Abstract
We examine the extent to which intrinsic and extrinsic factors influence reproductive phenology in male bats at the population level. Using data from thirteen breeding seasons (2006–2018), encompassing the reproductive histories of 1546 Myotis daubentonii and 530 M. nattereri males, we compare rates of sexual maturation and the temporal distribution of phases of spermatogenesis between juvenile (born that season) and adult (born in previous seasons) males. We found that (i) higher proportions of M. daubentonii (50.81%) than M. nattereri (12.85%) became sexually mature as juveniles, (ii) the proportion of juveniles in reproductive condition per annum was influenced by spring weather conditions, (iii) in both species males that reached puberty as juveniles had higher body mass, on average, than immature juveniles, (iv) older males (aged ≥4 years old) commenced spermatogenesis earlier than young adult males (aged 1–3 years old), whilst juveniles that commenced spermatogenesis did so later in the year than adults, in both species, and (v) M. daubentonii commenced and completed spermatogenesis earlier than M. nattereri in the equivalent age class. Our findings suggest that selection pressure exists for early mating readiness and synchronisation with female receptivity.
Highlights
Seasonal variation in climate and resource availability imposes energetic constraints on the timing of reproduction for many organisms in both temperate and tropical environments[1,2]
Daubentonii than M. nattereri became sexually mature during their birth year. 282/555 (50.81%) juvenile male M. daubentonii reached puberty, the other 273/555 (49.19%) were still sexually immature
Earlier parturition dates in M. daubentonii compared to M. nattereri corresponded with higher proportions of juvenile male M. daubentonii than M. nattereri reaching puberty at 2–5 months old
Summary
Seasonal variation in climate and resource availability (e.g. prey abundance) imposes energetic constraints on the timing of reproduction for many organisms in both temperate and tropical environments[1,2]. Prolonged sperm storage can occur in bats of either sex, enabling separation of spermatogenesis and mating effort for males[5], and an interval (often of several months duration) between copulation and conception in breeding females[10]. Previous studies on the phenology of reproductive condition in wild male bats have focused on opportunistic sampling during autumn swarming activities at hibernation sites[6]. To our knowledge this is the first study with repeat sampling of known individuals from their summer habitat, following male juveniles from volancy through to sexual maturation, including comparison of reproductive phenology between juveniles, young adults (aged 1–3 years old) and older males (aged ≥4 years old)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
