Factors influencing codling moth larval response to α-farnesene

Behavioral responses of newly-emerged codling moth (Cydia pomonella L.) larvae to α-farnesene were compared for a laboratory-reared strain (‘lab’, 160 generations inbred) and a recently collected strain (‘wild’, 3 generations). Video recordings of single larvae placed 20 mm from Bond papers releasing a range of seven α-farnesene concentrations were scored for head turning, head lifting, head direction, and movement across a Petri dish. The laboratory strain was significantly less successful at finding the treated papers than the wild strain. The lab strain was also significantly less active, shown by more random orientation, slower walking speed, less head turning and less head lifting. Both strains showed lower response to α-farnesene concentrations less than 10⁻⁶ (w/v) α-farnesene. Orientation, walking speed, and head turning rate were significantly higher in the presence of α-farnesene concentrations >10⁻⁷ w/v, for both strains. Head lifting did not show any effect from α-farnesene. Head turning was associated with both head lifting and walking speed and this association improved with the presence of α-farnesene. Increased attraction to odour source was correlated with improved direction finding at concentrations above 10⁻⁷ w/v. Activity factors such as head turning and walking speed influenced time to locate odour source more than orientation factors. Odour-guided orientation to α-farnesene in codling moth larvae was composed of both locomotory, and to a lesser extent, orientation responses, which increased in a directed fashion to the stimulus.     

From Haeckel to event-pairing: the evolution of developmental sequences

Summary Development involves a series of developmental events, separated by transformations, that follow a particular order or developmental sequence. The sequence may in turn be arbitrarily subdivided into contiguous segments (developmental stages). We discuss the properties of developmental sequences. We also examine the differing analytical approaches that have been used to analyse developmental sequences in an evolutionary context. Ernst Haeckel was a pioneer in this field. His approach was evolutionary and he introduced the idea of sequence heterochrony (evolutionary changes in the sequence of developmental events). Despite the availability of detailed developmental data (e.g. Franz Keibel’s ‘Normal Tables’), Haeckel was unable to undertake a quantitative analysis of developmental data. This is now possible through computer-based analytical techniques such as event-pairing, which can extract important biological information from developmental sequences by mapping them onto established phylogenies. It may also yield data that can be used in phylogeny reconstruction, although the inherent ‘non-independence’ of the data may make this invalid. In future, the methods discussed here may be applied to the analysis of patterns of gene expression in embryos, or adapted to studying gene order on chromosomes.     

On the barn owl’s visual pre-attack behavior: I. Structure of head movements and motion patterns

Barn owls exhibit a rich repertoire of head movements before taking off for prey capture. These movements occur mainly at light levels that allow for the visual detection of prey. To investigate these movements and their functional relevance, we filmed the pre-attack behavior of barn owls. Off-line image analysis enabled reconstruction of all six degrees of freedom of head movements. Three categories of head movements were observed: fixations, head translations and head rotations. The observed rotations contained a translational component. Head rotations did not follow Listing’s law, but could be well described by a second-order surface, which indicated that they are in close agreement with Donder’s law. Head translations did not contain any significant rotational components. Translations were further segmented into straight-line and curved paths. Translations along an axis perpendicular to the line of sight were similar to peering movements observed in other animals. We suggest that these basic motion elements (fixations, head rotations, translations along a straight line, and translation along a curved trajectory) may be combined to form longer and more complex behavior. We speculate that these head movements mainly underlie estimation of distance during prey capture.     

Mechanical behavior of human embryonic stem cell pellet under unconfined compression

