温度和培养体积对大型溞种群动态和两性生殖影响的研究

研究了5个培养体积(50、100、200、400、1000 mL)和2个温度(20℃、25℃)下大型溞(Daphnia magna Straus)种群动态和两性生殖的变化,结果表明:(1)在相同培养体积下,随温度升高,大型溞首次抱卵时间缩短、首次产幼涵时间提前.在相同温度下,大型涵首次抱卵体长随培养体积的增大而增大.20℃和25℃下,1000 mL组大型溞首次抱卵体长分别是(2.54±0.02)mm和(2.71±0.01)mm.(2)在一定时间内,大型溞种群数量快速增加.但在较小培养体积下大型溞种群增长明显受到抑制.20℃和25℃下1000 mL培养体积组最大种群数量是2152 ind./1000 mL和3085 ind./1000 mL,分别约为50 mL组的4倍和13倍.培养体积与大型溞最大种群数量间存在显著相关性(P<0.01,n=15).(3)所有种群实验组均产生雄体,且雄体数量随种群数量的增加而相应增加.20℃下1000 mL组产生的雄体数量明显高于其他培养体积组,最大比例可达36%,且第一次产幼溞即出现雄性.雄体数量与大型溞最大种群数量之间呈显著的相关性(20℃:P<0.01,n=15;25℃:P<0.05,n=15).(4)20℃和25℃下,1000 mL组大型涵累计产生卵鞍分别为814和359个,且均由母溞后代形成.而其他体积组仅产生少量卵鞍或不产卵鞍,且所产卵鞍均由培养时的母溞形成.20℃和25℃下1000 mL组所产卵鞍的空卵鞍率分别达61.18%和99.16%.实验期间,20℃、1000 mL组所产生的卵鞍中,含休眠卵的比例均在20%以上.     

温度和食用藻密度对发头裸腹溞种群动态和两性生殖的影响

研究了不同温度和食用藻密度对发头裸腹溞种群动态和两性生殖的影响.结果表明： 温度、食用藻密度对发头裸腹溞的种群密度、雄体密度和卵鞍数均有显著影响.高食用藻密度组的发头裸腹溞种群密度明显高于中、低食用藻密度组,其最大种群密度出现在20 ℃下的高食用藻密度组.在相同的温度下,发头裸腹溞的首次产幼溞数随食用藻密度的降低而减少,平均每个母溞首次产出的最大幼溞数出现在25 ℃下的高食用藻密度组.高食用藻密度组发头裸腹溞产生的雄体密度明显高于中、低食用藻密度组.发头裸腹溞的雄体密度与其种群密度之间存在极显著的相关性.发头裸腹溞所产的卵鞍数随食用藻密度的下降而下降,且25 ℃下发头裸腹溞所产的卵鞍数明显高于其他温度组.与温度相比,食用藻密度对发头裸腹溞的种群动态和两性生殖的影响更大.     

温度和食物浓度对大型溞Daphnia magna种群动态和两性生殖的影响

在4个温度(15、20、25、30℃)和3个食物浓度(1×104,1×105,5×105 cells ml-1)下研究了大型溞(Daphnia magna)淮河种群的动态和两性生殖,结果表明:(1)在实验初期,大型溞种群密度不断增加,达到最大值后种群密度呈现缓慢下降或趋于稳定的趋势.除15℃下最大瞬时增长率(1.36 d-1)出现在中食物浓度组外,20℃(1.51 d-1)、25℃(1.39 d-1)、30℃(0.69 d-1)下的最大瞬时增长率均出现在高食物浓度组.(2)相同温度下,食物浓度与大型溞最大种群密度间存在显著正相关(p<0.01).(3)相同食物浓度下,随温度升高,大型溞首次产幼溞时间(5～21d)和到达最大种群密度的时间(15～29d)缩短,首次抱卵时的体长(1.75～2.67 mm)减少.(4)在较低的温度和中食物浓度组下,大型溞产生了较多的休眠卵或卵鞍(15℃:(16.7±2.5) ind. 和20℃:(18.3±3.8) ind.);30℃下没有出现休眠卵或卵鞍.除15℃、中食物浓度组外,其它实验组均产生雄体.实验25d后,雄体密度与种群密度呈显著的相关性(30℃:p<0.05;15～25℃:p<0.01).(5)本研究结果暗示大型溞休眠卵的形成受温度、食物浓度和种群密度的共同影响,且较低的温度是大型溞休眠卵形成的主要诱因.     

