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Selected AbstractsEvolutionary history shapes the association between developmental instability and population-level genetic variation in three-spined sticklebacksJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 8 2009S. VAN DONGEN Abstract Developmental instability (DI) is the sensitivity of a developing trait to random noise and can be measured by degrees of directionally random asymmetry [fluctuating asymmetry (FA)]. FA has been shown to increase with loss of genetic variation and inbreeding as measures of genetic stress, but associations vary among studies. Directional selection and evolutionary change of traits have been hypothesized to increase the average levels of FA of these traits and to increase the association strength between FA and population-level genetic variation. We test these two hypotheses in three-spined stickleback (Gasterosteus aculeatus L.) populations that recently colonized the freshwater habitat. Some traits, like lateral bone plates, length of the pelvic spine, frontal gill rakers and eye size, evolved in response to selection regimes during colonization. Other traits, like distal gill rakers and number of pelvic fin rays, did not show such phenotypic shifts. Contrary to a priori predictions, average FA did not systematically increase in traits that were under presumed directional selection, and the increases observed in a few traits were likely to be attributable to other factors. However, traits under directional selection did show a weak but significantly stronger negative association between FA and selectively neutral genetic variation at the population level compared with the traits that did not show an evolutionary change during colonization. These results support our second prediction, providing evidence that selection history can shape associations between DI and population-level genetic variation at neutral markers, which potentially reflect genetic stress. We argue that this might explain at least some of the observed heterogeneities in the patterns of asymmetry. [source] ENVIRONMENTAL CONDITIONS AFFECT THE MAGNITUDE OF INBREEDING DEPRESSION IN SURVIVAL OF DARWIN'S FINCHESEVOLUTION, Issue 6 2002Lukas F. Keller Abstract Understanding the fitness consequences of inbreeding (inbreeding depression) is of importance to evolutionary and conservation biology. There is ample evidence for inbreeding depression in captivity, and data from wild populations are accumulating. However, we still lack a good quantitative understanding of inbreeding depression and what influences its magnitude in natural populations. Specifically, the relationship between the magnitude of inbreeding depression and environmental severity is unclear. We quantified inbreeding depression in survival and reproduction in populations of cactus finches (Geospiza scandens) and medium ground finches (Geospiza fortis) living on Isla Daphne Major in the Galapagos Archipelago. Our analyses showed that inbreeding strongly reduced the recruitment probability (probability of breeding given that an adult is alive) in both species. Additionally, in G. scandens, first-year survival of an offspring withf= 0.25 was reduced by 21% and adults withf= 0.25 experienced a 45% reduction in their annual probability of survival. The magnitude of inbreeding depression in both adult and juvenile survival of this species was strongly modified by two environmental conditions, food availability and number of competitors. In juveniles, inbreeding depression was only present in years with low food availability, and in adults inbreeding depression was five times more severe in years with low food availability and large population sizes. The combination of relatively severe inbreeding depression in survival and the reduced recruitment probability led to the fact that very few inbred G. scandens ever succeeded in breeding. Other than recruitment probability, no other trait showed evidence of inbreeding depression in G. fortis, probably for two reasons: a relatively high rate of extrapair paternity (20%), which may lead to an underestimate of the apparent inbreeding depression, and low sample sizes of highly inbred G. fortis, which leads to low statistical power. Using data from juvenile survival, we estimated the number of lethal equivalents carried by G. scandens, G. fortis, and another congener, G. magnirostris. These results suggest that substantial inbreeding depression can exist in insular populations of birds, and that the magnitude of the inbreeding depression is a function of environmental conditions. [source] Speciation via species interactions: the divergence of mating traits within speciesECOLOGY LETTERS, Issue 4 2010Conrad J. Hoskin Ecology Letters (2010) 13: 409,420 Abstract A species may overlap with a mosaic of species across its geographic range. Many types of species interaction cause selection on mating traits, but their role in generating within-species divergence has been neglected. The pattern of reproductive character displacement (RCD) has been classically attributed to reinforcement, a process driven by selection against hybridisation. Recent reinforcement research shows that sexual isolation can result between displaced and non-displaced populations. We argue that RCD (and hence potentially speciation) among populations can be generated by a variety of fundamental species interactions beyond reinforcement. We unify these interactions under one process of mating trait divergence and speciation (,RCD speciation'). This process can occur in many geographic settings. Because selection is acting directly on mating traits, rapid speciation can result involving little differentiation in other traits. This pattern of diversification is seen in many groups and regions, and has previously been attributed to sexual selection alone. [source] Predicting competition coefficients for plant mixtures: reciprocity, transitivity and correlations with life-history traitsECOLOGY LETTERS, Issue 4 2001R.P. Freckleton There are few empirical or theoretical predictions of how per capita or per individual competition coefficients for pairs of plant species should relate to each other. In contrast, there are a considerable number of general hypotheses that predict competitive ability as a function of a range of ecological traits, together with a suite of increasingly sophisticated models for competitive interactions between plant species. We re-analyse a data set on competition between all pairwise combinations of seven species and show that competition coefficients relate strongly to differences between the maximum sizes, root allocation, emergence time and seed size of species. Regressions suggest that the best predictor of competition coefficients is the difference in the maximum size of species and that correlations of the other traits with the competition coefficients occur through effects on the maximum size. We also explore the patterns of association between coefficients across the competition matrix. We find significant evidence for coefficient reciprocity (inverse relationships between the interspecific coefficients for species pairs) and transitivity (numerically predictable hierarchies of competition between species) across competition matrices. These results therefore suggest simple null models for plant community structure when there is competition for resources. [source] THE REACTION NORM FOR ABDOMINAL PIGMENTATION AND ITS