Evidence for Handedness in Bumblebees

We describe a simple study of how bumblebees (Bombus spp.) behave when visiting florets which are arranged in a circle around a vertical inflorescence. In four species of bees, individuals showed a tendency for rotation in the same direction around each inflorescence on successive visits, i.e., each individual tended to go either clockwise or anticlockwise. Similar behavior has also been observed in mammals including humans. The implications of this tendency to repeat tasks in the same way are discussed, particularly in relation to our understanding of the phenomenon known as flower constancy. In humans, the tendency for individuals to turn in a particular direction is strongly related to handedness. In three of the four bee species there was a significant overall tendency for the bees to rotate in a preferred direction, suggesting that they too may exhibit handedness.     

Evidence for Evolution Versus Evidence for Intelligent Design: Parallel Confusions

The popular defense of intelligent design/creationism (ID) theories, as well as theories in evolutionary biology, especially from the perspective that both are worthy of scientific consideration, is that empirical evidence has been presented that supports both. Both schools of thought have had a tendency to rely on the same class of evidence, namely, the observations of organisms that are in need of being explained by those theories. The result is conflation of the evidence that prompts one to infer hypotheses applying ID or evolutionary theories with the evidence that would be required to critically test those theories. Evidence is discussed in the contexts of inferring theories/hypotheses, suggesting what would be possible tests, and actual testing. These three classes of inference being abduction, deduction, and induction, respectively. Identifying these different inferential processes in evolutionary biology and ID allow for showing that the evidence to which theories and hypotheses provide understanding cannot be the same evidence supporting those theories and hypotheses. This clarification provides a strong criterion for showing the inability of an ID theory to be of utility in the ongoing process of acquiring causal understanding, that is the hallmark of science.     

A Model for the Genetics of Handedness

Experimental data and theoretical work on the inheritance of handedness and cerebral dominance are reviewed. A two-gene, four-allele model, one locus pertaining to left or right hemispheric dominance and the other to contralateral or ipsilateral hand control relative to the dominant hemisphere, is constructed. It is in excellent agreement with all quantitative information regarding this problem. Refinements designed to explain relevant qualitative facts are proposed and discussed.     

Structural Evidence for the Evolution of Pyrogenic Toxin Superantigens

Cells from metazoan organisms are eliminated in a variety of physiological and pathophysiological processes by apoptosis. In this report, we describe the cloning and characterization of molecules from the marine sponges Geodia cydonium and Suberites domuncula, whose domains show a high similarity to those that are found in molecules of the vertebrate Bcl-2 superfamily and of the death receptors. The Bcl-2 proteins contain up to four Bcl-2 homology regions (BH). Two Bcl-2-related molecules have been identified from sponges that are provided with two of those regions, BH1 and BH2, and are termed Bcl-2 homology proteins (BHP). The G. cydonium molecule, BHP1_GC, has a putative size of 28,164, while the related sequence from S. domuncula, BHP1_SD, has a M _r of 24,187. Phylogenetic analyses of the entire two sponge BHPs revealed a high similarity to members of the mammalian Bcl-2 superfamilies and to the Caenorhabditis elegans Ced-9. When the two domains, BH1 and BH2, are analyzed separately, again the highest similarity was found to the members of the Bcl-2 superfamily, but a clearly lower relationship to the C. elegans BH1 and BH2 domains in Ced-9. In unrooted phylogenetic trees the sponge BH1 and BH2 are grouped among the mammalian sequences and are only distantly related to the C. elegans BH domains. The analysis of the gene structure of the G. cydonium BHP showed that the single intron present is located within the BH2 domain at the same position as in C. elegans and rat Bcl-x_L. In addition, a sponge molecule comprising two death domains has been characterized from G. cydonium. The two death domains of the potential proapoptotic molecule GC_DD2, M _r 24,970, share a high similarity with the Fas-FADD/MORT1 domains. A death domain-containing molecule has not been identified in the C. elegans genome. The phylogenetic analysis revealed that the sponge domain originated from an ankyrin building block from which the mammalian Fas-FADD/MORT1 evolved. It is suggested that the apoptotic pathways that involve members of the Bcl-2 superfamily and of the death receptors are already present in the lowest metazoan phylum, the Porifera. Received: 27 July 1999 / Accepted: 28 December 1999     

