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Results for “trait plasticity”

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PubMed2003

Phenotypic plasticity of sternopleural bristle number in temperate and tropical populations of Drosophila melanogaster.

We investigated the phenotypic plasticity of sternopleural bristle (SB) number as a function of growth temperature in isofemale lines from temperate (France) and tropical (Congo) populations of Drosophila melanogaster. We found concave reaction norms with a maximum in the middle of the thermal range, except in four African lines which exhibited a regularly decreasing response curve. Genetic variability (intraclass correlation) and evolvability (genetic CV, coefficient of variation) were independent properties and did not change with temperature. Residual, within-line variability was, however, strongly influenced by growth temperature, showing a U-shaped response curve and a minimum CV of 9% at 21.5 degrees C. As expected from a previously known latitudinal cline, maximum values (MV) were higher in temperate than in tropical flies. The temperature of maximum value (TMV) was observed at a higher temperature in the tropical population, in agreement with similar adaptive trends already observed for other quantitative traits. Significant negative correlations within each population were observed between a plasticity curvature parameter and MV or TMV. No difference in curvature was, however, observed between populations, in spite of their very different MVs.

Animals↗

PubMed2006

Size correction: comparing morphological traits among populations and environments.

Morphological relationships change with overall body size and body size often varies among populations. Therefore, quantitative analyses of individual traits from organisms in different populations or environments (e.g., in studies of phenotypic plasticity) often adjust for differences in body size to isolate changes in allometry. Most studies of among population variation in morphology either (1) use analysis of covariance (ANCOVA) with a univariate measure of body size as the covariate, or (2) compare residuals from ordinary least squares regression of each trait against body size or the first principal component of the pooled data (shearing). However, both approaches are problematic. ANCOVA depends on assumptions (small variance in the covariate) that are frequently violated in this context. Residuals analysis assumes that scaling relationships within groups are equal, but this assumption is rarely tested. Furthermore, scaling relationships obtained from pooled data typically mischaracterize within-group scaling relationships. We discuss potential biases imposed by the application of ANCOVA and residuals analysis for quantifying morphological differences, and elaborate and demonstrate a more effective alternative: common principal components analysis combined with Burnaby's back-projection method.

Biological Evolution↗

PubMed2026

Marine Vibrio Biocatalysts as Unique Green Transformation (GX) Tools at the Time to Sustainable Development Goals (SDGs).

Vibrios have sustained various types of ocean ecosystems, being key players in marine mineral cycles and essential partners in specific groups of marine life. Observed genome plasticity and metabolic versatility are some of the unique biological features of vibrios, and these traits could contribute in expanding their ecological niche in marine environments. Vibrios are now recognized as ecophysiologically essential microbial species for our planet. At the time to "Sustainable Development Goals" (SDGs), their genome plasticity and metabolic versatility have also been studied with the aim of solving global issues such as energy production and plastic pollution by creating new microbial biocatalysts. Here, we introduce recent progress on the application of vibrios aiming towards green transformation (GX).

Vibrio↗

PubMed2000

Successful free flap transfer and salvage in sickle cell trait.

The presence of sickle cell haemoglobin is generally regarded as a contraindication to free tissue transfer. We present the case of a 42-year-old male with sickle cell trait who had free transfer of a latissimus dorsi flap to cover a gunshot wound to his thigh. His initial haemoglobin S was 36%. Early flap failure from venous thrombosis was successfully salvaged by re-anastomosis to alternative vessels.

Adult↗

PubMed1991

Preoperative anxiety and motives for surgery.

Preoperative anxiety was assessed in 20 patients undergoing surgery for esthetic reasons and 20 other surgical patients. Patients with plastic surgery reported significantly less anxiety than patients with general surgery, as measured by the State-Trait Anxiety Inventory.

Adult↗

PubMed2007

Reaction norms of life history traits in response to zinc in Thlaspi caerulescens from metalliferous and nonmetalliferous sites.