CURVE IN DROSOPHILA MEDIOPUNCTATA DEPEND ON THE MEAN PHENOTYPIC VALUEEVOLUTION, Issue 1 2009Felipe Rocha The idea of a general independence between the phenotypic plasticity and the mean value of a trait is, presently, a consensus. Here, we use the reaction norm of abdominal pigmentation (number of dark spots) of Drosophila mediopunctata in response to temperature, to test this idea. We raised eight strains, bearing two different chromosomal inversions and with varying mean phenotypic values, under 11 temperatures in a thermal gradient to test for predictions concerning mean phenotypic values, chromosomal inversions, and reaction norms. Our results revealed a strong effect of different phenotypic groups and no effect of different karyotypes on reaction norms. Moreover, we found a significant negative correlation between mean phenotypic value and the curvature of the reaction norms, revealing a high dependency of the reaction norm shape on mean phenotypic value. These results clearly reject the idea of genetic independence between mean value and phenotypic plasticity, and may indicate a pattern of correlation, which may include results from other traits and species, with an importance that has not been fully appreciated. [source] YOU CAN'T KEEP A GOOD PARASITE DOWN: EVOLUTION OF A MALE-KILLER SUPPRESSOR UNCOVERS CYTOPLASMIC INCOMPATIBILITYEVOLUTION, Issue 5 2008Emily A. Hornett Maternally inherited parasites are known to impose a wide variety of reproductive manipulations upon their host. These often produce strong selection on the host to suppress the parasite, resulting in a reduction in the frequency of the parasite. However, in the butterfly Hypolimnas bolina, infected with a Wolbachia bacterium, field data demonstrate that suppression of the male-killing phenotype does not depress parasite frequency. Here we test and verify one hypothesis to explain this apparent paradox,Wolbachia induces a second phenotype, Cytoplasmic Incompatibility (CI), in populations where host suppression has evolved. We further demonstrate that the capacity to induce CI has not evolved de novo, but instead is instantaneously expressed upon the survival of infected males. The significance of these results is threefold: (1) multiple phenotypes can provide Wolbachia with the means to maintain itself in a host following suppression of a single manipulative phenotype; (2) the ability to induce CI can remain hidden in systems in which male-killing is observed, just as the ability to induce male-killing may be obscured in strains exhibiting CI; (3) the evolutionary maintenance of CI in a system in which it is not expressed suggests a functional link with male-killing or other traits under selection. [source] SEXUAL SELECTION AND IMMUNE FUNCTION IN DROSOPHILA MELANOGASTEREVOLUTION, Issue 2 2008Kurt A. McKean The evolution of immune function depends not only on variation in genes contributing directly to the immune response, but also on genetic variation in other traits indirectly affecting immunocompetence. In particular, sexual selection is predicted to trade-off with immunocompetence because the extra investment of resources needed to increase sexual competitiveness reduces investment in immune function. Additional possible immunological consequences of intensifying sexual selection include an exaggeration of immunological sexual dimorphism, and the reduction of condition-dependent immunological costs due to selection of ,good genes' (the immunocompetence handicap hypothesis, ICHH). We tested for these evolutionary possibilities by increasing sexual selection in laboratory populations of Drosophila melanogaster for 58 generations by reestablishing a male-biased sex ratio at the start of each generation. Sexually selected flies were larger, took longer to develop, and the males were more sexually competitive than males from control (equal sex ratio) lines. We found support for the trade-off hypothesis: sexually selected males were found to have reduced immune function compared to control males. However, we found no evidence that sexual selection promoted immunological sexual dimorphism because females showed a similar reduction in immune function. We found no evidence of evolutionary changes in the condition-dependent expression of immunocompetence contrary to the expectations of the ICHH. Lastly, we compared males from the unselected base population that were either successful (IS) or unsuccessful (IU) in a competitive mating experiment. IS males showed reduced immune function relative to IU males, suggesting that patterns of phenotypic correlation largely mirror patterns of genetic correlation revealed by the selection experiment. Our results suggest increased disease susceptibility could be an important cost limiting increases in sexual competitiveness in populations experiencing intense sexual selection. Such costs may be particularly important given the high intersex correlation, because this represents an apparent genetic conflict, preventing males from reaching their sexually selected optimum. [source] THE LOCUS OF EVOLUTION: EVO DEVO AND THE GENETICS OF ADAPTATIONEVOLUTION, Issue 5 2007Hopi E. Hoekstra An important tenet of evolutionary developmental biology ("evo devo") is that adaptive mutations affecting morphology are more likely to occur in the cis -regulatory regions than in the protein-coding regions of genes. This argument rests on two claims: (1) the modular nature of cis -regulatory elements largely frees them from deleterious pleiotropic effects, and (2) a growing body of empirical evidence appears to support the predominant role of gene regulatory change in adaptation, especially morphological adaptation. Here we discuss and critique these assertions. We first show that there is no theoretical or empirical basis for the evo devo contention that adaptations involving morphology evolve by genetic mechanisms different from those involving physiology and other traits. In addition, some forms of protein evolution can avoid the negative consequences of pleiotropy, most notably via gene duplication. In light of evo devo claims, we then examine the substantial data on the genetic basis of adaptation from both genome-wide surveys and single-locus studies. Genomic studies lend little support to the cis -regulatory theory: many of these have detected adaptation in protein-coding regions, including transcription factors, whereas few have examined regulatory regions. Turning to single-locus studies, we note that the most widely cited examples of adaptive cis -regulatory mutations focus on trait loss rather than gain, and none have yet pinpointed an evolved regulatory site. In contrast, there are many studies that have both identified structural mutations and functionally verified their contribution to adaptation and speciation. Neither the theoretical arguments nor the data from nature, then, support the claim for a predominance of cis -regulatory mutations in evolution. Although this claim may be true, it is at best premature. Adaptation and speciation probably proceed through a combination of cis -regulatory and structural mutations, with a substantial contribution of the latter. [source] SPECIFICITY AND SPECIALIZATION OF CONGENERIC MONOGENEANS PARASITIZING CYPRINID FISHEVOLUTION, Issue 5 2006Andrea, Imková Abstract Patterns and likely processes connected with evolution of host specificity in congeneric monogeneans parasitizing fish species of the Cyprinidae were investigated. A