Lower evolutionary fitness in the offspring of older mothers
The offspring of older mothers are less fertile. A possible evolutionary mechanism has now been identified as the cause of this.
A recent joint study by the Woods Hole Oceanographic Institution and the University of Amsterdam examined why offspring from older mothers have reduced fertility. The results were published in the English-language journal "Proceedings of the National Academy of Sciences"
Studies on rotifers carried out
The new study used rotifers (microscopic invertebrates) to study the fertility of the offspring of older mothers in several real and simulated environments. The researchers observed that negative effects on fertility occur in the offspring of older mothers. So this was significantly reduced in all examined environments. The offspring of the older dams were often not as healthy or did not live as long.
This study is unique in that it combines laboratory data from previous research with mathematical models to resolve a long-standing question in the development of aging. Natural selection should actually sort out the less fit offspring of older mothers. So why is there the phenomenon that offspring of older mothers have an evolutionary disadvantage in so many species?
Selection pressure decreases with the age of the mother
To clarify this problem, the research group created mathematical models that made it possible for the first time to calculate the strength of natural selection pressure on the survival and fertility of offspring populations as a function of the age of the mothers. It was found that this selection pressure decreases with the age of the mothers.
Does decreasing selection pressure lead to less fit offspring?
Since the selection pressure decreases with increasing age of the mothers, it may not be strong enough to remove these less suitable offspring from the population, the researchers suspect. For this reason, the maternal effect of senescence (physical changes caused by aging) will continue and continue to develop in the population, even if it leads to reduced fitness, the researchers said.
Results enable further research
The models developed by the team can be applied to a wide range of species to assess the effects of maternal aging on the offspring. As long as experimental data on the lifespan and fertility of the offspring of mothers of different ages are available, the effect on many organisms can be investigated, the researchers emphasize. This now enables a broad spectrum of further investigations. (as)
Author and source information
This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
- Christina M. Hernández, Silke F. van Daalen, Hal Caswell, Michael G. Neubert, Kristin E. Gribble: A demographic and evolutionary analysis of maternal effect senescence, in Proceedings of the National Academy of Sciences (published May 29, 2020), Proceedings of the National Academy of Sciences