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Chloroplasts arose from cyanobacteria, mitochondria arose from proteobacteria. Both organelles have conserved their prokaryotic biochemistry, but their genomes are reduced, and most organelle proteins are encoded in the nucleus. Endosymbiotic theory posits that bacterial genes in eukaryotic genomes entered the eukaryotic lineage via organelle ancestors. It predicts episodic influx of prokaryotic genes into the eukaryotic lineage, with acquisition corresponding to endosymbiotic events. Eukaryotic genome sequences, however, increasingly implicate lateral gene transfer, both from prokaryotes to eukaryotes and among eukaryotes, as a source of gene content variation in eukaryotic genomes, which predicts continuous, lineage-specific acquisition of prokaryotic genes in divergent eukaryotic groups. Here we discriminate between these two alternatives by clustering and phylogenetic analysis of eukaryotic gene families having prokaryotic homologues. Our results indicate (1) that gene transfer from bacteria to eukaryotes is episodic, as revealed by gene distributions, and coincides with major evolutionary transitions at the origin of chloroplasts and mitochondria; (2) that gene inheritance in eukaryotes is vertical, as revealed by extensive topological comparison, sparse gene distributions stemming from differential loss; and (3) that continuous, lineage-specific lateral gene transfer, although it sometimes occurs, does not contribute to long-term gene content evolution in eukaryotic genomes., In prokaryotes, inheritance involves recombination superimposed upon clonal growth (1) and the mechanisms of recombination are the mechanisms of lateral gene transfer (LGT): transformation, conjugation, transduction, and gene transfer agents [...]

The mechanisms that underlie the origin of major prokaryotic groups are poorly understood. In principle, the origin of both species and higher taxa among prokaryotes should entail similar mechanisms--ecological interactions with the environment paired with natural genetic variation involving lineage-specific gene innovations and lineage-specific gene acquisitions (1-4). To investigate the origin of higher taxa in archaea, we have determined gene distributions and gene phylogenies for the 267,568 protein-coding genes of 134 sequenced archaeal genomes in the context of their homologues from 1,847 reference bacterial genomes. Archaeal-specific gene families define 13 traditionally recognized archaeal higher taxa in our sample. Here we report that the origins of these 13 groups unexpectedly correspond to 2,264 group-specific gene acquisitions from bacteria. Interdomain gene transfer is highly asymmetric, transfers from bacteria to archaea are more than fivefold more frequent than vice versa. Gene transfers identified at major evolutionary transitions among prokaryotes specifically implicate gene acquisitions for metabolic functions from bacteria as key innovations in the origin of higher archaeal taxa., Genome evolution in prokaryotes entails both tree-like components generated by vertical descent and network-like components generated by lateral gene transfer (LGT) (5,6). Both processes operate in the formation of prokaryotic [...]

Recombination is a powerful evolutionary force that merges historically distinct genotypes. But the extent of recombination within many organisms is unknown, and even determining its presence within a set of homologous sequences is a difficult question. Here we develop a new statistic, [[PHI].sub.w] that can be used to test for recombination. We show through simulation that our test can discriminate effectively between the presence and absence of recombination, even in diverse situations such as exponential growth (star-like topologries) and patterns of substitution rate correlation. A number of other tests, Max [X.sup.2], NSS, a coalescentbased likelihood permutation test (from LDHat), and correlation of linkage disequilibrium (both [r.sup.2] and |D'|) with distance, all tend to underestimate the presence of recombination under strong population growth. Moreover, both Max [X.sup.2] and NSS falsely infer the presence of recombination under a simple model of mutation rate correlation. Results on empirical data show that our test can be used to detect recombination between closely as well as distantly related samples, regardless of the suspected rate of recombination. The results suggest that [[PHI].sub.w] is one of the best approaches to distinguish recurrent mutation from recombination in a wide variety of circumstances.

