Phenotypic selection

Central to the ecology and evolution of a broad range of plants is understanding why they routinely have submaximal reproduction manifested as low seed : ovule and fruit : flower ratios. We know much less about the processes responsible for low seed : ovule ratios than we do for fruit : flower ratios. Current hypotheses for low seed : ovule ratios are largely drawn from those for fruit : flower ratios, including proximate (ecological) causes of pollen limitation, resource limitation, and pollen quality, as well as the ultimate (evolutionary) hypothesis of ''bet hedging'' on stochastic pollination. Yet, such mechanisms operating on fruit : flower ratios at the whole-plant level may not best explain low seed : ovule ratios at the individual-flower level. We tested each of these proximate and ultimate causes for low seed : ovule ratios using the specialized pollination mutualism between senita cacti (Pachycereus schottii) and senita moths (Upiga virescens). Seed : ovule ratios were consistently low (;0.61). Such excess ovule production by senita likely has a strong genetic component given the significant differences among plants in ovule number and the consistency in ovule production by plants within and among flowering seasons. Excess ovule production and low seed : ovule ratios could not be explained by pollen limitation, resource limitation, pollen quality, or bet hedging. Nevertheless, phenotypic selection analyses did show significant selection gradients for increased ovule number, suggesting that other evolutionary processes may be responsible for excess ovule production and low seed : ovule ratios. In contrast, low fruit : flower ratios at the whole-plant level were explained by an apparent equilibrium between pollen and resource limitation. Thus, mechanisms responsible for low fruit : flower ratios at the whole-plant level are not necessarily in accord with those of low seed : ovule ratios at the individual-flower level. This suggests that we may need to adopt a more pluralistic approach to seed : ovule ratios and consider alternative hypotheses, including a greater array of proximate and ultimate causes. Initial results of this study suggest that floral allometry, selection on correlated floral traits, stigma clogging with pollen grains, and style clogging with pollen tubes may provide promising avenues for understanding low seed : ovule ratios.

Leaf collection from the field, labeling and tracking back to the source plants after genotyping are rate limiting steps in leaf DNA-based genotyping. In this study, an optimized genotyping method using endosperm DNA sampled from single maize seeds was developed, which can be used to replace leaf DNA-based genotyping for both genetic studies and breeding applications. A similar approach is likely to be suitable for all plants with relatively large seeds. Part of the endosperm was excised from imbibed maize seeds and DNA extracted in 96-tube plates using individuals from eight F 2 populations and seven inbreds. The quality of the resultant DNA was functionally comparable to DNA extracted from leaf tissue. Extraction from 30 mg of endosperm yields 3-10 lg DNA, which is sufficient for analysis of 200-400 agarose-gel PCR-based markers, with the potential for several million chip-based SNP marker analyses. By comparing endosperm DNA and leaf DNA for individuals from an F 2 population, genotyping errors caused by pericarp contamination and hetero-fertilization were found to average 3.8 and 0.6%, respectively. Endosperm sampling did not affect germination rates under controlled conditions, although under normal field conditions the germination rate, seedling establishment, and growth vigor were significantly lower than that of non-sampled controls for some genotypes. However, careful field management can compensate for these effects. Seed DNA-based genotyping lowered costs by 24.6% compared to leaf DNA-based genotyping due to reduced field plantings and labor costs. A substantial advantage of this approach is that it can be used to select desirable genotypes before planting. As such it provides an opportunity for dramatic improvements in the efficiency and selective gain of breeding systems based on optimum combinations of markerassisted selection and phenotypic selection within and between generations.

