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PubMed1981

[Adaptation of the peripheral organs of rats to noradrenaline deficiency following chronic desympathization].

In 3--week guanetidine--desympathized rats, the noradrenaline (NA) concentration in myocardium, small intestine and ductus deferens constituted 1, 6 and 3% of the control, resp., whereas release of the NA from the ductus deferens on transmural stimulation dropped to 3%. From 4 to 16--week age the NA content in myocardium and small intestine reached 30 and 23%, resp., and its release was equal to control. The diminishing of NA content was followed by augmented adrenaline--sensitivity and diminished cholinosensitivity of the organs under study. Significance of local adaptive mechanisms for normalizing of activity of the adrenergic nervous system under conditions of desympathization, is considered.

Acetylcholine↗
PubMed2026

Comparative genomics of the monophasic variant of Salmonella Typhimurium: analysis of Colombian genomes and their relationship with international lineages.

The monophasic variant of Salmonella enterica serovar Typhimurium (STVM) represents a growing threat to global public health owing to its wide dissemination, capacity to adapt to multiple hosts, and antimicrobial resistance. In this study, 98 STVM isolates recovered in Colombia (57 from humans and 41 from pig farms and abattoirs) were genomically characterized between 2015 and 2022 and compared with 102 representative genomes of international lineages by whole-genome sequencing (WGS) and phylogenomic analysis. Phylogenomic analysis revealed the existence of two well-defined endemic lineages in Colombia (Clusters 1 and 2), arising from independent introduction events and subsequent local stabilization. Both lineages comprise isolates of human and swine origin without clear phylogenetic separation by host species, suggesting active zoonotic cocirculation and closely integrated interspecies transmission dynamics. Marked differences were observed in the accessory genome, including the differential presence of prophages (e.g., Gifsy-2, Fels-2, SW9), virulence plasmids, and resistance profiles. The Colombian lineages exhibited a high frequency of the pSTV plasmid (85%, n = 84/98) and a substantial burden of resistance determinants to quinolones (such as qnrB19, 74.5%; gyrA S83F mutation, 19.4%), phenicols (floR), tetracyclines (tetA, tetB), β-lactams (blaTEM-1B), and heavy metals. In contrast, the Colombian genomes clustered with the European ST34 lineage lacked pSTV but retained resistance and heavy metal operons. These findings demonstrate that international and endemic lineages coexist in Colombia with independent evolutionary trajectories, underscoring the need to strengthen genomic surveillance under the "One Health" approach to anticipate emerging threats and develop integrated control strategies.IMPORTANCEThe monophasic variant of Salmonella Typhimurium (STVM) has emerged as a predominant serovar in both humans and swine internationally. In Colombia, a fundamental question driving this study was whether local isolates belonged to international lineages or represented endemic strains. This study provides the first comprehensive genomic characterization demonstrating that two Colombian endemic lineages circulate simultaneously between humans and pigs without phylogenetic separation by host species, confirming active zoonotic transmission. The results demonstrate the coexistence of both lineages, each with distinctive repertoires of mobile genetic elements and specific antimicrobial resistance profiles. Understanding these transmission dynamics and evolutionary patterns is crucial for public health, as it demonstrates how zoonotic pathogens can establish locally adapted lineages with distinct resistance patterns. The genomic evidence of sustained interspecies circulation highlights the critical need for integrated surveillance strategies under the "One Health" framework. This will enable anticipating emerging threats, tracing transmission routes, and developing targeted interventions in food production systems.

One Health↗
PubMed2000

Evidence of adaptive divergence in plasticity: density- and site-dependent selection on shade-avoidance responses in Impatiens capensis.

We investigated the conditions under which plastic responses to density are adaptive in natural populations of Impatiens capensis and determined whether plasticity has evolved differently in different selective environments. Previous studies showed that a population that evolved in a sunny site exhibited greater plasticity in response to density than did a population that evolved in a woodland site. Using replicate inbred lines in a reciprocal transplant that included a density manipulation, we asked whether such population differentiation was consistent with the hypothesis of adaptive divergence. We hypothesized that plasticity would be more strongly favored in the sunny site than in the woodland site; consequently, we predicted that selection would be more strongly density dependent in the sunny site, favoring the phenotype that was expressed at each density. Selection on internode length and flowering date was consistent with the hypothesis of adaptive divergence in plasticity. Few costs or benefits of plasticity were detected independently from the expressed phenotype, so plasticity was selected primarily through selection on the phenotype. Correlations between phenotypes and their plasticity varied with the environment and would cause indirect selection on plasticity to be environment dependent. We showed that an appropriate plastic response even to a rare environment can greatly increase genotypic fitness when that environment is favorable. Selection on the measured characters contributed to local adaptation and fully accounted for fitness differences between populations in all treatments except the woodland site at natural density.

