title: Sperm morphology, adenosine triphosphate (ATP) concentration and swimming velocity: unexpected relationships in a passerine bird.
abstract: The relationship between sperm energetics and sperm function is poorly known, but is central to our understanding of the evolution of sperm traits. The aim of this study was to examine how sperm morphology and ATP content affect sperm swimming velocity in the zebra finch Taeniopygia guttata We exploited the high inter-male variation in this species and created extra experimental power by increasing the number of individuals with very long or short sperm through artificial selection. We found a pronounced quadratic relationship between total sperm length and swimming velocity, with velocity increasing with length up to a point, but declining in the very longest sperm. We also found an unexpected negative association between midpiece length and ATP content: sperm with a short midpiece generally contained the highest concentration of ATP. Low intracellular ATP is therefore unlikely to explain reduced swimming velocity among the very longest sperm (which tend to have a shorter midpiece).
authors: Department of Animal and Plant Sciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, UK.
authors: Clair
authors: C
authors: Bennison
authors: Department of Animal and Plant Sciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, UK n.hemmings@sheffield.ac.uk.
authors: Nicola
authors: 0000-0003-2418-3625
authors: N
authors: Hemmings
authors: Department of Animal and Plant Sciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, UK Zoological Society of London, London, UK.
authors: Lola
authors: L
authors: Brookes
authors: Department of Animal and Plant Sciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, UK.
authors: Jon
authors: J
authors: Slate
authors: Department of Animal and Plant Sciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, UK.
authors: Tim
authors: T
authors: Birkhead
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis*; D000818:Animals; D008297:Male; D010641:Phenotype; D020308:Songbirds / Q000502:physiology*; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology*
chemical_list: D000255:Adenosine Triphosphate
keywords: passerine sperm; sperm competition; sperm energetics; sperm motility; zebra finch