The secondary vascular system of Actinopterygii: interspecific variation in origins and investment

Vascular casts of 3 species of Chondrichthyes, 1 of Dipnoi, 1 of Chondrostei and 14 species of the Teleostei were examined by light and scanning electron microscopy in order to give a qualitative and quantitative analysis of interarterial anastomoses (iaas) that indicate the presence (or absence) of a secondary vascular system (SVS). Anastomoses were found to originate from a variety of different primary blood vessels, many of which have not been previously identified as giving rise to secondary vessels. Segmental arteries derived from the dorsal aorta and supplying body musculature were major sites of origin of the SVS, although there was considerable variation in where, in the hierarchy of arterial branching, the anastomoses occurred. The degree of investment in a SVS was species specific, with more active species having a higher degree of secondary vascularisation. This difference was quantified using an absolute count of iaas between Anguilla reinhardtii and Trachinotus baillonii. A range of general features of the SVS is also described. No evidence of iaas was found on the coeliac, mesenteric or renal circulation in any species. Evidence of iaas was lacking in the dipnoan and chondrichthyan species examined, suggesting that a SVS is restricted to Actinopterygii. The presence and distribution of a SVS does not appear to be exclusively linked to phylogenetic position, but rather to the physiological adaptation of the species.The online version of the original article can be found at     

Branchial vascular pathways in two species of Tetraodontiformes and the concept of secondary vessels and nutrient arteries

The vascular organisation of the branchial basket was examined in two Tetraodontiform fishes; the three-barred porcupinefish, Dicotylichthys punctulatus and the banded toadfish, Marylina pleurosticta by scanning electron microscopy of vascular casts and standard histological approaches. In D. punctulatus, interarterial anastomoses (iaas) originated at high densities from the efferent filamental and branchial arteries, subsequently re-anastomosing to form progressively larger secondary vessels. Small branches of this system entered the filament body, where it was interspersed between the intrafilamental vessels. Large-bore secondary vessels ran parallel with the efferent branchial arteries, and were found to constitute an additional arterio–arterial pathway, in that these vessels exited the branchial basket in company with the mandibular, the carotid and the afferent and efferent branchial arteries, from where they gave rise to capillary beds after exit. Secondary vessels were not found to supply filament muscle; rather these tissues were supplied by single specialised vessels running in parallel between the efferent and afferent branchial arteries in both species examined. Although the branchial vascular anatomy was generally fairly similar for the two species examined, iaas were not found to originate from any branchial component in the banded toadfish, M. pleurosticta, which instead showed a moderate frequency of iaas on other vessels in the cephalic region. It is proposed that four independent vascular pathways may be present within the teleostean gill filament, the conventional arterio–arterial pathway across the respiratory lamellae; an arterio–arterial system of secondary vessels supplying the filament and non-branchial tissues; a system of vessels supplying the filament musculature; and the intrafilamental vessels (central venous sinus). The present study demonstrates that phylogenetic differences in the arrangement of the branchial vascular system occur between species of the same taxon.     

Wood anatomy ofTrimeniaceae

Four collections of three species ofTrimenia and one collection ofPiptocalyx were studied; early-formed and later-formed wood was analyzed for oneTrimenia. Liquid-preserved material permitted analysis of mucilage and starch storage in wood ofT. neocaledonica andP. moorei. BecausePiptocalyx is scandent whereasTrimenia is arborescent, wood differences relative to evolution of a climbing habit could be examined.Piptocalyx contrasts withTrimenia in having wider vessels, more numerous per mm², resulting in a conductive area five times greater per unit area than that of theTrimenia woods averaged.Piptocalyx has appreciably fewer bars per perforation plate and thus much greater conductive area per perforation plate than have the species ofTrimenia. Rays inPiptocalyx are much taller and wider than those ofTrimenia. Wood ofTrimeniaceae is highly primitive in its scalariform perforation plates, scalariform lateral wall pitting on vessels, relatively long vessels elements, and heterocellular rays. Imperforate tracheary elements are septate nucleate fibertracheids (or even libriform fibers) rather than tracheids, but loss of borders on pits (and thus lowered conductive function of the imperforate tracheary elements) can be explained by the development of these elements into starchstoring cells. Some fiber-tracheids inT. neocaledonica are enlarged mucilagecontaining cells. Details of vessel structure inTrimeniaceae are similar to those ofMonimiaceae (s. s.), but similarity to some other lauralean (annonalean) families may be found: in mucilage presence,Trimeniaceae resembleLauraceae rather thanMonimiaceae. Wood ofTrimeniaceae may be regarded as highly mesomorphic, corresponding to the moist habitats in which all of the species occur.     

