PHYLOGENETIC ANALYSES OF THE CORRELATED EVOLUTION OF CONTINUOUS CHARACTERS: A SIMULATION STUDY

We use computer simulation to compare the statistical properties of several methods that have been proposed for estimating the evolutionary correlation between two continuous traits, and define alternative evolutionary correlations that may be of interest. We focus on Felsenstein's (1985) method and some variations of it and on several “minimum evolution” methods (of which the procedure of Huey and Bennett [1987] is a special case), as compared with a nonphylogenetic correlation. The last, a simple correlation of trait values across the tips of a phylogeny, virtually always yields inflated Type I error rates, relatively low power, and relatively poor estimates of evolutionary correlations. We therefore cannot recommend its use. In contrast, Felsenstein's (1985) method yields acceptable significance tests, high power, and good estimates of what we term the input correlation and the standardized realized evolutionary correlation, given complete phylogenetic information and knowledge of the rate and mode of character change (e.g., gradual and proportional to time [“Brownian motion”] or punctuational, with change only at speciation events). Inaccurate branch length information may affect any method adversely, but only rarely does it cause Felsenstein's (1985) method to perform worse than do the others tested. Other proposed methods generally yield inflated Type I error rates and have lower power. However, certain minimum evolution methods (although not the specific procedure used by Huey and Bennett [1987]) often provide more accurate estimates of what we term the unstandardized realized evolutionary correlation, and their use is recommended when estimation of this correlation is desired. We also demonstrate how correct Type I error rates can be obtained for any method by reference to an empirical null distribution derived from computer simulations, and provide practical suggestions on choosing an analytical method, based both on the evolutionary correlation of interest and on the availability of branch lengths and knowledge of the model of evolutionary change appropriate for the characters being analyzed. Computer programs that implement the various methods and that will simulate (correlated) character evolution along a known phylogeny are available from the authors on request. These programs can be used to test the effectiveness of any new methods that might be proposed, and to check the generality of our conclusions with regard to other phylogenies.     

中国血革螨科记述及一新属的建立：蜱螨亚纲：寄螨目

本文对中国血革螨科进行整理,总共记录了５３种和亚种,并建立了畸胸螨属Ｔｅｒａｓｔｅｒｎａｇｅｎ．ｎｏｖ．,新属与中国血革螨亚科中唯一的血革螨属Ｈａｅｍｏｇａｍａｓｕｓ相并列。     

EVOLUTION OF AVIAN COOPERATIVE BREEDING: COMPARATIVE TESTS OF THE NEST PREDATION HYPOTHESIS

Comparative analyses carried out on two different phylogenies of cooperatively and noncooperatively breeding Australian passerine birds (parvorder Corvida) were unable to detect a significant difference in nest predation rates after controlling for body mass and risk of predation due to location of the nest (nest safety). Nest predation rates, however, decrease as nest safety and body mass increase. We suggest that cooperative breeding does not bring about a current net change in rates of nest predation among Australian passerines. Species breeding cooperatively may have developed antipredator strategies that produce results similar to those adopted by noncooperatively breeding species. The function of cooperative breeding may lie outside of antipredator strategies.     

CONSTRAINTS FOR THE EVOLUTION OF FUNCTIONALLY COUPLED CHARACTERS: A NONLINEAR ANALYSIS OF A PHENOTYPIC MODEL

On the basis of a phenotypic model of R. Lande a nonlinear analysis is performed to investigate the evolutionary dynamics of functionally coupled quantitative traits. The underlying fitness topography has multiple peaks with a ridge and two hills adjacent to a saddle. Evolution of a complex of functionally constrained characters corresponds precisely to moving uphill along a ridge. For modelling the topology of the ridge, I follow ideas of Rechenberg and Wagner and use a so-called corridor model. The analysis reveals certain population-genetic constraints for the evolutionary emergence of a selectively favored complex of functionally constrained characters. Due to the population-genetic structure, as reflected in the pattern of variation and covariation, a population will often not be allowed to become adapted to existing physiological requirements, such as functional coupling of characters. Instead, within the present model where extinction cannot occur, it will evolve in some other direction toward an optimum that may be physiologically rather remote. In particular, there exists an optimal pattern of genetic and phenotypic variances and covariances in the following sense: on the one hand an increasing deviation from this pattern imposes increasing restrictions on the set of initial conditions enabling a population to move uphill along the ridge; on the other hand, an increasing deviation leads to a decreasing rate of adaptation along the ridge. Finally, some consequences of these constraints for possible interpretations of certain empirical results are discussed.     