total of 51 Dactylogyrus species was included. We investigated (1) the link between host specificity and parasite phylogeny; (2) the morphometric correlates of host specificity, parasite body size, and variables of attachment organs important for host specificity; (3) the evolution of morphological adaptation, that is, attachment organ; (4) the determinants of host specificity following the hypothesis of specialization on more predictable resources considering maximal body size, maximal longevity, and abundance as measures of host predictability; and (5) the potential link between host specificity and parasite diversification. Host specificity, expressed as an index of host specificity including phylogenetic and taxonomic relatedness of hosts, was partially associated with parasite phylogeny, but no significant contribution of host phylogeny was found. The mapping of host specificity into the phylogenetic tree suggests that being specialist is not a derived condition for Dactylogyrus species. The different morphometric traits of the attachment apparatus seem to be selected in connection with specialization of specialist parasites and other traits favored as adaptations in generalist parasites. Parasites widespread on several host species reach higher abundance within hosts, which supports the hypothesis of ecological specialization. When separating specialists and generalists, we confirmed the hypothesis of specialization on a predictable resource; that is, specialists with larger anchors tend to live on fish species with larger body size and greater longevity, which could be also interpreted as a mechanism for optimizing morphological adaptation. We demonstrated that ecology of host species could also be recognized as an important determinant of host specificity. The mapping of morphological characters of the attachment organ onto the parasite phylogenetic tree reveals that morphological evolution of the attachment organ is connected with host specificity in the context of fish relatedness, especially at the level of host subfamilies. Finally, we did not find that host specificity leads to parasite diversification in congeneric monogeneans. [source] EVOLUTION OF TEMPORAL ISOLATION IN THE WILD: GENETIC DIVERGENCE IN TIMING OF MIGRATION AND BREEDING BY INTRODUCED CHINOOK SALMON POPULATIONSEVOLUTION, Issue 4 2000Thomas P. Quinn Abstract. The timing of migration and breeding are key life-history traits; they are not only adaptations of populations to their environments, but can serve to increase reproductive isolation, facilitating further divergence among populations. As part of a study of divergence of chinook salmon, Oncorhynchus tshawytscha, populations, established in New Zealand from a common source in the early 1900s, we tested the hypotheses that the timing of migration and breeding are under genetic control and that the populations genetically differ in these traits despite phenotypic overlap in timing in the wild. Representatives of families from two populations were collected within a day or two of each other, reared in a common environment, and then released to sea from each of two different rivers, while other family representatives were retained in fresh water to maturity. The date of maturation of fish held in fresh water and the dates of return from the ocean and maturation of fish released to sea all showed significant differences between the two populations and among families within populations. The very high heritabilities and genetic correlations estimated for migration and maturation date indicated that these traits would respond rapidly to selection. Combined with the results of related studies on these chinook salmon populations, it appears that spawning time may not only evolve during the initial phases of divergence, but it may play an important role in accelerating divergence in other traits. [source] PERSPECTIVE: Rethinking the value of high wood densityFUNCTIONAL ECOLOGY, Issue 4 2010Markku Larjavaara Summary 1.,Current thinking holds that wood density mediates a tradeoff between strength and economy of construction, with higher wood density providing higher strength but at higher cost. 2.,Yet the further away wood fibres are from the central axis of the trunk, the more they increase the strength of the trunk; thus, a fat trunk of low-density wood can achieve greater strength at lower construction cost than a thin trunk of high-density wood. 3.,What then are the countervailing advantages of high wood density? 4.,We hypothesize that high wood density is associated with lower maintenance costs due to lower trunk surface area, as surface area correlates with maintenance respiration. 5.,This advantage would be particularly important to long-lived trees and could in part explain why they tend to have high wood density. 6.,High wood density has also been associated with lower risk of trunk breakage, xylem implosion and pathogen invasion, but we argue that these relationships are not causal and instead reflect correlated selection on other traits of value to long-lived trees. 7.,This revaluation of the costs and benefits of high wood density has important implications for understanding tree life-history evolution, functional diversity, forest carbon stocks and the impacts of global change. [source] Mouse inbred strain differences in ethanol drinking to intoxicationGENES, BRAIN AND BEHAVIOR, Issue 1 2007J. S. Rhodes Recently, we described a simple procedure, Drinking in the Dark (DID), in which C57BL/6J mice self-administer ethanol to a blood ethanol concentration (BEC) above 1 mg/ml. The test consists of replacing the water with 20% ethanol in the home cage for 4 h early during the dark phase of the light/dark cycle. Three experiments were conducted to explore this high ethanol drinking model further. In experiment 1, a microanalysis of C57BL/6J behavior showed that the pattern of ethanol drinking was different from routine water intake. In experiment 2, drinking impaired performance of C57BL/6J on the accelerating rotarod and balance beam. In experiment 3, 12 inbred strains were screened to estimate genetic influences on DID and correlations with other traits. Large, reliable differences in intake and BEC were detected among the strains, with C57BL/6J showing the highest values. Strain means were positively correlated with intake and BEC in the standard (24 h) and a limited (4 h) two-bottle ethanol vs. water test, but BECs reached higher levels for DID. Strain mean correlations with other traits in the Mouse Phenome Project database supported previously reported genetic relationships of high ethanol drinking with low chronic ethanol withdrawal severity and low ethanol-conditioned taste aversion. We extend these findings by showing that the correlation estimates remain relatively unchanged even after correcting for phylogenetic relatedness among the strains, thus relaxing the assumption that the strain means are statistically independent. We discuss applications of the model for finding genes that predispose pharmacologically significant drinking in mice. [source] Indices of Drought Tolerance in Wheat Genotypes at Early Stages of Plant GrowthJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2004S. S. Dhanda Abstract Thirty diverse genotypes of bread wheat were evaluated for seed vigour index, germination percentage, root length, shoot length, root-to-shoot length ratio, coleoptile length and osmotic membrane stability under laboratory