CRYSTALLOGRAPHY AND DIAGENESIS IN FOSSIL CRANIID BRACHIOPODS

Abstract:  One of the fundamental questions in biomineralization is how organisms control crystallographic orientation during biomineral production. The understanding of how diagenetic changes influence the preservation of original crystallographic patterns in fossilized biomineral structures provides a priori fundamental information for such an assessment. Fossil craniid brachiopods Petrocrania scabiosa (Late Ordovician) and Crania craniolaris (Late Cretaceous) are analysed using electron backscattered diffraction (EBSD) to provide crystallographic data at high spatial resolution in the structural context. EBSD analyses show that P. scabiosa maintains most of the original crystallographic signature, including data from individual calcite tablets and laminae, while C. craniolaris only retains fragmentary crystallographic data reflecting the crystallographic continuity of tablets across laminae. Data show that the preservation of the original crystallographic signature is independent of that of shell ultrastructure and geological time. In addition, results allow us to propose a series of steps in the evolution of 'crystallographic loss' due to diagenesis.     

SENSUAL ATTACHMENT AND INCEST AVOIDANCE IN HUMAN EVOLUTION AND CHILD DEVELOPMENT

The authors take issue with the critique of psychoanalysis and the depiction of human sexuality and incest avoidance in evolutionary psychology. Drawing on human neurobiology and evolutionary anthropology, they show that human beings have an evolved disposition toward pair-bonding and evolved capacities for self-regulation of sexual and aggressive impulses. The realization that these characteristics are not only important but also interrelated leads to a reassessment of the Oedipus complex, a new model of incest avoidance in humans, and a fresh perspective on the relation between reproductive behaviour and environmental conditions.     

EVOLUTION AND DEVELOPMENT OF BODY SIZE AND CELL SIZE IN DROSOPHILA MELANOGASTER IN RESPONSE TO TEMPERATURE

We examined the evolutionary and developmental responses of body size to temperature in Drosophila melanogaster, using replicated lines of flies that had been allowed to evolve for 5 yr at 25°C or at 16.5°C. Development and evolution at the lower temperature both resulted in higher thorax length and wing area. The evolutionary effect of temperature on wing area was entirely a consequence of an increase in cell area. The developmental response was mainly attributable to an increase in cell area, with a small effect on cell number in males. Given its similarity to the evolutionary response, the increase in body size and cell size resulting from development at low temperature may be a case of adaptive phenotypic plasticity. The pattern of plasticity did not evolve in response to temperature for any of the traits. The selective advantage of the evolutionary and developmental responses to temperature is obscure and remains a major challenge for future work.     

PERISTOME DEVELOPMENT IN MOSSES IN RELATION TO SYSTEMATICS AND EVOLUTION. II. TETRAPHIS PELLUCIDA (TETRAPHIDACEAE)

The Tetraphidae is a small subclass of mosses with a nematodontous peristome that has frequently been interpreted as primitive among the true mosses. The developmental cell sequence leading to the formation of the four peristome teeth of Tetraphis pellucida is described for the first time. Comparisons are made with sequences known for other nematodontous and arthrodontous mosses. Peristome development in T. pellucida is more like that described previously for arthrodontous peristomes than to published developmental sequences for nematodontous peristomes of species in the Polytrichaceae. On the other hand, our observations confirm a basic uniformity of the earliest developmental stages in all mosses studied thus far, regardless of their systematic position.     

