End of the Season Blues: Senescence and Reproductive Trade-Offs in Male Scorpions

Abstract

Seasonal reproductive dynamics and senescence have profound impacts on male fertility, yet these processes remain understudied in scorpions. This study investigates how reproductive Citation: Vrech, D.E.; Oviedo-Diego, M.A.; Olivero, P.A.; Peretti, A.V. End of the Season Blues: Senescence and Reproductive Trade-Offs in Male Scorpions. Insects 2024, 15, 916. https://doi.org/10.3390/insects 15120916 Academic Editor: Thomas Hesselberg Received: 1 November 2024 Revised: 18 November 2024 Accepted: 20 November 2024 Published: 23 November 2024 Copyright: © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). parameters—such as testicular mass, sperm quantity, and viability—change over the course of the reproductive season in Urophonius achalensis males. We found that early-season males exhibited higher sperm quality and testicular mass compared to their older counterparts, suggesting that senescence, rather than reproductive effort, drives the decline in sperm viability. Interestingly, isolated males accumulated more sperm without a reduction in viability, highlighting potential mechanisms that preserve sperm quality despite senescence. Body condition also played a key role, with males in better condition showing higher sperm counts but facing a sharper decline in sperm viability as the season progressed, suggesting trade-offs between early reproductive success and later-life reproductive costs. Our findings offer novel insights into the reproductive strategies of scorpions, emphasizing the interplay between senescence, environmental stressors, and reproductive investment. This work provides new insights into the reproductive biology of scorpions, with broader implications for understanding the role of senescence and mating systems in shaping reproductive strategies.