conditions. Considerable variation was observed for all the characters. Discrimination among the genotypes on the basis of mean values was better under normal than under moisture stress conditions, indicating suppression of variability under moisture stress conditions. Comparison of mean performance under normal and osmotic stress conditions indicated that the seed vigour index was the most sensitive trait, followed by shoot length, germination percentage and root length. The root-to-shoot length ratio, however, increased under osmotic stress. The magnitude of genetic components of variance and heritability were, in general, lower under osmotic stress than under normal conditions. All the characters except germination percentage, shoot length and coleoptile length showed considerable genetic variability. Heritability in the broad sense was also moderate to high for all the characters under both environments. Due to high heritability and genetic advance great benefit from selection can be expected for the osmotic membrane stability of leaf segments and root-to-shoot length ratio. Moderate progress can be expected from root length and seed vigour index. Correlation studies indicated that the osmotic membrane stability of the leaf segment was the most important trait, followed by root-to-shoot ratio and root length on the basis of their relationships with other traits. [source] Genome-wide linkage and QTL mapping in porcine F2 families generated from Pietrain, Meishan and Wild Boar crossesJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 6 2003H. Geldermann Summary Three informative pig F2 families based on European Wild Boar (W), Meishan (M) and Pietrain (P) crosses have been used for genome-wide linkage and quantitative trait loci (QTL) analysis. Altogether 129 microsatellites, 56 type I loci and 46 trait definitions (specific to growth, fattening, fat deposition, muscling, meat quality, stress resistance and body conformation) were included in the study. In the linkage maps of M × P, W × P and W × M families, average spacing of markers were 18.4, 19.7 and 18.8 cM, the numbers of informative meioses were 582, 534 and 625, and the total lengths of autosomes measured were 27.3, 26.0 and 26.2 Morgan units, respectively. Maternal maps were on average 1.3 times longer than paternal maps. QTLs contributing more than 3% of F2 phenotypic variance could be identified at p < 0.05 chromosome-wide level. Differences in the numbers and positions of QTLs were observed between families. Genome-wide significant QTL effects were mapped for growth and fattening traits on eight chromosomes (1, 2, 4, 13, 14, 17, 18 and X), for fat deposition traits on seven chromosomes (1, 2, 3, 4, 6, 7 and X), for muscling traits on 11 chromosomes (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 and X), for meat quality and stress resistance traits on seven chromosomes (2, 3, 6, 13, 16, 18 and X), and QTLs for body-conformation traits were detected on 14 chromosomes. Closely correlated traits showed similar QTL profiles within families. Major QTL effects for meat quality and stress resistance traits were found on SSC6 in the interval RYR1-A1BG in the W × P and M × P families, and could be attributed to segregation of the RYR1 allele T derived from Pietrain, whereas no effect in the corresponding SSC6 interval was found in family W × M, where Wild Boar and Meishan both contributed the RYR1 allele C. QTL positions were mostly similar in two of the three families for body conformation traits and for growth, fattening, fat deposition and muscling traits, especially on SSC4 (interval SW1073-NGFB). QTLs with large effects were also mapped on SSC7 in the major histocompatibility complex (MHC) (interval CYP21A2-S0102) and affected body length, weight of head and many other traits. The identification of DNA variants in genes causative for the QTLs requires further fine mapping of QTL intervals and a positional cloning. However, for these subsequent steps, the genome-wide QTL mapping in F2 families represents an essential starting point and is therefore significant for animal breeding. Zusammenfassung Drei informative F2 -Familien, die aus Kreuzungen von Europäischem Wildschwein (W), Meishan (M) und Pietrain (P) erstellt worden waren, wurden für eine genomweite Kopplungs- und QTL-Analyse benutzt. Insgesamt wurden 129 Mikrosatellitenloci, 56 Type-I-Loci und 46 Merkmalsdefinitionen (für Wachstum, Mastleistung, Fettansatz, Bemuskelung, Fleischqualität, Stressresistenz und Körperform) in die Untersuchungen einbezogen. In den Kopplungskarten der Familien M × P, W × P und W × M wurden durchschnittliche Markerabstände von 18.4, 19.7 bzw. 18.8 cM erreicht und 582, 534 bzw. 625 informative Meiosen beobachtet. Für die Gesamtlängen der Autosomen wurden in den drei Familien 27.3, 26.0 bzw. 26.2 Morgan-Einheiten gemessen. Die maternalen Kopplungskarten waren durchschnittlich 1.3-fach länger als die paternalen. QTLs, die mehr als 3% der phänotypischen Varianz in der F2 -Generation erklärten, konnten mit p < 0.05 chromosomenweitem Signifikanzniveau nachgewiesen werden. Zwischen den Familien wurden Differenzen in den Anzahlen und Positionen der QTLs beobachtet. Genomweit signifikante QTL-Effekte wurden für Wachstum und Fettansatz auf acht Chromosomen (1, 2, 4, 13, 14, 17, 18 und X) kartiert, für Fettansatz auf sieben Chromosomen (1, 2, 3, 4, 6, 7 und X), für Bemuskelung auf elf Chromosomen (1, 2, 3, 4, 6, 7, 8, 12, 14, 15 und X), für Fleischqualität/Stressresistenz auf sieben Chromosomen (2, 3, 6, 13, 16, 18 und X), und QTLs für die Körperform wurden auf 14 Chromosomen kartiert. Eng korrelierte Merkmale zeigten ähnliche QTL-Profile innerhalb Familien. Die bedeutsamsten QTL-Effekte wurden für Fleischqualitäts- und Stressresistenzmerkmale auf Chromosom 6, Intervall RYR1-A1BG, in den Familien W × P und M × P gefunden, während in diesem Chromosomenintervall in der Familie W × M, in der der RYR1 -Locus keine segregierenden Exon-Allele aufwies, kein QTL zu erkennen war. Mehrere der QTL-Positionen waren für die Körperform wie auch für Wachstum, Mastleistung, Fettansatz und Bemuskelung in zwei von drei Familien ähnlich. Dies galt besonders für Chromosom 4 (Intervall SW1073-NGFB). QTLs mit großen Effekten wurden auf Chromosom 7 im MHC (Intervall CYP21A2-S0102) kartiert; sie beeinflussten Körperlänge, Kopfgewicht, aber auch viele weitere Merkmale. Zur Identifizierung der DNA-Varianten, die einem QTL zugrunde liegen, ist eine Feinkartierung von QTLs und positionale Klonierung erforderlich. Für diese nachfolgenden Untersuchungsmethoden ist jedoch die genomweite QTL-Kartierung in F2 -Familien ein entscheidender Ausgangspunkt; sie ist deshalb bedeutungsvoll für die Tierzüchtung. [source] Linkage and QTL mapping for Sus scrofa chromosome 12JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2003G. Yue Summary The SSC12 (Sus scrofa chromosome 12) linkage and QTL maps were generated using 11 markers, of which seven to 10 have been used in the three F2 families based on Wild Boar (W), Meishan (M) and Pietrain (P) crosses. Linkage maps showed identical marker order among the families, but differed in total lengths. They were in agreement with the already published maps, except for the order SWR1021,SW605. Most quantitative trait loci (QTLs) affected fat or meat content in carcass, but were also found for some other traits (heart weight, CK20 values and teat number). They explained up to 5.4% of F2 phenotypic variance. Meishan