Differential effects of mate competition and mate choice on eastern tiger salamanders

Male tiger salamanders, Ambystoma tigrinum tigrinumare slightly larger in body size and have considerably higher and longer tails than females. To determine how these dimorphic traits affected reproductive performance and success, we conducted breeding trials using 12 males and six females per trial and monitored male-female and male-male interactions. Larger males had an advantage in most aspects of mate competition investigated. Males with higher tails had no advantage in either mate competition or mate choice. Males with longer tails also had no advantage in mate competition but were preferred as mates by females. Larger males interrupted courting males more often than smaller males did. The form of male-male interference was conditional on body size and not on either tail dimension. If the intruder was larger than the courting male, it would shove the female away from the courting male and initiate courtship; if the intruder was smaller, it adopted a female mimicry tactic in which it positioned itself between the courting male and female and performed female behaviours to the courting male while simultaneously courting the female. Our trials indicated that the two components of sexual selection may influence the evolution of different male morphological traits in tiger salamanders. Mate competition may favour increased male body length; mate choice may select for greater male tail length.     

Non-genetic benefits of mate choice: fecundity enhancement and sexy sons

I compared reproductive success (lifetime number of fertilized eggs) as a function of mate choice among females of the stink bug, Nezara viridula L. (Hemiptera: Pentatomidae). 'Choosing' (C) females were placed with one of two males on alternate days. CI females chose between inexperienced males while CR females chose between males previously rejected by CI females. 'Non-choosing' (N) females were placed with the same male every day. Non-choosing NI, NR and NA females encountered, respectively, inexperienced males, previously rejected males, or previously accepted and mated males. Reproductive success was highest for CI females, showing direct selection on mate preferences. Reproductive success did not differ between CR and NR females, indicating that male quality, not the act of choosing a mate, affects fitness. CI females preferred males with longer antennae and their fecundity (lifetime number of eggs) was correlated with male antenna length, consistent with antenna length as an indicator of male ability to transfer nutritive sperm produced in paired harlequin lobes of the testes. Harlequin lobes were smaller in rejected than chosen males. In second-generation mate choice trials, sons of NR females competed well against sons of NA females but not against sons of CI females. This suggests that non-genetic paternal contributions that decline with prior mating account for the attractiveness of sons because sons of CI and NA females shared the same fathers. Sons experiencing mating success came from larger eggs and egg size was greatest for CI females, perhaps as a consequence of paternal nutritional contributions. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

Mate choice and mate competition influence male body size in Japanese medaka

A sexual size dimorphism usually occurs when size-dependent reproductive advantages exist in only one sex. Studies on Japanese medaka, Oryzias latipes, have demonstrated reproductive size advantages in females but not in males, even though males and females are similar in body size. We conducted mate-choice and mate-copying tests in which a female could first associate with, then mate with, either a large (>/=1 sd+X standard length) or a small male (相似文献   

Mating behavior of the golden-orb-weaving spider, Nephila clavipes: II. Sperm capacitation, sperm competition, and fecundity.

60 female golden-orb-weaving spiders were permitted to mate at different times and were sacrificed at systematic intervals so that stored sperm could be examined microscopically for morphological changes. In order to assess female fecundity as a function of time of mating, some females from each of 10 mating groups were allowed to lay eggs. Results show that when females were mated immediately after final molt, sperm changed from an encysted to a flagellate state prior to oviposition. Following oviposition, many sperm became nonflagellate. For females mated later in adulthood, sperm became flagellate more rapidly, and the interval between final molt and oviposition was extended. Capacitation was reflected not only in morphological changes in the sperm but also in additional factors such as agglutinization and the extension of the time between final molt and oviposition in late-mated females. Findings are described as providing a link to the understanding of the sperm competition process. It is suggested that if the interval between matings with the 1st and 2nd male is long, sperm priority is likely; however, if successive matings are relatively close together, sperm priority may not occur. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confidence, uncertainty, and the use of information.

