Influence of rainfall and temperature on the spermatogenesis of Leptodactylus macrosternum (Anura: Leptodactylidae)

Abstract

In the semi-arid environment, the reproductive success of anurans depends on adaptations in their life cycle, which synchronizes with ideal environmental conditions to maximize the number of offspring. In this study changes in the histological and morphometric aspects of the testes of Leptodactylus macrosternum Miranda-Ribeiro, 1926 are characterized, to evaluate the influence of rainfall and temperature on them. Specimens were collected at Horto Florestal Olho d'Água da Bica-HFOB (06°49'20"S, 36°15'85"W) area, municipality of Cuité, state of Paraíba, Brazil. Search for specimens was active, happened at night, and amounted to 15 days from January to December 2013. The densities of spermatids (primary and secondary), sperm and area of the seminiferous locules of the testes were registered. The influence of climate variables (rainfall and temperature) on the density of primary and secondary spermatids, sperm and locular area were verified using Simple Linear Regression. Primary spermatids had the lowest density in July (57.90 ± 51.54 mm 2), with a peak in November (300.32 ± 117.35 mm 2); secondary spermatids had the lowest density in December (287.87 ± 79.05 mm 2), with a peak in May (135,727.00 ± 301.13 mm 2); sperm was in the lowest density in July (237.37 ± 121.10 mm 2), with a peak in June (2,270.45 ± 602.62 mm 2) and the locular area had the lowest density in December (40,292.9 ± 8,174.20 µm 2) and highest density in June (338,875.01 ± 2,262.10 µm 2). A notable decrease in sperm density was evident between June and July. That, associated with the observation of a larger locular area in June, allowed us to identify as June as the peak of spermatogenesis and the following month as the most potentially reproductive. The density of secondary spermatids(r = 0.02), sperm (r = 0.21) and locular area (r = 0.01) showed dependency on rainfall whereas only sperm (r = 0.09) showed dependency on temperature. Therefore, we can state that the reproductive cycle of L. macrosternum is potentially continuous, with a reproductive peak in July.

Sperm morphology and testicular histology of the polyandric species Leptodactylus podicipinus (Anura: Leptodactylidae) from an urban environment

“…The results regarding the locular area of L. podicipinus in an urban environment are unprecedented. Our results indicate that L. podicipinus individuals have a larger locular area than L. macrosternum (Chaves, Moura, et al, 2017), Physalaemus cuvieri , Dendropsophus minutus , and Boana albopunctata (Rezende et al, 2021) individuals, which suggests interspecific variation in testicular parameters. However, all of these species have been studied in an environment with water stress (Chaves, Moura, et al, 2017) or human interference (Rezende et al, 2021).…”

“…Our results indicate that L. podicipinus individuals have a larger locular area than L. macrosternum (Chaves, Moura, et al, 2017), Physalaemus cuvieri , Dendropsophus minutus , and Boana albopunctata (Rezende et al, 2021) individuals, which suggests interspecific variation in testicular parameters. However, all of these species have been studied in an environment with water stress (Chaves, Moura, et al, 2017) or human interference (Rezende et al, 2021). The results presented herein, may have been affected by the post‐rainy period during which the animals were studied, as the large locular size is associated with the presence of early stage germinative cysts, which are common in the post‐reproductive period (Sasso‐Cerri et al, 2004) even though L. podicipinus is classified as a species with continuous reproduction (Prado et al, 2000).…”

“…Therefore, environmental factors, such as the low humidity in the post‐rainy season, cannot be excluded from the influences capable of shaping sperm morphology (Pucci et al, 2020; Zeng et al, 2014). Many studies have reported reproductive responses in anuran species related to the environment, such as spermatogenesis influenced by temperature and humidity (Chaves, Moura, et al, 2017; Rastogi, 1976), the selection of breeding sites based on abiotic conditions (Yu & Guo, 2013), and species from different fertilization environments presenting unique sperm morphology (Pucci et al, 2020).…”

Evaluation of Nile tilapia (Oreochromis niloticus) fingerlings exposed to the pesticide pyriproxyfen

“…After experimental treatment, animals were anesthetized with 150 mg L -1 Tricaine MS222, producing unconsciousness to be sacrificed by cranial perfusion. Tissues were removed and stored for later lab analysis (Silva et al, 2015;Chaves et al, 2017).…”