* We examined phenotypic plasticity of fitness components in response to zinc (Zn) in the Zn hyperaccumulator, Thlaspi caerulescens. * Two populations from Zn-enriched soils (M) and two populations from normal soils (NM) were grown in pots at three Zn concentrations (0, 1000 and 8000 mg kg(-1) Zn), for an entire life cycle. Growth, Zn accumulation and fitness components were assessed. * Based on vegetative growth, M and NM populations had similar Zn tolerance at 1000 mg kg(-1) Zn. However, reproductive output was markedly decreased in NM at 1000 and 8000 mg kg(-1) Zn. In M populations, Zn did not affect fitness. However, low Zn status enhanced reproductive output in year 1 compared with year 2 and decreased survival after the first flowering season. * M populations are able to achieve equal fitness across a broad range of Zn concentrations in soil by different combinations of fecundity and longevity. No cost of higher tolerance was demonstrated in M populations. Reproductive traits appeared to be a more sensitive indicator of tolerance than vegetative growth.

Adaptation, Physiological↗

PubMed1998

Canalization, genetic assimilation and preadaptation. A quantitative genetic model.

We propose a mathematical model to analyze the evolution of canalization for a trait under stabilizing selection, where each individual in the population is randomly exposed to different environmental conditions, independently of its genotype. Without canalization, our trait (primary phenotype) is affected by both genetic variation and environmental perturbations (morphogenic environment). Selection of the trait depends on individually varying environmental conditions (selecting environment). Assuming no plasticity initially, morphogenic effects are not correlated with the direction of selection in individual environments. Under quite plausible assumptions we show that natural selection favors a system of canalization that tends to repress deviations from the phenotype that is optimal in the most common selecting environment. However, many experimental results, dating back to Waddington and others, indicate that natural canalization systems may fail under extreme environments. While this can be explained as an impossibility of the system to cope with extreme morphogenic pressure, we show that a canalization system that tends to be inactivated in extreme environments is even more advantageous than rigid canalization. Moreover, once this adaptive canalization is established, the resulting evolution of primary phenotype enables substantial preadaptation to permanent environmental changes resembling extreme niches of the previous environment.

Adaptation, Physiological↗

PubMed1994

Mammalian adrenal chromaffin cells coexpress the epinephrine-synthesizing enzyme and neuronal properties in vivo and in vitro.

Adrenal chromaffin cells and neurons of the sympathetic ganglia are derived from common precursors in the neural crest. The phenotype of the sympathoadrenal progenitor cell is unknown, but adult chromaffin cells are distinguished by the expression of phenylethanolamine-N-methyltransferase (PNMT) and the lack of neurofilament (NF) and neuritic processes. Mature neurons have processes and express NF, but are PNMT-. We hypothesize that embryonic adrenal cells are multipotential. This implies that the cells can coactivate all the traits characteristic of mature sympathetic neurons and chromaffin cells and then selectively extinguish expression of either the chromaffin or the neuronal traits, depending on the environment. We further asked whether this repression is plastic and can be environmentally modified in adult chromaffin cells. We demonstrate that, in vivo, embryonic (e-) rat adrenal cells coexpress PNMT and the intermediate- and high-molecular-weight neurofilaments at e-15.5 (21%), e-16.5 (40%), and e-20.5 (23%). When cultured in complete or glucocorticoid-depleted media for 5 to 14 days, 20% of adult bovine chromaffin cells which remain PNMT+ reexpress NF and extend NF+ and PNMT+ processes. Both the expression of NF and the extension of neurites are inhibited by the addition of 10(-7) M dexamethasone to complete media. We conclude that the embryonic adrenal medullary cells simultaneously express traits of mature chromaffin cells and neurons and that the phenotypes remain labile in the adult mammalian chromaffin cell. In addition, coexpression of PNMT, NF, and neurite extension are not mutually exclusive in either the embryonic or adult adrenal chromaffin cell.