Adaptation, Physiological↗
PubMed2002

Adaptive phenotypic plasticity and genetics of larval life histories in two Rana temporaria populations.

Phenotypic plasticity provides means for adapting to environmental unpredictability. In terms of accelerated development in the face of pond-drying risk, phenotypic plasticity has been demonstrated in many amphibian species, but two issues of evolutionary interest remain unexplored. First, the heritable basis of plastic responses is poorly established. Second, it is not known whether interpopulational differences in capacity to respond to pond-drying risk exist, although such differences, when matched with differences in desiccation risk would provide strong evidence for local adaptation. We investigated sources of within- and among-population variation in plastic responses to simulated pond-drying risk (three desiccation treatments) in two Rana temporaria populations originating from contrasting environments: (1) high desiccation risk with weak seasonal time constraint (southern population); and (2) low desiccation risk with severe seasonal time constraint (northern population). The larvae originating from the environment with high desiccation risk responded adaptively to the fast decreasing water treatment by accelerating their development and metamorphosing earlier, but this was not the case in the larvae originating from the environment with low desiccation risk. In both populations, metamorphic size was smaller in the high-desiccation-risk treatment, but the effect was larger in the southern population. Significant additive genetic variation in development rate was found in the northern and was nearly significant in the southern population, but there was no evidence for genetic variation in plasticity for development rates in either of the populations. No genetic variation for plasticity was found either in size at metamorphosis or growth rate. All metamorphic traits were heritable, and additive genetic variances were generally somewhat higher in the southern population, although significantly so in only one trait. Dominance variances were also significant in three of four traits, but the populations did not differ. Maternal effects in metamorphic traits were generally weak in both populations. Within-environment phenotypic correlations between larval period and metamorphic size were positive and genetic correlations negative in both populations. These results suggest that adaptive phenotypic plasticity is not a species-specific fixed trait, but evolution of interpopulational differences in plastic responses are possible, although heritability of plasticity appears to be low. The lack of adaptive response to desiccation risk in northern larvae is consistent with the interpretation that selection imposed by shorter growing season has favored rapid development in north (approximately 8% faster development in north as compared to south) or a minimum metamorphic size at the expense of phenotypic plasticity.

Adaptation, Physiological↗
PubMed2004

The biology and life history of arctic populations of the littoral mite Ameronothrus lineatus (Acari, Oribatida).

The present study attempts to elucidate possible microevolutionary adaptations of life-history traits of high-latitude populations of the holarctic, littoral oribatid mite Ameronothrus lineatus by comparing arctic and temperate populations. Additionally, the paper provides an overview of the limited research on general ecology and population biology of arctic populations. In the Arctic the larviparous A. lineatus has a 5-year life cycle (larva-to-larva), and adults survive a further 2-3 years. High survival to maturity is consistent with a low lifetime reproductive output of ca. 20 larvae. The life history can be regarded as an extreme version of the typical oribatid life history. However, several life-history features suggest specific adaptations of arctic populations. In particular, the pre-moult resting stage is synchronized with the warmest part of the arctic summer, which shortens this vulnerable part of development. High reproductive investment by females at relatively low temperatures may represent a physiological adaptation to the cool arctic summer. Finally, prolonged cold exposure positively affects reproduction and survival the following summer, suggesting adaptation of the species to the highly seasonal arctic environment. On the other hand, the ability of all life-cycle stages to overwinter, and a flexible life history with the species being able to take advantage of favourable climatic conditions to accelerate development and larviposition, seem to be ancestral features. Thus, the success of A. lineatus in arctic habitats is probably attributable to a combination of derived and ancestral life-history traits. Studies of conspecific temperate populations are required to elucidate further local adaptations of arctic populations.

Adaptation, Physiological↗
PubMed1989

Local brain haemodynamics and oxygen metabolism in cerebrovascular disease. Positron emission tomography.

