Effects of increasing temperatures on population dynamics of the zebra mussel Dreissena polymorpha: implications from an individual-based model
Effects of increasing temperatures on population dynamics of the zebra mussel Dreissena polymorpha: implications from an individual-based model
复制标题
温度升高对斑马贻贝 Dreissena polymorpha 种群动态的影响：基于个体的模型的影响
作者：
E. Griebeler;A. Seitz
斑马贻贝(Dreissena Polyma，Pallas，1771)在欧洲和北美水域的温度差异很大的情况下取得了前所未有的成功。因此，贻贝是一个很好的物种模型，能够应对预计在全球变化下不断上升的水温。我们研究了贻贝在温度升高时成功存活的三种基本情况：(1)不需要适应未来的温度条件，现有的性能足够好；(2)需要向更高的温度转变；或(3)需要扩大耐受温度范围(适应)。我们开发了一个基于随机个体的模型，该模型描述了多形螺旋藻的人口增长情况，以确定哪些替代方案可能使未来的生存成为可能。这是一个由环境水温决定的日度模型。每日气温是根据莱茵河的长期数据生成的。在最近对这条河流观测到的温度条件下，对繁殖物候、年龄分布和壳长分布的预测与野外观测结果一致。我们的模拟表明，在温度上升的情况下，贻贝生命周期的时间模式将发生变化。在所有情况下，产卵都是在今年早些时候开始的，种群的总生殖产出被产卵期晚些时候的事件所主导。在20到26°C的最高温度下，贻贝不需要热适应。在所研究的所有最高温度的情景2中，没有观察到物种灭绝和世代间稳定的年龄分布。相比之下，在情景3的最高气温(28、30、32℃)较高的情况下，没有固定耐受温度范围的种群存活。年龄分布显示超过0+1个个体，这导致在所调查的几个温度范围内种群灭绝。
Zebra mussels (Dreissena polymorpha, Pallas, 1771) have had unprecedented success in colonizing European and North American waters under strongly differing temperature regimes. Thus, the mussel is an excellent model of a species which is able to cope with increasing water temperatures expected under global change. We study three principle scenarios for successful survival of the mussel under rising temperatures: (1) no adaptation to future thermal conditions is needed, existing performance is great enough; (2) a shift (adaptation) towards higher temperatures is required; or (3) a broadening of the range of tolerated temperatures (adaptation) is needed. We developed a stochastic individual-based model which describes the demographic growth of D. polymorpha to determine which of the alternative scenarios might enable future survival. It is a day-degree model which is determined by ambient water temperature. Daily temperatures are generated based on long-term data of the River Rhine. Predictions under temperature conditions as recently observed for this river that are made for the phenology of reproduction, the age distribution and the shell length distribution conform with field observations. Our simulations show that temporal patterns in the life cycle of the mussel will be altered under rising temperatures. In all scenarios spawning started earlier in the year and the total reproductive output of a population was dominated by the events later in the spawning period. For maximum temperatures between 20 and 26°C no thermal adaptation of the mussel is required. No extinctions and stable age distributions over generations were observed in scenario 2 for all maximum temperatures studied. In contrast, no population with a fixed range of tolerated temperatures survived in scenario 3 with high maximum temperatures (28, 30, 32°C). Age distributions showed an excess of 0+ individuals which resulted in an extinction of the population for several thermal ranges investigated.