Species relationships and genetic variation in the diploid wheats (Triticum,Aegilops) as revealed by starch gel electrophoresis

Twenty enzyme loci were examined in the diploid species ofTriticum andAegilops for allelic variation by starch gel electrophoresis. SectionSitopsis, including the five species,Ae. speltoides, Ae. lingissima, Ae. sharonensis, Ae. bicornis andAe. searsii form a close subgroup withAe. speltoides slightly removed from the others.T. monococcum s. lat., was found to be closest to the species of theSitopsis group.Ae. comosa, Ae. umbellulata andAe. uniaristata form a second subgroup withAe. caudata most closely related to these species.Ae. squarrosa appears almost equally related to all of the species, showing no special affinity for any one species group. Nineteen out of twenty loci examined were polymorphic with a mean of 6.7 alleles per locus. Species could be, for most loci, characterized by the presence of predominant alleles. A conspicious genetic characteristic ofTriticum-Aegilops is the sharing of these predominant alleles between species. Within species variation is characterized by a diffuse distribution of secondary alleles.     

Incomplete congruence between morphobiological characters and sex-specific molecular markers in Pacific salmons: 1. Analysis of discrepancy in five species of the genus <Emphasis Type="Italic">Oncorhynchus</Emphasis>

The congruence between molecular markers, identifying the presence of the Y chromosome, and secondary sexual characters was examined in Asian populations of five Pacific salmon species: pink salmon (Oncorhynchus gorbuscha), chum salmon (O. keta), sockeye salmon (O. nerka), chinook salmon (O. tschawytscha), and sima (O. masou). It was demonstrated that in all species examined, the presence or absence of sex-specific molecular markers was to a considerable degree congruent with secondary sexual characters, but in some cases, an incongruence was found. These findings suggested that the mechanism underlying this phenomenon was similar or identical in all species examined. Possible genetic and physiological explanations of this phenomenon are discussed.     

Isolation and functional analysis of a set of auxin genes with low root-inducing activity from an Agrobacterium tumefaciens biotype III strain

A new type of root-inducing iaa gene set was cloned from the Ti plasmid of the biotype III Agrobacterium tumefaciens strain Tm-4. These iaa genes are characterized by a very low DNA homology with the well-characterized iaa gene set, iaaM and iaaH, of the common DNA region of the biotype I strain Ach5 and by a low root-inducing activity.The biological activities of both iaa gene sets were compared by transferring each into a disarmed Ti vector and by testing the resulting strains on Nicotiana rustica leaf discs, decapitated Datura stramonium stems, tomato plants and Kalanchoë daigremontiana. Tm-4 iaa genes have a reproducibly weaker root-inducing ability on Nicotiana rustica, induce very little tumour growth on decapitated Datura plants or on tomato plants and do not induce roots on Kalanchoë daigremontiana. The Tm-4 iaa region was mapped by :: Tn5 transposon mutagenesis and tested on Nicotiana rustica. These tests combined with complementation experiments map the iaa genes to a 4.5-kb region.The Tm-4 iaa genes were able to complement the corresponding Ach5 iaa genes on Nicotiana rustica, indicating that the differences between these genes are quantitative rather than qualitative. Complementation experiments on Kalanchoë showed the iaaM gene of Tm-4 responsible for the overall weak auxin activity of the intact iaa set. In view of the observed structural and functional differences we propose to call the Tm-4 iaa genes TB-iaaM and TB-iaaH and the Ach5 iaa genes A-iaaM and A-iaaH.     