Using position emission tomography (PET) and equilibrium imaging with oxygen-15 labelled gases, the cerebral blood flow (CBF), blood volume (CBV), oxygen extraction fraction (OEF) and oxygen consumption rate (CMRO2) were measured in multiple regions of interest over the cerebral cortex of 5 control subjects, 4 patients with strictly unilateral longstanding carotid artery occlusion, 1 patient with middle cerebral artery embolic stroke in the acute stage, and 4 patients with subcortical stroke and no cervical arterial disease. In each control subject, the regional CBV was linearly and positively correlated with both CBF and CMRO2, while the local mean transit time (t = CBV/CBF) was uniformly distributed, reflecting the local adaptation of both the vascular tone and the capillary density to the metabolic demand at constant cerebral perfusion pressure that characterizes the normal brain. In patients with subcortical stroke, cortical blood volume was reduced in proportion to the matched reduction in CBF and CMRO2, suggesting that the metabolic depression resulting from cortical deafferentation increases the resting tone of pial vessels. Unilateral carotid occlusion induced larger CBV and t, and steeper slopes of the CBV-CBF relationship, particularly on the occluded but also on the patent side. The assessment of the local cerebral perfusion pressure (CPP) as judged by the ratio CBF/CBV in 3 patients with focally raised OEF and preserved or reduced CMRO2, allowed the demonstration in multiple cerebral regions of single patients of two well-known physiological phenomena: the autoregulation of CBF, followed by the rise of the OEF as local CPP falls further. In addition, the depression of CMRO2 in the ischaemic cortex was associated with a trend for CBV to return towards normal values, compared with the maximally elevated CBV found in oligaemic but metabolically normal areas. This suggests that a process of metabolic vasoconstriction may participate, among other factors, in the vascular collapse that occurs, and would serve to regenerate some haemodynamic reserve, at very low CPP levels.

Arterial Occlusive Diseases↗
PubMed2000

Functional and physiological consequences of genetic variation at phosphoglucose isomerase: heat shock protein expression is related to enzyme genotype in a montane beetle.

Allele frequency variation at the phosphoglucose isomerase (PGI) locus in Californian populations of the beetle Chrysomela aeneicollis suggests that PGI may be undergoing natural selection. We quantified (i) apparent Michaelis-Menten constant (K(m)) of fructose 6-phosphate at different temperatures and (ii) thermal stability for three common PGI genotypes (1-1, 1-4, and 4-4). We also measured air temperature (T(a)) and beetle body temperature (T(b)) in three montane drainages in the Sierra Nevada, California. Finally, we measured 70-kDa heat shock protein (Hsp70) expression in field-collected and laboratory-acclimated beetles. We found that PGI allele 1 predominated in the northernmost drainage, Rock Creek (RC), which was also significantly cooler than the southernmost drainage, Big Pine Creek (BPC), where PGI allele 4 predominated. Allele frequencies and air temperatures were intermediate in the middle drainage, Bishop Creek (BC). Differences among genotypes in K(m) (1-1 > 1-4 > 4-4) and thermal stability (4-4 > 1-4 > 1-1) followed a pattern consistent with temperature adaptation. In nature, T(b) was closely related to T(a). Hsp70 expression in adult beetles decreased with elevation and differed among drainages (BPC > BC > RC). After laboratory acclimation (8 days, 20 degrees C day, 4 degrees C night) and heat shock (4 h, 28-36 degrees C), Hsp70 expression was greater for RC than BPC beetles. In RC, field-collected beetles homozygous for PGI 1-1 had higher Hsp70 levels than heterozygotes or a 4-4 homozygote. These results reveal functional and physiological differences among PGI genotypes, which suggest that montane populations of this beetle are locally adapted to temperature.

Acclimatization↗
PubMed1990

The evaluation of cortical bone remodeling with a new ultrasonic technique.

Total hip arthroplasty causes biomechanical changes in the normal femur including a redistribution and concentration of stress. These mechanical alterations in the femur cause local remodeling and resorption that affect the geometry and mechanical properties of the bone. Three complementary techniques were used to study the local adaptive remodeling of bone due to prosthesis implantation. A graphics package was used to obtain section geometrical information, an ultrasonic wave propagation technique to determine elastic properties, and a new scanning acoustic microscope (SAM) to map the acoustic impedance profile of each section. The effects of the implantation of two different types of hip prostheses were investigated, an uncemented bipolar prosthesis with an Austin-Moore type stem and a cemented Charnley prosthesis. Prosthesis implantation resulted in an increase in cortical area and mediolateral diameter and a decrease in anterio-posterior diameter. Both prostheses had a detrimental effect on local elastic properties as determined by acoustic velocity measurements. Finally, the SAM system provided information about local inhomogeneities in bone properties not obtainable by any other means. The acoustic impedance maps highlighted bone resorption and bone remodeling on a microstructural level.

