Diploid spermatozoa detection in urinary sperm from Pelophylax water frogs: sperm morphological traits and meiotic features
Full-length research papers → Herpetology
Authors
1. Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics of the CAS, v.v.i., Libechov, Czech Republic
2. School of Biology, V. N. Karazin Kharkiv National University, Kharkiv, Ukraine
3. Department of Biology and Ecology, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00 Ostrava, Czech Republic
4. Laboratory of Non-Mendelian Evolution, Institute of Animal Physiology and Genetics of the CAS, v.v.i., Libechov, Czech Republic
* Corresponding author: E. Pustovalova, E-mail: eleonorapustovalova@karazin.ua; and L. Choleva, E-mail: Choleva@iapg.cas.cz
Keywords
hybrid, FISH, spermatozoa length, spermatozoa area, metaphase.
Abstract
Spermiogenesis is a conserved process across taxa but often adapts to species-specific fertilization strategies, influencing sperm morphology and traits like motility and longevity, which are crucial for reproductive success. Water frogs of the genus Pelophylax are notable for producing fertile hybrids, such as P. esculentus, which generate both haploid and diploid spermatozoa with diverse genome compositions. Despite this, little is known about the morphology and genome content of hybrid, and particularly diploid, sperm. This study used fluorescent in situ hybridization (FISH) with species-specific markers to analyze sperm from hybrid P. esculentus and its parental species, P. ridibundus and P. lessonae. Spermatozoa measurements revealed no significant differences in head and tail traits between haploid sperm from hybrids and parental species. However, diploid spermatozoa in hybrids were significantly larger than haploid spermatozoa, likely reflecting doubled DNA content. Correlations between head and tail lengths were observed in spermatozoa with P. lessonae genomes, suggesting potential functional implications. Our findings show that hybrids produce haploid sperm with morphology similar to that of the parental species. However, they may also produce larger diploid spermatozoa with a possible impact on motility and fertility. This study presents a non-lethal method for examining amphibian spermatozoa morphology and genome content, providing new insights into the reproductive biology of Pelophylax frogs. These results align with patterns seen in other vertebrates, emphasizing the evolutionary and ecological significance of sperm traits in hybrid systems. This approach provides a foundation for future studies on amphibian reproduction while promoting ethical research practices.
Article history
Received: 08 October 2025 / Accepted: 21 March 2026 / Published online: 15 June 2026 / Printed: 30 June 2026
Authors` ORCID IDs
E. Pustovalova https://orcid.org/0000-0002-8396-4045
A. Fedorova https://orcid.org/0000-0002-5133-7928
V. Labajová https://orcid.org/0000-0002-4156-0392
D. Dedukh https://orcid.org/0000-0002-1152-813X
L. Сholeva https://orcid.org/0000-0002-3603-0266
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