Uniform sperm morphology in the lek-breeding wire-tailed manakin (Pipra filicauda)

Abstract

When females copulate with multiple males, selection on spermatozoa can reduce variation in sperm morphology. We describe sperm morphology for a polygynous lek-breeding suboscine, the Wire-tailed Manakin (Pipra filicauda). Total sperm length averaged 41.5 ± 0.7 mm and the among-individual coefficient of variation in total sperm length was 1.8%. Variation was considerably lower than in the other manakin species with known sperm morphology, the Lance-tailed Manakin (Chiroxiphia lanceolata), despite similar promiscuity levels. This result highlights the need for further work on spermatozoa in lek-breeding species.