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     

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.     

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.     

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.     

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     

ECOLOGY AND EVOLUTION OF MATING SYSTEMS OF FIDDLER CRABS (GENUS UCA)

1. General accounts of the natural history and behaviour of fiddler crabs suggest there exist two broad mating patterns in the genus. Most western and Indo-Pacific species mate on the surface of intertidal substrates near burrows females defend. The sexes associate only briefly during courtship and mating. In contrast, males of many American species court from and defend burrows to which females come for mating. Copulation occurs underground in burrows plugged at the surface; the sexes usually remain together for at least several hours. Here we summarize and contrast recent detailed field studies of the mating systems of U. pugilator, an American species, and U. vocans, a species widely distributed in the western and Indo-Pacific. We indicate how differences in the breeding ecology of these two species may account for basic differences in modes of sexual selection leading to the two broad mating patterns in the genus. 2. U. pugilator burrows in protected sandy substrates in the upper intertidal and supratidal zone. During ebb tide, nonbreeding crabs leave burrows they occupy during high tide to forage on food-rich substrates in the lower intertidal zone. Reproductively active males remain in the burrow zone where they fight for and defend burrows from which they court. Large males win most fights for burrows and tend to defend burrows high on the elevation gradient, especially during periods with relatively high tides. Females usually approach and descend the burrows of several males before choosing their mates by remaining in males' burrows. Males remain underground with their mates for 1–3 days until after they oviposit their eggs. Some males then emerge and leave their burrows while others sequester their mates in the chambers where mating and oviposition has occurred, dig new chambers and resume courtship, perhaps attracting additional females. In either case, females remain underground for approximately 2 weeks, finally emerging to release their planktonic larvae. Burrows that do not collapse due to tidal inundation or flooding by groundwater are best for breeding and usually are located relatively high on the elevation gradient. Females choose mates indirectly by preferring to breed in burrows that will remain intact while they oviposit and incubate their eggs. Large males mate more often than small males because they are better able to defend burrows at locations females prefer to breed. The mating system of U. pugilator may be classified as resource-defence polygyny. 3. U. vocans burrows in open muddy substrates in the mid- to lower intertidal zone. At a site near Chunda Bay, Australia, where the reproductive behaviour of this species has been studied in depth, both sexes feed near burrows they defend. Females tend to occupy their burrows for longer periods and move shorter distances than do males. Mating occurs on the surface near the burrows that females defend. Females accept both resident and wandering males as mates. They show no preference for mating with larger males. Female choice may be based on other male morphological or behavioural characteristics. Females oviposit their eggs either while on the surface or in their burrows. They produce relatively small clutches and are active on the surface throughout their breeding periods. Males fight both their neighbours and wandering males. Large males tend to win fights and defend burrows in areas where large females, which produce relatively many eggs, are most dense. Such areas may offer greater protection from predators than areas occupied by smaller females. Small males mate about as often as large males but may father fewer larvae. The mating system of U. vocans is resource-free and promiscuous. 4. The mating systems of U. pugilator and U. vocans differ fundamentally in that female U. pugilator require access to a specific microenvironment to breed successfully, while female U. vocans do not. We suggest this difference occurs because of contrasts in clutch sizes and the mobility and movement patterns of feeding females. Female U. pugilator produce relatively large clutches and probably experience more intense selection from factors that can cause egg loss and mortality than do U. oocans, which produce clutches of sufficiently small volume to be protected by their abdominal flaps. Hence, the range of suitable breeding environments for U. pugilator is small compared to that for U. vocans. In addition, U. pugilator burrows in areas that are relatively food-poor, leading to daily migrations to and from food-rich substrates in the lower intertidal zone, preventing female defence of an area suitable for both breeding and feeding. U. vocans, however, burrows in areas sufficiently rich to support feeding, leading to relatively low female mobility and defence of burrows that are also suitable breeding sites. 5. Adaptive radiation of the genus Uca in the Americas is manifest by trends toward smaller adult size, higher population densities, more frequent microgeographic sympatry and increased terrestriality, compared to species in the western and Indo-Pacific regions. We outline the general features of the selection mechanisms tying each of these trends to the evolution of resource—defence mating systems. Intraspecific variation in the courtship behaviour and site of mating in U. lactea and U. vocans supports our contention that resourse—defence behaviour tends to occur at high population densities. Additional data are needed to evaluate the other hypotheses critically.     