As a prelude to the understanding of mechanotransduction in human embryonic stem cell (hESC) differentiation, the mechanical behavior of hESCs in the form of cell pellet is studied. The pellets were tested after 3 or 5 weeks of cell culture in order to demonstrate the effect of the duration of cell culture on the mechanical properties of the pellets. A micromechanical tester was used to conduct unconfined compression on hESC pellet, and experimental, numerical, and analytical methods were combined to determine the mechanical properties of hESC pellet. It is assumed that the mechanical behavior of hESC pellets can be described by an isotropic, linear viscoelastic model consisting of a spring and two Maxwell units in parallel, and the Poisson’s ratio of the hESC pellet is constant based on pellet deformation in the direction perpendicular to the compression direction. Finite element method (FEM) simulation was adopted to determine the values of Poisson’s ratio and the five parameters contained in the viscoelastic model. The variations of Poisson’s ratio and the initial elastic modulus are found to be larger compared with those of the four other parameters. Results show that longer duration of cell culture leads to higher modulus of hESC pellet. The effect of pellet size error on the values of mechanical parameters determined is studied using FEM simulation, and it is found that the effect of size error on Poisson’s ratio and initial elastic modulus is much larger than that on the other parameters.     

Active navigation with a monocular robot

 A scheme is presented that uses the self-motion of a robot, equipped with a single visual sensor, to navigate in a safe manner. The motion strategy used is modelled on the motion of insects that effectively have a single eye and must move in order to determine range. The essence of the strategy is to employ a zigzag motion in order to (a) estimate the range to objects and (b) know the safe distance of travel in the present direction. An example is presented of a laboratory robot moving in a cluttered environment. The results show that this motion strategy can be successfully employed in an autonomous robot to avoid collisions. Received: 17 August 1993/Accepted: 2 May 1994     

Hairstyle as an adaptive means of displaying phenotypic quality

Although facial features that are considered beautiful have been investigated across cultures using the framework of sexual selection theory, the effects of head hair on esthetic evaluations have rarely been examined from an evolutionary perspective. In the present study the effects of six hair-styles (short, medium-length, long, disheveled, knot [hair bun], unkempt) on female facial attractiveness were examined in four dimensions (femininity, youth, health, sexiness) relative to faces without visible head hair (“basic face”). Three evolutionary hypotheses were tested (covering hypothesis, healthy mate theory, and good genes model); only the good genes model was supported by our data. According to this theory, individuals who can afford the high costs of long hair are those who have good phenotypic and genetic quality. In accordance with this hypothesis, we found that only long and medium-length hair had a significant positive effect on ratings of women’s attractiveness; the other hairstyles did not influence the evaluation of their physical beauty. Furthermore, these two hairstyles caused a much larger change in the dimension of health than in the rest of the dimensions. Finally, male raters considered the longer-haired female subjects’ health status better, especially if the subjects were less attractive women. The possible relationships between facial attractiveness and hair are discussed, and alternative explanations are presented.     

Interacting with an artificial partner: modeling the role of emotional aspects

In this paper we introduce a simple model based on probabilistic finite state automata to describe an emotional interaction between a robot and a human user, or between simulated agents. Based on the agent’s personality, attitude, and nature, and on the emotional inputs it receives, the model will determine the next emotional state displayed by the agent itself. The probabilistic and time-varying nature of the model yields rich and dynamic interactions, and an autonomous adaptation to the interlocutor. In addition, a reinforcement learning technique is applied to have one agent drive its partner’s behavior toward desired states. The model may also be used as a tool for behavior analysis, by extracting high probability patterns of interaction and by resorting to the ergodic properties of Markov chains. An early stage part of this work was presented at the 11th International Conference on Knowledge-Based and Intelligent Information and Engineering Systems (KES 2007).     

Mathematical modelling of neuronal dendritic branching patterns in two dimensions: application to retinal ganglion cells in the cat and rat

