Covariation in superoxide, sperm telomere length and sperm velocity in a polymorphic reptile

Christopher R Friesen, Nicky Rollings, Mark Wilson, Camilla M Whittington, Richard Shine, Mats Olsson

School Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia; Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, 2522, Australia; School of Life and Environmental Sciences, University of Sydney, Heydon-Laurence Building (A08), Camperdown, NSW, 2006, Australia; Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia;

Abstract: Telomeres are DNA-protein caps at the ends of chromosomes that have been shown to be associated with male fertility may be heritable, reflect environmental influences and predict life span in some taxa. If heritable, paternal telomere length would be transmitted via sperm in the form of sperm telomere length (STL). We, therefore, investigated STL, sperm number and velocity in the Australian-painted dragon lizard, Ctenophorus pictus, an agamid lizard with distinct male colour morphs and related reproductive tactics. We measured telomere length in the sperm and blood as well as superoxide levels, as a measure for the potential for oxidative stress and ejaculate quality. We also noted a male’s head colour (red, orange, yellow or blue) and whether or not they had a yellow gular bib. Previous research has reported that yellow males outcompete red males in sperm competition; we found that yellow males had significantly shorter STL than red males. Males with bibs had greater STL than did males without bibs. Superoxide levels measured in the blood were negatively correlated with STL. Whole blood TL and body length were weakly but positively correlated with STL. Superoxide measurements were negatively correlated with progressive sperm motility and straight line sperm velocity across all males. The ejaculates of males with bibs had lower sperm counts and velocity than males without bibs. Our research adds to the growing research that indicates the importance of considering both somatic and gametic telomeres when assessing the interaction between telomere dynamics, life history and reproductive strategies.

Behavioral Ecology and Sociobiology (2020) 74: 74 – https://doi.org/10.1007/s00265-020-02855-8
Received: 19 February 2020 / Revised: 19 May 2020 / Accepted: 22 May 2020 / Published online: 3 June 2020