Laterality in Maternal Cradling and Infant Positional Biases: Implications for the Development and Evolution of Hand Preferences in Nonhuman Primates

Left-sided maternal cradling has been widely reported in human populations. In this paper, I review the evidence of laterality in maternal cradling and infant positional biases in non-human primates. The review revealed some evidence of population-left sided cradling in great apes but little consistency in bias was found among Old and New World monkeys. Very little data have been reported in prosimians. I further describe how asymmetries in either maternal cradling or infant positional biases may explain individual and species differences in hand preference.     

Fear of Negative Evaluation Biases Social Evaluation Inference: Evidence from a Probabilistic Learning Task

Background

Fear of negative evaluation (FNE) defines social anxiety yet the process of inferring social evaluation, and its potential role in maintaining social anxiety, is poorly understood. We developed an instrumental learning task to model social evaluation learning, predicting that FNE would specifically bias learning about the self but not others.

Methods

During six test blocks (3 self-referential, 3 other-referential), participants (n = 100) met six personas and selected a word from a positive/negative pair to finish their social evaluation sentences “I think [you are / George is]…”. Feedback contingencies corresponded to 3 rules, liked, neutral and disliked, with P[positive word correct] = 0.8, 0.5 and 0.2, respectively.

Results

As FNE increased participants selected fewer positive words (β = −0.4, 95% CI −0.7, −0.2, p = 0.001), which was strongest in the self-referential condition (FNE × condition 0.28, 95% CI 0.01, 0.54, p = 0.04), and the neutral and dislike rules (FNE × condition × rule, p = 0.07). At low FNE the proportion of positive words selected for self-neutral and self-disliked greatly exceeded the feedback contingency, indicating poor learning, which improved as FNE increased.

Conclusions

FNE is associated with differences in processing social-evaluative information specifically about the self. At low FNE this manifests as insensitivity to learning negative self-referential evaluation. High FNE individuals are equally sensitive to learning positive or negative evaluation, which although objectively more accurate, may have detrimental effects on mental health.     

Patterns of Evolution in the Feeding Mechanism of Actinopterygian Fishes

SYNOPSIS. Structural and functional patterns in the evolutionof the actinopterygian feeding mechanism are discussed in thecontext of the major monophyletic lineages of ray-finned fishes.A tripartite adductor mandibulae contained in a maxillary-palatoquadratechamber and a single mechanism of mandibular depression mediatedby the obliquus inferioris, sternohyoideus, and hyoid apparatusare primitive features of the Actinopterygii. Halecostome fishesare characterized by having an additional mechanism of mandibulardepression, the levator operculi—opercular series coupling,and a maxilla which swings anteriorly during prey capture. Theseinnovations provide the basis for feeding by inertial suctionwhich is the dominant mode of prey capture throughout the halecostomeradiation. A remarkably consistent kinematic profile occursin all suction-feeding halecostomes. Teleost fishes possessa number of specializations in the front jaws including a geniohyoideusmuscle, loss of the primitive suborbital adductor component,and a mobile premaxilla. Structural innovations in teleost pharyngealjaws include fusion of the dermal tooth plates with endoskeletalgill arch elements, the occurrence of a pharyngeal retractormuscle, and a shift in the origin of the pharyngohyoideus. Thesespecializations relate to increased functional versatility ofthe pharyngeal jaw apparatus as demonstrated by an electromyographicstudy of pharyngeal muscle activity in Esox and Ambloplites.The major feature of the evolution of the actinopterygian feedingmechanism is the increase in structural complexity in both thepharyngeal and front jaws. Structural diversification is a functionof the number of independent biomechanical pathways governingmovement.     

