Comparative morphology of the euglenid pellicle. II. Diversity of strip substructure

The morphological diversity associated with the strip substructure of the euglenid pellicle was examined, and after identifying characters and states, we outlined hypotheses about their evolution. We have attempted to standardize terms necessary for analytical comparisons of strips by providing a glossary and comparing published synonyms. Most of the substructural diversity found in euglenids is demonstrated with 13 representative taxa. Strips are generally composed of two subcomponents: frames and projections. Frames support the basic shape of strips and many can be described as either S-shaped, plateau-shaped, M-shaped, or A-shaped. Projections branch laterally from the frames, are usually periodic, and can be described as thread-like structures, an indented plate, tooth-like structures, and plate-like structures. The ancestral state included strips that were few in number, flat, and fused. The strips became S-shaped and disjoined in the lineage leading to most euglenid taxa. These strips became secondarily flattened and fused in one lineage. In some lineages of phototrophs, the strips became increasingly robust. Two strips of different morphology formed the repeating pellicular unit or doublet in four taxa. These doublets evolved convergently at least three times and may provide insights into developmental patterns of the cytoskeleton.     

Ultrastructure and morphology of the cycliophoran female

Knowledge on the morphology of the cycliophoran female has mostly been based on observations of immature females in brood chambers of feeding stages. With the use of light‐ and transmission electron microscopy, the morphology and ultrastructure of the free and fully mature female of Cycliophora is described now for the first time. The external morphology is characterized by a ciliation consisting of an anteroventral ciliated field, a posterior ciliated tuft, and four sensory structures extending anteriorly from the anteroventral ciliated field. In addition, a small ciliated structure in the midventral region is interpreted as a round‐shaped gonopore. Internally, a bilateral cerebral ganglion is situated in the anterior region and a large oocyte is located medially in the body. Several glands are present anteriorly, while posteriorly a pair of glands is associated with the ciliated tuft. Dorsal and ventral longitudinal muscles, as well as, dorsoventral muscles are identified by electron microscopy. Muscle fibers attach to the endocuticle via the epidermis, by means of attachment fibers. An unknown endosymbiont is present throughout the body of the female. We discuss the functional implications of the morphological and ultrastructural aspects of the cycliophoran female. Finally, we compare this life cycle stage with that fromother phyla, suggested as phylogenetically close. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.     

Comparative gastrointestinal morphology of the Kori bustard and secretary bird

Two secretary birds and three Kori bustards were studied to determine differences between their body size and gastrointestinal morphology. Body measurements were made on captive, live birds and gastrointestinal measurements on fresh postmortem specimens. For predator species, such as the Kori bustard and secretary bird, body size is a function of their ability to capture and destroy prey. While the secretary bird was clearly the taller of the two species, superior body weight, wing length, and therefore body size was noted for the Kori bustard. The size and length of the gastrointestinal tract varied between species. The secretary bird had the shorter, less complex digestive tract, with a foregut well adapted for consumption of large quantities of flesh. The large intestine was devoid of ceca. The gastrointestinal tract of the Kori bustard was markedly different from that of the secretary bird. The foregut was less complex and the large intestine possessed large, voluminous ceca.     

绿僵菌无纺布菌条的制作(Ⅰ)液体种子培养条件

研究了金龟子绿僵菌菌株Ma83液体培养最佳营养及环境条件,为无纺布培养提供良好的液体种子.以生物量为指标,通过液体摇瓶试验确定了绿僵菌Ma83菌株液体种子培养参数,对不同的氮源、碳源及其浓度和初始pH进行单因素分析.结果表明,绿僵菌Ma83菌株液体种子培养最佳营养条件为4%黄豆粉,2%白砂糖,0.5%MgSO4·7H2O,0.05g/LKCl,0.1g/L FeSO4·7H2O,1.0g/L KH2PO4,pH6.3～6.5.70L发酵罐培养,干生物量第三天可达35g/L,显著优于筛选前培养基(SDA,28g/L,a=0.05).     

