新热带区两种潮虫的生态特征(甲壳纲:等足目)(英文)

Ecological traits of two neotropical oniscideans (Crustacea: Isopoda)

对体型大小不同的两种陆生等足类动物进行形态特征和行为特征研究,探讨环境变化对其繁殖特征和种群结构的影响。自2004年5月至2005年4月,在巴西Parque Estadual de Itapua进行野外采样,其中每月采集12个凋落物和土壤样品,实验室手拣法收集等足类,共获得2540只,同时进行个体性别鉴定与测量。结果表明,Atlantoscia floridana平均密度为114只Pm2,Balloniscus glaber平均密度为133只Pm2。A.floridana雌性个体全年可育,B.glaber雌性个体只在早春至初夏时段可育,其中春季这两种动物雌性可育个体数量高。2005年夏季干旱,该气候因子对两种动物种群影响存在差异,其中干旱使A.floridana种群减少,而B.glaber种群基本保持稳定,两种动物间形态结构不同是上述差异的主要原因,尤其是B.glaber,特殊的体型和腹肢肺的存在使其更能忍耐干燥。此外,B.glaber可能也依赖行为策略适应环境,例如挖掘活动,在不利气候条件下挖掘活动能够增加年轻个体生存的机会,也可能对成年个体起到保护作用。对于A.floridana来说,它具有连续繁殖、性成熟时间短和高雌性生育比率的特征。

Two terrestrial isopods, Adantoscia floriduna （Philosciidae） and BaUoniscus glaber （Balloniscidac） that differ in size, morphology and behaviour were studied with respect to the influence of the environmental variation on their reproduction and population structure. Samples were taken at Partlue Estadual de Itapuǎ, Brazil from May 2004 to April 2005. Twelve cores of litter and soil were extracted each month, and hand-searched in the lab. All specimens were sexed and measured. Overall, 2 540 individuals were captured. Atlantosciafloridana reproductive females were present throughout the year, while B. glaber showed a shorter reproductive period, from early spring to early autumn, and both species showed high numbers of reproductive females and maneas during spring. Mean density of A .floridana was 114 ind./m^2 and 133 ind./m^2 for B. glaber. The increased dryness observed in the summer of 2005 affected the populations differently, as it reduced population size of A.floridana while B. glaber population remained stable. It seems that the ditferences in morphology, more specifically body size and presence of pleopodal lungs, confer upon B. glaber a higher tolerance to desiccation. Moreover, B. glaber may rely on behavioral strategies, such as burrowing, to increase the survival of the young, and even the survival of the adults under stressful climatic conditions. It is postulated that the continuous reproduction, lower time to maturity and higher proportion of reproductive females of A .floridana are responses to its high juvenile mortality.