Electrophoretic Variation in Esterases, Peroxidases and Acid Phosphatases in Some Native Greek Taxa of the Genera Hordeum and Taeniatherum

Horizontal starch gel electrophoresis has been applied to thestudy of esterase, peroxidase and acid phosphatase patternsin seven taxa, namely Hordeum diploids (2n=14) (H. marinum,H. marinum I and H. hystrix), tetraploids (2n=28) (H. bulbosumand H. murinum subsp. leporinum) and Taeniatherum (2n=14) (T.caput-medusae and T. caput-medusae I) in order to elucidatetheir phylogenetic relationships. On the basis of our experimentalresults the seven taxa may be placed in the following threegroups; (1) diploid Hordeum (H. marinum, H. marinum I, H. hystrix);(2) tetraploid Hordeum (H. bulbosum, H. murinum subsp. leporinum);(3) Taeniatherum (T. caput-medusae, T. caput-medusae I). Esterase, peroxidase and acid phosphatase patterns of the twoHordeum diploid taxa (H. marinum and H. marinum I) are verysimilar suggesting their close phylogenetic relationship; thesame is true for both the taxa of the genus Taeniatherum (T.caput-medusae and T. caput-medusae I). The taxa of the Taeniatherumgroup compared with the diploid Hordeum (H. marinum, H. marinumI, H. hystrix) and the tetraploid Hordeum (H. bulbosum, H. murinumsubsp. leporinum) show a lower degree of phylogenetic relationshipand seem to be equally distant from them. The tetraploid Hordeumgroup shows a higher phylogenetic relationship with diploidHordeum group than with the Taeniatherum group. These results confirm that the genus Taeniatherum, previouslyconsidered as part of the genus Hordeum, should be regardedas a separate genus. Gramineae (Poaceae), Hordeum L., Taeniatherum Nevski., esterase, peroxidase and acid phosphatase patterns, phylogenetic relationships     

TRANSFER OF THE GASTROPOD FAMILY PLESIOTROCHIDAE TO THE CAMPANILOIDEA BASED ON SPERM ULTRASTRUCTURAL EVIDENCE

Using sperm ultrastructure the systematic placement and affinitiesof the caenogastropod family Plesiotrochidae are re-examined.The simultaneous hermaphrodite, Plesiotrochus crinitus Thiele,1930, produces both euspermatozoa (uniflagellate, fertile sperm)and paraspermatozoa (bi- or triflagellate, infertile sperm).Features of each type of sperm clearly indicate that the Plesiotrochidaeare closely related to the Campanilidae (Campaniloidea) andare not, as previously believed, referable to the superfamilyCerithioidea. Significant sperm synapomorphies of Plesiotrochus(Plesiotrochidae) and Campanile (Campanilidae) include the morphologyof the eusperm midpiece (seven to nine straight mitochondriasurrounded by a segmented, accessory sheath of membrane-boundvesicles) and morphology of the anucleate parasperm head (axialcore of mitochondria surrounded by a bilaterally symmetricalarrangement of axonemes and dense vesicles). The characteristicsubstructure of the cerithioidean eusperm midpiece (four straightmitochondria each containing parallel, cristal plates) is notobserved in Plesiotrochus or Campanile. Euspermatozoa of Plesiotrochusdiffer from Campanile principally in details of the acrosomalcomplex (Plesiotrochus with apical bleb, probable absence ofan accessory membrane; Campanile without apical bleb, accessorymembrane well developed), the transverse profile of all midpiecemitochondria (thin in Plesiotrochus; thick in Campanile), andmorphology of the annulus (double ring in Plesiotrochus; singlering in Campanile). In addition, all observed paraspermatozoaof Plesiotrochus are anucleate, whereas in Campanile anucleateand nucleate paraspermatozoa are present. On the basis of spermsynapomorphies of Plesiotrochus and Campanile, the Plesiotrochidaeare transferred from the Cerithioidea to the Campaniloidea. (Received 3 August 1992; accepted 18 September 1992)     

SPERM AND SPERMIOGENIC ULTRASTRUCTURE IN THE MATHILDIDAE WITH A REVIEW OF SPERM MORPHOLOGY AND ITS SYSTEMATIC IMPORTANCE IN THE ARCHITECTONICOIDEA (GASTROPODA)

