杉木不同生长类型对养分供应的持续效应

应用“正态分布标准差分类法”把杉木(Cunninghamia lanceolata)试验林分树高生长划分为5个生长类型，按不同生长类型进行施肥试验。结果表明，不同生长类型杉木施肥后2年生长期的树高年生长量表现为，生长类型好的群体对施肥有更好的持续促进高生长效应；生长类型差的群体，在施肥量相对少时高生长持续效应不明显，当施肥量较大时能有较好的树高年生长量持续生长效应。不同生长类型杉木胸径年生长量对施肥量的响应表现为，相同条件下，好的生长类型比差的生长类型有更好的胸径年生长量效果，施肥量相对不足时，差的生长类型群体胸径年生长持续效应逐渐衰退，好的生长类型对施肥有更好的持续促进生长效果，施肥量大对胸径年生长有更好的持续促进作用，与树高生长表现基本一致。研究表明，遗传品质好的杉木群体对立地适应能力越强，有更好的耐瘠薄能力和更好的年生长量。施肥措施对不同遗传品质生长类型杉木树高与胸径年生长量都有较好的促进效应，能有效恢复与提高杉木低产林分生长，为杉木低产与小老林林分改良提供理论指导。     

Maintenance of gynodioecy in Wurmbea biglandulosa (Colchicaceae): gender differences in seed production and progeny success

 In gynodioecious species, females contribute genes to future generations only through ovules, and to persist in populations they must have a compensatory advantage compared with hermaphrodites that reproduce via ovules and pollen. This compensation can result from greater fecundity and/or superior success of progeny from females. We examined differences in seed production and progeny success between females and hermaphrodites in the geophyte Wurmbea biglandulosa to explain the maintenance of females. Females produced more ovuliferous flowers and had more ovules per flower than did hermaphrodites but this did not necessarily result in greater fecundity, in part because seed production of females was pollen-limited. Over four years in one population, open-pollinated females produced 1.32 more seeds than open-pollinated hermaphrodites (range 1.09–1.63). In two other populations examined for one year only females produced 1.07 and 0.79 as many seeds as hermaphrodites. Seed production of open-pollinated females and hermaphrodites was only 55% and 73% that of cross-pollinated plants, respectively, indicating that both genders were pollen-limited but females more so than hermaphrodites. Open-pollinated seeds from females were 1.18–1.27 times more likely to germinate than seeds from hermaphrodites. No gender differences existed in seedling growth or survival. Hermaphrodites were self-compatible, but selfed seed set was only 80% that of crossed seed set. Crossed seed set of females and hermaphrodites did not differ. Assuming nuclear control of male sterility, relative female fitness is insufficient to maintain females at their current frequencies of 17%, and substantial female fitness advantages at later life-cycle stages are required. Received May 4, 2001 Accepted February 25, 2002     

Hostplants and classification: a review of nymphalid butterflies

In reviewing the hostplant associations of nymphalid butterflies, particular emphasis is placed on the intractable problem of nymphalid classification. Although offering few certain conclusions, if used in conjunction with more formal morphological characters, the data presented should contribute toward a resolution of the inter-relationships of the many widely recognized groupings within the Nymphalidae, several of which seem to be broadly characterized by typical host families. As a direct result of this analysis, the presumed association between larval hostplants and unpalatability is re-appraised.     

Evidence of a genetically distinct population of Vrljika softmouth trout Salmo obtusirostris Heckel evolved by vicariance

Mitochondrial DNA haplotypes (control region, partial cytochrome b and ATPase6 genes) indicate a sister relationship between Vrljika and Neretva softmouth (Adriatic) trout Salmo obtusirostris . This relationship was supported by a tree of individuals based on microsatellite results [allele sharing distances ( D _AS)], which revealed three distinctive clusters, corresponding to Jadro softmouth, Neretva brown trout Salmo trutta and Neretva softmouth trout. Within the latter taxon, Vrljika trout are clearly separated from other trout. The genetic results contradict the synonymy of Jadro with Vrljika softmouth trout, as recently proposed in the Red Book of Freshwater Fish in Croatia. Vrljika softmouth trout appear to have originated from a vicariance that split a common ancestor into large (Neretva) and small (Vrljika) fragmented populations 135 000–270 000 years ago. Vrljika softmouth trout can be distinguished by an array of derived phenotypic and molecular character states. For conservation, this population should be recognized formally at the same taxonomic level as the other geographically separated populations of softmouth trout.     

