Proceedings of the fifty-fourth Annual Meeting of the American Association of physical anthropologists to be held in Knoxville,Tennessee—Holiday Inn World's fair April 10–13, 1985

Empirical analyses and models of the lineal effects of fission indicate that considerable genetic differentiation may occur at the time of group formation, thus confusing the usual positive relationship between historical affiliation and genetic differentiation. We analyze the effects of fission pattern on variation in highly heritable morphological traits among eight social groups on Cayo Santiago. The analysis is performed using general network autocorrelation methods that quantitatively and directly measure the amount of variation in social group mean morphology that can be explained by fission. All of the fission autocorrelation coefficients are strongly negative, indicating that groups most recently formed by fission are most dissimilar. Also, most of the variation between groups can be explained by the fission pattern, indicating that lineal fission is the most important process generating between-group variation on Cayo Santiago.     

Geographic structure of chloroplast DNA polymorphisms in European oaks

Chloroplast DNA polymorphisms have been detected by the conventional Southern-blotting hybridization method in four species of European oaks (Quercus petraea, Q. robur, Q. pubescens and Q. pyrenaica). Three polymorphisms, shared by at least three of these species, can be scored directly in ethidium bromidestained gels and were used in a broad survey of the level of differentiation of the oak species and of their pattern of genetic structure in western Europe. The highly significant geographic variation and the high genetic differentiation (Gst=0.895, S_Gst=0.025) indicate a low level of cytoplasmic gene flow. We conclude that cytoplasmic genomes are well suited for the reconstruction of past migrational routes of such a complex of species.     

甘南高寒草甸土壤线虫营养功能群 的地统计学分析

土壤线虫是土壤生态系统的重要指示生物。研究高寒草甸土壤线虫营养功能群空间分布格局特征,有助于揭示土壤线虫分布对高寒草甸生态因子变化的响应。2019年7月中旬,采用网格法（1.0 m × 0.5 m）研究5.0 m × 4.0 m尺度土壤层（0 ~ 20 cm）土壤线虫营养功能群空间特征。采用改良湿漏斗法,共获得土壤线虫1 830条,隶属于49属,土壤线虫个体平均密度以50 g干土计量为63.2条,其中,绕线属（Plectus）和拟丽突属（Acrobeloides）为优势类群。土壤线虫以食细菌线虫、植物寄生线虫为主。土壤线虫营养功能群变异系数介于64.26% ~ 107.69%（n = 38）之间,存在较强的变异性。食真菌线虫与食细菌线虫（P < 0.001）、食真菌线虫与植物寄生线虫（P < 0.001）间空间分布均存在显著相关性。地统计分析显示,土壤线虫营养功能群的空间相关范围存在明显差异,有效变程介于0.50 ~ 27.07 m之间,其67.26% ~ 99.79%的变异与空间自相关过程有关。食细菌土壤线虫分布格局呈较均匀的斑块镶嵌结构,斑块较小;非食细菌土壤线虫呈斑块连接或斑块镶嵌结构,斑块较大且斑块间过渡明显,表明土壤线虫小尺度明显的斑块结构可能是高寒草甸受干扰后的一种常见分布模式,并受多种因素影响。     

Mosaic cycles in agricultural landscapes of Northwest Europe

Mosaic cycles were originally understood as cyclical regeneration phases in forests. In this review, we shall examine how far the concept can be extended towards cyclical mosaics of habitat quality in patterned landscapes as a special case of ‘dynamic landscapes’. We will concentrate on habitats and plants in European temperate agricultural landscapes and grasslands in particular. Mosaic cycles of habitat quality are characterised by spatiotemporal shifts between disturbance and secondary succession. We found evidence for mosaic cycles in traditional agricultural systems, modern crop farming, and in recent conservation management. The relevant disturbance parameters to describe land-use drivers of mosaic cycles are spatial extent, frequency, and magnitude (biomass loss). Land-use-related drivers are usually regular and deterministic in space and time, with the exception of year-round grazing by free-ranging large herbivores. Fluctuating soil resources such as water and nutrients in interaction with climate variability add a stochastic component to these (land-use-related) drivers. The proportion of deterministic and stochastic components and their autocorrelation in time and space divides purely deterministic mosaic cycles from purely stochastic dynamic landscapes. In a second part, we briefly review plant life-history traits that may facilitate survival of plants in mosaic cycles of habitat quality. Theoretical studies emphasise (i) dispersal functions for extinction and recolonisation processes of metapopulations, (ii) storage effects as a component of buffered population growth in response to temporal fluctuations of habitat quality, and (iii) competitive ability in metacommunities. We propose a simple scheme relating these functions to the temporal and spatial correlation of patterned landscapes. There are only a very limited number of field studies available that give some support for the proposed scheme. We provide perspectives for further research in this field.     