Aged↗
PubMed2006

Magnetic resonance imaging image intensity correction with extrapolation and adaptive smoothing.

A significant problem in magnetic resonance imaging (MRI) is the inhomogeneity of the image resulting from a number of factors that are hardware related. The obtained image can be treated as the true image multiplied by a signal modulator, which is usually smooth across the image. A class of MR image intensity correction methods extracts the slowly varying component from the image with low-pass filtering or smoothing to approximate the signal modulator. This usually causes the edge enhancement artifact in the corrected image. A novel method of extrapolating the image in advance is proposed to reduce this effect significantly. Closest point algorithm is implemented to minimize the calculation time for extrapolation. To remove bright spots caused by nonuniform sensitivity profiles, a gradient-weighted smoothing method is discussed in this work. The partial differential equations based model is applied for locally adaptive smoothing. The filtered gradient of the corrupted image is used as the weight for smoothing. Phantom and clinical data collected on various MRI systems are used for evaluation of our method. These experimental results show that the proposed method solves the edge enhancement and bright spots problem effectively and robustly.

Algorithms↗
PubMed1999

Teaching international animal agriculture.

Students who major in animal science at U.S. institutions are generally exposed to a curriculum that emphasizes commercial, large-scale production of the few traditional food animals: cattle, poultry, sheep, and swine. Globally, most farmers live in lesser-developed countries under limited-resource conditions of land, feed supplies, equipment, and capital. The promotion of commercial animal production enterprises may not be appropriate for such farms because it can subject farmers to considerable economic risk. Rather, use of limited numbers of large livestock, locally adapted breeds, or smaller livestock (e.g., ducks, goats, guinea pigs, and rabbits) may be more appropriate under subsistence, integrated farming systems. In this global context, a course in international animal agriculture has been taught for 15 yr to undergraduate and graduate students. The course consists of a review of traditional and potential livestock species well suited for impoverished families on small farms and methods to implement sustainable livestock projects, including feasibility, design, implementation, monitoring, and evaluation stages. To enhance student understanding, global food issues and challenges are illustrated with case studies. A term paper is also assigned for which students choose three suitable livestock species or local breeds that would be complementary on a small crop farm (< 5 ha). Daily dietary requirements of protein and energy per family member are calculated. Itemized enterprise budgets and production tables are prepared. Early in the course, the general consensus of students was that people who are malnourished and live in poverty have low personal ambition and motivation, and that their problems should be amenable to solution by application of American technology and expertise. The course modifies such attitudes and enhances a student's critical thinking and problem-solving abilities and communication skills. Course evaluations indicated that students believed that it is important to acquire some international knowledge and understanding when seeking a job, and that certain animal science courses should contain some international content. Students gain an understanding of global animal agriculture and an appreciation of the complexity of food production and hunger issues.

Agriculture↗
PubMed2003

Application and refinement of the WHO risk framework for recreational waters in Sydney, Australia.

Local adaptation of the World Health Organisation (WHO) Farnham approach to managing pathogen risk in recreational waters was readily achieved given the extensive microbiological beach data for Sydney, and a clear understanding of applying the 'Annapolis Protocol' sanitary survey component to beach classification. Daily enterococci counts were predicted by rainfall (>10 mm in 24 h or >5 mm over 4-5 days), or by wind direction/speed, sunlight and tide during dry periods. Quantitative microbial risk assessment models (maximum risk exponential model for gastroenteritis and adenovirus exponential model for respiratory illness) fitted the United Kingdom epidemiological data and show potential for use. Flexibility in interpreting what is important for local conditions is essential, illustrated by replacing the general descriptions in the Farnham report with more ridged values for stormwater-impacted beaches. Hence, a user-friendly format for bather risk management, based on key environmental predictors of faecal pollution (such as rainfall, wind direction and tide) should largely replace the need for regular and costly microbiological testing; providing risk estimates in real time and allowing immediate control measures, such as signage or temporary beach closures. Ongoing testing resources should be directed to understanding the source(s) of faecal contamination, comparing enterococci/enteric virus survival under warm Australian conditions and spot checks for recalibration of environmental factors.

Calibration↗
PubMed2003

Habitat preference and the marine-speciation paradox.