This paper presents an application of work-domain analysis (WDA) to the domain of the command and control of a multipurpose naval frigate--the Canadian Halifax Class frigate. This represents an application of this approach to a real system and, to the authors' knowledge, is the most extensive WDA of a naval work domain. In particular, and in contrast to other applications of cognitive work analysis, the authors extended the basic WDA framework to handle a multipurpose, loosely bound work domain. In addition, the naval domain is value driven, and this affects naval decision making. Values were incorporated as a social organizational analysis into the work-domain model and were represented as a type of soft constraint. A total of 38 submodels of the work domain were developed, whose primary models are discussed in this paper. From these models, 132 information requirements were extracted, substantiating that WDA is a worthwhile technique for supporting interface design. This paper makes a theoretical contribution by extending the WDA framework and a practical contribution by demonstrating the usefulness of the framework in a real design context. This paper concentrates on presenting WDA as a process, not as a finished product, showing intermediate levels of models and the design requirements that can be extracted from the early stages of the WDA. Index Terms--Cognitive work analysis (CWA), ecological interface design (EID), naval command and control, work-domain models.

Models of climate change generally predict rising mean global temperatures combined with greater variability in some regions. While relationships between mean temperature and several reproductive parameters are well documented, the effect of day-to-day variation in ambient temperature has received little attention. In our study, temperature variation had no significant effects on clutch size in a wild population of Great Tits (Parus major). In contrast, egg mass tended to be smaller when ambient temperatures during the week prior to laying were more variable. We suggest that variable temperatures may be disadvantageous to an egg-laying bird. Thermal variability should therefore be considered as a discrete factor, distinct from mean temperature, when assessing the consequences of climate changes for breeding birds. Key words: egg production, energy expenditure, Great Tits, Parus major, temperature variability.

Consequences of load carrying by birds during short flights are found to be behavioral and not energetic. Am J Physiol Regulatory Integrative Comp Physiol 283: R249-R256, 2002; 10.1152/ ajpregu.00409.2001.--The doubly-labeled water technique and video were used to measure the effect of mass loading on energy expenditure and takeoff performance in zebra finches, Taeniopygia guttata, that were making routine (nonalarm) short flights. Finches that carried 27% additional mass did not expend more energy during flight than unloaded controls. Carrying additional mass, however, led to a reduced body mass and a decreased velocity during takeoffs (by 12%). Calculations of instantaneous mechanical power indicated that energy expended by unloaded and loaded finches at takeoff was similar, due to the observed decrease in velocity by mass-loaded finches and a lowering of their body mass. During routine short flights, zebra finches appear to maintain their metabolic power input and mechanical power output regardless of mass loading. Here, the costs of carrying additional mass during routine short flights were revealed to be behavioral and not energetic. doubly-labeled water; energy expenditure; mass loading; zebra finch

The Christian imago dei is discussed in relation to responsibility toward the environment. Topics include the imago dei in Genesis; the central role of imagination; fall and original sin; imago, imagination, and Jesus Christ; love, dominion and human culture; criteria for judging possibilities; creation and letting be.

Two experiments are presented which detail the relationship between body asymmetry and the creation of a spatial framework. Results include differences in the accessibility of location recall of spatial scenes as influenced by the asymmetry of the body axes.

Brood parasitism in a sand martin colony in central Scotland, consisting of 45 broods and 167 nestlings, was investigated. Multilocus DNA fingerprinting was used to examine the frequency of monogamy, quasiparasitism (QP), intraspecific brood parasitism and extrapair fertilization (EPF). Both QP and EPF were found to result in multiple parentage within nests. The observed frequency may be due to a female-driven strategy.

This paper presents the results of and conclusions drawn from two experimental studies of low-elevation slant-path scintillation. Part I describes observations made on an 11.2 GHz, 3.3 [degrees] path over a two and a half year period. Received signal strength and a variety of concurrent meteorological parameters were recorded. The resulting database has enabled the veracity of the 1990 International Telecommunications Union-Radio [(ITU-R) - formerly International Consultative Radio Committee (CCIR)] model to be determined. An interesting discrepancy between the CCIR prediction procedure and the experimental data suggests an as yet unmodeled scintillation mechanism operating in wet summer weather. Index Terms - Radio propagation.