温度和食用藻密度对发头裸腹潘种群动态和两性生殖的影响

研究了不同温度和食用藻密度对发头裸腹潘种群动态和两性生殖的影响.结果表明:温度、食用藻密度对发头裸腹溞的种群密度、雄体密度和卵鞍数均有显著影响.高食用藻密度组的发头裸腹潘种群密度明显高于中、低食用藻密度组,其最大种群密度出现在20℃下的高食用藻密度组.在相同的温度下,发头裸腹溞的首次产幼溞数随食用藻密度的降低而减少,平均每个母潘首次产出的最大幼潘数出现在25℃下的高食用藻密度组.高食用藻密度组发头裸腹潘产生的雄体密度明显高于中、低食用藻密度组.发头裸腹溞的雄体密度与其种群密度之间存在极显著的相关性.发头裸腹溞所产的卵鞍数随食用藻密度的下降而下降,且25℃下发头裸腹溞所产的卵鞍数明显高于其他温度组.与温度相比,食用藻密度对发头裸腹潘的种群动态和两性生殖的影响更大.     

种群密度和培养体积对发头裸腹溞生长和繁殖的影响

研究了不同培养密度(D1=100 ind·L-1,D2=150 ind·L-1,D3 =300 ind·L-1)和培养体积(V1 =50 mL,V2=100 mL,V3 =400 mL)对发头裸腹溞生长和生殖的影响.结果表明:在相同培养密度下,发头裸腹溞首次怀卵体长、雌体第一窝幼溞数和后代总数均随着培养体积的增大而减少,而雌体所产后代的性比(雄体∶雌体)随着培养体积的增大而增大.在相同培养体积下,雌体产出后代总数随着培养密度的增加而减少.雌体最大首次怀卵体长(0.95±0.10 mm)和最大后代总数(171.3±19.8 ind)均出现在D1V1组合,最大性比(0.54±0.05)出现在D3V2组合.培养密度和培养体积及其协同作用对发头裸腹溞雌体后代总数、后代性比均具有显著影响(P＜0.001).     

温度对喜马拉雅低额溞生长与生殖的影响

对采自中国云南省高海拔地区-稀有低额溞-喜马拉雅低额溞(Simocephalus himalayensis)在低海拔地区实验室内不同温度梯度下的生长及生殖能力进行了研究.结果表明:高海拔地区生活的低额溞在低海拔地区的相应环境中同样生长繁殖良好,其繁殖率、最大生殖量及种群的增长能力不受海拔高度及不同环境条件的影响.在一定温度条件下(15-31℃,误差为±1℃),喜马拉雅低额溞的发育速率随温度的升高而加快,但在32℃时减慢.在通常培养条件下,喜马拉雅低额溞一般有4个幼龄期(15℃时部分溞体有5个幼龄),16-19个成龄,平均寿命通常为74d(15℃)、54d(20℃)、39d(25℃)和24d(30℃).平均总产仔量在15-25℃最高,分别为449个(15℃)、482个(20℃)和447个(25℃).各温度梯度下的体长增长模型都表明,其体长与龄期之间存在显著的对数关系.每溞平均生殖量以20℃时最高,种群的内禀增长率(rm)和一生的生殖次数都以25℃时最高,净增殖率(R0)以20℃最高.喜马拉雅低额溞最适合的繁殖温度范围在15-25℃.研究还对该种与相应种类在不同温度条件下的生殖量和生物学特性进行了比较.     

温度和食物浓度对老年低额溞生长与生殖的影响

在20℃和25℃培养温度下研究了3种食物浓度对老年低额(Simocephalus vetulusOF Müller)生长与生殖的影响。结果表明:老年低额有4个幼龄(在20℃、低食物浓度下有5个)和10-13个成龄。成龄的龄期明显高于幼龄,第一成龄的发育时间一般最长。在相同温度下,老年低额的首次怀卵所需时间及各龄期一般随食物浓度的增加而缩短,而各龄的平均体长及其生殖量则呈相反的趋势。在相同的食物条件下,25℃老年低额在生长后期的平均体长明显高于20℃,而各龄期却小于20℃。最大体长是2.82mm,出现在25℃、高食物浓度下的第16龄。老年低额的平均最大生殖量和最大内禀增长率分别为144个和0.41/d,均出现在25℃和高食物浓度下。统计分析显示老年低额的生殖量与体长之间存在显著的相关性。老年低额的食物浓度域值小于1×104cells/mL(Scenedesmus obliquus)。作者探讨了老年低额在渔业生产中作为活体饵料养殖对象的可能性。       