The ultrastructure of spermiogenesis and spermatozoa is examinedfor the first time in the heterogastropod family Mathildidae(Mathilda brevicula Bavay and Mathilda sp.). Mathildid spermatozoaexhibit the following features: (1) an ovoid acrosomal vesicleshowing curved dense layers basally and underlain by a thincurved plate; (2) a solid, rod-shaped nucleus showing a shallowbasal invagination (nucleus helically keeled in Mathilda sp.);(3) a midpiece composed of a 9+2 axoneme, 9 thick and periodicallybanded coarse fibres (associated with the axonemal doublets)and a continuous mitochondrial derivative; (5) glyco-gen piececomposed of the axoneme surrounded by dense granules; (6) andend piece (paddle-shaped terminally). Results of the study demonstratethat mathildids share the same key sperm and spermi-ogenic featuresobserved in the Architectonicidae. The monophyly of the Architectonicoidea,established by previous authors on anatomical grounds, is thereforeconfirmed using sperm morphology. Spermatozoa of the two mathildidsinvestigated lack the periodically banded midpiece structuresseen in investigated species of Architectonica (A. pcrspectiva(Linnaeus), A. perdix (Hinds)), Heliacus (H. (Heliacus) variegatus(Gmelin)) and Pseudotorinia (P. laseronorum (Iredale)) therebyresembling most closely the spermatozoaof Philippia lutea (Lamarck)and Psilaxis oxytropis (A. Adams) which also lack suchbandedstructures. Given the widely accepted primitive status of theMathildidae within the Architectonicoidea, the genera Philippiaand Psilaxis may prove to be relatively basal rather than advancedgenera within the Architectonicidae. Thi: view needs to be testedby examination of sperm morphology in other genera of the Architectonicidaeand also the basal mathildid genus Tuba sensu lato (= Gegania+ Tubena). Such information will be vital in any future cladisticstudy of the Architectonicoidea. (Received 16 June 1994; accepted 6 February 1995)     

中国的光肩星天牛类群

该文讨论我国光肩星天牛Anoplophoraglabrlpennis(Motschulsky)类群的外部形态和外生殖器的主要鉴别特征,寄主、地理分布、起源及其演化。光肩星天牛主要分布在山西吕梁山、太行山以东的广大平原地区,寄主广泛,主要有榆、复叶槭、杨、柳、五角枫等。黄斑星天牛主要分布在秦岭以北,山西吕粱山太行山以西的陕甘宁地区,向东已扩展到河南、河北;主要为害杨树,也为害柳、榆。四川星天牛主要分布于秦岭以南的西部地区,北限在陕西太白山到甘肃天水一带;主要为害柳。在秦岭以北到天水之间是黄斑星天牛和四川星天牛的重叠分布区,山西太行山两侧南北走向的狭长地带是光肩星天牛和黄肩星天牛重叠分布区,两个狭长地带交会处,大约在秦岭以北的陕西和(或)山西境内有三个种的重叠分布区域.在云、贵、川地区广泛分布着四川星天牛,至今还没有发现光肩星天牛、黄斑星天牛和蓝角星天牛,后者应该是一个值得怀疑的种。     

TAXONOMIC REVIEW OF THE TREE SNAIL AMPHIDROMUS ALBERS, 1850 (PULMONATA: CAMAENIDAE) IN THAILAND AND ADJACENT AREAS: SUBGENUS AMPHIDROMUS

Extensive series of Amphidromus Albers, 1850 were collectedfrom low-altitude areas (30–500 m above sea level)in Thailand, Laos, Malaysia, Singapore and Indonesia between1993 and 2004. Data on shell colour, genital and spermatophoremorphology, and radular structure are presented. Five speciesof Amphidromus (Amphidromus) are reviewed, of which four occurin Thailand. Intraspecific variation between populations ofAmphidromus (Amphidromus) atricallosus (Gould, 1843) is considered;three subspecies are accepted and a new subspecies described.Subspecies of A. (A.) inversus (Müller, 1774) and A. (A.)schomburgki (Pfeiffer, 1861) are reconsidered, and a new subspeciesof the latter is described. A dichotomous key to the speciesand subspecies of Amphidromus (Amphidromus) in Thailand is provided. (Received 7 May 2004; accepted 31 March 2005)     