Sholl’s analysis has been used for about 50years to study neuron branching characteristics based on a linear, semi-log or log—log method. Using the linear two- dimensional Sholl’s method, we call attention to a relationship between the number of intersections of neuronal dendrites with a circle and the numbers of branching points and terminal tips encompassed by the circle, with respect to the circle radius. For that purpose, we present a mathematical model, which incorporates a supposition that the number of dendritic intersections with a circle can be resolved into two components: the number of branching points and the number of terminal tips within the annulus of two adjoining circles. The numbers of intersections and last two sets of data are also presented as cumulative frequency plots and analysed using a logistic model (Boltzmann’s function). Such approaches give rise to several new morphometric parameters, such as, the critical, maximal and mean values of the numbers of intersections, branching points and terminal tips, as well as the abscissas of the inflection points of the corresponding sigmoid plots, with respect to the radius. We discuss these parameters as an additional tool for further morphological classification schemes of vertebrate retinal ganglion cells. To test the models, we apply them first to three groups of morphologically different cat’s retinal ganglion cells (the alpha, gamma and epsilon cells). After that, in order to quantitatively support the classification of the rat’s alpha cells into the inner and outer cells, we apply our models to two subgroups of these cells grouped according to their stratification levels in the inner plexiform layer. We show that differences between most of our parameters calculated for these subgroups are statistically significant. We believe that these models have the potential to aid in the classification of biological images.     

Evolutionary and population dynamics of host–parasitoid interactions

The role of evolutionary dynamics in understanding host–parasitoid interactions is interlinked with the population dynamics of these interactions. Here, we address the problems in coupling evolutionary and population dynamics of host–parasitoid interactions. We review previous theoretical and empirical studies and show that evolution can alter the ecological dynamics of a host–parasitoid interaction. Whether evolution stabilizes or destabilizes the interaction depends on the direction of evolutionary changes, which are affected by ecological, physiological, and genetic details of the insect biology. We examine the effect of life history correlations on population persistence and stability, embedding two types, one of which is competitively inferior but superior in encapsulation (for parasitoid, virulence), in a Nicholson–Bailey model with intraspecific resource competition for host. If a trade-off exists between intraspecific competitive ability and encapsulation (or virulence, as a countermeasure) in both the host and parasitoid, the trade-off or even positive correlation in the parasitoid is less influential to ecological stability than the trade-off in the host. We comment on the bearing this work has on the broader issues of understanding host–parasitoid interactions, including long-term biological control. Received: November 10, 1998 / Accepted: January 18, 1999     

Swarm cognition on off-road autonomous robots

This paper contributes with the first validation of swarm cognition as a useful framework for the design of autonomous robots controllers. The proposed model is built upon the authors’ previous work validated on a simulated robot performing local navigation on a 2-D deterministic world. Based on the ant foraging metaphor and motivated by the multiple covert attention hypothesis, the model consists of a set of simple virtual agents inhabiting the robot’s visual input, searching in a collectively coordinated way for obstacles. Parsimonious and accurate visual attention, operating on a by-need basis, is attained by making the activity of these agents modulated by the robot’s action selection process. A by-product of the system is the maintenance of active, parallel and sparse spatial working memories. In short, the model exhibits the self-organisation of a relevant set of features composing a cognitive system. To show its robustness, the model is extended in this paper to handle the challenges of physical off-road robots equipped with noisy stereoscopic vision sensors. Furthermore, an extensive aggregate of biological arguments sustaining the model is provided. Experimental results show the ability of the model to robustly control the robot on a local navigation task, with less than 1% of the robot’s visual input being analysed. Hence, with this system the computational cost of perception is considerably reduced, thus fostering robot miniaturisation and energetic efficiency. This confirms the advantages of using a swarm-based system, operating in an intricate way with action selection, to judiciously control visual attention and maintain sparse spatial memories, constituting a basic form of swarm cognition.     

Thermodynamical interpretation of evolutionary dynamics on a fitness landscape in an evolution reactor,II

In our previous report [Aita, T., Morinaga, S., Hosimi, Y., 2004. Thermodynamical interpretation of evolutionary dynamics on a fitness landscape in an evolution reactor I. Bull. Math. Biol. 66, 1371–1403], an analogy between thermodynamics and adaptive walks on a Mt. Fuji-type fitness landscape in an artificial selection system was presented. Introducing the ‘free fitness’ as the sum of a fitness term and an entropy term and ‘evolutionary force’ as the gradient of free fitness on a fitness coordinate, we demonstrated that the adaptive walk (=evolution) is driven by the evolutionary force in the direction in which free fitness increases. In this report, we examine the effect of various modifications of the original model on the properties of the adaptive walk. The modifications were as follows: first, mutation distance d was distributed obeying binomial distribution; second, the selection process obeyed the natural selection protocol; third, ruggedness was introduced to the landscape according to the NK model; fourth, a noise was included in the fitness measurement. The effect of each modification was described in the same theoretical framework as the original model by introducing ‘effective’ quantities such as the effective mutation distance or the effective screening size.     

