粘虫的发育和成活与环境湿度的关系——Ⅰ.卵和一龄幼虫

在25℃中,相对湿度为20—100%的范围内,卵的孵化率受湿度的影响不明显,在32℃中,相对湿度为40-100%的范围内,湿度对卵孵化率的影响亦不显著,但当相对湿度降至20%时,孵化率即有明显的下降;在25℃及32℃中,相对湿度对卵的发育速度有明显的影响,随相对湿度的增加,发育加快,二者呈直线正相关。 卵期湿度对一龄幼虫的成活及发育有明显的影响,在32℃中,随着卵期湿度的增加,幼虫成活率提高,二者呈正相关;在25℃及60%以下的相对湿度中,亦获得了相似的结果;25℃及32℃中,一龄幼虫的发育速率与卵期相对湿度呈正相关,随卵期湿度的增加,发育加快。 一龄幼虫期的湿度条件,对一龄幼虫有明显的影响,在25℃中,幼虫的成活率和发育速率与相对湿度均呈正相关,在32℃中,这种影响更为显著,当湿度降低到40%时,全部幼虫均不能存活,在60%以上的相对湿度中,成活率和发育速率均随湿度的提高而增加。     

望谟县蚊类初步调查报告

望谟县位于我省的最南部,在北纬25°—25°30′,东经106°—106°20′区内,南面隔红水河与广西呲隣。1958年3—5月间我们在该县南端的蔗乐板、陈乐康等乡迸行疟疾流行病学调查的同寸,对当地蚊虫孳生与栖息场所进行了全面的普查。据蔗乐水文站记录:当地海拔为400米左右,1953—1957年的年平均温度为20.16℃,月平均温度最低为11.52℃(1月),最高为27.08℃(7     

牵拉猫左心房所致的肾效应

本实验在50只麻醉猫中研究了牵拉左心房(LAS)对尿量(UV)、尿钠(U_(Na)V)和尿钾(U_KV)排出量的影响。在迷走神经完整的动物,LAS 导致 UV,U_(Na)V 和 U_KV(P<0.001)明显增加。切断迷走神经后 LAS 仍能使 UV,U_(Na)V 有所增加(p<0.01),但增加量明显低于迷走神经完整的动物(P<0.005)。在迷走神经完整的猫滴注肝素(10U/min/mg)后,LAS 也能引起 UV,U_(Na)V 和 U_KV 的增加,但增值明显低于没有滴注肝素的猫。在迷走神经切除后滴入肝素,则 LAS 的肾效应消失(p>0.05)。切断左侧肾神经后,LAS 引起神经完整肾尿量和尿钠排出显著增加(P<0.001)。而去神经肾对 LAS 的效应虽减弱,但其增值仍有显著性。两侧肾效应的差异,在统计学上是显著的(P<0.05)。上述结果说明,LAS 在麻醉猫中能引起尿量,尿钠和尿钾明显增加,这些效应是神经反射和体液机制共同作用的结果。     

Water Relations and Cell Wall Elasticity Quantities in Phaseolus vulgaris Leaves

The investigations were designed to test osmotic adjustment,cell wall bulk elastic modulus and stomatal behaviour duringand after water stress and rewatering in the primary and firsttrifoliolate leaf of Phaseolus vulgaris. Leaf water relationsquantities fully recovered after rewatering within a few hours;diffusion resistance to vapour flow, however, required 6 h.Leaf growth recovery was considerably delayed. Osmotic adjustmentwas absent during water stress in both the primary and the firsttrifoliolate leaf. The bulk elastic modulus (_v), however, waslower for the primary leaf (higher elasticity) than for thetrifoliolate leaves. These two types of leaves differed in theirdrought resistance in that the primary leaf exhibited wiltingat the end of the stress period (7 d) while the trifoliolateleaf remained relatively turgid. The bulk elastic modulus ofthe cell wall changed almost proportionally with the turgorpressure (_p). The structure coefficient (), an indicator forthe intensity of change of the bulk elastic modulus with turgorwas higher for the primary than for the first trifoliolate leaf.The leaf diffusion resistance (r), below the turgor loss point,changed proportionally with the solute potential with very similarregression lines for the relation of (r) versus RWC ¹. The datasuggest that greater drought resistance of the first trifoliolateleaf is related to a decreased bulk elastic modulus, but notto osmotic adjustment nor to differences in stomatal resistanceduring water stress. Key words: Phaseolus vulguris, Water stress, Recovery, Cell wall elasticity     

Evolution of the brain and sensory organs in Sphenisciformes: new data from the stem penguin Paraptenodytes antarcticus

