Algerian female damselflies preserve ‘sneaky’ mating

This reproductive trade off, observed in rare Calopteryx exul (Glittering Demoiselle), could help explain the evolutionary preservation of some sneaky mating behaviours that help lead to the birth of weaker progeny.

In many animal species, males that can’t get a mate through prevailing strategies, often involving physical dominance, adopt alternative tactics. Sneaky mating approaches, seen in some fish and frogs, for example, involve the use of various types of deception.

Rassim Khelifa, of the University of British Columbia, in Vancouver, Canada, surveyed C. exul damselflies in north-eastern Algeria. During the mating season, some males battle to defend patches of floating leaves that give them sexual access to females that land on them. Sneaker males perch nearby, waiting to fly in and remove females, which they then force to copulate.

When females return to the leaves, dominant males seek to re-copulate with them. Male C. exul can remove sperm from the female reproductive tract, and egg fertilization results from the final mating. 

Khelifa observed that a large number of female damselflies avoided mating with dominant males following a sneaker copulation by positioning themselves on the leaves near other females. This behaviour made it more likely that dominant males re-copulated with the other females.

“We know that repeated copulation can cause damage to the female’s wings and reproductive tract,” says Khelifa. “So when she returns, she avoids the dominant male and so selects a less fit male for her health and fitness.”

C. exul, which is listed as endangered on the IUCN Red List of Threatened Species, are only found in Morocco, Algeria, and Tunisia.

“This is the first evidence of indirect assistance by females of sneaker male fitness in damselflies,” adds Khelifa, “and I haven’t seen it mentioned for other taxa either.”

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