Effects of Male Age and Cervical Proprioceptors on Sexual Aerial Pursuit by Male Flesh Flies, <Emphasis Type="Italic">Neobellieria bullata</Emphasis> (Diptera: Sarcophagidae)

Information from multiple sensory systems is likely combined to provide guidance for male muscoid flies engaged in aerial pursuit of females. To specify the female’s position to the thoracic flight motor, head-centered visual information should be integrated with propriosensory information about head position relative to the thorax because the flies’ heads are flexible around the neck. Head position is encoded by a proprioceptive organ in the ventral neck membrane. We determined in the flesh fly Neobellieria bullata (Sarcophagidae) that accurate propriosensory information is necessary for aerial capture of females by shaving mechanosensory hairs from the organ in male flies and competing them against their sham operated brothers in pursuits of virgin females. We also determined that normal male flies are not successful at capturing females until the second day post-eclosion.     

Do facial gestures,visibility or speed of movement influence gaze following responses in pigtail macaques?

This study investigated whether a human model’s facial gestures, speed of head turn and visibility of face influenced gaze-following responses (GFR) in pigtail macaques. A human provided gaze cues by turning her head 90° in one of four directions. Head turns were immediately followed by a facial movement (pucker, eyebrow raise, tongue protrusion, neutral), or were executed swiftly (< 0.5 s), slowly (3 s) or whilst facing away from the monkeys. All monkeys reliably followed the gaze in all conditions with no differences between conditions. A greater frequency of GFR was found in females compared to males, and two hypotheses for this finding are discussed.     

Testing the rare-alleles model of quantitative variation by artificial selection

The rare-alleles model of quantitative variation posits that a common allele (the ‘wild-type’) and one or more rare alleles segregate at each locus affecting a quantitative trait; a scenario predicted by several distinct evolutionary hypotheses. Single locus arguments suggest that artificial selection should substantially increase the genetic variance (Vg) if the rare-alleles model is accurate. This paper tests the ‘ΔVg prediction’ using a large artificial selection experiment on flower size of Mimulus guttatus. Vg for flower size does evolve, increasing with selection for larger flower while decreasing in the other direction. These data are consistent with a model in which flower size variation is caused by rare, partially dominant alleles. However, this explanation becomes increasingly tenuous when considered with other data (correlated responses to selection and the effects of inbreeding). A combination of modern (marker-based mapping) and classical (biometric) techniques will likely to be required to determine the distribution of allele frequencies at loci influencing quantitative traits.     

Still More “Fancy” and “Myth” than “Fact” in Students’ Conceptions of Evolution

College students do not come to biological sciences classes, including biological anthropology, as “blank slates.” Rather, these students have complex and strongly held scientific misconceptions that often interfere with their ability to understand accurate explanations that are presented in class. Research indicates that a scientific misconception cannot be corrected by simply presenting accurate information; the misconception must be made explicit, and the student must decide for him or herself that it is inaccurate. The first step in helping to facilitate such conceptual change among college students is to understand the nature of the scientific misconceptions. We surveyed 547 undergraduate students at the University of Missouri-Columbia on their understanding of the nature and language of science, the mechanisms of evolution, and their support for both Lamarckian inheritance and teleological evolution. We found few significant sex differences among the respondents and identified some common themes in the students’ misconceptions. Our survey results show that student understanding of evolutionary processes is limited, even among students who accept the validity of biological evolution. We also found that confidence in one’s knowledge of science is not related to actual understanding. We advise instructors in biological anthropology courses to survey their students in order to identify the class-specific scientific misconceptions, and we urge faculty members to incorporate active learning strategies in their courses in order to facilitate conceptual change among the students.     