Penguins have undergone dramatic changes associated with the evolution of underwater flight and subsequent loss of aerial flight, which are manifest and well documented in the musculoskeletal system and integument. Significant modification of neurosensory systems and endocranial spaces may also be expected along this locomotor transition. However, no investigations of the brain and sensory organs of extinct stem lineage Sphenisciformes have been carried out, and few data exist even for extant species of Spheniscidae. In order to explore neuroanatomical evolution in penguins, we generated virtual endocasts for the early Miocene stem penguin Paraptenodytes antarcticus, three extant penguin species (Pygoscelis antarctica, Aptenodytes patagonicus, Spheniscus magellanicus), and two outgroup species (the common loon Gavia immer and the Laysan albatross Phoebastria immutabilis). These endocasts yield new anatomical data and phylogenetically informative characters from the brain, carotid arteries, pneumatic recesses, and semicircular canal system. Despite having undergone over 60 million years of evolution since the loss of flight, penguins retain many attributes traditionally linked to flight. Features associated with visual acuity and proprioception, such as the sagittal eminence and flocculus, show a similar degree of development to those of volant birds in the three extant penguins and Paraptenodytes antarcticus. These features, although clearly not flight‐related in penguins, are consistent with the neurological demands associated with rapid manoeuvring in complex aquatic environments. Semicircular canal orientation in penguins is similar to volant birds. Interestingly, canal radius is grossly enlarged in the fossil taxon Pa. antarcticus compared to living penguins and outgroups. In contrast to all other living birds, the contralateral anterior tympanic recesses of extant penguins do not communicate. An interaural pathway connecting these recesses is retained in Pa. antarcticus, suggesting that stem penguins may still have employed this connection, potentially to enhance directional localization of sound. Paedomorphosis, already identified as a potential factor in crown clade penguin skeletal morphology, may also be implicated in the failure of an interaural pathway to form during ontogeny in extant penguins. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 202–219.     

Contrasting levels of genetic diversity between the historically rare orchid Cypripedium japonicum and the historically common orchid Cypripedium macranthos in South Korea

Many terrestrial orchids are historically rare and occur in small, spatially isolated populations. Theory predicts that such species will harbour low levels of genetic variation within populations and will exhibit a high degree of population genetic divergence, primarily as a result of genetic drift. If the origin of the present‐day populations is relatively recent from the same genetically depauperate source population, a complete lack of genetic differentiation between conspecific populations is expected. If a terrestrial orchid was historically common with moderate or high levels of genetic diversity, but has experienced more recent anthropogenic disturbance as a result of over‐collection, it would still exhibit initial levels of genetic variation within populations and a low degree of genetic divergence between populations. To test these predictions, we examined the genetic diversity in six populations (N = 131) of the historically and currently rare Cypripedium japonicum and in four populations (N = 94) of the historically common but now rare C. macranthos from South Korea. Fourteen putative allozyme loci resolved from eight enzyme systems revealed no variation either within or among populations of C. japonicum, which supports the first prediction. In contrast, populations of C. macranthos harboured high levels of genetic variation (mean percentage of polymorphic loci %P = 46.7; mean expected heterozygosity H_e = 0.185) and exhibited a low degree of population genetic divergence (G_ST = 0.059), supporting the second prediction. The lack of genetic variation both within and among conspecific populations of C. japonicum may suggest that populations originated from the same genetically depauperate ancestral population. The high levels of genetic diversity maintained in populations of C. macranthos suggest that the collection‐mediated decrease in the number of individuals is still too recent for long‐term effects on genetic variation. Based on current demographic and genetic data, in situ and ex situ conservation strategies should be provided to preserve genetic variation and to ensure the long‐term survival of the two species in the Korean Peninsula. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 119–129.     

Sudden expansion of a single brown bear maternal lineage across northern continental Eurasia after the last ice age: a general demographic model for mammals?

The brown bear has proved a useful model for studying Late Quaternary mammalian phylogeography. However, information is lacking from northern continental Eurasia, which constitutes a large part of the species' current distribution. We analysed mitochondrial DNA sequences (totalling 1943 bp) from 205 bears from northeast Europe and Russia in order to characterize the maternal phylogeography of bears in this region. We also estimated the formation times of the sampled brown bear lineages and those of its extinct relative, the cave bear.
Four closely related haplogroups belonging to a single mitochondrial subclade were identified in northern continental Eurasia. Several haplotypes were found throughout the whole study area, while one haplogroup was restricted to Kamchatka. The haplotype network, estimated divergence times and various statistical tests indicated that bears in northern continental Eurasia recently underwent a sudden expansion, preceded by a severe bottleneck. This brown bear population was therefore most likely founded by a small number of bears that were restricted to a single refuge area during the last glacial maximum. This pattern has been described previously for other mammal species and as such may represent one general model for the phylogeography of Eurasian mammals. Bayesian divergence time estimates are presented for different brown and cave bear clades. Moreover, our results demonstrate the extent of substitution rate variation occurring throughout the phylogenetic tree, highlighting the need for appropriate calibration when estimating divergence times.     

Phylogeography of lions (Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity

Lions were the most widespread carnivores in the late Pleistocene, ranging from southern Africa to the southern USA, but little is known about the evolutionary relationships among these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA techniques, we obtained mitochondrial sequences from 52 individuals sampled across the present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i) modern lions, Panthera leo ; (ii) extinct Pleistocene cave lions, which formed a homogeneous population extending from Europe across Beringia (Siberia, Alaska and western Canada); and (iii) extinct American lions, which formed a separate population south of the Pleistocene ice sheets. The American lion appears to have become genetically isolated around 340 000 years ago, despite the apparent lack of significant barriers to gene flow with Beringian populations through much of the late Pleistocene. We found potential evidence of a severe population bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years, adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations underwent major genetic alterations throughout the last interstadial, potentially presaging the processes involved in the subsequent end-Pleistocene mass extinctions.