Abstract
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’Agua da Bica - HFOB (06°49’20”S, 36°15’85”W) area, municipality of Cuite, state of Paraiba, 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 mm2), with a peak in November (300.32 ± 117.35 mm2); secondary spermatids had the lowest density in December (287.87 ± 79.05 mm2), with a peak in May (135,727.00 ± 301.13 mm2); sperm was in the lowest density in July (237.37 ± 121.10 mm2), with a peak in June (2,270.45 ± 602.62 mm2) and the locular area had the lowest density in December (40,292.9 ± 8,174.20 µm2) and highest density in June (338,875.01 ± 2,262.10 µm2). 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.
Highlights
In anurans, the control of spermatogenesis and the reproductive cycles, are mediated by the interaction between the animal’s endogenous rhythms and the influence of environmental factors (Sasso-Cerri et al 2004)
Our results corroborate the results of Santos and Oliveira (2008), and Leite et al (2015), who pointed out that, in general, the spermatogenesis process in anurans is cystic, with the organization of germ cells always in the same stage of differentiation
The organization of these cysts may vary among different families of anurans and especially according to the environment where these animals occur, as found by Ferreira et al (2009) for Dendropsophus nanus (Boulenger, 1889), Pseudis limellum (Cope, 1862) and Pseudis paradoxa (Linnaeus, 1758) of Hylidae and the Leptodactylus chaquensis Cei, 1950 and Leptodactylus podicipinus (Cope, 1862), species of Leptodactilidae from the Pantanal region
Summary
The control of spermatogenesis and the reproductive cycles, are mediated by the interaction between the animal’s endogenous rhythms and the influence of environmental factors (Sasso-Cerri et al 2004). Among the latter, temperature and rainfall are the main climatic factors influencing the reproductive cycles of anurans (Cardoso and Martins 1987). Continuous and potentially continuous cycles, typical of tropical regions, are characterized by the constant production of gametes. In the latter, there is a partial interruption in gametogenesis during certain periods
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