The Evolution of the Motor Control of Feeding in Amphibians

Based on studies of a few model taxa, amphibians have been consideredstereotyped in their feeding movements relative to other vertebrates.However, recent studies on a wide variety of amphibian specieshave revealed great diversity in feeding mechanics and kinematics,and illustrate that stereotypy is the exception rather thanthe rule in amphibian feeding. Apparent stereotypy in some taxamay be an artifact of unnatural laboratory conditions. The commonancestor of lissamphibians was probably capable of some modulationof feeding movements, and descendants have evolved along twotrajectories with regard to motor control: (1) an increase inmodulation via feedback or feed-forward mechanisms, as exemplifiedby ballistic-tongued plethodontid salamanders and hydrostatic-tonguedfrogs, and (2) a decrease in variation dictated by biomechanicsthat require tight coordination between different body parts,such as the tongue and jaws in toads and other frogs with ballistictongue projection. Multi-joint coordination of rapid movementsmay hamper accurate tongue placement in ballistic-tongued frogsas compared to both short-tongued frogs and ballistic tongued-salamandersthat face simpler motor control tasks. Decoupling of tongueand jaw movements is associated with increased accuracy in bothhydrostatic-tongued frogs and ballistic-tongued salamanders.     

Feeding In Planktonic Protozoans: Evidence For Non-Random Acquisition of Prey

ABSTRACT The literature on discriminant feeding by planktonic protozoans using geometric and nongeometric criteria is reviewed with emphasis on recent studies that indicate phagotrophic protists can use information other than particle size or shape to sort among potential prey. Sufficient data are available for ciliates, aplastidic microflagellates, and phagotrophic dinoflagellates. Numerous representative taxa of all three groups have chemosensory capabilities, either to specific chemicals or to prey exudates, that modify their motility patterns resulting in aggregation or dispersal. Representatives of all three groups also have specific prey preferences. These considerations imply, but do not prove, selectivity in feeding through use of chemical cues. Although prey geometry is clearly a first-order determinant of ingestion through passive mechanical selection, recent studies illustrate that planktonic ciliates and flagellates can use other criteria to discriminate among prey. the evidence clearly implicates use of chemical cues, most likely perceived through contact chemoreception. Filter feeders as well as raptors have such abilities indicating that feeding mechanisms per se do not imply limitations on feeding behavior. Evidence of considerable flexibility and complexity in chemoperceptive feeding suggests that we have only glimpsed the more detailed features of feeding behavior in aquatic protozoans.     

Molecular Evidence and the Evolution of Maize

In this review, the contributions of isozyme and chloroplast DNA studies to questions surrounding the evolution of maize are summarized. These methods of analysis provide generally strong support for the hierarchical system of classification of Zea proposed by Iltis and Doebley (1980). Molecular evidence is fully congruent with the theory that teosinte is ancestral to maize and suggests thatZ. mays subsp.parviglumis was the ancestral teosinte taxon. Further, these data show that only those populations from the central region of the range of subsp. parviglumis resemble maize in both isozymic and chloroplast DNA constitution. Presuming no major changes in the distribution of subsp. parviglumis since the domestication of maize, these data would place the origin of maize in the Balsas River drainage southwest of Mexico City. Molecular systematic evidence provides no support for theories that maize was domesticated independently several times; however, this type of data can not disprove such theories. Analyses of isozyme and chloroplast DNA diversity in Zea provide evidence of limited gene flow between maize and teosinte, but are not consistent with models that postulate extensive genetic interchange between these taxa. Isozyme studies have added substantially to the understanding of evolutionary relationships among extant races of maize and suggest that there are a small number of major racial complexes in Meso- and North America which have often evolved in response to environmental constraints associated with altitude. Ultimately, molecular genetic studies may allow a resolution of the controversy surrounding the morphological evolution of the maize ear.     

Molecular Evidence and the Evolution of Maize

In this review, the contributions of isozyme and chloroplast DNA studies to questions surrounding the evolution of maize are summarized. These methods of analysis provide generally strong support for the hierarchical system of classification of Zea proposed by Iltis and Doebley (1980). Molecular evidence is fully congruent with the theory that teosinte is ancestral to maize and suggests thatZ. mays subsp.parviglumis was the ancestral teosinte taxon. Further, these data show that only those populations from the central region of the range of subsp. parviglumis resemble maize in both isozymic and chloroplast DNA constitution. Presuming no major changes in the distribution of subsp. parviglumis since the domestication of maize, these data would place the origin of maize in the Balsas River drainage southwest of Mexico City. Molecular systematic evidence provides no support for theories that maize was domesticated independently several times; however, this type of data can not disprove such theories. Analyses of isozyme and chloroplast DNA diversity in Zea provide evidence of limited gene flow between maize and teosinte, but are not consistent with models that postulate extensive genetic interchange between these taxa. Isozyme studies have added substantially to the understanding of evolutionary relationships among extant races of maize and suggest that there are a small number of major racial complexes in Meso- and North America which have often evolved in response to environmental constraints associated with altitude. Ultimately, molecular genetic studies may allow a resolution of the controversy surrounding the morphological evolution of the maize ear.     

