Separating the effects of paternal age and mating history: Evidence for sex‐specific paternal effect in eastern mosquitofish

Abstract

Paternal age and past mating effort by males are often confounded, which can affect our understanding of a father's age effects.To our knowledge, only a few studies have standardized mating history when testing for effects of paternal age, and none has simultaneously disentangled how paternal age and mating history might jointly influence offspring traits. Here, we experimentally manipulated male mating history to tease apart its effects from those of paternal age on female fertility and offspring traits in the eastern mosquitofish (Gambusia holbrooki). Male age did not affect female fertility. However, males with greater past mating effort produced significantly larger broods. Paternal age and mating history interacted to affect sons' body size: sons sired by oldvirgin males were larger than those sired by old-mated males, but this was not the case for younger fathers. Intriguingly, however, sons sired by old-virgin males tended to produce fewer sperms than those sired by old-mated males, indicating a potential tradeoff in beneficial paternal effects. Finally, neither paternal age nor mating history affected daughter's fitness. Our results highlight that variation in offspring traits attributed to paternal age effect could partly arise due to a father's mating history, and not simply to his chronological age.

Fluctuating salinity during development impacts fish productivity

“…Each measured trait was analyzed with a separate model. All models were run separately for each sex because there are well-known sex differences in life history traits in G. holbrooki 60, 75, 89, 90 . Brood identity (ID) was included in all models as a random factor using (1 + age | brood ID) to account for differences among broods in mean values and any difference in the effect of age.…”

What doesn’t kill you makes you stronger? Effects of paternal age at conception on fathers and sons

“…Reid et al, 2010; Torres et al, 2011). While valuable for their ecological relevance, these studies on wild populations have limited control over confounding factors such as maternal ageing and male mating history (a crucial modulator of male survival and reproductive output: Aich et al, 2022; Jones and Elgar, 2004; Partridge and Andrews, 1985; Paukku and Kotiaho, 2005).…”

“…For instance, old males across different species often have smaller ejaculate sizes (Cornwallis et al, 2014;Sanghvi et al, 2023), poorer quality sperm (Gasparini et al, 2019;Johnson et al, 2015), and lower abundance of seminal fluid proteins (Fricke et al, 2023), than young males. A growing body of literature however, challenges these patterns by documenting that advancing male age does not necessarily result in male reproductive senescence (Aich et al, 2022;Baudisch and Stott, 2019;Brooks and Kemp, 2001;Cooper et al, 2020Cooper et al, , 2021Finch, 2009;Forslund and Part, 1995;Heinze et al, 2018;Johnson and Gemmell, 2012;Jones et al, 2014;Jones and Vaupel, 2017;Lee and Chu, 2023;Moullec et al, 2023;Sandfoss et al, 2023;Segami et al, 2021;Vega-Trejo et al, 2019). In some cases, advancing age may even be associated with increased reproductive output (e.g.…”