JUL 03, 2020 9:31 PM PDT

Why Can Old Mothers Keep Producing Offspring?

WRITTEN BY: Carmen Leitch

In humans and many animals, older mothers have offspring that tend to be less healthy or have fewer offspring than others of their species. Scientists have long wondered why it is still biologically possible, in other words, why evolutionary pressures have maintained this ability in older mothers since their offspring don't fare as well. Researchers used a model organism called rotifers and mathematical modeling to learn more.

Image credit: Pxfuel

Rotifers are tiny invertebrate animals that can quickly produce many generations. The researchers tested the offspring and older mothers in several environments, such as a comfortable existence in a laboratory culture, a wild habitat that included predators, and one in which their food was limited.

The research, which was reported in the Proceedings of the National Academy of Sciences (PNAS), illustrated the impact of older maternal age, which is called maternal effect senescence. It showed that evolutionary fitness was reduced in offspring in every environment they tested, primarily through a reduction in fertility at what would be their prime reproductive age.

"This study is unique in that combines laboratory data from our prior work with mathematical modeling to address a longstanding question in the evolution of aging," said the co-leader of the study Kristin Gribble of the Marine Biological Laboratory. "Natural selection should weed out these less-fit offspring of older mothers. So why do we see this phenomenon across so many species?"

To answer this question, study co-leader Christina Hernández of Woods Hole Oceanographic Institution and colleagues created models that would calculate how strong the natural selection pressure was in the fertility and lifespan of offspring. They found that this pressure, which is called the selection gradient, gets lower as mothers get older.

"Because the selection pressure decreases as the mothers age, it may not be strong enough to remove these less-fit [offspring] from the population," Hernandez explained.

"Because of this, maternal effect senescence will persist and continue to evolve in the population, even though it results in decreased fitness," Gribble added. More research will be needed to understand the genetic mechanisms that affect offspring fitness.

The mathematical models that were made can be applied to many species to understand the impact of maternal effect senescence. "As long as you have experimental data, as we did, on lifespan and fecundity of offspring from mothers of different ages, you can address this question in many organisms," Gribble said.

Sources: AAAS/Eurekalert! via Marine Biological Laboratory, PNAS

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
MAY 09, 2021
Microbiology
Bacteria Can Read Genes Forwards or Backwards
MAY 09, 2021
Bacteria Can Read Genes Forwards or Backwards
One of the most basic processes in life in the creation of proteins from mRNA molecules, which are transcribed from DNA. ...
MAY 19, 2021
Health & Medicine
Who Ages Better, Men or Women?
MAY 19, 2021
Who Ages Better, Men or Women?
The answer depends on what's considered more important – quantity or quality of years?  Previous studies ...
MAY 28, 2021
Genetics & Genomics
Some Biofilms Seem to Activate Cancer Genes
MAY 28, 2021
Some Biofilms Seem to Activate Cancer Genes
New research assessed bacterial and fungal biofilms, tenacious microbial communities that are tougher than small groups ...
JUN 03, 2021
Genetics & Genomics
Activating Neurons in the Brain with a Combo of Ultrasound & Genetics
JUN 03, 2021
Activating Neurons in the Brain with a Combo of Ultrasound & Genetics
Devices that can stimulate deep regions of the brain have been in development as treatment options for disorders like ep ...
JUL 20, 2021
Cell & Molecular Biology
Do Phages Drive Bacterial Evolution?
JUL 20, 2021
Do Phages Drive Bacterial Evolution?
Antibiotics are a standard treatment for bacterial infections, but more and more of these bacterial infections can't be ...
JUL 27, 2021
Drug Discovery & Development
Immune related genes influence antipsychotic-induced weight gain.
JUL 27, 2021
Immune related genes influence antipsychotic-induced weight gain.
Mental disorders such as Schizophrenia and Bipolar disorder are currently incurable, but some symptoms can be treated wi ...
Loading Comments...