alleles had stimulating effects on fat deposition and decreasing effects on lean content and CK20 value. The QTL profiles differed between families, with QTL effects in the vicinity of the GH1 locus found solely in the M × P family. Zusammenfassung Auf der Basis von elf Markern wurden Kopplungs- und QTL-Karten für Chromosom 12 (SSC12) in drei F2 -Familien aus Kreuzungen von Wildschwein (W), Meishan (M) und Pietrain (P) erstellt. Hierbei wurden sieben bis zehn Marker pro F2 -Familie benutzt. Die Kopplungskarten zeigten eine gleichartige Anordnung der Loci für alle Familien, jedoch mit verschiedenen Kartenlängen. Sie stimmen, außer in der Anordnung SWR1021,SW605, mit bereits publizierten Karten überein. Quantitative Trait Loci (QTLs) waren hauptsächlich für Merkmale des Fett-oder Fleischanteils im Schlachtkörper festzustellen, daneben aber auch für weitere Merkmale (Herzgewicht, CK20 -Wert, Zitzenzahl). Sie erklärten bis zu 5,4% der phänotypischen Varianz in der F2 -Generation. Meishan-Allele waren assoziiert mit einer Steigerung des Fettansatzes sowie einer Reduktion der Anteile wertvoller Teilstücke und der CK20 -Werte. Die QTL-Profile unterschieden sich zwischen den Familien und ließen Assoziationen mit dem GH1 -Locus nur in der Familie M × P erkennen. [source] Interactive effects of environmental stress and inbreeding on reproductive traits in a wild bird populationJOURNAL OF ANIMAL ECOLOGY, Issue 6 2006A. B. MARR Summary 1Conservation biologists are concerned about the interactive effects of environmental stress and inbreeding because such interactions could affect the dynamics and extinction risk of small and isolated populations, but few studies have tested for these interactions in nature. 2We used data from the long-term population study of song sparrows Melospiza melodia on Mandarte Island to examine the joint effects of inbreeding and environmental stress on four fitness traits that are known to be affected by the inbreeding level of adult birds: hatching success, laying date, male mating success and fledgling survival. 3We found that inbreeding depression interacted with environmental stress to reduce hatching success in the nests of inbred females during periods of rain. 4For laying date, we found equivocal support for an interaction between parental inbreeding and environmental stress. In this case, however, inbred females experienced less inbreeding depression in more stressful, cooler years. 5For two other traits, we found no evidence that the strength of inbreeding depression varied with environmental stress. First, mated males fathered fewer nests per season if inbred or if the ratio of males to females in the population was high, but inbreeding depression did not depend on sex ratio. Second, fledglings survived poorly during rainy periods and if their father was inbred, but the effects of paternal inbreeding and rain did not interact. 6Thus, even for a single species, interactions between the inbreeding level and environmental stress may not occur in all traits affected by inbreeding depression, and interactions that do occur will not always act synergistically to further decrease fitness. [source] Insect pests and natural enemies in two varieties of quinua (Chenopodium quinoa) at Cusco, PeruJOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2002E. Yábar The quinua varieties differ, among other traits, in their content of saponins (secondary metabolites associated to plant resistance) late in the season. Whereas Agromyzidae and Cicadellidae were abundant only in the early season, both Chrysomelidae and Aphididae populations showed fluctuations. Likewise, Araneae and Braconidae showed fluctuating numbers during the season. The abundance of Coccinellidae peaked at mid-season whereas that of Syrphidae was high only in the late season. Although the overall abundance of insects was very similar in both varieties of quinua, there were different patterns depending on the season. In the early season there was a tendency towards greater insect numbers on Blanca, but in contrast, in the late season Amarilla (the high-saponin variety) had a higher load of insect pests. This suggests that saponins do not play a major role in quinua resistance against insects. In the early season, no significant relationship between pests and natural enemies held across quinua varieties. In the late season, Aphididae and Coccinellidae were negatively and significantly correlated in both varieties. The temporal population dynamics of Aphididae and both Coccinellidae and Braconidae resembled the traditional predator,prey dynamics. [source] Intrapopulation variation in reproduction by female eastern kingbirds Tyrannus tyrannus: the impacts of age, individual performance, and breeding siteJOURNAL OF AVIAN BIOLOGY, Issue 3 2004Michael T. Murphy I used data from a 13-year study of eastern kingbirds Tyrannus tyrannus from central New York, USA, to evaluate the relative impact of female age and body size on reproduction. I also calculated repeatabilities of reproductive traits for both females and the sites where they bred in an attempt to evaluate the relative contribution of each to intrapopulation variation in reproduction. Female age had a strong influence on timing of breeding (breeding date advanced by one day for each year of life), but was not a significant source of variation for clutch size, egg mass, number of young to hatch or fledge, or total seasonal production. Repeatabilities of breeding date for females and sites were both significant (0.284 and 0.181, respectively), but the only other significant repeatabilities were for female clutch size (0.282) and female egg mass (0.746). Among-year repeatabilities of breeding date for females who bred at two or more sites over their lifetime were as high as those for females that were site faithful. Thus, breeding date was probably affected independently by the female and site. No measure of productivity exhibited a repeatable pattern in comparisons made among females or sites. All reproductive traits were entered as dependent variables in a series of stepwise multiple regression analyses in an attempt to identify female properties (size, lifespan and condition) that might be linked proximately to differences in breeding statistics. I found that (a) large birds tended to breed the earliest, (b) clutch size was independent of female size, condition and lifespan, (c) female body size and egg size were correlated positively, but (d) production of young was independent of all measured female properties. Reproduction appears to be linked more closely to the female than to the site. Body size accounts for a portion of the repeatable portion of breeding date and egg mass, but most of the intrapopulation variation in these and other traits remained unexplained. [source] Morph-specific selection on floral traits in a polymorphic plantJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2010D. VANHOENACKER Abstract Correlations between phenotypic traits are common in many organisms, but the relative importance of nonadaptive mechanisms and selection for the evolution and maintenance of such correlations are poorly understood. In polymorphic species, morphs may evolve quantitative differences in additional characters as a result of morph-specific selection. The perennial rosette herb Primula farinosa is polymorphic for scape length. The short-scaped morph is less damaged by grazers and seed predators but is more strongly pollen