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Trait Expression (trait + expression)

Distribution by Scientific Domains

Life Sciences	70%

Selected Abstracts

SEXUAL SELECTION AND INTERACTING PHENOTYPES IN EXPERIMENTAL EVOLUTION: A STUDY OF DROSOPHILA PSEUDOOBSCURA MATING BEHAVIOR

EVOLUTION, Issue 7 2008
Leonardo D. Bacigalupe
Sexual selection requires social interactions, particularly between the sexes. When trait expression is influenced by social interactions, such traits are called interacting phenotypes and only recently have the evolutionary consequences of interacting phenotypes been considered. Here we investigated how variation in relative fitness, or the opportunity for sexual selection, affected the evolutionary trajectories of interacting phenotypes. We used experimentally evolved populations of the naturally promiscuous Drosophila pseudoobscura, in which the numbers of potential interactions between the sexes, and therefore relative fitness, were manipulated by altering natural levels of female promiscuity. We considered two different mating interactions between the sexes: mating speed and copulation duration. We investigated the evolutionary trajectories of means and (co)variances (P) and also the influence of genetic drift on the evolutionary response of these interactions. Our sexual selection treatments did not affect the means of either mating speed or copulation duration, but they did affect P. We found that the means of both traits differed among replicates within each selection treatment whereas the Ps did not. Changes as a consequence of genetic drift were excluded. Our results show that although variable potential strengths of sexual interactions influence the evolution of interacting phenotypes, the influence may be nonlinear. [source]

Diverse developmental mechanisms contribute to different levels of diversity in horned beetles

EVOLUTION AND DEVELOPMENT, Issue 3 2005
Armin P. Moczek
Summary An ongoing challenge to evolutionary developmental biology is to understand how developmental evolution on the level of populations and closely related species relates to macroevolutionary transformations and the origin of morphological novelties. Here we explore the developmental basis of beetle horns, a morphological novelty that exhibits remarkable diversity on a variety of levels. In this study, we examined two congeneric Onthophagus species in which males develop into alternative horned and hornless morphs and different sexes express marked sexual dimorphism. In addition, both species differ in the body region (head vs. thorax) that develops the horn. Using a comparative morphological approach we show that prepupal growth of horn primordia during late larval development, as well as reabsorption of horn primordia during the pupal stage, contribute to horn expression in adults. We also show that variable combinations of both mechanisms are employed during development to modify horn expression of different horns in the same individual, the same horn in different sexes, and different horns in different species. We then examine expression patterns of two transcription factors, Distal-less (Dll) and aristaless (al), in the context of prepupal horn growth in alternative male morphs and sexual dimorphisms in the same two species. Expression patterns are qualitatively consistent with the hypothesis that both transcription factors function in the context of horn development similar to their known roles in patterning a wide variety of arthropod appendages. Our results suggest that the origin of morphological novelties, such as beetle horns, rests, at least in part, on the redeployment of already existing developmental mechanisms, such as appendage patterning processes. Our results also suggest, however, that little to no phylogenetic distance is needed for the evolution of very different modifier mechanisms that allow for substantial modulation of trait expression at different time points during development in different species, sexes, or tissue regions of the same individual. We discuss the implications of our results for our understanding of the evolution of horned beetle diversity and the origin and diversification of morphological novelties. [source]

Lingual cortical mandibular defects (Stafne's defect): an anthropological approach based on prehistoric skeletons from the Canary Islands

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2002
John R. Lukacs
Abstract While posterior lingual mandibular depressions (Stafne's defect) are often discussed in clinical reports, they are rarely the subject of anthropological research. This situation is paradoxical since osteologists and skeletal biologists are in a position to enhance understanding of the trait's aetiology by systematically recording the trait in recent and prehistoric skeletal collections. This report reviews anthropological studies of cortical defects of the mandible, recommends a protocol for recording observations in trait variation, and presents new data for the prevalence of Stafne's defect,lingual cortical defects of the mandibular corpus. Among the Guanches of Tenerife in the Canary Islands (Spain), the prevalence of lingual cortical defects is 3.32% (15/452), males are more frequently affected than females, and there is a tendency for individuals with antemortem tooth loss to display larger lesions than individuals without antemortem loss of teeth. Defects of the left side are somewhat more variable in position than defects located on the right. In comparative perspective, prevalence of lingual cortical defects among the Guanches is high, given the overall 1.07% prevalence reported for archaeological series (Finnegan & Marcsik,1980), but is similar to figures reported for the Avar period sample from Hungary 3.73%. Prospects for the use of lingual cortical defects as non-metric traits of value in population distance studies remain uncertain since variation in trait expression may have a high environmental component. However, if human osteologists routinely include observations of lingual mandibular cortical defects in their analysis of skeletal collections, the data required to elucidate factors responsible for the trait's cultural, ecological, temporal and geographical patterning will more rapidly become established. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Beyond taxonomy: a review of macroinvertebrate trait-based community descriptors as tools for freshwater biomonitoring