Adrenal Medulla↗

PubMed2006

The adaptive dynamics of function-valued traits.

This study extends the framework of adaptive dynamics to function-valued traits. Such adaptive traits naturally arise in a great variety of settings: variable or heterogeneous environments, age-structured populations, phenotypic plasticity, patterns of growth and form, resource gradients, and in many other areas of evolutionary ecology. Adaptive dynamics theory allows analysing the long-term evolution of such traits under the density-dependent and frequency-dependent selection pressures resulting from feedback between evolving populations and their ecological environment. Starting from individual-based considerations, we derive equations describing the expected dynamics of a function-valued trait in asexually reproducing populations under mutation-limited evolution, thus generalizing the canonical equation of adaptive dynamics to function-valued traits. We explain in detail how to account for various kinds of evolutionary constraints on the adaptive dynamics of function-valued traits. To illustrate the utility of our approach, we present applications to two specific examples that address, respectively, the evolution of metabolic investment strategies along resource gradients, and the evolution of seasonal flowering schedules in temporally varying environments.

Adaptation, Biological↗

PubMed2006

BDNF Val66Met allele is associated with reduced hippocampal volume in healthy subjects.

BACKGROUND: A frequent polymorphism of the brain-derived neurotrophic factor (BDNF) gene (val(66)met) has been suggested to modulate hippocampal neuronal plasticity and has been associated with individual variations in emotional reactivity traits and episodic memory. METHODS: The hippocampal formation was outlined in high-resolution anatomical magnetic resonance imaging (MRI) data in a sample of 36 healthy volunteers and compared between individuals as a function of the presence of the met-BDNF allele. Both whole-brain volume corrected and uncorrected data were tested for effects of genotype, sex, and age. RESULTS: The met-BDNF allele was associated with an 11% reduction in the volume of the hippocampal formation. CONCLUSIONS: In spite of a relatively small sample size, the presence of the met-BDNF allele was found associated with a reduced volume of the hippocampal formation in healthy volunteers and may represent a vulnerability factor for the development of disease processes associated with the dysfunction of this brain region.

Adolescent↗

PubMed2004

Optimization modeling of plant root architecture for water and phosphorus acquisition.

An optimization model is presented that examines the relationship between root architecture and multiple resource acquisition, specifically water and phosphorus in spatially heterogeneous environments. The basal root growth angle of an individual common bean plant, which determines the orientation and localization of the bulk of the root system, was modeled as the decision variable. The total payoff to the plant, the benefit obtained from water and phosphorus acquisition, minus the costs of spatial competition between roots, is given as a function of the (x,y) coordinates of the basal root in two-dimensional Cartesian space. We obtained a general solution and applied it to four unique environmental cases which are as follows: (1) the case of uniformly distributed water and phosphorus; (2) the case of localized shallow phosphorus; (3) the case of localized deep water; and (4) the case of shallow phosphorus and deep water. The general solution states that the optimal basal root growth angle will occur at the point where the total rate of change in the value of the resources acquired equals the total rate of change in cost that results from locating the root deeper in the soil. An optimizing plant locates its roots deeper in the soil profile until the marginal benefit exactly equals the marginal cost. The model predicts that the basal root angle of an optimizing plant will be shallower for Case 2 and deeper for Case 3, relative to the basal root angle obtained in the case of uniformly distributed water and phosphorus. The optimal basal root angle for Case 4 will depend on the marginal rate of substitution of water availability for phosphorus availability that occurs with depth. Empirical observations of bean root architecture in the greenhouse and in the field confirm model results and are discussed. In addition, the potential importance of phenotypic plasticity and phenotypic variation are discussed in relation to optimization of traits and adaptation to spatially heterogeneous environments.

Adaptation, Physiological↗

PubMed2004

Flycatcher song in allopatry and sympatry--convergence, divergence and reinforcement.