limited than the long-scaped morph. We examined whether morph-specific differences in biotic interactions are associated with differences in selection on two other traits affecting floral display (number of flowers and petal size) and on one trait likely to affect pollination efficiency (corolla tube width) in three P. farinosa populations. Differences in selection between morphs were detected in one population. In this population, selection for more flowers and larger petals was stronger in the short-scaped than in the long-scaped morph, and although there was selection for narrower corolla tubes in the short-scaped morph, no statistically significant selection on corolla tube width could be detected in the long-scaped morph. In the study populations, the short-scaped morph produced more and larger flowers and wider corolla tubes. Current morph-specific selection was thus only partly consistent with trait differences between morphs. The results provide evidence of morph-specific selection on traits associated with floral display and pollination efficiency, respectively. [source] The genetic basis of early-life morphological traits and their relation to alternative male reproductive tactics in Atlantic salmonJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2010D. J. PáEZ Abstract Although heritability estimates for traits potentially under natural selection are increasingly being reported, their estimation remains a challenge if we are to understand the patterns of adaptive phenotypic change in nature. Given the potentially important role of selection on the early life phenotype, and thereby on future life history events in many fish species, we conducted a common garden experiment, using the Atlantic salmon (Salmo salar L.), with two major aims. The first objective is to determine how the site of origin, the paternal sexual tactic and additive genetic effects influence phenotypic variation of several morphological traits at hatching and emergence. The second aim is to test whether a link exists between phenotypic characteristics early in life and the incidence of male alternative tactics later in life. We found no evidence of a site or paternal effect on any morphological trait at hatching or emergence, suggesting that the spatial phenotypic differences observed in the natural river system from which these fish originated are mainly environmentally driven. However, we do find significant heritabilities and maternal effects for several traits, including body size. No direct evidence was found correlating the incidence of precocious maturation with early life characteristics. We suggest that under good growing conditions, body size and other traits at early developmental stages are not reliable cues for the surpassing of the threshold values associated with male sexual development. [source] Evolutionary biology of starvation resistance: what we have learned from DrosophilaJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2007S. RION Abstract Most animals face periods of food shortage and are thus expected to evolve adaptations enhancing starvation resistance (SR). Most of our knowledge of the genetic and physiological bases of those adaptations, their evolutionary correlates and trade-offs, and patterns of within- and among-population variation, comes from studies on Drosophila. In this review, we attempt to synthesize the various facets of evolutionary biology of SR emerging from those studies. Heritable variation for SR is ubiquitous in Drosophila populations, allowing for large responses to experimental selection. Individual flies can also inducibly increase their SR in response to mild nutritional stress (dietary restriction). Both the evolutionary change and the physiological plasticity involve increased accumulation of lipids, changes in carbohydrate and lipid metabolism and reduction in reproduction. They are also typically associated with greater resistance to desiccation and oxidative stress, and with prolonged development and lifespan. These responses are increasingly seen as facets of a shift of the physiology towards a ,survival mode', which helps the animal to survive hard times. The last decade has seen a great progress in revealing the molecular bases of induced responses to starvation, and the first genes contributing to genetic variation in SR have been identified. In contrast, little progress has been made in understanding the ecological significance of SR in Drosophila; in particular it remains unclear to what extent geographical variation in SR reflect differences in natural selection acting on this trait rather than correlated responses to selection on other traits. Drosophila offers a unique opportunity for an integrated study of the manifold aspects of adaptation to nutritional stress. Given that at least some major molecular mechanisms of response to nutritional stress seem common to animals, the insights from Drosophila are likely to apply more generally than just to dipterans or insects. [source] Creativity Defined: Implicit Theories in the Professions of Interior Design, Architecture, Landscape Architecture, and EngineeringJOURNAL OF INTERIOR DESIGN, Issue 1 2002Margaret Portillo Ph.D. ABSTRACT The purpose of this study was to examine implicit theories of creativity in related fields through a mail survey of 3 1 3 professors randomly selected from accredited programs in interior design, architecture, landscape architecture, and engineering. To describe a highly creative practitioner in their respective fields, the respondents completed the Gough Adjective Check List (ACL), scored with the Domino creativity scale (Cr). The interior design professors generated a profile of the creative practitioner that obtained a significantly higher mean score than did the architecture or engineering groups on the ACL-Cr scale. No other significant differences on the creativity scale appeared between groups. Exploratory analyses of individual ACL-Cr items found considerable agreement as to what constituted creativeness in implicit theories. At least 75 percent of the respondents in each group described the creative practitioner in their respective fields as imaginative, inventive, and adventurous. Disciplinary differences among groups surfaced in 21 traits on the ACL-Cr scale that were statistically significant in areas of artistic creativity, scientific creativity, intelligence, self-confidence, and task orientation. Further, the creative interior design practitioner was perceived as significantly more individualistic and original than in the other three fields, and sixteen other traits significantly differentiated interior design profiles from those posited in architecture, landscape architecture, or engineering. By promoting a scholarship of integration, findings reveal perceived traits of the creative practitioner in allied fields and advance interdisciplinary understanding. Design educators are encouraged to reflect on their own implicit theories of creativity and those of their students to acknowledge underlying assumptions about creativity that can influence innovation and collaboration. [source] Can We Identify Genes For Alcohol Consumption In Samples Ascertained For Heterogeneous Purposes?ALCOHOLISM, Issue 4 2009Narelle K. Hansell Background:, Previous studies have identified evidence of genetic influence on alcohol use in samples selected to be informative for alcoholism research. However, there are a growing number of genome-wide