ON THE STATUS OF THE GENERIC NAMES OF THE NUDIBRANCH GENERA CATRIONA, CRATENA, HERVIA, RIZZOLIA AND TRINCHESIA

The genus Catriona Winckworth (1941) is synonymous with TrinchesiaPruvot-Fol (1951) but not with Trinchesia von Jhering (1879). It has priority over Trinchesia Pruvot-Fol. The genus Cratena Bergh (1864) is valid and synonymous withRizzolia Trinchese (1877) but not with Hervia Bergh (1871). The genus Hervia Bergh (1871) is synonymous with Facelina Alderand Hancock (1855), but not all species of Hervia can be includedin the latter genus, and these should, therefore, be distributedamong other genera, some of which are listed. (Received 8 October 1954;     

Differential expression pattern of C4 bundle sheath expression genes in rice, a C3 plant

NADP-malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase(PCK) are specifically expressed in bundle sheath cells (BSCs)in NADP-ME-type and PCK-type C₄ plants, respectively. Unlikethe high activities of these enzymes in the green leaves ofC₄ plants, their low activities have been detected in the leavesof C₃ plants. In order to elucidate the differences in the geneexpression system between C₃ and C₄ plants, we have producedchimeric constructs with the ß-glucuronidase (GUS)reporter gene under the control of the maize NADP-Me (ZmMe)or Zoysia japonica Pck (ZjPck) promoter and introduced theseconstructs into rice. In leaves of transgenic rice, the ZmMepromoter directed GUS expression not only in mesophyll cells(MCs) but also in BSCs and vascular cells, whereas the ZjPckpromoter directed GUS expression only in BSCs and vascular cells.Neither the ZjPck nor ZmMe promoters induced GUS expressiondue to light. In rice leaves, the endogenous NADP-Me (OsMe1)was expressed in MCs, BSCs and vascular cells, whereas the ricePck (OsPck1) was expressed only in BSCs and vascular cells.Taken together, the results obtained from transgenic rice demonstratethat the expression pattern of ZmMe or ZjPck in transgenic ricewas reflected by that of its counterpart gene in rice. (Received August 8, 2004; Accepted February 20, 2005 )     

Leaf area index determination in an alder forest: a comparison of three methods

Leaf area index (LAI) of a stand of adult black alder trees(Alnus glutinosa L., Gaertn.) was determined by means of threeindependent methods. (1) The seasonal course of LAI was directlyobtained by counting leaves in situ and adding up their areas,estimated from harvested subsamples of leaves. (2) The seasonalvariation of LAI in the stand was estimated using the Li-CorLAI-2000 PCA in parallel and with this instrument a VegetationArea Index (VAI, projected area of all phyto-elements) was actuallymeasured. (3) Maximum LAI was calculated from leaf litter collectionstaking into account specific leaf area within different layersof the alder crown. Direct LAI estimates (1) and calculationsfrom leaf litter (3) revealed the same figure of maximum LAI(4.8). This LAI was reached in August. The LAI-2000 PCA capturedthe seasonal variation and underestimated, by 11% on average,the LAI obtained directly. Compared with results gained withother broad-leaved tree species the LAI-2000 PCA values foralder were reliable. It is suggested that this is due to thehorizontal homogeneous structure of the main leaf layer. Thisis in the periphery of the crown, where 90% of the light interceptionoccurs. Taking the het-erogeneity into account a satisfactorycompatibility of the three methods applied to the alder standwas achieved. Key words: Alnus glutinosa, leaf area index, in situ counting, LAI-2000 PCA, litter collections     

Background context and decision making in hoarding gray jays

If decision makers assign stable fitness-related values to options, preference for the most valuable of simultaneously encounteredoptions should be independent of background context (i.e.,prior options). The tendency to choose optionx versus y shouldbe unaffected by whether the decision maker has already beengiven a choice betweenx' and y' or between x' and y'. Here, food-hoarding gray jays (Perisoreus canadensis) were given aninitial choice between x' (one raisin, 0.5 m into a tube) and y' (three raisins, 0.5 m) or between x' and y' (both identicalto x'). All subjects were then given a choice between x' (oneraisin, 0.3 m) and y' (three raisins, 0.7 m). In violationof the principle of irrelevant alternatives, the "market share"ofx depended on prior options. Subjects initially exposed tocontext {x', y'} showed a stronger preference for x than did subjects initially exposed to {x', y'}, which implies thatthe jays did not assign a fixed value to each option. Subjectsthat initially could obtain a large reward (y') for about thesame "price" (perceived danger) as a small reward (x') apparentlydevalued the large reward (y) in the subsequent choice. Thiseffect may be the joint byproduct of cognitive constraints andan adaptive tendency to use information provided by the context.     