绿僵菌无纺布菌条的制作(I)液体种子培养条件

研究了金龟子绿僵菌菌株M a83液体培养最佳营养及环境条件,为无纺布培养提供良好的液体种子。以生物量为指标,通过液体摇瓶试验确定了绿僵菌M a83菌株液体种子培养参数,对不同的氮源、碳源及其浓度和初始pH进行单因素分析。结果表明,绿僵菌M a83菌株液体种子培养最佳营养条件为4%黄豆粉,2%白砂糖,0.5%MgSO4.7H2O,0.05g/LKC l,0.1g/L FeSO4.7H2O,1.0g/L KH2PO4,pH6.3~6.5。70L发酵罐培养,干生物量第三天可达35g/L,显著优于筛选前培养基(SDA,28g/L,a=0.05)。     

Variations in the hypotarsus morphology of birds and their evolutionary significance

Crown group (neornithine birds) exhibit a great variation in the morphology of the hypotarsus, a structure on the proximal end of the tarsometatarsus, which guides the tendons of the flexor muscles of the toes. Hypotarsus morphology is of significance for the identification of fossil taxa, and several extant groups show characteristic patterns that are of phylogenetic interest. So far, however, the diversity of hypotarsus morphologies has been little studied, and there are no comprehensive studies across all neornithine birds. In particular, the identities of the involved canals and sulci remain elusive, and some confusion exists about their correct homologies. In this study, hypotarsus morphologies are for the first time surveyed among all extant birds, and basic patterns are characterized. Instances are identified, in which particular hypotarsus morphologies are correlated with certain locomotion types, inferences are made about possible ancestral morphologies, and some patterns of phylogenetic interest are discussed.     

Decoupled evolution of display morphology and display behaviour in phrynosomatid lizards

A widespread trend in animals is the evolution of morphological ornaments and behaviours that are involved in aggressive and courtship displays. These display traits are important from the standpoint of communication, sexual selection, and speciation. Previous authors have suggested that the evolution of display morphology and display behaviour should be closely linked. In this study, I tested for this association with behavioural and morphological data for 59 taxa of phrynosomatid lizards using phylogenetic comparative methods (Mad-dison's concentrated changes test and Felsenstein's independent contrasts). The results showed little significant association between features of display morphology and behaviour, suggesting that the evolution of these traits is not tightly coupled. This decoupling is particularly evident in the genus Sceloporus , in which several species have lost the display coloration but retain unmodified display behaviour. The results also suggest that display morphology is more evolutionarily labile than display behaviour in this group.     

Comparative evolution of flower and fruit morphology

Angiosperm diversification has resulted in a vast array of plant morphologies. Only recently has it been appreciated that diversification might have proceeded quite differently for the two key diagnostic structures of this clade, flowers and fruits. These structures are hypothesized to have experienced different selective pressures via their interactions with animals in dispersal mutualisms, resulting in a greater amount of morphological diversification in animal-pollinated flowers than in animal-dispersed fruits. I tested this idea using size and colour traits for the flowers and fruits of 472 species occurring in three floras (St John, Hawaii and the Great Plains). Phylogenetically controlled analyses of nearest-neighbour distances in multidimensional trait space matched the predicted pattern: in each of the three floras, flowers were more divergent from one another than were fruits. In addition, the spacing of species clusters differed for flowers versus fruits in the flora of St John, with clusters in flower space more divergent than those in fruit space. The results are consistent with the idea that a major driver of angiosperm diversification has been stronger selection for divergent floral morphology than for divergent fruit morphology, although genetic, physiological and ecological constraints may also play a role.     