瘿螨染色体核型分析及其亲缘关系

本文采用玻璃纸压片法测定了瘿螨总科中分属于３科１０种瘿螨的染色体,其数目均为ｎ＝３或４。同时,选取染色体相对长度和形态特征数值两因子进行聚类分析,计算出欧氏距离并绘制谱系图。结果表明同科种的欧氏距离都较近,不同科间的欧氏距离都超过同科内的距离,其中瘿螨科和羽爪瘿螨科的亲缘关系较近,归并科间亲缘关系为：纳氏瘿螨科→瘿螨科→羽爪瘿螨科。     

皖南低山丘陵农业生态系统的土壤甲螨及2新种记述（蜱螨亚纲：甲螨亚目）

报道皖南低山丘陵农业生态系统土壤甲螨的部分种类,计51科84属86种,其中新种2个;三齿梨甲螨Pyroppia tridentifera sp.nov.和邓氏鳞翼甲螨Leplog alumna dengi sp.nov.     

AN INTEGRATIVE TEST OF THE DEAD‐END HYPOTHESIS OF SELFING EVOLUTION IN TRITICEAE (POACEAE)

Self‐fertilization is hypothesized to be an evolutionary dead end because reversion to outcrossing can rarely happen, and selfing lineages are thought to rapidly become extinct because of limited potential for adaptation and/or accumulation of deleterious mutations. We tested these two assumptions by combining morphological characters and molecular‐evolution analyses in a tribe of hermaphroditic grasses (Triticeae). First, we determined the mating system of the 19 studied species. Then, we sequenced 27 protein‐coding loci and compared base composition and substitution patterns between selfers and outcrossers. We found that the evolution of the mating system is best described by a model including outcrossing‐to‐selfing transitions only. At the molecular level, we showed that regions of low recombination exhibit signatures of relaxed selection. However, we did not detect any evidence of accumulation of nonsynonymous substitutions in selfers compared to outcrossers. Additionally, we tested for the potential deleterious effects of GC‐biased gene conversion in outcrossing species. We found that recombination and not the mating system affected substitution patterns and base composition. We suggest that, in Triticeae, although recombination patterns have remained stable, selfing lineages are of recent origin and inbreeding may have persisted for insufficient time for differences between the two mating systems to evolve.     

MITES OF THE GENUS EUSTIGMAEUS FROM JIANGXI PROVINCE (ACARI:STIGMAEIDAE)*

Abstract Five species of Eustigmseus are reported from Jiangxi, of which E. segnis (Koch) is a new record from China and three spccies, E. logngi Hu and Chen, E. gulingensis Hu and Chen and E. jiangxiensis Hu and Chen are new. An identification key to females of the five species is given.     

广东鼎湖山自然保护区土壤甲螨的调查研究（蜱螨亚纲：甲螨亚目）

以种类名录报道广东鼎湖山自然保护区的土壤甲螨58种,并记述新种巨杆棱甲螨Mochlozetes grandis sp.nov.此外还对该地区甲螨区系的特点作了初步分析。     

EVOLUTION OF PELVIC REDUCTION IN THREESPINE STICKLEBACK FISH: A TEST OF COMPETING HYPOTHESES

Reimchen hypothesized that pelvic reduction in threespine stickleback is favored by an absence of piscivorous fishes and the resulting increase in predation by insects, but Giles hypothesized that the predation regime is unimportant and that a low dissolved calcium concentration favors evolution of pelvic reduction. Substantial pelvic reduction in threespine stickleback sampled from 179 lakes around Cook Inlet, Alaska is strongly associated both with an absence of predatory fishes and a low calcium concentration. However, the association of pelvic reduction with low calcium concentration appears to be contingent on the absence of predatory fishes. These results emphasize the importance of interactions between seemingly unrelated environmental variables for selection of a single trait. However, these results also conflict with some observations elsewhere and do not rule out the possibility that other environmental factors are important for selection for pelvic reduction in threespine stickleback.