A Study of the Evolutionary Relationships of Fundulus Topminnows (Teleostei: Fundulidae)

A hypothesis of the evolutionary relationships of thirty-fourspecies of Fundulus and their closer relatives is presented.The study is restricted to morphological characters which couldbe determined to be primitive or derived using the methods ofphylogenetic systematics. Following Parenti, a family Fundulidaeis recognized. It is composed of four genera of North Americankillifishes. (Cyprinodontidae as usually constitutedis polyphyletic.)No convincing characters demonstrate that Fundulus is a naturalgroup (a monophyletic group). However, all species of Fundulusshare four derived characters with Lucania. The sister group(closest genealogical relative) of Fundulus plus Lucania isa group composed of the genera Adinia and Leptolucania. Fourmonophyletic groups of Fundulus can be recognized based on sharedderived characters: (1) subgenus Fundulus (seven species excludingthree species placed in Fontinus); (2) subgenus Fonlinus (sixspecies); (3) subgenus Xensima (five species); and (4) subgenusZygonectes (thirteen species). Three species, F. (Plancterus)zebrinus, F. lima, and F. parvipinnis are of uncertain affinitieswithin the Lucania-Fundulus clade     

Molecular Phylogeography of Oncomelania Lindoensis (Gastropoda: Pomatiopsidae), the Intermediate Host of Schistosoma Japonicum in Sulawesi

Oncomelania lindoensis from Lake Lindu, Sulawesi, was characterizedfor genetic variation at 21 allozyme loci and compared withO. hupensis (China) and O. quadrasi (Philippines). Geneticdistances and interpopulation patterns of allele-sharing pointto a closer relationship between Sulawesi and the Philippines(Nei's unbiased genetic distances (D) averaged 0.50) than betweenSulawesi and China (D= 0.79). These data, coupled with a considerationof the geographic distribution of the genus, support the hypothesisthat the Sulawesi Oncomelaniaoriginated by avian-facilitated colonizationfrom the Philippines about two million years ago. Oncomelania from Sulawesi were originally described as subspecificallydistinct: Oncomelania hupensis lindoensis. However, the allopatricdistribution, unique alleles at five loci, and significant geneticdistances from congeners in Mindanao and elsewhere in the Philippinessuggest that this taxon should be distinguished as a full specieswithin the Oncomelania hupensis species group, namely: O. lindoensisDavis & Carney 1973. Comparison with published data on variationwithin quadrasi and in three Chinese subspecies of hupensisshowed that D values increase with taxonomic level in this speciesgroup. D averaged 0.15 (0–0.26) within Chinese subspeciesand 0.04 (0–0.13) within the Philippines, but was 0.30(0.20–0.45) between Chinese subspecies, and 0.48–0.80between the three species (hupensis, quadrasi and lindoensis).The genotypic cluster species concept and these multilocus geneticdistances can be used to help define species and subspeciesin these medically important snails. (Received 14 May 1997; accepted 20 April 1998)     

寄生中国樟子松木蠹象的新姬蜂(膜翅目：姬蜂科，瘤姬蜂亚科)

寄生中国樟子松木蠹象的新姬蜂（膜翅目：姬蜂科,瘤姬蜂亚科）王淑芳（中国科学院动物研究所北京１０００８０）岳书奎（东北林业大学林学系哈尔滨１５００４０）中国樟子松木级象是危害樟子松球果的一种重要害虫,＂七·五＂期间我们在我国内蒙古自治区呼伦贝尔盟地区进...     