Patterns of variation in wing morphology in the cactophilic Drosophila buzzatii and its sibling D. koepferae

Drosophila buzzatii and D. koepferae are two sibling species that breed on the necrotic tissues of several cactus species and show a certain degree of niche overlap. Also, they show differences in several life history traits, such as body size and developmental time, which probably evolved as a consequence of adaptation to different host plants. In this work we investigate the ecological and genetic factors affecting wing morphology variation both within and between species. Three wing traits were scored, distal and proximal wing length and width in isofemale lines reared in two of the most important host cacti: Opuntia sulphurea and Trichocereus terschekii. Our results revealed that differences between species and sexes in wing size and shape were significant, whereas the cactus factor was only significant for wing size. Intraspecific analyses showed that differences among isofemale lines were highly significant for both size and shape in both species, suggesting that an important fraction of variation in wing morphology has a genetic basis. Moreover, the line by cactus interaction, which can be interpreted as a genotype by environment interaction, also accounted for a significant proportion of variation. In summary, our study shows that wing size is phenotypically plastic and that populations of D. buzzatii and D. koepferae harbour substantial amounts of genetic variation for wing size and shape. Interspecific differences in wing size and shape are interpreted in terms of spatial predictability of the different host plants in nature.     

Development of the pellicle and thecal plates following ecdysis in the dinoflagellateGlenodinium foliaceum

Summary The ultrastructure and development of the amphiesma of the dinoflagellateGlenodinium foliaceum was studied using conventional electron microscopy and immunocytochemistry. Ecdysis (shedding of the flagella, the outer two membranes of the cell, and the thecal plates) was induced by centrifugation. The cells were resuspended and the thickening of the pellicle and the development of the new thecal vesicles and plates was studied over a 9 h period. After ecdysis, the thin pellicle which underlay the thecal plates in the motile cells thickens to form a complex structure of four distinct layers: an outer layer of randomly oriented fibrils, a 50 nm layer of fibrils oriented perpendicular to the dense layer, the dense layer which has a trilaminate structure, and a wide inner homogeneous layer. The new thecal vesicles form in these pelliculate cells by the migration of electron translucent amphisomal vesicles over the layer of peripheral microtubules to a position directly under the plasmalemma. The thecal vesicles then flatten and elongate. A discontinuous pellicular layer appears within them. Subsequently, the thecal vesicles widen and are filled with a fibrillogranular substance overlying the pelliculate layer. The thecal plates form on top of this fibrillogranular material. By this time, most cells have escaped from the pellicle and are motile. At first, the outer thecal vesicle membrane is continuous with the inner thecal vesicle membrane at the sutures, but when this connection is broken, the dense pelliculate layers become continuous across the suture as does the inner thecal vesicle membrane. At ecdysis, this membrane becomes the new plasmalemma of the cell. Cells at each stage of pellicle thickening and thecal development were labelled with a polydonal antiserum raised against the 70 kDa epiplasmic protein ofEuglena acus. This antiserum labelled both the thecal plates of the motile cells and the inner homogeneous layer of the pellicle of ecdysed non-motile cells. No other amphiesmal structure was labelled, nor was any intracellular compartment.Abbreviations PBS phosphate-buffered saline - PIPES piperazine-N,N-bis[2-ethane sulfonic acid]     

Phylogeny and biogeography of Zelkova (Ulmaceae sensu stricto) as inferred from leaf morphology, ITS sequence data and the fossil record