三种甲壳纲浮游动物与萼花臂尾轮虫的种间关系

为研究隆线溞(Daphnia carinata)、锯缘真剑水蚤(Eucyclops serrulatus)及中华薄壳介(Dolerocypris sinensis)3种甲壳纲动物种群与萼花臂尾轮虫(Brachionus calyciflorus)种群的相互关系,作者分别将其以不同接种密度与萼花臂尾轮虫(接种密度为350 ind/L)进行混合培养。轮虫种群密度增长率自混合培养后的第3或4天开始下降,且随着甲壳纲动物接种密度的增加轮虫种群受到的抑制作用增大。当轮虫接种密度为350 ind/L时,3种甲壳纲动物的种群变化有所不同:(1)当隆线溞起始密度低于150 ind/L时,其种群生长受到轮虫的明显抑制;而当隆线溞起始密度达到350 ind/L时,其在混合培养与单独培养下的种群变化基本一致,这表明轮虫对隆线溞种群生长无抑制作用。(2)与隆线溞不同,锯缘真剑水蚤和中华薄壳介在混合培养下的种群数量持续增长。但与锯缘真剑水蚤相比,中华薄壳介在混合培养下的种群增长速度较慢。     

新安江水域(屯溪段)轮虫的种群增长研究

应用群体培养法对采自新安江水域(屯溪段)的萼花臂尾轮虫在4种不同温度(15℃、20℃、25℃和30℃)下的种群动态进行研究。结果表明,温度对轮虫的种群增长率和休眠卵产量均有显著影响(P<0.05)。随着培养温度的升高,轮虫的种群增长率逐渐增大;休眠卵产量在15℃时最小,其余温度下无显著差异。轮虫的总雌体密度在25℃最大,15℃最小;4温度下,雄体和产雄卵的混交雌体的生产量15℃下最小,25℃下最大;而产休眠卵的混交雌体的生产量在15℃下最小,20℃下最大。温度对轮虫的平均混交雌体百分率和平均混交雌体受精率均无显著影响。     

温度及pH对隆线溞生长和生殖的影响

研究了隆线溞(Daphnia carinata)在不同温度(15、20、25、30℃)和pH(6、7、8、9、10)影响下的内禀增长率(rm)、周限增长率(λ)、平均世代周期(T)、净生殖率(R0)、平均寿命、第一怀卵日、平均生殖间隔期和总生殖量.结果表明,温度对隆线溞的生命参数有显著影响,30℃组的内禀增长率(rm)...     

The effect of food availability, female culture-density and photoperiod on ephippia production in Daphnia magna Straus (Crustacea: Cladocera)

SUMMARY. A method is described whereby ephippia (sexual eggs plus protective membranes) are experimentally induced at low food levels (≤ 0.05 mg spinach D. magna ^-1), high female culture-densities (≤ 0.4 D. magna ml^-1) and in short-day photoperiods (L:D < 12:12, 12°C). The density-dependent ephippial response was related to an increased encounter rate between females at the higher densities. External metabolites had no significant effect on ephippia production. Ephippia were formed in the second generation after exposure to short day-lengths. Five clones from the same population exhibited genetic variation in their critical photoperiods for induction of sexual reproduction (≥= 10% ephippia). There was evidence of a genetic difference in photoresponse between two populations of D. magna. The evolution of timing mechanisms for ephippia production are discussed in relation to the predictability of environmental change.     