林氏果蝇线粒体DNA分析

本文对Tamura(1988)提纯mtDNA的方法进行改进,建立了林氏果蝇Drosophila lini 线粒体DNA大量制备的方法;对采自原产地台湾省的单雌晶系TAW3146.1的线粒体DNA用10种限制性内切酶进行了酶切,得出了林氏果蝇mtDNA的分子量大小为16.3kb;用双酶切法制作了林氏果蝇线粒体DNA酶切图谱,并与属于同一复合种组的D.Kikkawai的酶切图谱进行比较。所用的内切酶有XbaI、AvaI、EcoRV、ScaI、SacI、EcoR I、HindIII、PvuⅡ、BamHI、PstⅡ。     

The N-glycosylation defect of cwh8Delta yeast cells causes a distinct defect in sphingolipid biosynthesis

CWH8/YGR036c of Saccharomyces cerevisiae has been identifiedas a dolichylpyrophosphate (Dol-PP) phosphatase that removesa phosphate from the Dol-PP generated by the oligosaccharyltransferase(OST), while it adds N-glycans to nascent glycoproteins in theendoplasmic reticulum (ER). Lack of CWH8 was proposed to interruptthe so called dolichol (Dol) cycle by trapping Dol in the formof Dol-PP in the ER lumen. Indeed, cwh8D mutants display a severedeficiency in N-glycosylation. We find that cwh8D mutants havestrongly reduced levels of inositolphosphorylceramide (IPC),whereas its derivative, mannosyl-(inositol-P)₂-ceramide (M(IP)₂C)is not affected. Microsomes of cwh8D contain normal ceramidesynthase and IPC synthesis activities. Within a large panelof mutants affecting Dol dependent pathways such as N- or O-glycosylation,or glycosylphosphatidyl inositol (GPI)-anchoring, only the mutantshaving a deficiency of N-glycan addition show the defect inIPC biosynthesis. By mutating genes required for the additionof N-glycans or by treating cells with tunicamycin (Tm) onecan similarly reduce the steady state level of IPC and exactlyreproduce the phenotype of cwh8D cells. Some potential mechanismsby which the lack of N-glycans could lead to the sphingolipidabnormality were further explored.     

THE GENUS TRICOLIA IN THE EASTERN ATLANTIC AND THE MEDITERRANEAN

The genus Tricolia(Phasianellidae) in the Eastern Atlantic andMediterranean is reviewed on the bases of radular morphology,shell characters and polychromatism. The taxa included within the T. pullus (L.) group are not clearlyseparable and are treated as geographical subspecies:T. pulluspullus (L.), T. pullus picta (da Costa), T. pullus azorica (Dautzenberg),T. pullus canarica Nordsieck. The case of T. tenuis (Michaud)is problematic since it is clearly separable from sympatricT. pullus pullus in most parts of the Mediterranean but transitionalto T. pullus picta, towards the Atlantic. Other taxa are considered as having specific status since theyare consistently separable when found in sympatric populations.These include T. speciosa (Muhlfeldt), T. miniata (Monterosato),T. tingitana n.sp., T. petiti (Craven), T. nordsiecki (Talavera)and T. algoidea (Pallary). The last two species are stated forthe first time as belonging to the Phasianellidae. The genusEpheriella Pallary, based on T. algoidea, is synonymized withTricolia. (Received 6 April 1981;     

Effects of environmental factors on ichthyoplankton communities in the Miramichi estuary, Gulf of St Lawrence

Ichthyoplankton in 20 taxa (17 identified to species, threeto genus) representing 14 families were collected in 10 surveysof the Miramichi estuary between May and September 1992. Thetaxonomic composition was typical of other estuaries in theGulf of St Lawrence and Gulf of Maine. Larvae of three anadromousspecies [rainbow smelt (Osmerus mordax), alewife (Alosa pseudoharengus)and blueback herring (Alosa aestivalis)] were several ordersof magnitude more abundant than any other taxon. The upper estuary(Miramichi River and its tributaries) probably serves as a nurseryground for larvae of these species and others such as Atlantictomcod (Microgadus tomcod). The species composition of the lowerestuary (Miramichi Bay) was dominated by typically marine formsand probably serves as a nursery ground for winter flounder(Pleuronectes americanus), smooth flounder (Pleuronectes putnami).sculpin (Myoxocephalus sp ) and sand lance (Ammodytes sp) Ofthe environmental factors investigated, salinity was the mostuseful predictor of larval distribution in the estuary.     

