关于Taylor幂法则的统计学讨论

自Greenwood于1920年把负二项分布引做昆虫种群空间格局模型以来,昆虫种群空间格局分析的理论和方法大致经历了两个阶段的发展:五、六十年代以前,是以少数离散型概率分布为主要模型;其后,各种聚集性指标和一些回归公式被提出,显示了比原有     

EPISTASIS AS A SOURCE OF INCREASED ADDITIVE GENETIC VARIANCE AT POPULATION BOTTLENECKS

The role of epistasis in evolution and speciation has remained controversial. We use a new parameterization of physiological epistasis to examine the effects of epistasis on levels of additive genetic variance during a population bottleneck. We found that all forms of epistasis increase average additive genetic variance in finite populations derived from initial populations with intermediate allele frequencies. Average additive variance continues to increase over many generations, especially at larger population sizes (N = 32 to 64). Additive-by-additive epistasis is the most potent source of additive genetic variance in this situation, whereas dominance-by-dominance epistasis contributes smaller amounts of additive genetic variance. With additive-by-dominance epistasis, additive genetic variance decreases at a relatively high rate immediately after a population bottleneck, rebounding to higher levels after several generations. Empirical examples of epistasis for murine adult body weight based on measured genotypes are provided illustrating the varying effects of epistasis on additive genetic variance during population bottlenecks.     

Comparative study of two meromictic basins of Lake Banyoles (Spain) with sulphur phototrophic bacteria

The annual limnological dynamics of two meromictic basins of Lake Banyoles (C-III and C-IV) have been studied and compared on the basis of their physical, chemical and biological characters. Stability values calculated for both basins gave 865 g cm cm⁻² and 495 g cm cm⁻² for C-III and C-IV respectively. These values are in agreement with the fact that C-IV was almost completely mixed during winter. In this basin, during stratification, the monimolimnion increased in thickness as the stability increased. Isolation of the respective monimolimnia resulted in the development of anoxic conditions and the accumulation of sulphide in both C-III and C-IV, which favoured the development of dense populations of sulfur phototrophic bacteria. The purple sulphur bacterium Chromatium minus and the green sulphur bacterium Chlorobium phaeobacteroides were identified as the main components of these photosynthetic populations. The different depths at which the O₂/H₂S boundary was situated in both basins (and consequently the different light intensity reaching this zone) determined the growth of these bacteria. Light intensities at the chemocline of C-IV reached values up to 5% of surface incident light. In contrast, in C-III this variable was sensibly lower, with values depending on season and seldom reaching 1%. Phototrophic bacteria were consequently found earlier in C-IV than in C-III, where no significant concentrations were found until August. Finally stability is discussed as an important factor controlling chemical and biological dynamics in meromictic lakes.     

Isozyme analysis of Galaxias species (Teleostei: Galaxiidae) from the Taieri River, South Island, New Zealand: a species complex revealed

We examined genetic differentiation among 23 samples of non-migratory river galaxias from 17 streams in the Taieri River system, South Island, New Zealand. Four major genetic types were found, two of which occur in narrow sympatry in one location. These were compared with topotypical material representing Galaxias anomalus from the Clutha system (Otago) and G. vulgaris from the Waimakariri system (Canterbury) in order to establish identity. Morphological examination of these four major genetic types revealed consistent concomitant differences. The results suggest that there are at least three species of river galaxias in the Taieri system: G. anomalus, G. vulgaris and at least one previously undescribed species. We propose that the genetic structuring and subsequent speciation of this group has been promoted by the absence of the marine juvenile phase that is found in five other members of the genus native to New Zealand. This structuring may be exacerbated by population fragmentation over the last century owing to the negative influence of introduced trout. The phylogenetic diversity within the river system mirrors the diverse flora and invertebrate fauna of the region, and has conservation implications that parallel those resulting from our improved knowledge of the New Zealand herpetofauna through the application of genetic analysis.     

Continuity,Collapse or Metamorphosis? Demographic anthropology and the study of change within human populations.Foreword

this first paper introduces the topic of the volume, outcomes of a symposium organised at the 13th ICAES held in Mexico in August 1993. It briefly reminds of the convergence between anthropology and demography up to date and stresses on the need of real transdisciplinary work in this challenging domain. The aim of the symposium was to make a contribution on the central theme chosen by the congress — the cultural and biological dimensions of global change — while examining the place of demographic anthropology in the study of change. The papers presented at the symposium have been organised in three parts which form the present volume: the composition of population, the choice of spouse and mobility, the reproduction and dynamics of populations. The basic mechanisms of change are considered through examples at the level of local populations. This also leads to question the definitions of human groups and to make a “declaration” stressing on the importance of individual heterogeneity and the arbitrariness and reductive nature of any grouping of individuals, stating therefore the misapprehension of the most recent scientific work inherent to the rationale of programs of “ethnic cleasing”. Translated from the french by prof. Derek F. Roberts     

华北棉区夏播棉田害虫发生特点分析

分析和比较了华北棉区夏季播种与春季播种的棉田主要害虫（棉铃虫与棉蚜）的发生特点,探讨了它们的管理对策。     

闽北地区四代三化螟发生动态Fuzzy预测模型研究

根据Fuzzy数学原理和三化螟生物学特性,组建了四代三化螟发生动态综合预测模型经对福建省将乐县16年四代三化螟发生期、发生量回报及1995年的预报,拟合率及正确率均达100％。     

Identification of QTLs affecting traits of agronomic importance in a recombinant inbred population derived from a subspecific rice cross

To detect QTLs controlling traits of agronomic importance in rice, two elite homozygous lines 9024 and LH422, which represent the indica and japonica subspecies of rice (Oryza sativa), were crossed. Subsequently a modified single-seed-descent procedure was employed to produce 194 recombinant inbred lines (F₈). The 194 lines were genotyped at 141 RFLP marker loci and evaluated in a field trial for 13 quantitative traits including grain yield. Transgressive segregants were observed for all traits examined. The number of significant QTLs (LOD 2.0) detected affecting each trait ranged from one to six. The percentage of phenotypic variance explained by each QTL ranged from 5.1% to 73.7%. For those traits for which two or more QTLs were detected, increases in the traits were conditioned by indica alleles at some QTLs Japonica alleles at others. No significant evidence was found for epistasis between markers associated with QTLs and all the other markers. Pleitropic effects of single QTLs on different traits are suggested by the observation of clustering of QTLs. No QTL for traits was found to map to the vicinity of major gene loci governing the same traits qualitatively. Evidence for putative orthologous QTLs across rice, maize, oat, and barley is discussed.     

Genetic diversity and hierarchical population structure of a rare autotetraploid plant,Aster kantoensis (Asteraceae)

We sampled 17 populations of a rare autotetraploid Aster kantoensis (Asteraceae) from three river systems located in central Japan, and studied them for allelic variation at 22 enzyme loci. There was no significant correlation between the actual population size and three genetic diversity parameters, suggesting that the effective population size was very small even for the large populations, i.e., even large populations may still have a high probability of being of recent origin and remain influenced by the founder effect. Compared to other autotetraploid species, the total genetic variation of A. kantoensis is small. The number of alleles and gene diversity of a population were not significantly different among the river systems, although the percentage of polymorphic loci was different. Genetic differentiation among river systems was larger than between populations within the river systems, thereby indicating that gene flow between river systems is small, especially between the Kinu River system and Tama or Sagami River systems.