The evolution and biological significance of seeds

1983 ◽  
Vol 61 (12) ◽  
pp. 3550-3560 ◽  
Author(s):  
T. A. Steeves
Keyword(s):  
Adaptive Radiation ◽  
Fossil Record ◽  
Vascular Plants ◽  
Biological Significance ◽  
Free Water ◽  
Significant Component ◽  
Early Mesozoic ◽  
Evolutionary Event ◽  
Fossil Floras ◽  
The Relationship

No evolutionary event in the colonization of the land by vascular plants is of greater significance than the appearance of the seed habit. What apparently began as an adaptation enhancing sexual reproduction in the absence of external free water has assumed a far broader importance in terms of survival and dispersal. The essential features of the seed habit are identified in relation to heterospory, megaspore retention, and endosporic gametophyte development and approaches to the seed habit by nonseed plants are reviewed. Seeds first appear in the fossil record of the Late Devonian Period and, in diverse forms and sizes, constitute a significant component of Carboniferous fossil floras. The rise to dominance of plants of gymnospermous affinity in the early Mesozoic and the appearance and rapid adaptive radiation of the angiosperms are discussed in relation to the significance of the seed habit. The structure and development of modern gymnosperm and angiosperm seeds are compared, and the contrasting patterns of embryogenesis in these two types of seeds are interpreted in terms of the relationship between the embryo and its nutritive support system.

Brains of early carnivores

Paleobiology ◽  
1977 ◽  
Vol 3 (4) ◽  
pp. 333-349 ◽  
Author(s):  
Leonard Radinsky
Keyword(s):  
Fossil Record ◽  
Brain Size ◽  
Biological Significance ◽  
Evolutionary Trends ◽  
Relative Brain Size

It is commonly believed that the brains of the ancestors of modern carnivores (miacids) were superior to (e.g., larger than) those of other early carnivores (creodonts and mesonychids). Examination of the fossil record of brains of early carnivores reveals no evidence to support that belief. Moreover, evolutionary trends towards increasing relative brain size and an expansion of neocortex are seen in both miacids and creodonts. The neocortex expanded in a different way in miacids than in creodonts and mesonychids (evidenced by different sulcal patterns), but the biological significance of the observed differences is unknown.

A guide to the nomenclature of heterochrony

1986 ◽  
Vol 60 (1) ◽  
pp. 4-13 ◽  
Author(s):  
Kenneth J. McNamara
Keyword(s):  
Twentieth Century ◽  
Causal Relationship ◽  
Fossil Record ◽  
Biogenetic Law ◽  
The Relationship

Since Haeckel's Biogenetic Law (‘ontogeny recapitulates phylogeny’) fell into disrepute early in the twentieth century, there has been intermittent debate, particularly in recent years (de Beer, 1958; Gould, 1977; Alberch et al., 1979; Alberch, 1980; Bonner, 1982; McNamara, 1982a), on the nature of the relationship between an individual's development and phylogenetic history. Important questions under discussion include the following: If a strong causal relationship does exist, what is its nature? How does it work? What is its importance in evolution? How can it be recognized in the fossil record?

scholarly journals The effects of geographic range size and abundance on extinction during a time of “sluggish”’ evolution

Paleobiology ◽  
2020 ◽  
pp. 1-14
Author(s):  
Michelle M. Casey ◽  
Erin E. Saupe ◽  
Bruce S. Lieberman
Keyword(s):  
North American ◽  
Fossil Record ◽  
Extinction Risk ◽  
Geographic Range ◽  
Range Size ◽  
Late Paleozoic ◽  
The North ◽  
Geographic Range Size ◽  
The Relationship ◽  
Habitat Tracking

Abstract Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

scholarly journals Eutherians experienced elevated evolutionary rates in the immediate aftermath of the Cretaceous–Palaeogene mass extinction

2016 ◽  
Vol 283 (1833) ◽  
pp. 20153026 ◽  
Author(s):  
Thomas John Dixon Halliday ◽  
Paul Upchurch ◽  
Anjali Goswami
Keyword(s):  
Phylogenetic Analysis ◽  
Adaptive Radiation ◽  
Mass Extinction ◽  
Fossil Record ◽  
Morphological Evolution ◽  
Placental Mammal ◽  
Stochastic Methods ◽  
Ecological Niches ◽  
Evolutionary Radiation ◽  
Quantitative Analyses

The effect of the Cretaceous–Palaeogene (K–Pg) mass extinction on the evolution of many groups, including placental mammals, has been hotly debated. The fossil record suggests a sudden adaptive radiation of placentals immediately after the event, but several recent quantitative analyses have reconstructed no significant increase in either clade origination rates or rates of character evolution in the Palaeocene. Here we use stochastic methods to date a recent phylogenetic analysis of Cretaceous and Palaeocene mammals and show that Placentalia likely originated in the Late Cretaceous, but that most intraordinal diversification occurred during the earliest Palaeocene. This analysis reconstructs fewer than 10 placental mammal lineages crossing the K–Pg boundary. Moreover, we show that rates of morphological evolution in the 5 Myr interval immediately after the K–Pg mass extinction are three times higher than background rates during the Cretaceous. These results suggest that the K–Pg mass extinction had a marked impact on placental mammal diversification, supporting the view that an evolutionary radiation occurred as placental lineages invaded new ecological niches during the Early Palaeocene.