长爪沙鼠寄生蚤指数和气象因子关系的研究

根据内蒙古自治区土默特平原1983～1985年长爪沙鼠 Meriones unguiculatus巢蚤、体蚤、洞干蚤指数和6项气象资料进行分析,得到如下结果。① 共获蚤11种, 其中秃病蚤蒙冀亚种Nosopsyllus laeviceps kuzenkovi(67.50%)是优势种, 二齿新蚤Neopsylla bidentatiformis(22.65%)为次优势种。② 3种蚤指数的均值差异显著(P<0.0001)。③ 体蚤与洞干蚤指数相关显著(P<0.05), 模型为(洞干蚤指数)=0.0049+0.0248(体蚤指数), 巢蚤与体蚤、巢蚤与洞干蚤指数的相关不显著(P>0.25)。④ 沙鼠密度与3种蚤指数的相关均不显著(P>0.10)。⑤ 在巢蚤中,月温度是影响巢秃病蚤唯一的气象因子(P<0.05)。⑥ 分别求出鼠体的秃病蚤和同形客蚤指名亚种Xenopsylla conformis conformis与气象因子的最优回归子集(P<0.003、P<0.05), 洞干的秃病蚤和二齿新蚤与气象因子的最优回归子集(P<0.0007、P<0.01), 月蒸发量是影响秃病蚤的最重要因子。⑦ 春季与冬季、夏季与冬季巢蚤指数差异显著(P<0.05); 春季与冬季、夏季与冬季体蚤指数差异显著(P<0.05); 春季与冬季、夏季与秋季、夏季与冬季洞干蚤指数差异显著(P<0.05)。     

Modification of Leaf Formation by Cytokinin and Chlormequat (CCC) in Vitis

Application of the cytokinin, 6-(benzylamino)-9-(2-tetrahydropyrany1)-9H-purine(PBA, 1mM) and 2-chloroethyl trimethyl ammonium chloride (chlormequat;3 mM), a growth retardant, to grapevines induced the formationof fused leaves (two laminae and two petioles) and double leaves(two separate petioles each with a single lamina). Double leaveswere found in Vitis vinifera L. seedlings, in Vitis ripariaand in Muscadinia (Vitis) rotundifolia. In some of the treatedvines, leaves arose with opposite phyllotaxy. Other anomaliesincluded production of two opposite axillary buds in axils ofopposite leaves and production of two tendrils per node. Sometendrils grew into shoots. In Muscat of Alexandria, applicationof GA₃ (3 µM, 15 µM), followed by an applicationof chlormequat (0.4 mM, 1.2 mM), led to a marked reduction inthe extension growth of axillary shoots. Vitis vinifera L., Vitis riparia, Muscadinia (Vitis) rotundifolia, grapevines, leaf formation, cytokinin, chloromequat     

Rapid Evaluation of Least-Squares and Minimum-Evolution Criteria on Phylogenetic Trees

We present fast new algorithms for evaluating trees with respectto least squares and minimum evolution (ME), the most commonlyused criteria for inferring phylogenetic trees from distancedata. The new algorithms include an optimal O(N2) time algorithmfor calculating the edge (branch or internode) lengths on atree according to ordinary or unweighted least squares (OLS);an O(N3) time algorithm for edge lengths under weighted leastsquares (WLS) including the Fitch-Margoliash method; and anoptimal O(N4) time algorithm for generalized least-squares (GLS)edge lengths (where N is the number of taxa in the tree). TheME criterion is based on the sum of edge lengths. Consequently,the edge lengths algorithms presented here lead directly toO(N2), O(N3), and O(N4) time algorithms for ME under OLS, WLS,and GLS, respectively. All of these algorithms are as fast asor faster than any of those previously published, and the algorithmsfor OLS and GLS are the fastest possible (with respect to orderof computational complexity). A major advantage of our new methodsis that they are as well adapted to multifurcating trees asthey are to binary trees. An optimal algorithm for determiningpath lengths from a tree with given edge lengths is also developed.This leads to an optimal O(N2) algorithm for OLS sums of squaresevaluation and corresponding O(N3) and O(N4) time algorithmsfor WLS and GLS sums of squares, respectively. The GLS algorithmis time-optimal if the covariance matrix is already inverted.The speed of each algorithm is assessed analytically—thespeed increases we calculate are confirmed by the dramatic speedincreases resulting from their implementation in PAUP* 4.0.The new algorithms enable far more extensive tree searches andstatistical evaluations (e.g., bootstrap, parametric bootstrap,or jackknife) in the same amount of time. Hopefully, the fastalgorithms for WLS and GLS will encourage the use of these criteriafor evaluating trees and their edge lengths (e.g., for approximatedivergence time estimates), since they should be more statisticallyefficient than OLS.