To address the evolution and geographical diversification of the genus Zelkova (Ulmaceae) a phylogenetic analysis of morphological data and the sequences of the internal transcribed spacers (ITS1 and ITS2) of nuclear ribosomal DNA were used. Cladistic analyses suggested that the Chinese species Z. schneideriana and Z. sinica are basal within Zelkova. The western Asian Z. carpinifolia either appears nested between the East Asian Z. schneideriana and Z. sinica and a clade formed by the Japanese Z. serrata and two Mediterranean species, Z. abelicea and Z. sicula (ITS), or forms a clade with Z. serrata that is sister to a clade Z. abelicea plus Z. sicula (morphology). Nucleotide data suggested that gene flow occurred between Z. schneideriana and Z. serrata, and Z. carpinifolia and a lineage ancestral to Z. abelicea/sicula. Character evolution in Zelkova appears to have gone from long leaves with numerous secondary veins, coarse to shallow teeth with blunt or slightly pointed apex and small stomata, to leaves that are either long or short with numerous or few secondary veins, coarse teeth with cuspidate or obtuse apex or conspicuously shallow teeth, and dimorphic stomata displaying ‘giant stomata’ surrounded by a ring of small stomata or uniform large stomata. These results are in agreement with fossil data. Early Cainozoic fossils attributed to Zelkova from North America and Central Asia closely resemble the modern Z. schneideriana and Z. carpinifolia. The genus could have originated in the northern Pacific area and migrated to Europe after the Turgai Strait was closed during the Late Oligocene. Geographical differentiation may have started with the isolation of Chinese populations (leading to modern Z. schneideriana and Z. sinica) from high‐latitude Eurasian (North American) populations. This widespread Early Cainozoic type may have diversified into the western Asian Z. carpinifolia and the more derived Japanese and Mediterranean species during the latest Cainozoic. The modern Japanese and European/western Asian species would have differentiated relatively late, while two locally endemic Mediterranean species are the result of the cooling and development of a Mediterranean climate belt in Europe during the Pleistocene. Fossils from the Miocene and Pliocene of Europe resemble modern Z. carpinifolia and Z. serrata. Differentiation of the two Mediterranean species Z. abelicea and Z. sicula in the Late Cainozoic cannot be traced by leaf morphology. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 147 , 129–157.     

Patterns and rates of nucleotide substitution,insertion and deletion in the endosymbiont of ants Blochmannia floridanus

Genome reduction is a general process that has been studied in numerous symbiotic bacteria associated with insects. We investigated the last stages of genome degradation in Blochmannia floridanus, a mutualistic bacterial endosymbiont of the ant Camponotus floridanus. We determined the tempo (rates of insertion and deletion) and mode (size and number of insertion–deletion events) of the process in the last 200 000 years by analysing a total of 16 intergenic regions in several strains of this endosymbiont from different ant populations. We provide the first calculation of the reduction rate for noncoding DNA in this endosymbiont (2.2 × 10^?8 lost nucleotides/site/year) and compare it with the rate of loss in other species. Our results confirm, as it has been observed in other organisms like Buchnera aphidicola or Rickettsia spp., that deletions larger than one nucleotide can still appear in advanced stages of genome reduction and that a substitutional deletion bias exists. However, this bias is not due to a higher proportion of deletion over insertion events but to a few deletion events being larger than the rest. Moreover, we detected a substitutional AT bias that is probably responsible for the increase in the number of the small and moderate indel events in the last stages of genome reduction. Accordingly, we found intrapopulational polymorphisms for the detected microsatellites in contrast to the stability associated with these in free‐living bacteria such as Escherichia coli.     

Comparative morphology and molecular phylogeny of aplanochytrids (Labyrinthulomycota)

Aplanochytrids comprise one of three major subgroups within the Labyrinthulomycota. We have surveyed the diversity of aplanochytrids and have discovered that most isolates are difficult to identify to species because of character plasticity and ambiguity. Ten isolates were studied using molecular phylogenies based on small subunit ribosomal gene sequences (SSU rDNA) and morphological characters derived from light microscopy, SEM and TEM (e.g., colony size, colony shape, colony pattern, agar penetration, cell shape, cell surface patterns, cell inclusion characteristics and ectoplasmic net morphology). Of these isolates, we could positively identify two of them to species, namely Aplanochytrium yorkensis (Perkins, 1973) Leander and Porter, 2000 and A. minuta (Watson and Raper, 1957) Leander and Porter, 2000. We used standardized conditions for growing aplanochytrid isolates in order to minimize environmentally induced phenotypic plasticity in our comparative studies of morphology. By mapping the morphological characters listed above onto a conservative phylogenetic topology derived from SSU rDNA sequences, we were able to identify several synapomorphies (e.g., gross colony characteristics and cell surface patterns) that serve as valuable taxonomic characters for the identification of species and specific clades of aplanochytrids.     