JOURNAL OF APPLIED ECOLOGY, Issue 4 2010
Salomé Menezes
Summary 1.,Species traits have been frequently used in ecological studies in an attempt to develop a general ecological framework linking biological communities to habitat pressures. The trait approach offers a mechanistic alternative to traditional taxonomy-based descriptors. This review focuses on research employing traits as biomonitoring tools for freshwater ecosystems, although the lessons learned have wider application in the assessment of other ecosystem types. 2.,We review the support from ecological theory to employ species traits for biomonitoring purposes (e.g. the habitat templet concept, landscape filtering hypothesis), and the subsequent studies that test the hypotheses arising from these theories, and apply this knowledge under real freshwater biomonitoring scenarios. We also include studies that deal with more specific issues such as trait trade-offs and trait syndromes. 3.,We highlight the functional trait approach as one of the most promising tools emerging for biomonitoring freshwater ecosystems. Several technical issues are addressed and solutions are proposed. We discuss the need for: a broader unified trait biomonitoring tool; a more accurate understanding of the natural variation of community patterns of trait expression; approaches to diminish the effects of trait trade-offs and trait syndromes; additional life history and ecological requirement studies; and the detection of specific impacts under multiple stressor scenarios. 4.,Synthesis and applications. This review provides biologists with the conceptual underpinning for the use of species traits as community descriptors and for freshwater biomonitoring and management. We expect that the functional trait approach will ultimately improve communication to managers and legislators of the importance of protecting freshwater ecosystem functions. [source]

Legionella pneumophila couples fatty acid flux to microbial differentiation and virulence

MOLECULAR MICROBIOLOGY, Issue 5 2009
Rachel L. Edwards
Summary During its life cycle, Legionella pneumophila alternates between at least two phenotypes: a resilient, infectious form equipped for transmission and a replicative cell type that grows in amoebae and macrophages. Considering its versatility, we postulated that multiple cues regulate L. pneumophila differentiation. Beginning with a Biolog Phenotype MicroArray screen, we demonstrate that excess short-chain fatty acids (SCFAs) trigger replicative cells to cease growth and activate their panel of transmissive traits. To co-ordinate their response to SCFAs, L. pneumophila utilizes the LetA/LetS two-component system, but not phosphotransacetylase or acetyl kinase, two enzymes that generate high-energy phosphate intermediates. Instead, the stringent response enzyme SpoT appears to monitor fatty acid biosynthesis to govern transmission trait expression, as an altered distribution of acylated acyl carrier proteins correlated with the SpoT-dependent differentiation of cells treated with either excess SCFAs or the fatty acid biosynthesis inhibitors cerulenin and 5-(tetradecyloxy)-2-furoic acid. We postulate that, by exploiting the stringent response pathway to couple cellular differentiation to its metabolic state, L. pneumophila swiftly acclimates to stresses encountered in its host or the environment, thereby enhancing its overall fitness. [source]

Contribution of direct and maternal genetic effects to life-history evolution

NEW PHYTOLOGIST, Issue 3 2009
Laura F. Galloway
Summary ,,Maternal effects are ubiquitous in nature. In plants, most work has focused on the effects of maternal environments on offspring trait expression. Less is known about the prevalence of genetic maternal effects and how they influence adaptive evolution. Here, we used multivariate genetic models to estimate the contributions of maternal and direct genetic (co)variance, the cross-generation direct-maternal covariance, and M, the matrix of maternal effect coefficients, for life-history traits in Campanulastrum americanum, a monocarpic herb. ,,Following a three-generation breeding design, we grew paternal half-sib families with full-sib relatives of each parent and measured juvenile and adult traits. ,,Seed size was influenced exclusively by maternal environmental effects, whereas maternal genetic effects influenced traits throughout the life cycle, including strong direct and maternal additive genetic correlations within and between generations for phenological and size traits. Examination of M suggested that both juvenile and adult traits in maternal plants influenced the expression of offspring traits. ,,This study reveals substantial potential for genetic maternal effects to contribute to adaptive evolution including cross-generation direct-maternal correlations that may slow selection response, maternal effects on phenology that reinforce genetic correlations, and within- and between-generation genetic correlations that may influence life-history polymorphism. [source]