In mice, proliferating T cells in MLN were CD62L neg CD38 + during both tolerance induction and abrogation of intestinal homeostasis. This mucosal CD62L neg CD38 + T-cell phenotype was effi ciently induced by RA and TGF-β in mice, whereas for human CD4 + T cells RA alone was suffi cient. The CD4 + CD62L neg CD38 + T-cell phenotype could be used to identify T cells with mucosal origin in human peripheral blood, as expression of the gut-homing chemokine receptor CCR9 and ␤ 7 integrin were highly enriched in this subset whereas expression of cutaneous leukocyte-associated antigen was almost absent. Tetramer staining revealed that gluten-specifi c T cells appearing in blood of treated celiac disease patients after oral gluten challenge were predominantly CD4 + CD62L neg CD38 + . The total percentage of circulating CD62L neg CD38 + of CD4 T cells was not an indicator of intestinal infl ammation as percentages did not differ between pediatric celiac disease patients, infl ammatory bowel disease patients and respective controls. However, the phenotypic selection of mucosal T cells allowed cytokine profi ling as upon restimulation of CD62L neg CD38 + cells interleukin-10 (IL-10) and interferon-␥ (IFN -␥ ) transcripts were readily detected in circulating mucosal T cells.

Selective pressures on seed size could vary among the different stages of plant life cycles, so no simple relation could explain a priori its evolution. Here, we determined the relationships between seed size and two fitness components-seed dispersal and survival from predation-in a bird-dispersed tree, Crataegus monogyna. We interpret these relationships in relation to the patterns of mass allocation to fruit and seed components. Selection patterns were assessed at two levels (1) selection pressures on the parent tree; comparing seed dispersal efficiency among individual plants and (2) selection pressures at the individual seed level; comparing seed size variation (i) before and after dispersal, and (ii) before and after postdispersal seed predation. Dispersal efficiency (percentage of seed crop dispersed) was positively correlated with fruit mass and fruit width. Differences in crop size did not offset this effect, and larger seeds were overrepresented in the seed rain relative to the seed pool before dispersal. However, the advantage of larger seeds during the dispersal stage was cancelled later by an opposite selection pressure exerted by seed predators. As a result, smaller seeds had a higher probability of surviving postdispersal seed predation, establishing an evolutionary conflict imposed by the need for dispersal and the danger of being predated. Birds and rodents preferentially selected highly profitable fruits and seeds in terms of the relative proportion of their components. Larger fruits had a higher pulp to seed proportion than smaller ones, and all seeds had the same proportion of coat relative to the embryo-plus-endosperm fraction. Hence, although predator pressures were stronger than disperser ones, larger seeds invested proportionally less in structural defense than in dispersal.

Sexual selection is generally caused by female choice and male-male competition. In female choice process, female preference is favored indirectly and/or directly by sexual selection. In indirect selection, females expressing the preference might gain indirect genetic benefits. In direct selection, females expressing the preference might gain direct benefits or avoid male-imposed costs. The white-tailed zygaenid moth Elcysma westwoodii is monandrous, and males often gather around a female to mate with her, suggesting a high opportunity for sexual selection on male traits. We quantified phenotypic selection on male morphology in this species in the field. The morphological characters analyzed included body weight, antenna length, forewing length, hind wing length, hind wing tail length, genital clasper length, and the fluctuating asymmetry (FA) of these bilateral traits. In E. westwoodii, selection favored males with more symmetric genital claspers, as well as longer and more symmetrical hind wings and antennae. Negative correlations between FA and size were also detected in the clasper and the antenna. Our results suggest that FAs of male traits, in particular the genital clasper, may have indirect and direct influences on mating success. During a copulatory attempt, an E. westwoodii male will try to grasp the female's abdominal tip with his claspers but often fail to do so because of the female's reluctance to mate. The female abdominal tips are smooth and strongly sclerotized and could thus be difficult for males to grasp. We hypothesize that more symmetrical male claspers are more efficient in overcoming female reluctance.

The core of Darwin’s theory includes two ideas about natural selection: that it explains the evolution of the organisms’ characteristics and that it pushes these characteristics towards an optimum of organization and design. While the first idea is formalised in Population Genetics models, only informal descriptions support the second one. Moreover, Population Genetics models focus on loose characteristics and cannot explain the coordination among their functions, nor do they suggest that natural selection leads to the optimization of the organism design. Facing this bicephalous and at first sight contradictory situation, Grafen’s Formal Darwinism Project provides a mathematical foundations for the argument of design, through an optimization model, and shows that the results of the optimization are coherent with these from Population Genetics. It therefore formally demonstrates that natural selection, modifying genetic frequencies, optimizes the individual characteristics and leads them to complex designs: in other words, that Darwin was right in claiming that the ‘struggle for life’ is the source of the variety and the complexity of the biological world. However, Grafen’s model is not universally accepted: additionally to the critics around its hypothesis and conclusions that can be found in the literature, others can be advanced regarding the lack of precise definitions of some of the concepts used. Nevertheless, his program, irrespective of whether it will prove adequate or not, contributes to the reflection around central subjects within the Philosophy of Biology.