When a person makes predictions about an unknown quantity, a distinction can be made between beliefs about possible values for the quantity and the belief that a given prediction is correct. We use the term uncertainty to refer to the former, and confidence to refer to the latter. Four experiments demonstrated that confidence and uncertainty are affected in different ways by the available information. Confidence increased as the amount of information increased, especially if this variable was manipulated within subjects. Confidence was reduced by increasing the apparent difficulty of the task if manipulated within subjects, but not between subjects. Uncertainty increased with the amount of information (i.e., certainty was reduced), a result that is inconsistent with statistical theory. We proposed that uncertainty is determined by the number of different predictions that can be generated, whereas confidence is influenced by salient factors that people believe affect the accuracy of their predictions. Information is used to suggest possible outcomes in the former case, and to evaluate hypotheses in the latter case. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The variable discharge of cortical neurons: implications for connectivity, computation, and information coding

Cortical neurons exhibit tremendous variability in the number and temporal distribution of spikes in their discharge patterns. Furthermore, this variability appears to be conserved over large regions of the cerebral cortex, suggesting that it is neither reduced nor expanded from stage to stage within a processing pathway. To investigate the principles underlying such statistical homogeneity, we have analyzed a model of synaptic integration incorporating a highly simplified integrate and fire mechanism with decay. We analyzed a "high-input regime" in which neurons receive hundreds of excitatory synaptic inputs during each interspike interval. To produce a graded response in this regime, the neuron must balance excitation with inhibition. We find that a simple integrate and fire mechanism with balanced excitation and inhibition produces a highly variable interspike interval, consistent with experimental data. Detailed information about the temporal pattern of synaptic inputs cannot be recovered from the pattern of output spikes, and we infer that cortical neurons are unlikely to transmit information in the temporal pattern of spike discharge. Rather, we suggest that quantities are represented as rate codes in ensembles of 50-100 neurons. These column-like ensembles tolerate large fractions of common synaptic input and yet covary only weakly in their spike discharge. We find that an ensemble of 100 neurons provides a reliable estimate of rate in just one interspike interval (10-50 msec). Finally, we derived an expression for the variance of the neural spike count that leads to a stable propagation of signal and noise in networks of neurons-that is, conditions that do not impose an accumulation or diminution of noise. The solution implies that single neurons perform simple algebra resembling averaging, and that more sophisticated computations arise by virtue of the anatomical convergence of novel combinations of inputs to the cortical column from external sources.     

Fluctuating asymmetry, mate choice and experimental designs

No Abstract Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour     

Local use of levomycetin in neurosurgery]

A method of local application of the unsoluble medicinal form of chloramphenicol during operations has been developed. Administration of the preparation in a dose up to 2g under an osteal or cutaneous graft induces no side complications and forms a depot of the agent therapeutic concentrations for more than 8 days. There exists a direct relationship between the increasing of staphylococcus resistance to chloramphenicol and the quantity of the agent used in patients.     

Reading ability and use of a story schema in recalling and reconstructing information.

Examined the differences between 48 good and 48 poor 6th-grade readers' use of a story schema in recall and reconstruction tasks. Ss heard a story either in canonical (standard) or interleaved (a form of scrambling) format and were instructed to recall the story and reconstruct the order of story events either directly as they heard it or as it should be. Performance in the reconstruction and recall tasks showed that both good and poor readers could use a story schema when the story followed canonical format; however poor readers' story schema was either not as well-developed or as efficiently used. Both recall and reconstruction data provided evidence that schematic retrieval is not obligatory for either type of reader. Good readers could use a story schema when cued to do so in any task, but poor readers could do so only in the reconstruction task. Differential improvement of poor readers' performance relative to that of good readers' in a 2nd phase of the experiment due to previous experience in the 1st phase was obtained only in the reconstruction task. Conclusions support the view that poor readers perform differently from younger normal children. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Robust and optimal use of information in stereo vision