association studies (GWAS) using samples unselected for alcohol consumption (i.e., selected on other traits and forms of psychopathology), which nevertheless assess consumption as a risk factor. Is it reasonable to expect that genes contributing to variation in alcohol consumption can be identified in such samples? Methods:, An exploratory approach was taken to determine whether linkage analyses for heaviness of alcohol consumption, using a sample collected for heterogeneous purposes, could replicate previous findings. Quantity and frequency measures of consumption were collected in telephone interviews from community samples. These measures, and genotyping, were available for 5,441 individuals (5,067 quasi-independent sibling pairs). For 1,533 of these individuals, data were collected on 2 occasions, about 8.2 years apart, providing 2 datasets that maximize data collected at either a younger or an older age. Analyses were conducted to address the question of whether age and heavier levels of alcohol consumption effects outcome. Linkage results were compared in the younger and older full samples, and with samples in which approximately 10, 20, and 40 of drinkers from the lower end of the distribution of alcohol consumption were dropped. Results:, Linkage peaks varied for the age differentiated samples and for percentage of light drinkers retained. Larger peaks (LOD scores >2.0) were typically found in regions previously identified in linkage studies and/or containing proposed candidate genes for alcoholism including AGT, CARTPT, OPRD1, PIK3R1, and PDYN. Conclusions:, The results suggest that GWAS assessing alcohol consumption as a covariate for other conditions will have some success in identifying genes contributing to consumption-related variation. However, sample characteristics, such as participant age, and trait distribution, may have substantial effects on the strength of the genetic signal. These results can inform forthcoming GWAS where the same restrictions apply. [source] Morphological analysis of male mating organ in the Drosophila virilis species group: a multivariate approachJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 2 2004A. M. Kulikov Abstract The shape of the male mating organ differs among 11 closely related species of the Drosophila virilis species group. Multivariate analyses of variation of a suite of 35 morphological traits (indices) describing the phallus shape were carried out in order to characterize interspecies variability of the traits. An overwhelming majority of the traits displayed species-specific variability. The main result of the investigation was the revelation of the differences involved in the traits studied in the evolution of the D. virilis species group. The structure of species-specific variability of some traits was discovered to be in accordance with the generally accepted taxonomy of the species group, while that of other traits required isolation of D. virilisper se from lummei phylad (former virilis phylad), and confirmed separation of montana phylad into three subphylads: montana proper, littoralis and kanekoi. Several subsets of traits having separate variability were determined in different parts of the male mating organ which correspond to spots of evolutionarily significant variability. Zusammenfassung Die Form des männlichen Begattungsorgans zeigt innerhalb von 11 nahe verwandten Arten der Drosophila virilis - Gruppe Unterschiede. Eine multivariate Variationsanalyse einer Gruppe von 35 morphologischen Merkmalen (Indizes), die die Form des Penis erfassen, wurde durchgeführt, um die zwischenartliche Variabiltät des Merkmals zu charakterisieren. Die überwältigende Mehrheit der Merkmale erwies sich als artspezifisch. Das vorrangige Ergebnis der Untersuchung war, den unterschiedlichen Anteil dieses Merkmals an der Evolution der Drosophila virilis - Gruppe aufzuklären. Die Struktur der artspezifischen Variabilität einiger Merkmale konnte als übereinstimmend mit der allgemein akzeptierten Taxonomie der Artengruppe erkannt werden, während andere Merkmale es notwendig machten, D. virilis von der D. lummei - Phylade (der früheren D. virilis - Phylade) abzutrennen; bestätigt wurde auch die Auftrennung der D. montana - Phylade in drei Subphyladen: die eigentlich montana -, die littoralis - und die kanekoi - Phylade. [source] Genetic divergence and migration patterns in a North American passerine bird: implications for evolution and conservationMOLECULAR ECOLOGY, Issue 8 2006LESLIE A. DAVIS Abstract Like many other migratory birds, the black-throated blue warbler (Dendroica caerulescens) shows pronounced differences in migratory behaviour and other traits between populations: birds in the southern part of the breeding range have darker plumage and migrate to the eastern Caribbean during the winter, whereas those in the north have lighter plumage and migrate to the western Caribbean. We examined the phylogeography of this species, using samples collected from northern and southern populations, to determine whether differentiation between these populations dates to the Pleistocene or earlier, or whether differences in plumage and migratory behaviour have arisen more recently. We analysed variation at 369 bp of the mitochondrial control region domain I and also at seven nuclear microsatellites. Analyses revealed considerable genetic variation, but the vast majority of this variation was found within rather than between populations, and there was little differentiation between northern and southern populations. Phylogeographic analyses revealed a very shallow phylogenetic tree, a star-like haplotype network, and a unimodal mismatch distribution, all indicative of a recent range expansion from a single refugium. Coalescent modelling approaches also indicated a recent common ancestor for the entire group of birds analysed, no split between northern and southern populations, and high levels of gene flow. These results show that Pleistocene or earlier events have played little role in creating differences between northern and southern populations, suggesting that migratory and other differences between populations have arisen very recently. The implications of these results for the evolution of migration and defining taxonomic groups for conservation efforts are discussed. [source] Variation at two flowering time genes within and among populations of Arabidopsis thaliana: comparison with markers and traitsMOLECULAR ECOLOGY, Issue 13 2005V. LE CORRE Abstract Flowering Locus C (FLC) and Frigida are two interacting genes controlling flowering time variation in Arabidopsis thaliana. Variation at these genes was surveyed in 12 A. thaliana populations sampled in France. These populations were also screened for variation at molecular markers [12 microsatellites and 19 cleaved amplified polymorphic sequence (CAPS) markers] and at seven quantitative traits measured with and without vernalization. Seven populations were highly polymorphic at markers (HS = 0.57 at microsatellites, 0.24 at CAPS) and showed heritable variation for bolting time and some other traits. Five populations were genetically fixed or nearly fixed. QST for bolting time without vernalization was significantly higher than FST, suggesting local divergent selection. One of the two haplotype groups at FLC (FLCA) was very predominant (frequency of 99%). The first exon of Frigida showed elevated nonsynonymous variation, and nine loss-of-function mutations were