The theory of reinforcement predicts that natural selection against the production of unfit hybrids favours traits that increase assortative mating. Whether culturally inherited traits, such as bird song, can increase assortative mating by reinforcement is largely unknown. We compared songs of pied (Ficedula hypoleuca) and collared flycatchers (F. albicollis) from two hybrid zones of different ages with songs from allopatric populations. Previously, a character divergence in male plumage traits has been shown to reinforce premating isolation in sympatric flycatchers. In contrast, we find that the song of the pied flycatcher has converged towards that of the collared flycatcher (mixed singing). However, a corresponding divergence in the collared flycatcher shows that the species differences in song characters are maintained in sympatry. Genetic analyses suggest that mixed song is not caused by introgression from the collared flycatcher, but rather due to heterospecific copying. Circumstantial evidence suggests that mixed song may increase the rate of maladaptive hybridization. In the oldest hybrid zone where reinforcement on plumage traits is most pronounced, the frequency of mixed singing and hybridization is also lowest. Thus, we suggest that reinforcement has reduced the frequency of mixed singing in the pied flycatcher and caused a divergence in the song of the collared flycatcher. Whether a culturally inherited trait promotes or opposes speciation in sympatry may depend on its plasticity. The degree of plasticity may be genetically determined and accordingly under selection by reinforcement.

Animals↗

PubMed2007

Phenotypic flexibility in the basal metabolic rate of laughing doves: responses to short-term thermal acclimation.

Many birds exhibit considerable phenotypic flexibility in maintenance energy requirements, and up- or downregulate basal metabolic rate (BMR) over time scales of days to weeks during thermal acclimation. However, the extent to which individual birds can reverse the direction of BMR adjustments over short time scales remains unknown. In this study, we examined metabolic responses to short-term thermal acclimation in laughing doves Streptopelia senegalensis. In 30 wild-caught doves (mean body mass=92.6 g) divided into three experimental groups of 10 birds each, initial BMR averaged 0.760+/-0.036 W. Thereafter, each group was acclimated to one of three acclimation air temperatures (T(acc)=10, 22 or 35 degrees C) for 21 days, during which time the doves were housed in individual cages. Following the first acclimation period (acclimation I), BMR (W) was significantly lower and was negatively and linearly related to T(acc) [BMR=0.714-0.005T(acc)]. Acclimation I BMR varied from 0.546+/-0.039 W in doves acclimated to T(acc)=35 degrees C to 0.665+/-0.058 W at T(acc)=10 degrees C. A second acclimation period of a further 21 days (acclimation II) revealed that the direction of BMR adjustments could be reversed within individuals, with acclimation II BMR again negatively and linearly related to T(acc). The slope of the relationship between BMR and T(acc) following acclimation II was not significantly different to that following acclimation I. BMR exhibited consistent inter-individual variation, with a low but significant repeatability of 0.113. The within-individual BMR variation of up to 26% that we observed in laughing doves reveals that BMR is a highly flexible trait in this species, and reiterates the need to take phenotypic plasticity into account in comparative analyses of avian energetic parameters.

Acclimatization↗

PubMed1993

Metric characters of the hard palate and their cephalometric correlations in Namibian !Kung San and Kenyan tribes.

The metric characters of the head and hard palate of 138 black males from Kenya and 110 male !Kung San from Namibia have for the first time been compared to describe the black and Khoisan variation with respect to these special trait systems. The palate measurements were taken from prints of self-hardening plastic. Nearly all metric characters show significant differences between the two populations, which are reflected in a relevant discriminant function. The analyses of correlations between the individual head and palate measurements yield different correlation patterns in the two samples also with regard to their significance and direction. These results and the generally low correlation coefficients can be explained by the complex processes of allometric head growth, resulting in the Sans' pedomorphous and the blacks' more adultiform head and palate trait combinations.