Evidence for Nonindependent Evolution of Adjacent Microsatellites in the Human Genome

Microsatellites are short tandem repeats that evolve predominantly through a stepwise mutation model. Despite intensive study, many aspects of their evolution remain unresolved, particularly the question of how compound microsatellites containing two different motifs evolve. Previous work described profound asymmetries in the probability that any given second motif lies either 3′ or 5′ of an AC repeat tract. Here we confirm and extend this analysis to examine the length dependence of these asymmetries. We then use the differences in length between homologous human and chimpanzee microsatellites as a surrogate measure of the slippage-based mutation rate to explore factors that influence this process. We find that the dominant predictor of mutation rate is the length of the tract being considered, which is a stronger predictor than the length of the two tracts combined, but other factors also have a significant impact, including the length of the second tract and which of the two tracts lies upstream. We conclude that compound microsatellites rarely arise through random point mutations generating a second motif within a previously pure tract. Instead, our analyses point toward a model in which poorly understood mutation biases, probably affecting both slippage and point mutations and often showing 3′-5′ polarity, promote the formation of compound microsatellites. The result is convergent evolution. We suggest that, although their exact nature remains unclear, these biases are likely attributable to structural features, such as the propensity of AC tracts to form Z-DNA.     

The Effects of Evolution are Local: Evidence from Experimental Evolution in Drosophila

One of the enduring temptations of evolutionary theory is theextrapolation from short-term to long-term, from a few speciesto all species. Unfortunately, the study of experimental evolutionreveals that extrapolation from local to general patterns ofevolution is not usually successful. The present article supportsthis conclusion using evidence from the experimental evolutionof life-history in Drosophila. The following factors demonstrablyundermine evolutionary correlations between functional characters:inbreeding, genotype-by-environment interaction, novel fociof selection, long-term selection, and alternative genetic backgrounds.The virtual certainty that at least one of these factors willarise during evolution shreds the prospects for global theoriesof the effects of adaptation. The effects of evolution apparentlydon't generalize, even though evolution is a global process.     

Evolution of the EF-hand calcium-binding protein family: Evidence for exon shuffling and intron insertion

Summary The evolutionary history of the intracellular calcium-binding protein superfamily is well documented. The members of this gene family are all believed to be derived from a common ancestor, which, itself, was the product of two successive gene duplications. In this study, we have compared and analyzed the structures of the recently described genes coding for these proteins. We propose a series of evolutionary events, which include exon shuffling and intron insertion, that could account for the evolutionary origin of all the members of this super-family. According to this hypothesis, the ancestral gene, a product of two successive duplications, consisted of at least four exons. Each exon coding for a peptide (a calcium-binding domain) was separated by an intron that had mediated the duplication. Each distinct lineage evolved from this ancestor by genomic rearrangement, with insertion of introns being a prominent feature.     

Individual Biases,Cultural Evolution,and the Statistical Nature of Language Universals: The Case of Colour Naming Systems

Language universals have long been attributed to an innate Universal Grammar. An alternative explanation states that linguistic universals emerged independently in every language in response to shared cognitive or perceptual biases. A computational model has recently shown how this could be the case, focusing on the paradigmatic example of the universal properties of colour naming patterns, and producing results in quantitative agreement with the experimental data. Here we investigate the role of an individual perceptual bias in the framework of the model. We study how, and to what extent, the structure of the bias influences the corresponding linguistic universal patterns. We show that the cultural history of a group of speakers introduces population-specific constraints that act against the pressure for uniformity arising from the individual bias, and we clarify the interplay between these two forces.