The fate ofDrosophila hydei anlagen in heteroplastic transplantations

Summary Imaginal discs and larval brains of wildtype andlethal (3) giant larvae ofDrosophila hydei were transplanted into adult foreign hosts and examined after about 2 weeks. The transplants behaved very differently in different host species, viz. 6 species ofDrosophila, 5 other species of Diptera, and 3 species belonging to the Coleoptera or Dictyoptera, whereby the degree of incompatibility was more or less correlated with taxonomic distances. One notable exception was found in the cheese skipper,Piophila casei, an entirely compatible host.     

Systematic significance of seed coat morphology inSilene L. s. str. (sileneae-caryophyllaceae) from Korea

Seeds of eight species ofSilene s. str. in Korea were examined with a dissecting stereomicroscope and a scanning electron microscope (SEM) to evaluate the systematic significance of seed coat microstructure. The seeds ofSilene s. str. were characterized by triangular or reniform shape, planed or concave dorsal surface in outline, tuberculate or colliculate testa, and sinuated cell margin. Based on the degree of grooves and invagination at dorsal surface, the seeds of the examined taxa ofSilene s. str. fall into two distinct groups: (I) dorsal grooves inconspicuous, surface planed (Silene jenisseensis andS. repens), (II) dorsal grooves conspicuous, surface concave (six remaining taxa). Within each group, seeds of all species may be further distinguished based on shape, size, and testa surface sculpturing. A key to the different species or groups of species is provided, and the systematic significance between/among the taxa is also briefly discussed.     

The development of phloem anastomoses between vascular bundles and their role in xylem regeneration after wounding in Cucurbita and Dahlia

The differentiation of phloem anastomoses linking the longitudinal vascular bundles has been studied in stem internodes of Cucurbita maxima Duchesne, C. pepo L. and Dahlia pinnata Cav. These anastomoses comprise naturally occurring regenerative sieve tubes which redifferentiate from interfascicular parenchyma cells in the young internodes. In all three species, severing a vascular bundle in a young internode resulted in regeneration of xylem to form a curved by-pass immediately around the wound. The numerous phloem anastomoses in these young internodes were not involved in this process, the regenerated vessels originating from interfascicular parenchyma alone. Conversely, in mature internodes of Dahlia, the regenerated vessels originated from initials of the interfascicular cambia, and their phloem anastomoses did not influence the pattern of xylogenesis. On the other hand, in old internodes of Cucurbita, in which an interfascicular cambium was not yet developed, the parenchyma cells between the bundles had lost the ability to redifferentiate into vessel elements, and instead, regenerated vessels were produced in the phloem anastomoses. Thus, the wounded region of the vascular bundle was not bypassed via the shortest, curved pathway, but by more circuitous routes further away from the wound. Some of the regenerated vessels produced in the phloem anastomoses were extremely wide, and presumably efficient conductors of water. It is proposed that the dense network of phloem anastomoses developed during evolution as a mechanism of adaptation to possible damage in mature internodes by providing flexible alternative pathways for efficient xylem regeneration in plants with limited or no interfascicular cambium.This paper is dedicated to the memory of the late Isaac Blachmann (deceased 19 November 1995), father-in-law of the senior author, for encouragement and advice throughout the yearsThis research was supported by an International Scientific Exchange Award to R.A. from the Israel Academy of Sciences and The Royal Society.     

