Queen reproductive tract secretions enhance sperm motility in ants.
Queens of Acromyrmex leaf-cutting ants store sperm of multiple males after a single mating flight, and never remate even though they may live for decades and lay tens of thousands of eggs. Sperm of different males are initially transferred to the bursa copulatrix and compete for access to the long-term storage organ of queens, but the factors determining storage success or failure have never been studied. We used in vitro experiments to show that reproductive tract secretions of Acromyrmex echinatior queens increase sperm swimming performance by at least 50% without discriminating between sperm of brothers and unrelated males. Indiscriminate female-induced sperm chemokinesis makes the likelihood of storage directly dependent on initial sperm viability and thus provides a simple mechanism to secure maximal possible reproductive success of queens, provided that initial sperm motility is an accurate predictor of viability during later egg fertilization.
Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark joanito.liberti@bio.ku.dk.
Joanito
0000-0002-4158-2591
J
Liberti
Centre for Integrative Bee Research (CIBER), The University of Western Australia, Bayliss Building M316, Crawley, Western Australia 6009, Australia.
Boris
B
Baer
Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark jjboomsma@bio.ku.dk.
Jacobus J
JJ
Boomsma
D000818:Animals; D001000:Ants / Q000235:genetics / Q000502:physiology*; D005260:Female; D005836:Genitalia, Female / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology
cryptic female choice; sexual selection; social insects; sperm competition; sperm motility