STUDY OF THE ESSENTIAL LEAF OILS OF THE GENUS MONARDA (LABIATAE)

Vapor-phase chromatographic patterns obtained from the distilled essential oils of 20 taxa in the genus Monarda (Labiatae) are discussed. The influence of leaf tissue maturity, plant habitat, and oil storage upon the composition of the essential oils was investigated, as well as similarities of leaf and flower oils in the same plant. The taxa of the subgenus Cheilyctis have very similar chromatographic “fingerprints” which confirm their homogeneity. On the other hand, the polyploid subgenus Monarda has heterogeneous patterns of essential oil composition among its species. A population of M. fistulosa gave evidence of being a chemical race.     

EVOLUTION OF THE GENUS CHRYSOCOCCYX

Modern geological ideas on ocean-floor spreading are briefly reviewed. Pangea began to break up at the end of the Trias, but Africa, Antarctica and Australia remained together or close to each other till the end of the Cretaceous. The position of western New Guinea at the start of the Miocene could have been approximately where Arnhem Land is now, and at the start of the Pliocene somewhat north of the present-day Aru Islands. Its size until the end of the Pliocene was much smaller than it is today. Friedmann's proposal for the evolutionary spread of Chrysococcyx therefore demands that the whole process occurred since about the start of the Pliocene. There may not have been enough time in these seven million years for the evolutionary dispersal of a genus of parasitic cuckoos halfway round the world. His proposal also regards C. osculans as an awkward throw-back, and leaves a gap between species in New Guinea and southeastern Asia that is not bridged by intermediates. If a stock of cuckoos had been in Gondwanaland before it broke up, that stock could have given rise to the genus Cacomantis and the forerunners of C. osculans. The lineage of osculans would have quickly given rise to a lineage of glossy cuckoos that then divided into two branches. One could have penetrated Africa, south of where Madagascar then was, produced the species klaas, cupreus, caprius and flavigularis (an aberrant end-product), and much later, after Madagascar had drifted south from India (having been separate from Africa since the Cretaceous), colonised Asia where maculatus and xanthorhynchus would have differentiated. The other line could have differentiated, perhaps more slowly, in Australia into basalts, lucidus, ruficollis and malayanut (minutillus). When Australia had drifted near enough to the Malay Archipelago and as New Guinea grew, ruficollis and minutillus could have moved forward to colonise the islands, where minutillus would have produced the many races oimalayanus and meyerii differentiated as an aberrant end-product. This proposal overcomes some of the objections to Friedmann's theory because it arranges events to accord better with geological developments and avoids the evolutionary discontinuities of his proposal. The migratory habits of the cuckoos, thought by Friedmann to be significant, are discounted as evidence for evolutionary history. The parasitic habits are re-interpreted. Better data are presented for the parasitic behaviour of basalis and lucidus; they suggest that both species are sophisticated and probably host-specific parasites. Jensen & Jensen (1969) have already given evidence that some African glossy cuckoos are highly host-specific. There seems to be a trend of decreasing parasitic sophistication in Australian species, correlated with the possible age of the species. In Africa parasitism seems to be far in advance of that in Australia, probably because the opportunities for parasitism are far better in Africa. These trends and differences in parasitic behaviour are compatible with an evolutionary spread from Gondwanaland. The crucial question is whether the stock of Cacomantis and Chrysococcyx could have existed before the break-up of Gondwanaland, i.e. before the early Eocene. The present fossil record suggests that this is unlikely, but the paucity of fossils and the difficulties of palaeoclimates do not seem to be insuperable and it is suggested that a southern origin for these cuckoos should be considered seriously.     

山茶属植物的进化与分布

山茶属Ｃａｍｅｌｌｉａ植物在其进化过程中,以雄芯不定数、在某些类群中存在心皮离生至合生的中间过渡,认为是山茶科中较原始的一属,分布于亚洲东部和东南部,中国长江以南广袤的亚热带地区是该属的现代分布中心,中南半岛和我国云南、广西南部的热带地区种类虽少,却集中了本属原始或较原始的类群和种类。本属演化上的近缘属或姐妹群－核果茶属Ｐｙｒｅｎａｒｉａ（包括石笔木属Ｔｕｔｃｈｅｒｉａ）分布区大致与本属相似,其原     

THE GENETICS AND EVOLUTION OF CANNIBALISM IN FLOUR BEETLES (GENUS TRIBOLIUM)