found throughout the gene. The association between loss-of-function and earlier bolting was confirmed. Overall, 18 Frigida haplotypes were detected. The pattern of variation at Frigida was largely similar to that found at markers and traits, with the same populations being fixed or highly diverse. Metapopulation dynamics is thus probably the main factor shaping genetic variation in A. thaliana. However, FST for functional (FRI) vs. nonfunctional (FRI,) haplotypes was significantly higher than FST at markers. This suggested that loss-of-function at Frigida is under local selection for flowering time. [source] Mutations in two global regulators lower individual mortality in Escherichia coliMOLECULAR MICROBIOLOGY, Issue 1 2008Fanette Fontaine Summary There has been considerable investigation into the survival of bacterial cells under stress conditions, but little is known about the causes of mortality in the absence of exogenous stress. That there is a basal frequency of cell death in such populations may reflect that it is either impossible to avoid all lethal events, or alternatively, that it is too costly. Here, through a genetic screen in the model organism Escherichia coli, we identify two mutants with lower frequencies of mortality: rssB and fliA. Intriguingly, these two genes both affect the levels of different sigma factors within the cell. The rssB mutant displays enhanced resistance to multiple external stresses, possibly indicating that the cell gains its increased vitality through elevated resistance to spontaneous, endogenous stresses. The loss of fliA does not result in elevated stress resistance; rather, its survival is apparently due to a decreased physical stress linked to the insertion of the flagellum through the membrane and energy saved through the loss of the motor proteins. The identification of these two mutants implies that reducing mortality is not impossible; rather, due to its cost, it is subject to trade-offs with other traits that contribute to the competitive success of the organism. [source] Architectural and growth traits differ in effects on performance of clonal plants: an analysis using a field-parameterized simulation modelOIKOS, Issue 5 2007Radka Wildová Individual traits are often assumed to be linked in a straightforward manner to plant performance and processes such as population growth, competition and community dynamics. However, because no trait functions in isolation in an organism, the effect of any one trait is likely to be at least somewhat contingent on other trait values. Thus, to the extent that the suite of trait values differs among species, the magnitude and even direction of correlation between values of any particular trait and performance is likely to differ among species. Working with a group of clonal plant species, we assessed the degree of this contingency and therefore the extent to which the assumption of simple and general linkages between traits and performance is valid. To do this, we parameterized a highly calibrated, spatially explicit, individual-based model of clonal plant population dynamics and then manipulated one trait at a time in the context of realistic values of other traits for each species. The model includes traits describing growth, resource allocation, response to competition, as well as architectural traits that determine spatial spread. The model was parameterized from a short-term (3 month) experiment and then validated with a separate, longer term (two year) experiment for six clonal wetland sedges, Carex lasiocarpa, Carex sterilis, Carex stricta, Cladium mariscoides, Scirpus acutus and Scirpus americanus. These plants all co-occur in fens in southeastern Michigan and represent a spectrum of clonal growth forms from strong clumpers to runners with long rhizomes. Varying growth, allocation and competition traits produced the largest and most uniform responses in population growth among species, while variation in architectural traits produced responses that were smaller and more variable among species. This is likely due to the fact that growth and competition traits directly affect mean ramet size and number of ramets, which are direct components of population biomass. In contrast, architectural and allocation traits determine spatial distribution of biomass; in the long run, this also affects population size, but its net effect is more likely to be mediated by other traits. Such differences in how traits affect plant performance are likely to have implications for interspecific interactions and community structure, as well as on the interpretation and usefulness of single trait optimality models. [source] Quantitative trait loci and epistatic interactions in barley conferring resistance to net type net blotch (Pyrenophora teres f. teres) isolatesPLANT BREEDING, Issue 4 2010S. Gupta With 2 figures and 5 tables Abstract Net type net blotch (NTNB) is an important barley disease in Australia and elsewhere, with significant yield reduction. This trait is important in selection along with other traits of quality and agronomic value. Two-hundred doubled-haploid lines were generated through anther culture from a cross between ,Pompadour' and ,Stirling'. Quantitative trait loci (QTL) were identified against five isolates of Pyrenophora teres f. teres, which represent virulences across Australia. QTL were mapped on chromosomes 3H and 6H using simple sequence repeat (SSR) markers. The resistance locus on 6H was detected with all isolates while the 3H locus was detected with two isolates. The 6H QTL from ,Pompadour' contributed resistance to isolates 97NB1, 95NB100 and NB81, whereas 6H QTL from ,Stirling' contributed resistance to isolates NB50 and NB52B. The 3H QTL from ,Pompadour' contributed resistance to NB50 and NB52B. Significant epistatic interactions were detected between QTL on 3H and 6H. These resistance QTL are a useful resource and identifying closely linked SSR markers with allelic combinations will facilitate in marker-assisted selection to develop NTNB resistant breeding lines. [source] Quantitative trait loci associated with soybean tolerance to low phosphorus stress based on flower and pod abscissionPLANT BREEDING, Issue 3 2010D. Zhang With 2 figures and 5 tables Abstract Low phosphorus (P) stress limits soybean production. A population of 152 recombinant inbred lines (RILs) derived from a cross between ,Bogao' (P sensitive variety) and ,Nannong 94-156' (P tolerant variety) and 248 markers were used to map quantitative trait loci (QTLs) for low-P tolerance. Two pot culture trials were conducted and low-P tolerance evaluated using flower and pod abscission rate under low P and normal P. Conditional QTLs and epistasis for tolerance to low P were also analysed. A conditional QTL (near Satt274) on linkage group D1b+W was identified which conferred low-P tolerance epistatic effects and coincided with previously discovered QTLs. An additive QTL, qFARLPG-07, for flower abscission rate under low P was detected with a LOD score of 7.79 and explained 32.3% of phenotypic variation. It was detected at the same interval of the corresponding QTL for other traits across years. This region coincided with two conditional QTLs (cqFARLPG-07 and cqPARLPG-07), from the P-tolerant parent ,Nannong 94-156' related to low-P tolerance. These results will provide a basis for further fine mapping and eventual cloning of the P-efficiency genes in soybean. [source] | ||||||||||||||||||||||||||||||||||