Marine organisms challenge the classical theories of local adaptation and speciation because their planktonic larvae have the potential to maintain high gene flow. The marine-speciation paradox is illustrated by contact zones between incipient species that are so large that allopatric divergence seems unlikely. For this reason any mechanism preventing sympatric larvae of two incipient species from coexisting in the same habitats can be a powerful promoter of speciation. The contact zone between two hybridizing taxa of mussel, Mytilus edulis and M. galloprovincialis, in Europe provides an excellent example. Although the zone itself extends over thousands of kilometres, the opportunities for interbreeding are considerably reduced by the small-scale mosaic structure of the zone, where local patches of each taxon alternate at scales of kilometres or less, in response to locally variable ecological factors. Habitat choice by settling larvae would be a less costly mechanism than post-settlement selection to maintain such a mosaic structure. Unfortunately the role of selective settlement has remained hypothetical because larvae could not be scored by classical genetic markers. PCR markers allowed us to study larvae and settlement in ecologically contrasting sites within the zone. We show that only a subset of the genotypes present in the plankton settle in some sites, and that the adults on these sites show the same genetic bias. Genetically based variation in pre-settlement processes therefore accounts for the ecological segregation observed, though it is not the only factor involved in limiting successful interbreeding. The present dataset also supports previous reports of partial spawning asynchrony.

Animals↗
PubMed2002

Variation in cannibalistic polyphenism between populations in the salamander Hynobius retardatus.

Organisms sometimes change their phenotype to maximize fitness according to local environments. If the frequency of the broad-headed "cannibal" morph in the larvae of the salamander Hynobius retardatus has been evolutionarily maintained at a certain level within a population as a result of local adaptation, variations in its frequency should be found among different populations with environmental variation. We investigated whether variations in the frequency of the broad-headed morph were present in 2 different populations, Nopporo (a low-density population) and Erimo (a high-density population), by raising larvae from the respective populations under the same experimental conditions. The occurrence rate of the broad-headed "cannibal" morph was significantly different between the 2 populations when examined with different experimental larval densities. These results suggest that the reaction norm with respect to the frequency of the broad-headed morph is different between the Nopporo and Erimo populations. Because the local populations are assumed to be selected for under different environments, the different reaction norm might have evolved in response to different selection pressures.

Animals↗
PubMed2005

Nonrandom larval dispersal can steepen marine clines.

Sharp and stable clinal variation is enigmatic when found in species with high gene flow. Classical population genetic models treat gene flow as a random homogenizing force countering local adaptation across habitat discontinuities. Under this view, dispersal over large spatial scales will lower the effectiveness of adaptation by natural selection at finer spatial scales. Thus, random gene flow will create a shallow phenotypic cline across an ecotone in response to a steep selection gradient. In sedentary marine species that disperse primarily as larvae, nonrandom dispersal patterns are expected due to coastal hydrodynamics. Surprisingly sharp phenotypic and genotypic clines have been documented in marine species with high gene flow. We are interested in the extent to which nonrandom dispersal could accentuate such clines. We model a linear species range in which populations have stable and uniform densities along a selection gradient; in contrast to random dispersal, convergent advection of larvae can amplify phenotypic differentiation if coupled with a semipermeable dispersal barrier in the convergence zone. The migration load caused by directional dispersal pushes the phenotypic mean away from the local trait optimum in downstream populations, that is, near the convergence zone. A dispersal barrier is possible as a result of colliding currents if the water and larvae are mostly displaced offshore, away from suitable settlement habitat. Disjunctions in a quantitative trait were enlarged in the convergence zone by faster current flows or a more complete dispersal barrier. With advection of larvae per generation one-third as far as the average dispersal distance by diffusion, convergence on a dispersal barrier with 40% permeability generated a trait disjunction across the convergence zone of two phenotypic standard deviations. Without directional dispersal, similar clines also developed across a habitat gap, where population density was low, or across dispersal barriers with less than 1% permeability. These findings suggest that the types of hydrographic phenomena often associated with marine transition zones can strongly affect the balance between gene flow and selection and generate surprisingly steep clines given the large-scale gene flow expected from larvae.

Animal Migration↗
PubMed2002

Phylogenetic evidence for adaptive evolution of dengue viruses in nature.

A maximum-likelihood approach was used to analyse selection pressures acting on genes from all four serotypes of dengue virus (DEN). A number of amino acid positions were identified within the envelope (E) glycoprotein that have been subject to relatively weak positive selection in both DEN-3 and DEN-4, as well as in two of the five genotypes of DEN-2. No positive selection was detected in DEN-1. In accordance with the function of the E protein as the major antigenic determinant of DEN, the majority of these sites were located in, or near to, potential T- or B-cell epitopes. A smaller number of selected sites was located in other well-defined functional domains of the E protein, suggesting that cell tropism and virus-mediated membrane fusion may also confer fitness advantages to DEN in nature. Several positively selected amino acid substitutions were also identified in the NS2B and NS5 genes of DEN-2, although the cause of this selection is unclear, whereas the capsid, membrane and non-structural genes NS1, NS2A, NS3 and NS4 were all subject to strong functional constraints. Hence, evidence was found for localized adaptive evolution in natural isolates of DEN, revealing that selection pressures differ among serotypes, genotypes and viral proteins.