Further report on object manipulation in non-human primates: A comparison within 13 species of the genusMacaca

Thirteen captive species of the genusMacaca were presented with certain non-edible objects and the subsequent manipulation was observed. The following results were obtained: (1) Thefascicularis group species displayed a great variety in rolling the manipulandum, which has been reported to be one of the actions characterizing cercopithecine species; (2) manipulating the object with one finger was typical of thesilenus-sylvanus andsinica groups, whereas use of the fingers moving opposably was common to all species ofMacaca; (3) secondary manipulations in relation to the wire-mesh were observed only inM. silenus, M. sinica, andM. nemestrina, whereas those in relation to water were common to allMacaca species; and (4) within-subgroup differences were great in thesilenus-sylvanus andsinica groups as compared to thefascicularis group.     

DNA evidence for multiple origins of intergeneric allopolyploids in annualMicroseris (Asteraceae)

Seventy populations of North American annualMicroseris, Stebbinsoseris, andUropappus species were examined for chloroplast and nuclear ribosomal DNA restriction site variability to determine the origin of the allotetraploid speciesS. heterocarpa andS. decipiens. Previously identified chloroplast DNA restriction site variants were used in concert with restriction site variation forNco I in the nuclear-encoded ribosomal DNA repeat. The presence of two, mutually exclusive restriction site gains were observed in diploid populations ofM. douglasii; these same variants were also found in populations of allotetraploidS. heterocarpa, indicating mutiple origins of this species from different maternal diploid populations ofM. douglasii. Variation in the rDNA repeat between the diploid annual species and the putative paternal genome ofU. lindleyi was found to be additive inS. heterocarpa. A similar relationship was observed for the origin ofS. decipiens; cpDNA restriction site variants found inM. bigelovii andM. douglasii were present inS. decipiens. The rDNANco I variants also were additive in this purported allotetraploid. These results confirm the reticulate evolutionary pattern inStebbinsoseris and provide another example of multiple origins of intergeneric allopolyploids.     

Phenetic investigation of non-nodulating African species ofAcacia (Leguminosae) using morphological and molecular markers

Morphological and RAPD markers were used to assess the relationships among nodulating and non-nodulating species of AfricanAcacia. Non-nodulating species of AfricanAcacia are only found within subg.Aculeiferum sect.Monacanthea. African species of sect.Monacanthea examined were found to form a group distinct from the other African species examined on a morphological and molecular basis. All lack the ability to nodulate, suggesting that non-nodulation may be used as a taxonomic tool. The species of sect.Aculeiferum were separated by RAPD and morphological analysis into two groups depending on whether they were armed with prickles in pairs and/or prickles in threes, or solitary. A third group of species was identified within sect.Acacia: further subdivision of this group was achieved into subsectt.Pluriseriae andUniseriae. The position ofA. albida relative to other AfricanAcacia species was found to be distinct but not totally independent of the genus. The partitioning and distribution of the genetic variability within the genus is further elucidated by the RAPD analysis of populations ofAcacia species. A population analysis ofA. polyacantha demonstrated geographical and site-specific variation.     

Does sample length influence the shape of xylem embolism vulnerability curves? A test with the Cavitron spinning technique

The Cavitron spinning technique is used to construct xylem embolism vulnerability curves (VCs), but its reliability has been questioned for species with long vessels. This technique generates two types of VC: sigmoid ‘s’‐shaped and exponential, levelling‐off ‘r’‐shaped curves. We tested the hypothesis that ‘r’‐shaped VCs were anomalous and caused by the presence of vessels cut open during sample preparation. A Cavitron apparatus was used to construct VCs from samples of different lengths in species with contrasting vessel lengths. The results were compared with VCs obtained using other independent techniques. When vessel length exceeded sample length, VCs were ‘r’‐shaped and anomalous. Filling vessels cut open at both ends with air before measurement produced more typical ‘s’‐shaped VCs. We also found that exposing segments of 11 woody species in a Cavitron at the pressure measured in planta before sampling considerably increased the degree of embolism above the native state level for species with long vessels. We concluded that open vessels were abnormally more vulnerable to cavitation than intact vessels. We recommend restricting this technique to species with short conduits. The relevance of our conclusions for other spinning techniques is discussed.     

