. In incest, then increase the probability that the same defects in both chromosomes occur. In any case, males have only one X chromosome and would therefore be less affected by inbreeding.

To verify this, the researchers bred incest beetles and observed how the average lifespan of normal animals changed. The surprising result: The lifespan of the males was not only shortened by inbreeding less than that of the females, it even extended. That can not be justified by the different chromosomes, explain the researchers.

As an alternative explanatory approach, the researchers call the so-called gender-specific selection: For males completely different breeding strategies may be advantageous than for females. For example, it could be useful for males to invest a lot of energy in mating at an early age and to accept a relatively early death. Females, on the other hand, need time to lay eggs and have to live longer to mate several times. Inbreeding leads to disorders of these strategies. Thus, the prolonged life of the seed beetle male may be an evolutionary disadvantage. In fact, the males, as well as the females, produced fewer offspring? her reproductive fitness decreased as a result of inbreeding.

Trine Bilde (University of Uppsala) et al .: BMC Evolutionary Biology (Vol. 9, p.33). ddp / Martin Rötzschke advertisement


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