Comparative morphology of the amphibian opercularis system: I. General design features and functional interpretation

The morphology of the opercularis system of anuran and caudate amphibians suggests that it acts to produce motion of the operculum that in turn produces fluid motion within the inner ear. The operculum and opercularis muscle form a lever system, with a narrow connection between the operculum and otic capsule acting as a fulcrum about which the operculum moves in response to forces applied via the muscle. The opercula of many species possess a muscular process on which the muscle inserts, thereby increasing the moment arm through which the muscle acts. The tonicity of the opercularis muscle allows tensile forces produced by substrate vibration or other mechanical energy applied to the forelimb to be effectively transmitted to the operculum; the elasticity of the connective tissue holding the operculum in place should act to return the operculum to its original position. The opercularis systems of frogs and non-plethodontid salamanders are similar structurally and functionally; that of plethodontid salamanders is structurally distinct but also functions as a lever system. Fluid motion produced by opercular motion could stimulate various end organs of the inner ear; the saccule, lagena, and amphibian papilla are in close approximation and wave energy could directly affect their otoconial or tectorial structures. In those anurans with a tympanic ear, the stapedial footplate and operculum articulate, but this articulation allows both to move independently. The stapes-tympanum complex and opercularis system therefore appear to be independent functional systems, and it is unlikely that the opercularis system modulates middle ear responsiveness. The general design of the opercularis system is consistent with a function in reception of substrate vibrations.     

Comparative pollen morphology and ultrastructure of Platanus: Implications for phylogeny and evaluation of the fossil record

Pollen of Platanus was studied using light (LM) and electron microscopy (SEM and TEM). Overall, pollen is uniform in modern Platanus (small, tricolpate, prolate to spheroidal, reticulate, semitectate). A number of characters, however, display remarkable variability within a taxon and even a single anther (size; foveo‐reticulate, fine to coarse reticulate ornamentation). Platanus kerrii (subgenus Castaneophyllum) differs from the remaining species by its high and “folded” reticulum and possibly the smooth colpus membrane. Moreover, to our knowledge, pollen of the P. kerrii – type is not known from the fossil record. The exine in modern and fossil Platanaceae shows great structural similarity, but the thickness of the foot layer within the ectexine is less variable and normally smaller in modern taxa. Furthermore, in Early Cretaceous to Early Cainozoic Platanaceae a number of distinct pollen types occurred that are not known within the modern Platanus. Considering pollen of Platanaceae from the Early Cretaceous to today, a dynamic picture of the evolution of the family emerges. In the first phase (Early Cretaceous) pollen of extinct genera such as Aquia differed considerably from modern Platanus and shows strong similarity to basal eudicot taxa such as Ranunculales (e.g. Lardizabalaceae). The Late Cretaceous Platananthus hueberi displays a distinct coarse reticulum that is unknown from modern Platanus but similar to some taxa of Hamamelidaceae (e.g. Exbucklandia). After the first phase of eudicot radiation that appears to have been characterized by strongly reticulate evolution, platanaceous diversity decreased in the course of the Cainozoic. Despite this, the pollen type of the modern subgenus Castaneophyllum (P. kerrii type) seems to be an innovation that originated after the initial radiation of the family.     

Comparative morphology of the bursal nozzles in acoels (Acoela, Acoelomorpha)

Systematics of the Acoela is particularly difficult because of the paucity of readily discernible morphological features. In other soft-bodied worms, sclerotized structures, such as copulatory stylets, provide important characters that can be seen in whole mounts, but acoels generally lack such features. Among the few sclerotized structures in acoels are bursal nozzles-tubiform outlets on the seminal bursae that are believed to be conduits (spermatic ducts) through which allosperm are transported to the oocytes. Early classifications of the Acoela used features of the female reproductive system, including bursal nozzles, for distinguishing major groups, but the current system essentially ignores them as too plastic to provide higher-level distinctions. We used confocal and electron microscopy to further characterize bursal nozzles in five acoel species, and found all composed of actin-reinforced extensions of stacked, flat mesenchymal cells. In Notocelis gullmarensis, Aphanostoma bruscai, and Daku woorimensis, the nozzle is a stiffened region of the same cells forming the wall of the bursa. By contrast, in Wulguru cuspidata cells forming the nozzle are distinct from those of the bursa. The so-called bursal cap of A. bruscai and D. woorimensis has small sclerotized disjunct units within it, also composed of stacked, flat, actin-reinforced cells. The nozzle of W. cuspidata, prominent like that of other convolutid acoels, is relatively complex, its actin-reinforced cells sandwiched with secretory cells and its base bearing a "sorting apparatus" of egg-shaped cells that send narrow processes inside the spermatic duct. Cases of sperm inside the nozzle corroborate its assumed role in reproduction. Whereas most nozzles sit at the end of the bursa facing the ovary, in species of Pseudmecynostomum and purportedly in a few other acoels, they sit between the female pore and the bursa, constituting what we call a vaginal nozzle. All bursal nozzles of acoels show a common ground pattern indicating common ancestry, but certain features discerned through electron and confocal microscopy show promise of providing synapomorphies for grouping some species.     