Adult↗

PubMed2003

Phenotypic plasticity and evolutionary potential in somatic cells of Armillaria gallica.

Somatic cells of Armillaria gallica fruit bodies have been shown to possess different genotypes for molecular-marker and mating-type loci. Here we report experiments on six quantitative traits and demonstrate that somatic cells of fruit bodies possess almost as much genetic variation for growth rate and phenotypic plasticity as do spores, the products of meiosis. Genetically distinct somatic cells therefore have the potential to grow at different rates relative to one another during primordial fruit body formation. This may confer an advantage on all cell lines within a fruit body, not just those that happen to grow better under a particular set of conditions. To our knowledge, genetic variation for fitness-related traits that make up a single genetic individual has not been reported before.

Adaptation, Physiological↗

PubMedDate not supplied

Haploid vegetative mycelia of Armillaria gallica show among-cell-line variation for growth and phenotypic plasticity.

Vegetative mycelial cells of Armillaria are expected to have diploid nuclei. Cells from a single mycelium therefore would not be expected to differ from one another for ecologically relevant quantitative traits. We isolated two sets of basidiome cell lines (from spores and stipe cells) and one set of vegetative cell lines (from an attached rhizomorph) from a single contiguous Armillaria gallica mycelium. We isolated a second set of vegetative cell lines from the soil 20 cm from the above basidiome-rhizomorph complex. In all four sets of cell lines in situ DAPI-DNA measurements showed cells are haploid and quantitative-trait analyses of cell lines grown at different water potentials revealed high levels of among-cell-line genetic variation for both growth and phenotypic plasticity. Haploidy and the existence of ecologically relevant genetic variation within vegetative individuals are unexpected and mean that a process similar to evolutionary adaptation could take place within the soma of a genetic individual. We believe this is a key to understanding how large A. gallica mycelia survive exposure to variation in ecological conditions during lives that potentially span several tree (host) generations.

Agaricales↗

PubMed2005

Early seasonal development of brain song control nuclei in male blue tits.

In songbirds, the seasonal growth of the song system is generally thought to be controlled by the spring increase in plasma levels of testosterone and/or related changes in singing activity. Here we report an extremely early seasonal growth (before February) of the song control nuclei HVC and RA in Corsican blue tits (Parus caeruleus) indicating that the vernal development of these nuclei occurs well before the vernal increase in plasma testosterone, testes size and song activity. The development of HVC and RA occurred simultaneously in two populations that are known to breed consistently 1 month apart as an adaptation to heterogeneous landscapes (predominance of broad-leaved deciduous versus evergreen oak trees). The unidentified environmental and/or physiological cues controlling the plasticity in the song system must therefore differ, at least in part, from those affecting other morphological and physiological traits controlling reproduction.

Adaptation, Physiological↗

PubMed2000

Relations between variable rates of growth, metabolic costs and growth efficiencies in individual Sydney rock oysters (Saccostrea commercialis).

Rock oysters from a mass selection trial were compared with wild-caught (control) oysters of the same age to determine the physiological basis for faster growth rates amongst the selected individuals, and to describe the associated flexibility in phenotypic traits of feeding, metabolism and growth. In confirmation of earlier studies, fast growth was associated with faster rates of feeding, reduced metabolic rates and lower metabolic costs of growth. Selected individuals deposited more protein, at a lower metabolic cost, than the controls. Control oysters, however, deposited more lipid than the selected oysters, though the unit costs of lipid deposition did not differ between categories. The results indicated a wide plasticity of physiological rates and efficiencies and demonstrated how, by selection, interactions between physiological traits can serve to enhance growth. If differences in lipid deposition observed here were indicative of different rates of gametogenesis, then the results also suggest that selection alters the balance between growth and reproduction. Whether these differences can be termed compensatory with respect to the life history of the species remains to be determined, but the results indicate some of the ways in which physiological flexibility may be expressed to effect different patterns of energy allocation.

Journal Article↗