Cannibalism plays a major role in population regulation in Tribolium confusum, accounting for up to tenfold differences in population size between different genetic strains. I characterized the within- and between-strain genetic variation for cannibalism using standard quantitative-genetic methods. The four laboratory strains studied have similar birth and death rates but differ in their strain-specific cannibalistic tendencies. The cannibalism rates of the strains were stable for more than 60 generations of laboratory husbandry. I found considerable genetic variation for cannibalism within each strain. A genetic analysis of the between-strain differences in each of three types of cannibalism (larvae eating eggs, adults eating eggs, and adults eating pupae) showed that all three cannibalism pathways are autosomally inherited and exhibit minor degrees of dominance. Adult cannibalism of eggs and larval cannibalism of eggs appear to be genetically correlated. The differences between the “high” and “low” cannibalism strains appear to be polygenic for two kinds of cannibalism, larvae eating eggs and adults eating pupae. However, strain differences in adult cannibalism of eggs may be due to only two loci. The stability of the between-strain differences for more than 60 generations, the additive nature of inheritance, and the demonstration of considerable within-strain genetic variation suggest that cannibalism may be selectively neutral or under stabilizing selection with many adaptive peaks.     

杜鹃属的系统发育与进化

本文以形态学为基础,结合一些新的有关资料,如解剖学、细胞学、化学等方面的证据讨论了杜鹃属的系统发育与进化问题,认为常绿杜鹃亚属在本属系统发育中处于原始地位,其中的云锦杜鹃亚组、耳叶杜鹃亚组、大叶杜鹃亚组和杯毛杜鹃亚组等4个亚组是原始类群,也即是其祖先的直接后裔。本属的原始祖先是具常绿习性,各部无毛(也无鳞片),花部不定数,具复合三叶隙构造的乔木,即类似现存原始类群的植物,它们生长于白垩纪至早第三纪古北大陆南缘,大约在我国西南部的热带山区森林环境中。随着地史的变迁,杜鹃属在漫长的进化过程中平行进化和发展为两个进化枝,一枝分化成各部被鳞片的热带附生类群或高山类群(包括4个亚属),另一枝演变为多少被毛的温带林下的半常绿至落叶类群(3个亚属),有鳞的髯花杜鹃组及落叶的日本马银组和落叶杜鹃组是两个进化枝演化上的高级类群。     

EVOLUTION OF BREEDING DISTRIBUTIONS IN THE OLD WORLD LEAF WARBLERS (GENUS PHYLLOSCOPUS)

Among Palearctic warblers of the genus Phylloscopus those species that breed farther north occupy larger geographical ranges than those which breed farther south (Rapoport's rule). We suggest that much of this pattern is a consequence of the differential ability of species to occupy areas rendered inhospitable during the Pleistocene. In support of this suggestion, the midpoint of breeding range in a north-south direction has been an exceptionally labile trait through evolutionary time. Comparisons of ecological attributes of those species breeding in the Himalayas with close relatives in Siberia implies a role for habitat tracking in determining which species have been able to colonize northern areas; hypotheses based on climate and climatic variability have less support. In addition there is a likely role for geographic barriers and/or biotic interactions in preventing some taxa from spreading from small southern ranges.     

金线鲃属鱼类的起源及其适应演化

根据地史和东亚地区鱼类区系演化史,推测了金线属鱼类的起源时代及其与当时古地质和古气候事件的关系,认为该类群的原始祖先可能在第三纪晚期已经存在于云贵高原一带;较系统地研究了金线属鱼类的洞穴适应演化趋势,表明该类群在穴居适应过程中既表现出穴居鱼类的共同演化趋势,也表现出其独特的穴居适应方式。       

鼠兔属两对“近缘种”的分子进化与环境变迁的关系

通过对６种鼠兔限制性内切酶图谱的分析,发现传统的形态学研究公认的两对近缘物种,即高原鼠兔与达乌尔鼠兔及甘肃鼠兔与藏鼠兔实际上来自两个不同的母系群。该结果提示这４种鼠兔两两间彼此形态的相似性可能因趋同进化所致。通过遗传距离计算的各物种分化的时间表明,鼠兔在晚上新世可能有一个快速进化时期。这与在地史上发生的相应的地质事件相吻合。     

APERTURE EVOLUTION IN THE GENUS PTYCHOPETALUM BENTH. (OLACACEAE)

The genus Ptychopetulum (Olacaceae), disjunct between South America (2 spp.) and Africa (2 spp. West Africa; I sp. Rhodesia), exhibits predominantly diploporate pollen among the West African species and predominantly triporate pollen among the South American taxa. An analysis of aperture evolution suggests two possible schemes of aperture evolution for the genus. Scheme I avers the independent origin of both triporate and diploporate apertures from a basic brevicolpate condition while scheme II proposes a basic diploporate condition in which the diploporate apertures have migrated to the equator, fused to form brevicolpi and have ultimately become reduced to pores. Pollen evidence in support of both schemes is discussed. The distribution of aperture types within the genus also suggests West Africa as the original site of aperture evolution and South America as the second area of aperture development with types traceable to West African stock.     