Differences between the left and right eye's views of the world carry information about three-dimensional scene structure and about the position of the eyes in the head. The contemporary Bayesian approach to perception implies that human performance in using this source of eye-position information can be analysed most usefully by comparison with the performance of a statistically optimal observer. Here we argue that the comparison observer should also be statistically robust, and we find that this requirement leads to qualitatively new behaviours. For example, when presented with a class of stereoscopic stimuli containing inconsistent information about eccentricity of gaze, estimates of this gaze parameter recorded from one robust ideal observer bifurcate at a critical value of stimulus inconsistency. We report an experiment in which human observers also show this phenomenon and we use the experimentally determined critical value to estimate the vertical acuity of the visual system. The Bayesian analysis also provides a highly reliable and biologically plausible algorithm that can recover eye positions even before the classic stereo-correspondence problem is solved, that is, before deciding which features in the left and right images are to be matched.     

Religious ideology, a neglected variable.

Comments on an article by J. T. Jost (see record 2006-12925-001), which presented interesting data relating some personality dimensions to voting patterns in the last three U.S. presidential elections. R. K. Unger is surprised that in his extensive review of the role of ideology, Jost ignored the role of religious ideology in political attitudes and voting behavior. There is ample evidence that level of religious observance (sometimes labeled religiosity, hierarchical religious beliefs, or religious fundamentalism) played a role in 2004 and earlier presidential elections. The relationship between religious ideology and political attitudes is correlational, and one needs to look further for an explanation of their impact. A number of studies indicate relationships between religious fundamentalism and what Jost has termed "system-justifying ideologies." Unger suggests that religiosity has been largely ignored by psychologists interested in social and political behaviors. It is quite possible that religiosity is related to the various personality dimensions discussed by Jost. But we cannot learn more about these potential connections if we continue to ignore the importance of religious ideology as a psychological variable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhesus monkeys use geometric and nongeometric information during a reorientation task.

Rhesus monkeys (Macaca mulata) were subjected to a place finding task in a rectangular room perfectly homogeneous and without distinctive featural information. Results of Experiment 1 show that monkeys rely on the large-scale geometry of the room to retrieve a food reward. Experiments 2 and 3 indicate that subjects use also nongeometric information (colored wall) to reorient. Data of Experiments 4 and 5 suggest that monkeys do not use small angular cues but that they are sensitive to the size of the cues (Experiments 6, 7, and 8). Our findings strengthen the idea that a mechanism based on the geometry of the environment is at work in several mammalian species. In addition, the present data offer new perspectives on spatial cognition in animals that are phylogenetically close to humans. Specifically, the joint use of both geometric and landmark-based cues by rhesus monkeys tends to demonstrate that spatial processing became more flexible with evolution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Life-cycle, longevity and fecundity of Blomia tropicalis (Acari: Glycyphagidae) in a tropical laboratory

HSV-1716 is a replication-restricted, neuroattenuated ICP 34.5 gene mutant of herpes simplex virus type 1 (HSV-1). Because of the attenuated phenotype of ICP 34.5 mutants in rodent models of HSV disease, they have been promoted as potential vaccine strains and gene therapy vectors and have been used by us and others as therapeutic agents for the treatment of experimental malignant tumors. However, all data on the phenotype of HSV-1716 and other ICP 34.5 mutants are from animal model systems, while humans are the natural hosts of HSV-1. To achieve an initial characterization of the phenotype of 1716 in human tissue, we have studied its replication in mature human skin xenografts on SCID mice. We find that replication of 1716 is severely restricted in such human skin grafts relative to both parental wild-type HSV-1 strain 17+ and the HSV-1716 revertant virus 1716R, in which the 759-bp ICP 34.5 gene deletions have been repaired. Moreover, the replication of both 1716 and 17+ is significantly better in the human skin grafts than it is in mouse skin. The implications of these findings are discussed.     

Sex and contextual effects on children's use of interference competition.