The field metabolic rate (FMR) of nesting Northern Fulmars (Fulmarus glacialis) was measured using the doubly labeled water technique. Although some labeled Northern Fulmars showed marked differences in behavior compared to controls, FMR did not change correspondingly. At-sea FMR averaged 1444 kJ/d, equivalent to 4.5 x basal metabolic rate (BMR). As a multiple of BMR it was independent of sex, wing length, body mass, mass change, and duration of the period at sea, but was strongly dependent on wind speed, being higher during slack winds. There was also a trend for higher wingbeat frequency at winds too low for sustained dynamic soaring. The high energetic cost of flapping flight during windless conditions may explain patterns of nest attendance: in particular, why nest site attendance by Northern Fulmars in winter is greater during calm weather. Lack of wind might limit the breeding range of this species and other Procellariiformes with high flapping-flight costs. Key words: breeding distribution; procellariiform; energetics; flight characteristics; foraging; labeled water; Northern Fulmar; seabird; weather effects., INTRODUCTION The Northern Fulmar (Fulmarus glacialis) has been identified as one of the main avian consumers of sand-eels (Ammodytes marinus) in Shetland (Furness 1990) and in the North Sea (Anonymous [...]

The accessibility of objects in mental spatial frameworks depends on their relation to the spatial axes of the world and people's typical interactions with space. The current study investigated perception of space. Subjects viewed either a physical model of a person surrounded by objects (Exp. 1) or diagrams of scenes (Exp. 2). Subjects named objects at directions from their own external perspective. For physical scenes, subjects were faster to name objects at Above/Below locations, followed by Front/Behind locations, followed by Left/Right locations. This finding indicates that subjects used spatial frameworks to locate objects perceptually. For diagrams, response times to name objects did not conform to this pattern, perhaps because the spatial axes of a diagram do not correspond to stable spatial axes of the world.

We investigated the accuracy of haptic reproduction of line length and whether accuracy is influenced by line orientation. 13 blindfolded subjects felt along different line lengths at various orientations in the horizontal plane, then reproduced the line lengths in the same orientation as that felt. Efforts were made to equate learning and reproductive scanning movements. Reproductions of line lengths were a nonveridical power function of their true lengths, but the power function exponents did not differ across spatial orientations. It was concluded that people can encode line lengths across spatial orientations by a common power function if care is taken to equate proprioceptive information across learning and reproduction.

A study of the nestlings of house martins showed broods which had extra pair of chicks unrelated to their putative fathers. The production of the extra offsprings were attributed to extra-pair fertilization, where females copulate with males other than their mates to become fertilized with sperms that have better genetic quality. Extra-pair fertlization was also observed to take place only after the female starts to lay eggs because the males' guarding behavior becomes less aggressive during this period.

Four experiments investigated the use of cognitive strategies for encoding spatial location in visual figures. Subjects reproduced the position of a dot in a square figure that had distance markers placed along two sides. Subjects' responses were biased toward imaginary points of intersection formed by the distance markers when subjects responded from memory (Experiment 1) or while viewing the figures (Experiment 2). Dots located at an intersection point were reproduced more accurately than those located off an intersection. These findings demonstrate that empty regions of a figure can serve as subjective landmarks for spatial localization. In Experiment 3, dot relocation was found to be similarly distorted toward physical cross marks placed at the intersections of distance markers, supporting the landmark hypothesis. The attraction of dots to intersection points depends on the viewer employing a strategy of mentally projecting from distance markers to form imaginary intersections, which makes intersection points salient landmarks for coding location of nearby stimulus dots. In Experiment 4, attraction toward intersection points was observed only when subjects employed the projection strategy and not when instructed to use a different encoding strategy.