Dikes on permafrost foundations in northern Manitoba

1970 ◽  
Vol 7 (4) ◽  
pp. 356-364 ◽  
Author(s):  
J. G. Macpherson ◽  
G. H. Watson ◽  
A. Koropatnick
Keyword(s):  
Electric Power ◽  
Heat Loss ◽  
Free Water ◽  
Northern Canada ◽  
Discontinuous Permafrost ◽  
Ice Content ◽  
The Relationship ◽  
Design And Construction

The development of hydro-electric power within the areas of low relief of northern Canada often requires long dikes to impound a reservoir. Much of this region lies within a zone of discontinuous permafrost, and dike design must allow for foundations varying from soft alluvial materials which will settle during or shortly after construction, to frozen strata with a high ice content which will settle as the ice thaws due to heat loss from the reservoir.This paper describes the approach to design and construction of dikes for the Kettle Generating Station in northern Manitoba, and includes a description of the instrumentation installed in an attempt to correlate the relationship between the rate of thawing of the permafrost and the rate of drainage of free water from the foundation.

Deterioration of the cell wall in waterlogged wooden archeological artifacts, 2400 years old

IAWA Journal ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 820-844 ◽  
Author(s):  
Juan Guo ◽  
Lin Xiao ◽  
Liuyang Han ◽  
Hao Wu ◽  
Tao Yang ◽  
...  
Keyword(s):  
Cell Wall ◽  
Free Water ◽  
Crystalline Cellulose ◽  
Ftir Microscopy ◽  
Ms Imaging ◽  
State Of Water ◽  
Spongy Texture ◽  
Gab Model ◽  
Archeological Artifacts ◽  
The Relationship

ABSTRACT The relationship between the cell wall ultrastructure of waterlogged wooden archeological artifacts and the state of water bound to cell walls and free in voids is fundamental to develop consolidating and drying technologies. Herein, a lacquer-wooden ware and a boat-coffin dating 4th century BC were selected as representative artifacts to study. Wood anatomy results indicated that they belonged to Idesia sp. and Machilus sp., respectively. They exhibited a typical spongy texture, as revealed by SEM observations, and their water contents had increased significantly. Solid state NMR, Py-GC/MS, imaging FTIR microscopy and 2D-XRD results demonstrated that the deterioration resulted from the partial cleavages of both polysaccharide backbones and cellulose hydrogen-bonding networks, almost complete elimination of acetyl side chains of hemicellulose, the partial depletion of β-O-4 interlinks, as well as oxidation and demethylation/demethoxylation of lignin. These further caused the disoriented arrangement of crystalline cellulose, and the decrease in cellulose crystallite dimensions and crystallinity. In consequence, mesopores and macropores formed, and the number of moisture-adsorbed sites and their accessibility increased. Moreover, results on free water deduced by the changes of pore structure and the maximum monolayer water capacity achieved by the GAB model indicated that water in waterlogged archeological wooden artifacts was mainly free water in mesopores.

Notes on the genus Cactodera Krall & Krall, 1978 and proposal of Betulodera betulae gen. nov., comb. nov. (Nematoda: Heteroderidae)

Nematology ◽  
2002 ◽  
Vol 4 (7) ◽  
pp. 875-882 ◽  
Author(s):  
Dieter Sturhan
Keyword(s):  
Adaptive Radiation ◽  
New Genus ◽  
Morphological Characteristics ◽  
Sensu Stricto ◽  
Lateral Field ◽  
Second Stage ◽  
Species Inquirenda ◽  
Definition Of ◽  
Relationship Of ◽  
The Relationship

AbstractBased mainly on an analysis of the host ranges of the species presently placed in Cactodera, sensu lato, and of selected morphological characteristics, an attempt is made to improve the definition of the genus which, after exclusion of C. betulae and C. johanseni, is considered to be monophyletic. The host range of Cactodera, sensu stricto, appears to be restricted to the subclass Caryophyllidae with the ten known species showing an adaptive radiation on host genera in five families of the orders Caryophyllales and Polygonales. This may be a result of co-evolution. Cactodera betulae cannot be assigned to any of the presently recognised genera of cyst-forming nematodes and therefore Betulodera gen. nov. is proposed with B. betulae comb. nov. as the type and only species. The relationship of Betulodera gen. nov. to other genera of Heteroderidae and to some undescribed heteroderid species has still to be evaluated. The new genus is characterised by circumfenestrate cysts with only a slightly protruding vulval cone, three incisures in the lateral field of the second-stage juveniles and presence of phasmids in the males. The hosts are in unrelated plant orders and subclasses. Cactodera aquatica, a species inquirenda, is returned to the genus Heterodera and Heterodera johanseni (Sharma et al. , 2001) comb. nov. is proposed for C. johanseni.