Prior research with children and nonhuman animals suggests that females engage in interference competition, in which 1 individual reduces another's chances of gaining access to a resource, only when resources are scarce, whereas males use it ore widely. This study was designed to compare males' and females' use of interference competition in games in which resources were scarce or plentiful. Forty groups of 4 same-sex children from kindergarten or Grade 4 played the 2 games on 2 days. Grade 4 girls used less interference competition when resources were plentiful than when they were scarce. Results are useful for generating a contextually based model of the development of sex differences in competitive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficient identification of postdischarge surgical site infections: use of automated pharmacy dispensing information, administrative data, and medical record information

Although most surgical site infections (SSIs) occur after hospital discharge, there is no efficient way to identify them. The utility of automated claims and electronic medical record data for this purpose was assessed in a cohort of 4086 nonobstetric procedures following which 96 postdischarge SSIs occurred. Coded diagnoses, tests, and treatments were assessed by use of recursive partitioning, with 10-fold cross-validation, and logistic regression with bootstrap resampling. Specific codes and combinations of codes identified a subset of 2% of all procedures among which 74% of SSIs had occurred. Accepting a specificity of 92% improved the sensitivity from 74% to 92%. Use of only hospital discharge diagnosis codes plus pharmacy dispensing data had sensitivity of 77% and specificity of 94%. All of these performance characteristics were better than questionnaire responses from patients or surgeons. Thus, information routinely collected by health care systems can be the basis of an efficient, largely passive, surveillance system for postdischarge SSIs.     

Developmental differences in the use of distinctiveness, consensus, and consistency information for making causal attributions.

Examined developmental differences in the use of distinctiveness, consensus, and consistency information for making causal attributions. 144 1st, 3rd and 6th graders and college students were presented with brief story pairs consisting of an act manifested by an agent toward a target person. Each story in a pair was accompanied by a different level of a particular type of information (e.g., high consensus for one and low consensus for the other). Ss were asked to make causal inferences about both the agents and the targets. Results reveal significant age-related differences in the ability to use each type of information. Young children's use of distinctiveness information yielded the predicted agent attributions significantly more often than it yielded the predicted target attributions, while the reverse was true for consensus information. Findings are interpreted in terms of causal principles: Information was used in the predicted manner at a younger age when a covariation principle was required than when a discounting principle was required. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Condom use as a dependent variable: measurement issues relevant to HIV prevention programs

The value of condoms in efforts to slow the spread of HIV infection has been well established in the literature. Behavioral science faces the challenge of promoting condom use through intervention programs. As these programs are evaluated, multiple issues should be considered in relation to measuring participant use of condoms for the purposes of preventing HIV infection. Lack of attention to these issues is likely to create a large number of Type I and Type II errors. Ten common sources of error are described and corresponding recommendations for eliminating these errors are offered. A review of published studies shows that there is little consistency relevant to controlling for these sources of error. Incorporation of standardized methodology will allow for more accurate program evaluation and benefit researchers by facilitating comparisons across studies.     

Local control of information flow in segmental and ascending collaterals of single afferents

In the vertebrate spinal cord, the activation of GABA(gamma-amino-butyric acid)-releasing interneurons that synapse with intraspinal terminals of sensory fibres leading into the central nervous system (afferent fibres) produces primary afferent depolarization and presynaptic inhibition. It is not known to what extent these presynaptic mechanisms allow a selective control of information transmitted through specific sets of intraspinal branches of individual afferents. Here we study the local nature of the presynaptic control by measuring primary afferent depolarization simultaneously in two intraspinal collaterals of the same muscle spindle afferent. One of these collaterals ends at the L6-L7 segmental level in the intermediate nucleus, and the other ascends to segment L3 within Clarke's column, the site of origin of spinocerebellar neurons. Our results indicate that there are central mechanisms that are able to affect independently the synaptic effectiveness of segmental and ascending collaterals of individual muscle spindle afferents. Focal control of presynaptic inhibition thus allows the intraspinal branches of afferent fibres to function as a dynamic assembly that can be fractionated to convey information to selected neuronal targets. This may be a mechanism by which different spinal postsynaptic targets that are coupled by sensory input from a common source could be uncoupled.