Encoding spatial location in a frame of reference is often biased by both perceptual and strategic factors. For example, tilt contrast occurs when a line presented in the frame of horizontal and vertical axes appears to be repulsed from the nearest axis, including the diagonal axis of symmetry, due to symmetry perception mechanisms. Research has demonstrated, however, that people can adopt particular viewing strategies that eliminate this effect. In Experiment 1, a similar tilt contrast effect was observed when subjects reproduced from memory the position of a single dot in this reference frame. It was hypothesized that this effect resulted from a combination of strategic and perceptual factors. Specifically, people employ an origin strategy, coding the location of the dot relative to the origin of the horizontal and vertical axes, thereby establishing a virtual line that appears tilted away from the axes due to the same perceptual processes affecting physically present lines. Two additional experiments support this hypothesis. In Experiment 2, no clear tilt contrast effect was observed in a perception condition, indicating that the tilt effect for dots cannot be accounted for by purely perceptual processes. In Experiment 3, the tilt contrast effect was found to be contingent upon the use of the origin strategy as opposed to a different strategy. The results demonstrate the importance of a viewer's strategy in determining the pattern of distortion observed in spatial encoding.

The relation of the recognition failure of recallable words to overall recognition rates is largely invariant across conditions that influence both recall and recognition separately. In two experiments, the influence of the integration of the members of A-B word pairs on this relation was investigated. In Experiment 1, it was found that deviations of observed recognition failure from predictions of the Tulving-Wiseman function (Tulving & Wiseman, 1975) were produced by shallow, nonsemantic encoding. In Experiment 2, the association of category-to-instance pairs was varied. It was found that weak associates caused larger deviations of observed recognition failure from predicted recognition failure than did strong associates. Such results suggest that a strongly encoded association between cue and target elements of A-B pairs is a necessary condition for the adherence of data to the Tulving-Wiseman functin. The implications of these findings for general models of memory are discussed.

In list-learning experiments, the orienting question asked of one item may influence the processing of, and memory for, later items in the list. Four experiments demonstrated that words that are not related to their own orienting question, but that are semantically related to the question asked of a previous item, are better recalled than are words that are not related to any question in the list. Factors that influence this memory enhancement include the number of times relevant orienting questions appear during study, as well as the retention interval. Experiment 4 revealed that this effect is contingent upon conscious awareness: Item-category relations do not enhance recall if the subject is not aware of them. The results of the four experiments imply that semantic categories can be primed as implicit associative responses to words, which influence memory.

Investigations were made whether expertise is more likely to mitigate age declines when experts rely on environmental support in a pilot

This study explored whether people create Euclidean representations of 2-dimensional right triangles from touch and use them to make spatial inferences in accord with Euclidean distance axioms. Blindfolded participants who were instructed to form visual images of triangles felt the vertical and horizontal sides of right triangles, then estimated the lengths (but not the angles) of the 3 triangle sides. In these 3 experiments, length estimates conformed closely to the Euclidean metric when evaluated on application of the Pythagorean theorem. Participants who used a visual imaging strategy were accurate more often than those who used visual imagery less often. In Experiments 2 and 3, a hypotenuse inference was as accurate as a direct haptic judgment of the hypotenuse. These results demonstrated similar accuracy of the hypotenuse judgments when participants made verbal rather than haptic estimates. The findings indicate that participants can form Euclidean representations under certain conditions from felt 2-dimensional right triangles based on visual images.

As we move about and interact in the world, we keep track of different spaces, among them the space of navigation, the space immediately around the body, and the space of the body. We review research showing that these spaces are conceptualized differently. Knowledge of the space of navigation is systematically distorted. For example, people mentally rotate roads and land masses to greater correspondence with global reference frames, they mentally align roads and land masses, they overestimate distances near the viewpoint relative to those far from it. These and other distortions indicate that the space of navigation is schematized to elements and spatial relations relative to reference frames and perspective. The space around the body is organized into a mental framework consisting of extensions of the major axes of the body. Times to report objects around the body suggest that the relative accessibility of the axes depends on their perceptual and functional properties and the relation of the body to the world. Finally, times to verify named or depicted body parts indicate that body schemas depend on perceptual and functional significance. Thus, these spaces (and they are not the only ones important to human interaction) differ from one another and are not conceptualized as Euclidean. Rather they are schematized into elements and spatial relations that reflect perceptual and conceptual significance. Key Words: cognitive map, body schema, mental model, spatial thinking.