title: Measuring sperm movement within the female reproductive tract using Fourier analysis.
abstract: The adaptive significance of variation in sperm phenotype is still largely unknown, in part due to the difficulties of observing and measuring sperm movement in its natural, selective environment (i.e., within the female reproductive tract). Computer-assisted sperm analysis systems allow objective and accurate measurement of sperm velocity, but rely on being able to track individual sperm, and are therefore unable to measure sperm movement in species where sperm move in trains or bundles. Here we describe a newly developed computational method for measuring sperm movement using Fourier analysis to estimate sperm tail beat frequency. High-speed time-lapse videos of sperm movement within the female tract of the neriid fly Telostylinus angusticollis were recorded, and a map of beat frequencies generated by converting the periodic signal of an intensity versus time trace at each pixel to the frequency domain using the Fourier transform. We were able to detect small decreases in sperm tail beat frequency over time, indicating the method is sensitive enough to identify consistent differences in sperm movement. Fourier analysis can be applied to a wide range of species and contexts, and should therefore facilitate novel exploration of the causes and consequences of variation in sperm movement.
authors: 1ARC Centre of Excellence in Molecular Imaging,School of Medical Sciences,The University of New South Wales,Sydney,NSW 2052,Australia.
authors: Philip R
authors: PR
authors: Nicovich
authors: 3Evolution & Ecology Research Centre,School of Biological,Earth and Environmental Sciences,The University of New South Wales,Sydney,NSW 2052,Australia.
authors: Erin L
authors: EL
authors: Macartney
authors: 2Biomedical Imaging Facility,Mark Wainwright Analytical Centre,The University of New South Wales,Sydney,NSW 2052,Australia.
authors: Renee M
authors: RM
authors: Whan
authors: 3Evolution & Ecology Research Centre,School of Biological,Earth and Environmental Sciences,The University of New South Wales,Sydney,NSW 2052,Australia.
authors: Angela J
authors: AJ
authors: Crean
mesh_terms: D000818:Animals; D004175:Diptera; D005260:Female; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted; D008297:Male; D018715:Microscopy, Video; D012098:Reproduction; D013081:Sperm Motility; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology*
keywords: diptera