Rates of cross-pollination inLycopersicon pimpinellifolium: Impact of genetic variation in floral characters

Cross-pollination was tested between different genotypes ofLycopersicon pimpinellifolium in an experimental plot situated in the southerly range of the species. Rates of cross-pollination were found to be highly correlated with flower size and were related to a lesser extent with degree of stigma exsertion. Comparisons of fertility suggest that exsertion of 1.5 mm or more from the anther tube orifice interferes with automatic self-pollination, thereby increasing rates of cross-pollination. A single species ofExomalopsis (Anthophoridae), observed to visit all tested genotypes ofL. pimpinellifolium, was responsible for most of the pollination. Other species of solitary bees and other bee families participated in cross-pollination.     

Stigma morphology in distylous and non-heterostylous species ofVillarsia (Menyanthaceae)

Stigma morphology was examined with the SEM in 14 of the 16 species ofVillarsia. In nine of the ten distylous species studied, stigmas of the floral morphs were strongly dimorphic in length, shape, configuration of the receptive surface, and in the size and density of their papillae. Thrum stigmas ofVillarsia, in contrast to those of most other distylous species, are not simply smaller versions of the conspecific pin stigmas, but generally exhibit an array of morph-specific characters. Thrum stigma lobes may be broader than those of pins, they may have undulate margins, lobes subdivided into secondary lobes, papillae more extensively distributed than in pins, and various combinations of these traits occur. The traits that distinguish thrum from pin stigmas achieve an increase in the receptive area and may enhance more efficient pollen capture by the shorter and less accessible thrum stigmas. The morphogenesis of the stigma shape dimorphism appears to involve processes more complex than inhibition of elongation in thrum styles. InVillarsia, the stigma dimorphisms are species-specific. No correlations were found between morphologies of the stigma and the different breeding systems in distylous species. Stigmas of the four non-heterostylous species examined resemble the thrum stigma type found in most distylousVillarsia species.     

Respiratory Metabolism of sub-Antarctic insects from different habitats on Marion Island

Oxygen uptake of the foliage-dwelling larvae ofEmbryonopsis halticella Eaton (Lepidoptera: Yponomeutidae) and adults ofEctemnorhinus marioni Jeannel (Coleoptera: Curculionidae), the litter-dwelling larvae ofPringleophaga marioni (Lepidoptera: Tineidae) and the wrack-dwellingParactora dreuxi Séguy (Diptera: Helcomyzidae) was examined over the range of temperatures experienced by these insects in their microhabitats. With the exception of the kelp fly,P. dreuxi, Q₁₀s and activation energies were generally lower than those found in temperate and Arctic insects, but were similar to values found in beetles from sub-Antarctic South Georgia Island. Q₁₀ and activation energy of each species reflected the temperature regime found in its microhabitat. Activation energies of the Marion Island species were intermediate between those found in temperate and polar arthropods, but towards the polar end of the range. The hypothesis that insects are capable of showing respiratory adaptation to temperature is supported.     

Dynamics of species richness and composition in a limestone grassland restored after tree cutting

