Genetic differences influence aging rates in the wild

Dec 12, 2007

Long-lived, wild animals harbor genetic differences that influence how quickly they begin to show their age, according to the results of a long-term study reported online on December 13th in Current Biology, a Cell Press publication. Evidence for the existence of such genetic variation for aging rates—a central tenet in the evolutionary theory that explains why animals would show physiological declines as they grow older—had largely been lacking in natural populations until now, the researchers said.

“We’ve found that individuals differ in their rates of aging, or senescence, and that these differences are (at least in part) caused by genetic effects so they will be inherited,” said Alastair Wilson of the University of Edinburgh. “While the genetic effects we found are completely consistent with existing theory, scientists hadn’t previously managed to test this theory properly except in controlled laboratory experiments.

“We’ve also done this work on long-lived mammals,” he added. “For someone interested in the evolution of aging and senescence in humans, these are going to be more relevant organisms than Drosophila [fruit flies].”

Scientists normally expect genetic mutations having bad effects to be removed by natural selection, Wilson explained. Conversely, selection will lead to an increase in the frequency of mutations that are beneficial. “On this basis, any genes with bad effects on survival or reproduction should be removed by selection,” he said. “But if that were true then there is no reason for individuals to deteriorate as they get old.”

Aging therefore raises a critical question: How has natural selection failed to remove genetic effects responsible for such reduced fitness among older individuals" Current evolutionary theory explains this phenomenon by showing that, as a result of the risk of death from environmental causes that individuals experience over the course of their lives, the force of selection inevitably weakens with age, he continued. This, in turn, means that genetic mutations having detrimental effects that are only felt late in life may persist in a population. Although widely accepted, this theory rests on the assumption that there is genetic variation for aging in natural systems.

To look for such genetic variation in the new study, the researchers examined wild Soay sheep and red deer living on two Scottish islands. Those populations were ideal for the study because they provide unparalleled levels of data, including individual survival and reproductive success, for large numbers of long-lived animals, Wilson said. In both study systems, individually marked animals are followed throughout their lives from birth until death, and their relationships to one another are known.

In both the red deer and sheep populations, they found evidence for age-specific genetic effects on “fitness”—a measure combining the animals’ probability of survival and reproduction. “The present study provides, to our knowledge, the first evidence for additive genetic variance in aging rates from a wild, non-model study organism,” the researchers concluded. “Furthermore, the age-specific patterns of additive genetic (co)variation evident in the two populations examined here were entirely consistent with the hypothesis that declines in fitness with age are driven by a weakening of natural selection.”

Source: Cell Press

Explore further: Dwindling wind may tip predator-prey balance

add to favorites email to friend print save as pdf

Related Stories

Protecting privacy also means preserving democracy

Sep 01, 2014

What impact does the proliferation of new mobile technologies have? How does the sharing of personal data over the Internet threaten our society? Interview with Professor Jean-Pierre Hubaux, a specialist ...

'Zombie' bacteria are nothing to be afraid of

Aug 28, 2014

A cell is not a soap bubble that can simply pinch in two to reproduce. The ability to faithfully copy genetic material and distribute it equally to daughter cells is fundamental to all forms of life. Even ...

From eons to seconds, proteins exploit the same forces

Aug 12, 2014

(Phys.org) —Nature's artistic and engineering skills are evident in proteins, life's robust molecular machines. Scientists at Rice University have now employed their unique theories to show how the interplay ...

Recommended for you

Dwindling wind may tip predator-prey balance

Sep 19, 2014

Bent and tossed by the wind, a field of soybean plants presents a challenge for an Asian lady beetle on the hunt for aphids. But what if the air—and the soybeans—were still?

Environmental pollutants make worms susceptible to cold

Sep 19, 2014

Some pollutants are more harmful in a cold climate than in a hot, because they affect the temperature sensitivity of certain organisms. Now researchers from Danish universities have demonstrated how this ...

Research helps steer mites from bees

Sep 19, 2014

A Simon Fraser University chemistry professor has found a way to sway mites from their damaging effects on bees that care and feed the all-important queen bee.

User comments : 0