Summer and perennial planktonic rotifers from temperate regions can vary greatly in their ability to reproduce at low temperatures. The population growth rate (r day⁻¹) of a Patagonian Keratella tropica was 0.025 at 3.9 °C and gradually increased to 0.083 at 9.3 °C. The ability of this rotifer to survive and reproduce at low winter temperatures suggests that populations in permanent waters with cold winters may have life cycles with little or no commitment to sexually produced diapausing eggs. In contrast, three Brachionus taxa from two localities in southeastern Australia reproduced poorly at low temperatures. At 3.9 °C, all females died before reproducing. At 6.1 °C, only a single amictic female of the Darling Brachionus (B. calyciflorus species complex) from Lake Littra survived to produce a few offspring. At 9.3 °C, amictic females of the Darling Brachionus from both Lake Littra and a billabong produced many more offspring (7–9 offspring female⁻¹) than those of the Lake Littra B. calyciflorus and the billabong B. rubens (1–2 offspring female⁻¹). At 14.9 °C, amictic females of the latter two taxa, and the Darling Brachionus from Lake Littra, produced many (14–17) offspring female⁻¹. Seasonal changes in temperature occurring in natural populations of these Brachionus taxa should have important ecological and evolutionary implications. Low temperatures likely favor the occurrence and reproduction of the Darling taxon. The inability of active individuals to survive and reproduce at low winter temperatures may be a factor favoring selection for sexual reproduction and production of resting eggs in both permanent and temporary water bodies.

中文翻译：

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低温对温带地区夏季和多年生轮虫繁殖的影响：对生态和生命周期的影响

温带地区的夏季和多年生浮游性轮虫在低温下繁殖的能力可能有很大差异。巴塔哥尼亚热带Keratella tropica的种群增长率（r day ^-1）在3.9°C时为0.025，在9.3°C时逐渐增加至0.083。这种轮虫在较低的冬季温度下生存和繁殖的能力表明，在冬季寒冷的永久水域中，种群的生命周期可能很少或根本没有承诺性繁殖的卵。相比之下，来自澳大利亚东南部两个地区的三个Brachionus分类群在低温下繁殖差。在3.9°C，所有雌性在繁殖前死亡。在6.1°C，只有一位亲爱的达令雌性来自Littra湖的Brachionus（B。calyciflorus种复合体）幸存下来，产生了一些后代。在9.3°C时，来自Littra湖和Billabong的Darling Brachionus的雌性亲代产生的后代（7–9个后代雌性^-1）比Littra B. calyciflorus和Billabong B. rubens（1-2后代雌^-1）。在14.9°C时，后两个类群的友善雌性和来自Littra湖的亲爱的Brachionus产生了许多（14-17）个后代雌性^-1。这些Brachionus自然种群中温度的季节性变化分类单元应该具有重要的生态和进化意义。低温可能有利于达令分类单元的发生和繁殖。活跃个体无法在较低的冬季温度下生存和繁殖可能是有利于选择永久性和暂时性水体中有性繁殖和产卵的一个因素。