Brocchi’s Subapennine Fossil Conchology

The Italian geologist Giambattista Brocchi (1771–1826) is presented as a key figure in the historical period preceding young Charles Darwin’s first work on transmutational theory while on the Beagle. The brief biographical account focuses on Brocchi’s writings related to his analogy that species have births and deaths like individuals, and culminates in his most important work, Subapennine Fossil Conchology of 1814. Brocchi’s analogy as an original and fertile way to approach the fossil record was to influence Darwin’s first evolutionary thinking. Relevant passages of the book are presented for the first time in an English translation.     

Post-Haeckelian comparative biology — Adolf Naef’s idealistic morphology

Summary The present study describes the conceptual framework of Adolf Naef’s idealistic morphology as presented at the onset of the 20^th century. According to Naef, Haeckel’s and Gegenbaur’s approaches towards a phylogenetic biology were insufficient. He made it clear that Haeckel’s ideas were based on typological morphology. Thus, Haeckel’s views on comparative biology pointed back to pre-Darwinian concepts. Naef’s consequence was not to work out his own evolutionary morphology but to systematize the earlier typological concept. Consequently, he separated comparative morphology from phylogenetic studies. This idea was adopted by Hennig and was even imported into modern cladism.     

Why do parasitized hosts look different? Resolving the “chicken-egg” dilemma

Phenotypic differences between infected and non-infected hosts are often assumed to be the consequence of parasite infection. However, pre-existing differences in hosts’ phenotypes may promote differential susceptibility to infection. The phenotypic variability observed within the host population may therefore be a cause rather than a consequence of infection. In this study, we aimed at disentangling the causes and the consequences of parasite infection by calculating the value of a phenotypic trait (i.e., the growth rate) of the hosts both before and after infection occurred. That procedure was applied to two natural systems of host–parasite interactions. In the first system, the infection level of an ectoparasite (Tracheliastes polycolpus) decreases the growth rate of its fish host (the rostrum dace, Leuciscus leuciscus). Reciprocally, this same phenotypic trait before infection modulated the future level of host sensitivity to the direct pathogenic effect of the parasite, namely the level of fin degradation. In the second model, causes and consequences linked the growth rate of the fish host (the rainbow smelt, Osmerus mordax) and the level of endoparasite infection (Proteocephalus tetrastomus). Indeed, the host’s growth rate before infection determined the number of parasites later in life, and the parasite biovolume then decreased the host’s growth rate of heavily infected hosts. We demonstrated that reciprocal effects between host phenotypes and parasite infection can occur simultaneously in the wild, and that the observed variation in the host phenotype population was not necessarily a consequence of parasite infection. Disentangling the causality of host–parasite interactions should contribute substantially to evaluating the role of parasites in ecological and evolutionary processes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A Comparison of the Mechanical and Structural Properties of Fibrin Fibers with Other Protein Fibers

In the past few years a great deal of progress has been made in studying the mechanical and structural properties of biological protein fibers. Here, we compare and review the stiffness (Young’s modulus, E) and breaking strain (also called rupture strain or extensibility, ε_max) of numerous biological protein fibers in light of the recently reported mechanical properties of fibrin fibers. Emphasis is also placed on the structural features and molecular mechanisms that endow biological protein fibers with their respective mechanical properties. Generally, stiff biological protein fibers have a Young’s modulus on the order of a few Gigapascal and are not very extensible (ε_max < 20%). They also display a very regular arrangement of their monomeric units. Soft biological protein fibers have a Young’s modulus on the order of a few Megapascal and are very extensible (ε_max > 100%). These soft, extensible fibers employ a variety of molecular mechanisms, such as extending amorphous regions or unfolding protein domains, to accommodate large strains. We conclude our review by proposing a novel model of how fibrin fibers might achieve their extremely large extensibility, despite the regular arrangement of the monomeric fibrin units within a fiber. We propose that fibrin fibers accommodate large strains by two major mechanisms: (1) an α-helix to β-strand conversion of the coiled coils; (2) a partial unfolding of the globular C-terminal domain of the γ-chain. The senior authors R. R. Hantgan and S. T. Lord have contributed equally to this article.