Biological Evolution↗
PubMed1995

[Comparative analysis of the immune response in a case of primary regressive melanoma followed by gastric metastasis].

The theory of immunosurveillance against cancer has been an extensively debated question over the last decades. Multiple indirect arguments have supported the view that the immune system may control, at least in certain cases, malignant cell growth while direct demonstration is still lacking in the human. In an attempt to address this issue, we have selected a study model, namely spontaneously regressive melanoma. A primary cutaneous lesion was investigated. T cell repertoire analysis showed the in situ amplification of at least two tumor infiltrating lymphocyte (TILs) expressing the V beta 13 and V beta 16 variable TCR gene segments respectively. The two clones were precisely characterized by sequence of the TCR beta chain junctional region. Further functional study demonstrated that both lymphocytes displayed a selective cytotoxic activity against autologous tumor cells. The V beta 16+ cells, predominant in vivo, were shown to be closely opposed to the melanoma cells. Together, these studies demonstrated the existence of a local adaptative immune response associated to tumor regression, thus strongly supporting the validity of the immunosurveillance concept. A gastric metastasis which occurred three years after the primary lesion has been studied here. Overexpression of the V beta 13 and V beta 16 TCR segments was no longer detected by direct PCR analysis in situ. Sequencing transcripts from V beta 13+ and V beta 16+ TILs confirmed that the two CTLs, identified in the primary lesions, were not represented with high frequency. The V beta 13+ cell was however shown to be present while the V beta 16+ CTL was not detected. Yet, characterization of a tumor cell line derived from the gastric site indicated that the peptidic antigen(s) which induced the initially successfully immune response was still expressed. The present data illustrate that it has become possible to perform very precise analysis of local immune responses during cancer development. Such an improvement together with the recently initiated molecular characterization of tumor associated peptidic antigens, should provide the basis for improved strategies of cancer immunotherapy.

Aged↗
PubMed2005

Polymorphic mimicry, microhabitat use, and sex-specific behaviour.

In order to assess the adaptive importance of microhabitat segregation for the maintenance of mimetic diversity, I explore how flight height varies between the sympatric forms of the polymorphic butterfly Heliconius numata and their respective models in the genus Melinaea. There is no evidence for vertical stratification of mimicry rings in these tiger-patterned butterflies, but males of H. numata tend to fly significantly higher than females and the Melinaea models. This difference in microhabitat preference likely results from females searching for host plants whereas males are patrolling for mates. I then present an extension of Muller's mimicry model for the case of partial behavioural or spatial segregation of sexes. The analysis suggests that sex-specific behaviours can make mimicry more beneficial, simply by reducing the effective population size participating in mimicry. The interaction between mimicry and sex-specific behaviours may therefore facilitate the evolution of polymorphism via enhanced, fine-scale local adaptation.

Adaptation, Physiological↗
PubMed2005

Maternal inheritance and rapid evolution of sexual size dimorphism: passive effects or active strategies?

Adaptive evolution is often strongly influenced by maternal inheritance that transfers the parental strategies across generations. The consequences of maternal effects for the offspring generation depend on the between-generation similarity in environments and on the evolved sensitivity of the offspring's ontogeny to maternal effects. When these factors differ between sons and daughters, maternal effects can influence the evolution of sexual dimorphism. The establishment of house finch populations across western Montana during the last 30 years was accompanied by rapid evolutionary change in sexual size dimorphism. Here I show that traits that changed the most across generations were most influenced by maternal effects in males but not females. Maternal effects differentially affected sons' and daughters' survival; greater maternal effects were commonly associated with higher survival of sons, especially when maternal and offspring environments were similar. Stronger maternal effects extended preselection phenotypic variance in morphological traits of males, thereby producing some locally adaptive phenotypes and lessening juvenile mortality. Thus, the observed sex-specific maternal effects and their contribution to the evolution of sexual size dimorphism are likely a passive consequence of the distinct sensitivity of sons and daughters to maternal adaptations to breeding in ecologically distinct parts of the house finch's expanding range.

Animals↗