TRIPLOCHITIOXYLON (STERCULIACEAE): A NEW GENUS OF WOOD FROM THE EOCENE OF OREGON AND ITS BEARING ON XYLEM EVOLUTION IN THE EXTANT GENUS TRIPLOCHITON

A new sterculiaceous wood, Triplochitioxylon oregonensis gen. et sp. n., was collected from a Middle Eocene locality in the Clarno Formation of Oregon. Anatomical data indicate a close natural relationship between T. oregonensis and the living species of Triplochiton, a genus endemic to tropical Africa. The fossil is believed to represent a population of the group or complex from which Triplochiton evolved. The basic differences in the xylem organizations of the two genera are explained by a significant reduction of fusiform initial length and by a complete suppression of post-cambial parenchyma strand elongation in the extant genus. Paleobotanical and biogeographical evidence suggest that the xylem evolution has been strongly influenced by the increasing aridity of the African continent.     

EVOLUTION OF THE TELLINACEA (BIVALVIA)

The suspension feeding Astartacea appear to be among the earliestheterodonts. These organisms may have given rise to the Carditaceaand the rest of the heterodonts including the Tellinacea. Paleontological evidence indicates that the earliest Tellinaceawere suspension feeders with members that lived vertically ina burrow in shifting sand. These conditions resemble those foundin species of modern Donax in the Donacidae. From a Donax-likestate of suspension feeding evolution most likely proceededto non-selective feeders. Extant organisms that resemble thisstage are found in the Solecurtidae. A later stage resemblessome of the extant Psammobiidae. The final stage in tellinaceanevolution is the acquisition of deposit feeding with its associatedmorphology. These stages are observed in the Scrobiculariidae,Tellinidae and a few members of the Semelidae. (Received 27 April 1981;     

赤■属的胚胎学研究(英)

描述了葫芦科赤爬属植物生活史的主要过程以及胚胎学的重要特征,它们是：腺质绒毡层,胞质分裂同时型,小孢子四分体四面体型和等面体型,花粉粒散发时具两细胞,双珠被,厚珠心,寥型胚囊,珠孔端受精,胚胎发育柳叶菜型。     

POPULATION GENETIC CONSEQUENCES OF DEVELOPMENTAL EVOLUTION IN SEA URCHINS (GENUS HELIOCIDARIS)

Within the sea urchin genus Heliocidaris, changes in early embryonic and larval development have resulted in dramatic differences in the length of time larvae spend in the plankton before settling. The larvae of one species, H. tuberculata, spend several weeks feeding in the plankton before settling and metamorphosing into juveniles. The other species, H. erythrogramma, has modified this extended planktonic larval stage and develops into a juvenile within 3–4 days after fertilization. We used restriction site polymorphisms in mitochondrial DNA to examine the population genetic consequences of these developmental changes. Ten restriction enzymes were used to assay the mitochondrial genome of 29 individuals from 2 localities for H. tuberculata and 62 individuals from 5 localities for H. erythrogramma. Within H. tuberculata, 11 mitochondrial genotypes were identified. A G_ST analysis showed high levels of genetic exchange between populations separated by 1,000 kilometers of open ocean. In contrast, in H. erythrogramma, 13 mitochondrial genotypes differing by up to 2.33% were geographically partitioned over spatial scales ranging from 800 to 3,400 kilometers. Between distant localities, there was complete mitochondrial lineage sorting and large sequence divergence between resulting clades. Over much smaller spatial scales (< 1,000 km), genetic differentiation was due to the differential sorting of very similar genotypes. This pattern of mitochondrial variation suggests that these population differences have arisen recently and may reflect the historical interplay between the restricted dispersal capabilities of H. erythrogramma and the climatic and geological changes associated with Pleistocene Ice Ages.