Patterns of temporal variation in Lake Titicaca. A high altitude tropical lake. I. Background,physical and chemical processes,and primary production

A statistical analysis is presented of patterns of variation in some physical, chemical, and biological variables for a 6 year series of data from the tropical, high altitude Lake Titicaca (Peru-Bolivia). ANOVA techniques and autocorrelation analyses were used to partition the variance in Titicaca, and in some comparison tropical and temperate series, into components with repeatable annual cycles and components attributable to other kinds of patterns.In Titicaca, insolation and stratification are highly seasonal in pattern of variation, although the amount of variance relative to means is small compared to temperate lakes. However, the seasonal pattern of physical variation is only weakly imposed on chemical and biological processes, to judge from analyses of silicate, oxygen, and primary production series. Comparable temperate series of primary production and chlorophyll a are much more seasonal.     

Breakdown in correlations during laboratory evolution. I. Comparative analyses of Drosophila populations

We provide evidence from comparisons of populations of Drosophila that evolutionary correlations between longevity and stress resistance break down over the course of laboratory evolution. Using 15 distinct evolutionary regimes, we created 75 populations that were differentiated for early fecundity, longevity, starvation resistance, desiccation resistance, and developmental time. In earlier experiments, selection for postponed aging produced increases in stress resistance, whereas selection for increased stress resistance produced increases in longevity. Direct estimates of correlations also indicated an antagonistic relationship between early fecundity on one hand and longevity or stress resistance on the other. Laboratory evolution of extreme values of stress resistance, however, led to a breakdown in these evolutionary relationships. There was no evidence that these significant changes in correlation resulted from genotype-by-environment interactions or inbreeding. These findings suggest that correlations between functional characters are not necessarily durable features of a species, and that short-term evolutionary responses cannot be extrapolated reliably to longer-term evolutionary patterns.     

The female reproductive unit of Ephedra (Gnetales): comparative morphology and evolutionary perspectives

Morphological variation in Ephedra (Gnetales) is limited and confusing from an evolutionary perspective, with parallelisms and intraspecific variation. However, recent analyses of molecular data provide a phylogenetic framework for investigations of morphological traits, albeit with few informative characters in the investigated gene regions. We document morphological, anatomical and histological variation patterns in the female reproductive unit and test the hypothesis that some Early Cretaceous fossils, which share synapomorphies with Ephedra, are members of the extant clade. Results indicate that some morphological features are evolutionarily informative although intraspecific variation is evident. Histology and anatomy of cone bracts and seed envelopes show clade‐specific variation patterns. There is little evidence for an inclusion of the Cretaceous fossils in the extant clade. Rather, a hypothesized general pattern of reduction of the vasculature in the ephedran seed envelope, probably from four vascular bundles in the fossils, to ancestrally three in the living clade, and later to two, is consistent with phylogenetic and temporal analyses, which indicate that extant diversity evolved after the Cretaceous–Tertiary boundary. Notwithstanding striking similarities between living and Cretaceous Ephedra, available data indicate that the Mesozoic diversity went almost entirely extinct in the late Cretaceous causing a bottleneck effect in Ephedra, still reflected today by an extraordinarily low level of genetic and structural diversity. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 387–430.