New Insights into the Physiology of Peritoneal Fluid Transport

2008 ◽  
Vol 28 (3_suppl) ◽  
pp. 144-149
Author(s):  
Raymond T. Krediet ◽  
Annemieke M. Coester ◽  
Alena Parikova ◽  
Watske Smit ◽  
Dirk G. Struijk
Keyword(s):  
Water Transport ◽  
Fluid Transport ◽  
Free Water ◽  
Osmotic Gradient ◽  
Ultrafiltration Failure ◽  
Ultra Filtration ◽  
Relationship Of ◽  
The Relationship

A review is given on the mechanisms of free water transport, the various methodologies for its measurement, its dependency on the osmotic gradient, and the assessment of osmotic conductance in individual patients. The importance of impaired free water transport in long-term ultra-filtration failure is discussed, relative to peritoneal solute transport status. Furthermore, the relationship of free water transport with locally released potassium is considered, together with a potential role of impaired K+ channel function with peritoneal alterations. Finally, the role of impaired osmotic conductance to glucose and its effects on free water transport in long-term patients with ultrafiltration failure is reviewed.

scholarly journals BCL-6 Protein Expression in Human Peripheral T-Cell Neoplasms Is Restricted to CD30+ Anaplastic Large-Cell Lymphomas

Blood ◽  
1997 ◽  
Vol 90 (6) ◽  
pp. 2445-2450 ◽  
Author(s):  
Antonino Carbone ◽  
Annunziata Gloghini ◽  
Gianluca Gaidano ◽  
Riccardo Dalla-Favera ◽  
Brunangelo Falini
Keyword(s):  
T Cell ◽  
Protein Expression ◽  
Lymph Nodes ◽  
Cell Lines ◽  
Biological Significance ◽  
Large Cell ◽  
Lymphoid Cells ◽  
Null Cell ◽  
The Relationship ◽  
Cell Proliferations

Abstract The expression pattern of the BCL-6 transcription factor has been assessed in normal and neoplastic B-cell populations and in Hodgkin's disease. However, little is known about BCL-6 expression and its biological significance in T-cell neoplasms. In this study, a series of 59 lymphoma samples, including 27 CD30+ anaplastic large-cell lymphomas (ALCLs), 24 other peripheral T-cell neoplasms, and 8 T-cell lymphoblastic lymphomas (T-LBLs), as well as a panel of t(2; 5)-positive lymphoma-derived human cell lines, were evaluated for BCL-6 protein expression by immunohistochemistry on frozen sections and cell smears. To define the relationship between BCL-6 protein and CD30 antigen in CD30+ ALCLs and in non-neoplastic lymph nodes, serial section immunohistochemistry and two-color staining were used in selected CD30+ ALCLs as well as in reactive lymph nodes with non-neoplastic T-cell proliferations. BCL-6 protein was expressed in 12 of 27 (45%) CD30+ ALCL cases, irrespective of their antigenic phenotypes (T-cell or null-cell type), and in the t(2; 5)-positive cell lines. In contrast, the remaining 24 peripheral T-cell neoplasms as well as the 8 T-LBLs were considered negative for BCL-6 expression. Coexpression of CD30 and BCL-6, as detected in CD30+ ALCLs, was also found in a subset of non-neoplastic lymphoid elements, namely the large lymphoid cells scattered in the interfollicular areas of reactive lymph nodes. These findings suggest that CD30+ ALCLs may represent the neoplastic transformation of extrafollicular CD30+ cells and that BCL-6 may provide an additional marker for characterizing CD30+ ALCLs.

Comparative physiology of suspension-feeding in living brachiopods and bivalves: evolutionary implications

Paleobiology ◽  
1993 ◽  
Vol 19 (3) ◽  
pp. 322-334 ◽  
Author(s):  
Melissa Clark Rhodes ◽  
R. J. Thompson
Keyword(s):  
Body Size ◽  
Fossil Record ◽  
Benthic Communities ◽  
Suspension Feeding ◽  
Metabolic Rates ◽  
Comparative Physiology ◽  
Feeding Rates ◽  
Bivalve Molluscs ◽  
Significant Component ◽  
Experimental Conditions

This paper presents scaling equations relating suspension-feeding rates to body size for articulate brachiopods and bivalve molluscs, two classes which represent a significant component of the fossil record of marine benthic communities. Clearance (feeding) rates of five species of living articulate brachiopods and three species of epifaunal suspension-feeding bivalve molluscs collected from mid-latitude fjords of Newfoundland and New Zealand were measured in similar experimental conditions. In comparisons within and between the two classes, we found that both plectolophous and spirolophous brachiopods had significantly lower feeding rates than mytilids, which are filibranchs, but that a sympatric primitive eulamellibranch veneroid bivalve had rates comparable to the brachiopods. Articulate brachiopods do not appear to feed effectively at the high algal concentrations which bivalves can exploit. The data on comparative suspension-feeding rates support the hypothesis that past changes in diversity and distribution of bivalves and brachiopods may be related to an overall increase in energy flux and escalation of metabolic rates during the Phanerozoic.

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