Brief communication: Familial resemblance in digit ratio (2D:4D)

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009
Martin Voracek
Abstract Familial resemblance in the second-to-fourth digit ratio (2D:4D), a proxy for prenatal androgen action, was studied in 1,260 individuals from 235 Austrian families. In agreement with findings from twin studies of 2D:4D, heritability estimates based on parent,child and full-sib dyad similarity indicated substantial genetic contributions to trait expression (57% for right hand, 48% for left hand 2D:4D). Because twin studies have found nonadditive genetic as well as shared environmental effects on 2D:4D to be negligible or nil, these family-based estimates in all likelihood reflect the narrow-sense (additive genetic) heritability of the trait. Directional (right-minus-left) asymmetry in 2D:4D was only weakly heritable (6%). The pattern of same-sex and different-sex parent,child and full-sib correlations yielded no evidence for X-linked inheritance. This is surprising, considering evidence for associations of male 2D:4D with sensitivity to testosterone (functional variants of the X-linked androgen receptor gene). 2D:4D was particularly strongly heritable through male lines (father,son and brother,brother correlations), thus raising the possibility that Y-linked genes (such as the sex-determining region SRY) might influence 2D:4D expression. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source]

Linking personality states, current social roles and major life goals

EUROPEAN JOURNAL OF PERSONALITY, Issue 6 2009
Wiebke BleidornArticle first published online: 23 JUN 200
Abstract Employing an experience-sampling design, the interplay between personality states, social roles and major life goals was examined as it unfolds in the stream of people's daily lives. Multilevel analyses revealed a considerable amount of both within- and between-person variability in state expressions of personality traits justifying further examination of predictors at both levels of analyses. Roles proved as predictors of current personality states albeit effects differed significantly between individuals. Life goals accounted for between-person differences in average personality states but were not effective in predicting differences in relations between personality states and roles. Altogether, findings testify to the viability of the employed research strategy to analyse the interplay between both dispositional and fluctuating influences on individuals' trait expressions in behaviour. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Cranial Nonmetric Variation and Estimating Ancestry,

JOURNAL OF FORENSIC SCIENCES, Issue 5 2009
Joseph T. Hefner Ph.D.
Abstract:, Historically, when predicting the ancestry of human skeletal remains, forensic anthropologists have not fully considered the variation within human populations, but instead have relied on a typological, experience-based approach. Unfortunately, reliance on observer experience has produced a method that is as much an art as it is a science. This research focuses on the frequency distribution and inter-trait correlations of 11 common morphoscopic traits to demonstrate that the experience-based approach to ancestry prediction is indeed an art that is unscientific, because it is unreplicable, unreliable, and invalid. Ten of 11 traits examined had frequency distributions with significant differences (p < 0.001) between groups, but the range in variation of these traits far exceeds previous assumptions. Such within group variation clearly demonstrates that extreme trait expressions are not reliable for estimating ancestry through visual observation alone, but instead that these traits should be analyzed within a statistical framework. [source]

Auricular surface aging: Worse than expected?

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2006
A test of the revised method on a documented historic skeletal assemblage
Abstract This study presents results and recommendations arising from a blind test of the revised age estimation method for the auricular surface as proposed by Buckberry and Chamberlain (2002 Am. J. Phys. Anthropol. 119:321,329). Auricular surfaces of 167 individuals from St. Bride's, London, a documented skeletal assemblage spanning the late 17th to early 19th century, were analyzed for the following traits: transverse organization, surface texture appearance, macroporosity, microporosity, and morphological changes to the apex. Composite scores of trait expressions were found to generally correlate with age and to show a positive association with known chronological age (P < 0.01). However, when composite scores were combined to define auricular surface phases, which ultimately assign age estimations, only three distinct developmental stages, compared with seven suggested by Buckberry and Chamberlain (2002 Am. J. Phys. Anthropol. 119:321,329), could be identified and statistically supported, all showing a considerable degree of individual variation in age. The most well-defined stage in the St. Bride's assemblage was the new stage III, where the majority of individuals were older than 60 years, whereas middle-aged adults displayed a large variation in composite scores. These results provide little hope for a promising application of age-at-death estimation of auricular surface morphology traits with higher resolution, but rather suggest indications of broad stages of life. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source]