Population genetic structure of Sorex unguiculatus and Sorex caecutiens (Soricidae, Mammalia) in Hokkaido, based on microsatellite DNA polymorphism

We investigated the genetic structure of Sorex unguiculatus and Sorex caecutiens populations in Hokkaido, Japan, using hypervariable microsatellite DNA markers. We used five microsatellite loci to type 475 S. unguiculatus individuals from 20 localities on the Hokkaido mainland and four localities from each of four offshore islands (and 11 shrews from one locality in southern Sakhalin for a particular analysis). We used six microsatellite loci to type 240 S. caecutiens individuals from 13 localities on the Hokkaido mainland. Genetic variation was high in mainland populations of both species and low in the island populations of S. unguiculatus. Allelic richness and island size were positively correlated for S. unguiculatus, suggesting that genetic drift occurred on those islands due to small population size. In addition, four insular populations of S. unguiculatus were genetically differentiated from the mainland populations, although clear phylogeographic clustering was not confirmed among populations on the Hokkaido mainland for either S. unguiculatus or S. caecutiens. Heterozygosity excess was observed in more than half of the populations including the mainland populations of the two species, suggesting recent bottleneck events in these populations. Population dynamics of the shrews might be explained by a metapopulation scheme. According to autocorrelation analysis, the extent of non-random spatial genetic structure was approximately 100 km. Isolation by distance was observed in S. unguiculatus, but not in S. caecutiens although there is a positive trend. The lack of correlation for S. caecutiens might have been due to small sample size. Thus, no obvious differences in population genetic structure were found between the two species on the Hokkaido mainland in the present study, while previous investigations using mitochondrial DNA sequences inferred that these two species might have rather different biogeographic histories.     

An autocorrelation model of bat sonar

Their sonar system allows echolocating bats to navigate with high skill through a complex, three- dimensional environment at high speed and low light. The auditory analysis of the echoes of their ultrasonic sounds requires a detailed comparison of the emission and echoes. Here an auditory model of bat sonar is introduced and evaluated against a set of psychophysical phantom-target, echo-acoustic experiments. The model consists of a relatively detailed simulation of auditory peripheral processing in the bat, Phyllostomus discolor, followed by a functional module consisting of a strobed, normalised, autocorrelation in each frequency channel. The model output is accumulated in a sonar image buffer. The model evaluation is based on the comparison of the image-buffer contents generated in individually simulated psychophysical trials. The model provides reasonably good predictions for both temporal and spectral behavioural sonar processing in terms of sonar delay-, roughness, and phase sensitivity and in terms of sensitivity to the temporal separations in two-front targets and the classification of spectrally divergent phantom targets.     

中国板栗居群间等位酶基因频率的空间分布

中国板栗21个自然群间等位酶遗传变异的空间自相关分析及F－统计分析结果表明：其多数等位基因频率在居群间呈随机分布模式,缺乏一定的空间结构;而部分等位基因表现为渐变或双向渐变的非随机分布模式,又具有特定空间结构。中国板栗遗传变异空间结构模式的形成可能是长距离基因流、自然气候、人类活动、地理距离隔离等诸因素综合作用的结果。文中还就居群等位基因分布格局的成因进行了讨论：在第四纪冰川后,中国板栗以长江流域中下游的孑遗中心为起点,等位基因分别沿着向北和向南的不同方向迁移形成现在的居群结构;季风气候和人类活动干扰是削弱居群分化的主要因素,而基于环境梯度的选择,是形成由北向南渐变分布的原因。     

Distinct Stages of Protein Evolution as Suggested by Protein Sequence Analysis

Evolution of proteins encoded in nucleotide sequences began with the advent of the triplet code. The chronological order of the appearance of amino acids on the evolution scene and the steps in the evolution of the triplet code have been recently reconstructed (Trifonov, 2000b) on the basis of 40 different ranking criteria and hypotheses. According to the consensus chronology, the pair of complementary GGC and GCC codons for the amino acids alanine and glycine appeared first. Other codons appeared as complementary pairs as well, which divided their respective amino acids into two alphabets, encoded by triplets with either central purines or central pyrimidines: G, D, S, E, N, R, K, Q, C, H, Y, and W (Glycine alphabet G) and A, V, P, S, L, T, I, F, and M (Alanine alphabet A). It is speculated that the earliest polypeptide chains were very short, presumably of uniform length, belonging to two alphabet types encoded in the two complementary strands of the earliest mRNA duplexes. After the fusion of the minigenes, a mosaic of the alphabets would form. Traces of the predicted mosaic structure have been, indeed, detected in the protein sequences of complete prokaryotic genomes in the form of weak oscillations with the period 12 residues in the form of alteration of two types of 6 residue long units. The next stage of protein evolution corresponded to the closure of the chains in the loops of the size 25–30 residues (Berezovsky et al., 2000). Autocorrelation analysis of proteins of 23 complete archaebacterial and eubacterial genomes revealed that the preferred distances between valine, alanine, glycine, leucine, and isoleucine along the sequences are in the same range of 25–30 residues, indicating that the loops are primarily closed by hydrophobic interactions between the ends of the loops. The loop closure stage is followed by the formation of typical folds of 100–200 amino acids, via end-to-end fusion of the genes encoding the loop-size chains. This size was apparently dictated by the optimal ring closure for DNA. In both cases the closure into the ring (loop) rendered evolutionarily advantageous stability to the respective structures. Further gene fusions lead to the formation of modern multidomain proteins. Recombinational gene splicing is likely to have appeared after the DNA circularization stage. Received: 21 December 2000 / Accepted: 28 February 2001