Reproductive biology of two species of Hyalella Smith, 1874 (Crustacea: Amphipoda: Hyalellidae) from southern Brazil

Reproduction is a critical event in the life cycle of animals, and a high amount of energy is allocated to it. The aim of this study was to characterize the reproductive biology of two recently described species of Hyalella from the north-east region of state of Rio Grande do Sul in southern Brazil. The specimens were collected during 12 months from a stream source (Hyalella georginae) and from a water reservoir (H. gauchensis), in Palmeira das Missões municipality, state of Rio Grande do Sul. Upon sampling, ovigerous females and pairs in precopulatory behaviour were separated into microtubes. In the laboratory, the cephalothorax length (CL in mm) of all specimens was measured. Male size at onset of sexual maturity was larger than that of the females, in both species. There was a correlation between the size of paired males and females: larger males carried larger females, in both Hyalella species. Precopulatory pairs were found throughout the year; however, H. georginae had a higher frequency in spring, and H. gauchensis in autumn. There was a positive correlation between the CL of ovigerous females and the number of eggs/juveniles. A reduction in the number of eggs throughout the embryonic development was observed in H. georginae. The average fecundity of H. georginae was significantly higher than H. gauchensis. The differences between the reproductive biology of these species may be related to the physical and environmental conditions at which they are exposed in their habitats.     

温度对三突花蛛发育和繁殖力影响的研究

研究了温度对三突花蛛发育和繁殖的影响，结果表明：（１）在３５℃恒温下，卵不能孵化；（２）在１５℃～３２℃恒温条件下，随温度升高历期逐渐缩短，蜕皮次数也随之减少。发育及生殖的最适温度为２５℃，以２５℃～３０℃恒温度条件下幼蛛的存活率最高；（３）２８℃下产卵率最高，产卵量也最大，２５℃下孵化率最高，３０℃下生育力最强，三突花蛛在繁殖上具有种的稳定性。根据实验数据所呈现的规律，建立了模拟温度对三突花蛛发育、存活和生殖影响的数学模型；组建了其在５种温度下的实验种群生命表。讨论了影响三突花蛛生活史的有关系参数及其生物学意义。