A MODEL FOR DEVELOPMENT AND EVOLUTION OF COMPLEX MORPHOLOGICAL STRUCTURES

How 'complex' or composite morphological structures like the mammalian craniomandibular region arise during development and how they are altered during evolution are two major unresolved questions in biology. Herein, we have described a model for the development and evolution of complex morphological structures. The model assumes that natural selection acts upon an array of phenotypes generated by variation in a variety of underlying genetic and epigenetic controlling factors. Selection refines the integration of the various morphogenetic components during ontogeny in order to produce a functioning structure and to adapt the organisms to differing patterns of environmental heterogeneity. The model was applied to the development and evolution of the mammalian mandible (which is used as a paradigm of complex morphological structures). The embryology of the mandible was examined in detail in order to identify the fundamental developmental units which are necessary to assemble the final morphological structure. The model is quite general since equivalent units exist for the development of many other biological structures. This model could be applied to many other developing morphological structures as well as other groups of organisms. For example, it can be applied to cell parameters during Drosophila development (Atchley, 1987). The model as discussed in this paper assumes that morphological changes in the mandible result from evolutionary changes in its underlying developmental units. The developmental units relate to characteristics of cellular condensations which are produced from the differentiation of embryonic neural crest cells. The developmental units include: the number of stem cells in preskeletal condensations (n), the time of initiation of condensation formation (t), the fraction of cells that is mitotically active within a condensation (f), the rate of division of these cells (r), and their rate of cell death (d). These units and their derivative structures are discussed in terms of types of tissue differentiation (chondrogenesis, osteogenesis, primary/secondary osteogenesis, intramembranous/endochondral ossification) and growth properties of major morphological regions of the mandible. Variation in these five units provides the developmental basis for ontogenetic and phylogenetic modification of mandibular morphology. We have discussed how these developmental units are influenced by (a) the cell lineage from which they arise, (b) epithelial-mesenchymal (inductive tissue) interactions, (c) regulation of cell differentiation, and (d) extrinsic factors such as muscles, teeth and hormones. Evidence was provided that variation in mandibular morphology is heritable, subject to modification by natural selection, and that divergence among different genetic stocks has apparently occurred through changes in these developmental units and their derivative structures.(ABSTRACT TRUNCATED AT 400 WORDS)     

蜘蛛的性二型现象及其进化

对蜘蛛的性二型现象进行了初步的概括,并试图以食物对种群繁衍的影响为线索说明其进化机制。蜘蛛的性二型现象主要表现在体形大小上,一般雌性大于雄性;食物的数量和分布制约着蜘蛛性二型现象的进化。     

论三白草科的系统演化和地理分布

根据细胞学、孢粉学、花器官发生和发育、花部维管结构、胚胎学、比较形态及解剖学等方面的证据,对三白草科４属６种的系统演化关系进行了详细论证。并联系古地理、古气候和古植物的有关史料对三白草科分布区的起源作了据理推论。三白草科大约起源于早白垩纪古北大陆东南部。它的原始类型可能与现代三白草属的形态大体相似,为一种多年生具根状茎的草本,花小、无被、具苞片。白垩纪末期三白草的原始类群已完成它在古北大陆的迁移和     

EVOLUTION AND MITOCHONDRIAL DNA IN NEUROSPORA CRASSA

We studied mitochondrial DNA variability in 19 natural Neurospora crassa isolates and one wild-type isolate to examine evolution of these fungi and their mitochondrial DNA (mtDNA). We combined restriction endonuclease analysis of natural isolate mtDNA with DNA-DNA hybridization to cloned EcoR I fragments of a wild-type genome to discriminate between length mutations and site changes due to nucleotide substitution. Most variability was due to length mutations (insertions and deletions); genome size could vary 25% between pairs of isolates. Length-mutation distribution was not random, nor simply explained by the presence of coding versus noncoding regions. Restriction-site changes were few; the estimated amount of nucleotide substitution per nucleotide between the most divergent pair of isolates was 0.78%. Evolutionary relationships among isolates based on both types of mutations were compatible, and suggest that geographically distinct populations of mitochondrial DNA exist in the biological species, N. crassa. In contrast, no such correlation was shown by the previously determined distribution of nuclear heterokaryon incompatibility genes in the same isolates (Mylyk, 1975, 1976).     

ANATOMY AND DEVELOPMENT IN SOLISIA

Boke , Norman H. (U. Oklahoma, Norman.) Anatomy and development in Solisia. Amer. Jour. Bot. 47(1): 59—65. Illus. 1960.–The genus Solisia contains a single species of small cacti which resemble certain mammillarias in having: pink, lateral flowers; milky juice; and dimorphic areoles. Adult specimens have elongate spiniferous areoles with an unusual sequence of spine initiation. The first four or five primordia appear at the posterior end of the areole meristem; the next are initiated near its center, after which initiation proceeds both acropetally and basipetally until the single, elliptical series of primordia is complete. A similar pattern of spine initiation occurs in Pelecyphora aselliformis, but this species differs markedly from S. pectinata in other respects. In seedlings of S. pectinata the areoles are broadly elliptical and spine initiation is strictly acropetal, a situation found in certain species of Mammillaria. Seeds of S. pectinata are black with a large hilum and a small perisperm. Since the perisperm has apparently been overlooked, it appears that only the black seed coat and relatively large hilum keep the species out of Mammillaria. If Buxbaum's postulates concerning the value of seed structure in tracing phylogeny in the Cactaceae are valid, S. pectinata must have diverged from the main line of evolution somewhere below Neobesseya. In that event, the species probably merits generic rank; otherwise, it seems preferable to return it to Mammillaria.