American Society of Naturalists

A membership society whose goal is to advance and to diffuse knowledge of organic evolution and other broad biological principles so as to enhance the conceptual unification of the biological sciences.

“Royal Darwinian demons: enforced changes in reproductive efforts do not affect the life expectancy of ant queens”

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Alexandra Schrempf, Julia Giehr, Ramona Röhrl, Sarah Steigleder, and Jürgen Heinze

A forced increase in reproduction of ant queens is not reflected in a shortened life span

Workers of the ant <i>Cardiocondyla obscurior</I> with larvae.<br />(Photo © Julia Giehr)
Workers of the ant Cardiocondyla obscurior with larvae.
(Photo © Julia Giehr)

The trade-off between reproduction and longevity appears to be fundamental throughout animals and plants: to optimize their reproductive success, organisms have to find the best way of allocating limited resources to either the production of offspring or the maintenance of their own bodies. Accordingly, increased reproduction usually results in a decrease in lifespan and vice versa. In a study appearing in The American Naturalist, scientists of the university of Regensburg, Germany, report on the extraordinary lack of this trade-off in ant queens.

Young queen of the ant <i>C.&nbsp;obscurior</I>.<br />(Photo © Julia Giehr)
Young queen of the ant C. obscurior.
(Photo © Julia Giehr)

In the study, they were able to show that ant queens actually do not suffer from artificially boosted reproduction: by continuously removing eggs from single-queen colonies of the ant Cardiocondyla obscurior, they induced randomly selected queens to augment their efforts into reproduction. Increased egg laying rate did not result in a decrease of longevity. Instead, they found a positive correlation between mean egg number and the lifespan of the females, suggesting that exhaustive reproduction even extends longevity. The results imply that queens are able to reduce the costs of reproduction without affecting other fitness traits negatively, and that they are able to counter or at least delay senescence. Read the Article

Ant colony of <i>C.&nbsp;obscurior</I>.<br />(Photo © Julia Giehr)
Ant colony of C. obscurior.
(Photo © Julia Giehr)