Local adaptation of sex induction in a facultative sexual crustacean: insights from QTL mapping and natural populations of Daphnia magna

Dormancy is a common adaptation in invertebrates to survive harsh conditions. Triggered by environmental cues, populations produce resting eggs that allow them to survive temporally unsuitable conditions. Daphnia magna is a crustacean that reproduces by cyclical parthenogenesis, alternating between the production of asexual offspring and the sexual reproduction of diapausing eggs (ephippia). Prior to ephippia production, males (necessary to ensure ephippia fertilization) are produced parthenogenetically. Both the production of ephippia and the parthenogenetic production of males are induced by environmental factors. Here, we test the hypothesis that the induction of D. magna resting egg production shows a signature of local adaptation. We postulated that Daphnia from permanent ponds would produce fewer ephippia and males than Daphnia from intermittent ponds and that the frequency and season of habitat deterioration would correlate with the timing and amount of male and ephippia production. To test this, we quantified the production of males and ephippia in clonal D. magna populations in several different controlled environments. We found that the production of both ephippia and males varies strongly among populations in a way that suggests local adaptation. By performing quantitative trait locus mapping with parent clones from contrasting pond environments, we identified nonoverlapping genomic regions associated with male and ephippia production. As the traits are influenced by two different genomic regions, and both are necessary for successful resting egg production, we suggest that the genes for their induction co‐evolve.     

铜绿微囊藻对萼花臂尾轮虫与大型溞竞争关系的影响

为探究铜绿微囊藻(Microcystis aeruginosa)浓度变化对浮游动物竞争关系的影响, 通过控制实验法, 评估了在 3个铜绿微囊藻浓度梯度下, 萼花臂尾轮虫(Brachionus calyciflorus)和大型溞(Daphnia magna)之间的种间竞争关系。结果表明不同浓度铜绿微囊藻对萼花臂尾轮虫、大型溞的增长及二者种间竞争影响具有差异, 并且在3种铜绿微囊藻浓度下均以大型溞为主要优势类群。低浓度(5×104 cells/mL)铜绿微囊藻仅促进大型溞种群增长(P<0.01), 大型溞占据主要优势地位; 中浓度(1×105 cells/mL)铜绿微囊藻对萼花臂尾轮虫和大型溞增长均有显著影响(P<0.01), 在此浓度下大型溞在种群竞争中依旧占优势地位, 使得萼花臂尾轮虫种群衰亡; 在高浓度铜绿微囊藻(5×105 cells/mL)环境中种群生长均受到抑制(P<0.01), 在共培养体系中仅大型溞种群存活。在无其他外在影响因素存在时, 实验结果显示在不同浓度的铜绿微囊藻下, 大型溞均占优势, 说明铜绿微囊藻的浓度可能不是影响大型溞与萼花臂尾轮虫的竞争地位的主要因素。研究不同浓度铜绿微囊藻条件下浮游动物种间竞争关系对于理解蓝藻水华暴发的生态效应有重要意义。     

Overcrowding,food and phosphorus limitation effects on ephipphia production and population dynamics in the invasive species <Emphasis Type="Italic">Daphnia lumholtzi</Emphasis>

Daphnia lumholtzi has been very successful in colonizing North America since its appearance in Texas in 1990. Although previous studies have sought to link its success as an invasive species with various aspects of its population biology, there is little experimental data linking the invasion success of D. lumholtzi with its autecology, specifically its reproduction strategy. In this study we sought to link food quality and quantity to diapause in D. lumholtzi through a variation in phosphorus (P) content of algae, food quantity, and light level. We also assessed the effect of Daphnia peak population densities on reproductive rates and production of resting eggs. We found that when food is abundant, per capita ephippia production may be limited by P, but under food limitation conditions, there is no significant effect of food quality on ephippia production. Our results suggest that a combination of food quality/quantity and population density may work together to induce the production of resting eggs in this invasive species. Handling editor: S. Declerk     

Intraspecific variability in response to stimuli for male and ephippia formation in Daphnia pulex

Natural clones and clones from laboratory crossings of Daphnia pulex have been tested in their response to stimuli for male and ephippia formation. The clones are from ponds in Illinois, USA, an area with both obligate and cyclical clones of D. pulex. The progeny from two types of crosses were studied: 1) crosses between an obligate clone producing males and a cyclical clone producing only females, and 2) self-fertilization within a cyclical clone producing both sexes. Both the natural and the artificial clones showed great variation in response to environmental stimuli for males. Ephippia response seems more equal among the clones, but two of the artificial clones could hardly be stimulated to produce ephippia in the induction experiments. In crowded cultures, however, they produced a few. Crossings between cyclicals and obligates yielded mostly cyclical progeny. Progeny from the selfed clone had low survival and fecundity.