A CYTOLOGICAL CONSPECTUS OF THE GENUS CALYCADENIA (ASTERACEAE): AN EXAMPLE OF CONTRASTING MODES OF EVOLUTION

The chromosome numbers of 12 taxa of Calycadenia are documented by determinations in 77 widespread populations of the genus. Results of biosystematic studies indicate that hybrids among C. multiglandulosa, C. ciliosa, C. pauciflora, C. hispida, C. spicata, and C. oppositifolia characteristically have multiple associations of chromosomes producing complex meiotic configurations, whereas hybrids among C. villosa, C. mollis, C. truncata, and C. tenella generally yield few or no bivalents and a predominance of univalents during meiosis. Hybrids between C. multiglandulosa and C. hispida exhibit strict bivalent pairing and high pollen stainability. It is demonstrated that C. pauciflora and C. ciliosa comprise several sibling taxa that are morphologically cryptic, yet highly differentiated cytologically. Conversely, it is concluded that C. multiglandulosa and C. hispida comprise at least five morphologically distinct taxa that so far as known are highly interfertile (as judged by pollen stainability of hybrids) and cytologically uniform. Reproductive biology, chromosome mutation rates, habitats, flowering time, and genetic recombination mechanisms of the C. pauciflora-C. ciliosa and C. multiglandulosa-C. hispida complexes are compared in an attempt to account for the different modes of evolution observed in these closely related groups of Calycadenia. Lacking other plausible explanations, it is suggested that differential methods for limiting recombination of critical adaptive gene complexes might account for the divergent evolutionary patterns encountered in Calycadenia.     

CHATTAWAYA (STERCULIACEAE): A NEW GENUS OF WOOD FROM THE EOCENE OF OREGON AND ITS IMPLICATIONS FOR XYLEM EVOLUTION OF THE EXTANT GENUS PTEROSPERMUM

A new sterculiaceous wood, Chattawaya paliformis gen. et sp. n., was collected from a Middle Eocene locality in the type area of the Clamo Formation of north central Oregon. The wood differs from all known extant woods in having very large and irregularly shaped tile cells. However, other features of the xylem indicate a close natural relationship between Chattawaya and the extant paleotropical genus, Pterospermum. It is suggested that the xylem organization of the Eocene fossil represents a more primitive condition than that observed in Pterospermum. Comparative xylotomy indicates three evolutionary trends within the complex to which Chattawaya and Pterospermum belong: development of storied structure, increased uniformity in shape and size of tile cells and loss of multiseriate rays. Chattawaya is part of a growing body of paleobotanical evidence indicating that the Sterculiaceae was well differentiated by the early Tertiary, but that the lineages leading to extant genera have undergone an appreciable amount of evolutionary change since the Eocene.     

THE EVOLUTION OF THERMOTOLERANCE IN HOT SPRING CYANOBACTERIA OF THE GENUS SYNECHOCOCCUS

The extension of ecological tolerance limits may be an important mechanism by which microorganisms adapt to novel environments, but it may come at the evolutionary cost of reduced performance under ancestral conditions. We combined a comparative physiological approach with phylogenetic analyses to study the evolution of thermotolerance in hot spring cyanobacteria of the genus Synechococcus. Among the twenty laboratory clones of Synechococcus isolated from collections made along an Oregon hot spring thermal gradient, four different 16S ribosomal RNA gene sequences were identified. Phylogenies constructed using these sequence data indicated that the clones were polyphyletic but also that three of the four sequence groups formed a clade. Differences in thermotolerance were observed for clones with different 16S rRNA gene sequences, and comparison of these physiological differences within a phylogenetic framework provided evidence that more thermotolerant lineages of Synechococcus evolved from less thermotolerant ancestors. The extension of the thermal limit in these bacteria was correlated with a reduction in thermal niche breadth, which may have implications for the geographic distributions of these organisms. This study illustrates the utility of using phylogenetic comparative methods to investigate how evolutionary processes have shaped historical patterns of ecological diversification in microorganisms.     

中国麻黄属的地理分布与演化

中国现有麻黄属植物１５种,２变种和１变型,这些种属于膜果麻黄组和麻黄组中的麻黄亚组,没有原始类型藤麻黄亚组的代表。我国除长江中下游及珠江流域的省区处,其他省区都有分布。麻黄花粉的化石－麻分在地层中的分布说明,麻黄在过去曾遍布我国各地,发现的最早时期是在侏罗纪,到白垩纪－早第三纪时,种类较现在丰富,将近５０种,根据麻黄粉在世界各地地层中的分布和时期,结合大陆飘移和海底扩张板块构造学说推断,原麻黄在各