Coupled reactions for the determination of analytes and enzymes based on the use of luminescence

Immobilized enzymes are widely used in the clinical laboratory in the assay of several analytes and enzymes. The use of immobilized enzymes makes these reagents recoverable and re-usable, and in most cases increases their stability and catalytic activity. In conjunction with bioluminescent enzymes (firefly and bacterial luciferases) and chemiluminescent catalyst (peroxidase) we set up high-sensitive flow methods based on the use of nylon tube coil or epoxy methacrylate column as solid support. All the NAD(P)/NAD(P)H-dependent dehydrogenases (bacterial luciferase), ATP-dependent enzymes (firefly luciferase) and oxidases producing H₂O₂ (peroxidase) can be immobilized and a large variety of analytes have been sensitively measured. As an alternative format we also reported a dry chemistry method in which all the enzymes, substrates and cofactors are ready to use, supported on dry cellulose disks. Methodological problems such as flow conditions, stability, pH, ionic strength and analytical performances are also reported.     

INBREEDING DEPRESSION IN MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS OF SCHIEDEA LYDGATEI (CARYOPHYLLACEAE) IN TWO ENVIRONMENTS

We compared inbreeding depression in hermaphroditic Schiedea lydgatei and its gynodioecious sister species, S. salicaria, to infer the level of inbreeding depression in their common ancestor. With measurements of selfing rates, this information can be used to assess the importance of inbreeding depression in the evolution of breeding systems in S. lydgatei and S. salicaria. Morphological and physiological characters related to fitness were compared for inbred and outcrossed S. lydgatei in high- and low-fertilizer environments in the greenhouse. Seed mass, number of seeds per capsule, germination, survival, biomass, number of flowers, and age at first flowering were compared for inbred versus outcrossed progeny. We also measured inbreeding depression in maximal rates of photosynthetic carbon assimilation and stomatal conductance to water vapor, traits that affect fitness through their influence on plant carbon balance and water-use efficiency (ratio of carbon gain to water loss). All traits except number of seeds per capsule in parents and survival showed inbreeding depression, with the magnitude depending on family and environment. High inbreeding depression is likely in the ancestor of S. lydgatei and S. salicaria, indicating that, with sufficiently high selfing rates, females could spread in populations. Hermaphroditism in S. lydgatei is probably favored by low selfing rates. In contrast, the evolution of gynodioecy in S. salicaria apparently has been favored by relatively high selfing rates in combination with high inbreeding depression.     

A conceptual model of the dynamics of the Syamozero Lake community

We present a conceptual mathematical model of the dynamics of a spatially heterogeneous population system whose prototype is the fish community of Lake Syamozero. Analysis of the solutions of this model is used to demonstrate that interactions between the predator and prey populations in two neighboring biotopes (the pelagic and coastal zones) may result in either undamped oscillations or steady states of the population sizes. The model population densities are of the same order of magnitude as the values obtained in long-term observations of the Syamozero biota. It is also demonstrated that the transition to steady states may be accompanied by long-term (dozens or hundreds of years) damped oscillations of the prey and predator population densities. Under natural conditions, long transitional periods may prevent fish communities from reaching stationary modes.     

A computational algorithm for classifying step and spin turns using pelvic center of mass trajectory and foot position

Transient changes in direction during ambulation are typically performed using a step (outside) or spin (inside) turning strategy, often identified through subjective and time-consuming visual rating. Here, we present a computational, marker-based classification method utilizing pelvic center of mass (pCOM) trajectory and time-distance parameters to quantitatively identify turning strategy. Relative to visual evaluation by three independent raters, sensitivity, specificity, and overall accuracy of the pCOM-based classification method were evaluated for 90-degree turns performed by 3 separate populations (5 uninjured controls, 5 persons with transtibial amputation, and 5 persons with transfemoral amputation); each completed turns using two distinct cueing paradigms (i.e., laser-guided “freeform” and verbally-guided “forced” turns). Secondarily, we compared the pCOM-based turn classification method to adapted versions of two existing computational turn classifiers which utilize trunk and shank angular velocities (AV). Among 366 (of 486 total) turns with unanimous intra- and inter-rater agreement, the pCOM-based classification algorithm was 94.5% accurate, with 96.6% sensitivity (accuracy of spin turn classification), and 93.5% specificity (accuracy of step turn classification). The pCOM-based algorithm (vs. both AV-based methods) was more accurate (94.5% vs. 81.1–80.6%; P < 0.001) overall, as well as specifically in freeform (92.9 vs. 80.4–76.8%; P < 0.003) and forced (96.0 vs. 83.8–81.8%; P < 0.001) cueing, and among individuals with (92.4 vs. 80.2–78.8%; P < 0.001) and without (99.1 vs. 86.2–80.8%; P < 0.001) amputation. The pCOM-based algorithm provides an efficient and objective method to accurately classify 90-degree turning strategies using optical motion capture in a laboratory setting, and may be extended to various cueing paradigms and/or populations with altered gait.