Abstract. After abandonment many limestone grasslands have been overgrown by trees and shrubs; as a result, species-rich communities with many regionally rare and endangered species are vanishing. Some studies suggest that, in cases where grassland is being restored, the species composition and rate of change is strongly dependent on the initial conditions, i.e. the earlier presence of grassland species and the opportunity for colonization of new sites by grassland species. These hypotheses were tested in a five-year restoration experiment after the clearing of a 35-yr-old secondary pine wood developed on abandoned grassland. Tree cutting induced rapid changes in the floristic composition and species cover. The number of grassland species from the class Festuco-Brometea increased significantly in the restored grassland, but their cover was much lower than in the old grassland. Canonical Correspondence Analysis showed significant differences in species composition between the grassland restored in former wood gaps and that developed in former closed wood. In wood gap sites the cover of species from the class Molinio-Arrhenatheretea and tufted perennials was much higher, whereas the cover of Festuco-Brometea species was lower. Significantly more shrubs, woodland species, ruderal and nitrophilous species as well as annual and biennial species occurred in the former closed wood site. It was found that richness and composition of the restored grassland depended strongly on the community composition before tree cutting, as well as on the presence of grassland species in the neighbourhood. Periodical tree cutting enables the maintenance of a temporal-spatial mosaic of scrub-grassland communities in isolated habitats and the preservation of local species diversity.     

Litterfall in a secondary forest with special reference to the relationships between leaf-fall rate,basal area and relative growth rate on a species basis

Total basal area (BA), mean relative growth rate of individual basal area (RGR _bam), annual leaf-fall rate (L), and number of trees (N) on a species basis were measured in a secondary forest mixed with evergreen and deciduous trees in the warm-temperate zone of Japan. Every species had a characteristic tree size and composed the tree and the shrub layers. The layer for each species, and the tree size of the species were represented by the species mean basal area per tree (BA/N orba _m). A power form equation was obtained for the relation between the species mean leaf-fall rate per tree (L/N orl _m) andba _m.RGR _bam was correlated with leaf-fall rate per unit basal area (L/BA) rather than withba _m. This suggested thatRGR _bam is associated less with mean tree size (ba _m) and dominance as total basal area (BA), and more with annual leaf production per unit basal area, provided thatL is equal to the annual leaf production per species.Rhus succedanea, the most dominant species in the forest plot, was typical in that it showed lower values ofRGR _bam andL/BA than other tree species. This would suggest a decline ofR. succedanea in a secondary forest.     

Phylogenetic relationship withinFusarium sambucinum Fuckel sensu lato,determined from ribosomal RNA sequences

Partial ribosomal RNA nucleotide sequences were determined for 11 strains ofFusarium sambucinum Fuckelsensu lato to assess by molecular genetic means, Nirenberg's recent morphotaxonomic interpretation which split the species into three distinct taxa:F. sambucinum sensu stricto, F. torulosum, and one other species, as yet unnamed (Fusarium species nova). Four sequence patterns were identified among the 11 strains. Two sequences that varied at one site were found among strains ofF. sambucinum, strains ofF. torulosum andFusarium sp. nov. showed no intraspecific variation. Interspecific comparisons revealed nucleotide sequence differences of 3–9 substitutions in the ca. 240 nucleotide rRNA segment examined. Although interspecific differences are not large in terms of percent nucleotide substitution, they are much larger than the observed intraspecific variation and support the morphological interpretation distinguishing three taxa. When the data were analysed using parsimony and bootstrapping, the three taxon tree was well supported. The phylogenetic arrangement of these strains is congruent with secondary metabolite profile similarities.     

Molecular phylogenetic analysis ofChrysosplenium (Saxifragaceae) in Japan

The phylogeny of Japanese species ofChrysosplenium (Saxifragaceae) was examined using variation in DNA sequences. Sequences ofrbcL andmatK genes were compared for their feasibility for reconstructing the phylogeny ofChrysosplenium, and thematK sequences was found to give greater resolution. All but one of the 17 Japanese species have been examined formatK gene sequences and phylogenetic analysis of these data resulted in eight most parsimonious trees of 390 steps and a consistency index (Cl) of 0.823. The molecular phylogeny obtained was generally in agreement with Hara's (1957) classification based upon phenotypic similarity, although a conclusion needs extensive examination of the genus on a world-wide level. Using the phylogenetic data, character evolution was examined, especially in the characters traditionally used for grouping infrageneric taxa. Differentiation of opposite and alternate phyllotaxis appears to have occurred only once in the course of evolution ofChrysosplenium.