DNA-based technology has dramatically enhanced the efficiency of plant breeding, especially when selections are to be done under unfavourable conditions. Although significant strides have been made in crop improvement trough phenotypic selections for ergonomically important traits, this often encounters considerable difficulties, particularly those posed by genotype x environment interactions. Besides testing procedure may be many times difficult, unreliable or expensive due to the nature of the target traits (e.g. abiotic and biotic stresses) or the target environment. The most widespread use of Marker Assisted Selection (MAS) to date is to assist backcrossing of major gene already proven elite cultivars. If individual genes or Quantitative Trait Loci (QTL) significantly influencing specific target traits can be identified based on their linkage to molecular markers, the efficiency of incorporating the desired traits in elite germplasm could be greatly enhanced. By combining QTL approach with backcrossing, useful genes that control quantitative traits have been identified in plant germplasm that are not for agriculture and have successfully been transferred to danced breeding lines. Indonesian molecular breeders should have a research program on DNA marker work that leads to application of useful selection tools and valuable germplasm. As molecular breeders adopt more rigorous experimental guidelines and ambitious goals, they also need to integrate the growing body of knowledge from genomics and bioinformatics.

Several single-base substitution mutations have been introduced into the lacZa gene in cloning vector M13mp2, at 40-60% efficiency, in a rapid procedure requiring only transfection of the unfractionated products of standard in vitro mutagenesis reactions. Two simple additional treatments of the DNA, before transfection, produce a sitespecific mutation frequency approaching 100%. The approach is applicable to phenotypically silent mutations in addition to those that can be selected. The high efficiency, %10-fold greater than that observed using current methods without enrichment procedures, is obtained by using a DNA template containing several uracil residues in place of thymine. This template has normal coding potential for the in vitro reactions typical of site-directed mutagenesis protocols but is not biologically active upon transfection into a wild-type (i.e., ung') Escherichia coli host cell. Expression of the desired change, present in the newly synthesized non-uracil-containing covalently closed circular complementary strand, is thus strongly favored. The procedure has been applied to mutations introduced via both oligonucleotides and error-prone polymerization. In addition to its utility in changing DNA sequences, this approach can potentially be used to examine the biological consequences of specific lesions placed at defined positions within a gene.

Substantial improvements in production efficiency and quality of beef and dairy products have been made possible through manipulation of bovine genetics. The advent of modern breeds in the last two centuries, the institution of phenotypic selection practices and quantitative genetics, even the process of domestication in the distant past, have all represented means to make use of naturally occurring variation in the genome to tailor the animal for a desired outcome. We discuss the history of genome research in cattle and recent technological advances that promise a leap forward in the use of DNA sequence to facilitate selection, in which a detailed genome-level view for individual animals may provide comprehensive and relatively accurate assessment of the consequences, both desired and unintended, of genetic selection for livestock production.

Molecular markers (RAPD, AFLP and microsatellites) were used to generate a linkage map and to identify QTLs associated to witches' broom (Crinipellis perniciosa) resistance in cacao (Theobroma cacao), using 82 individuals of an F 2 population derived from the clones ICS-1 (susceptible) and Scavina-6 (resistant). Fifteen evaluations of the number of brooms have been carried out in six years (1997-2002). In order to increase the precision and accuracy in the measures of resistance, each F 2 plant was cloned in three replications in a randomized block design with singletree plots and evaluated over 2 years. Three hundred and forty-two markers were obtained, being 33 microsatellites, 77 AFLPs and 232 RAPDs. The distribution of the number of brooms in the F 2 population was skewed to resistance, suggesting the involvement of major genes controlling resistance and the repeatability estimated for resistance was 44%. A strong putative QTL was detected as being related to witches' broom resistance. Associated to this QTL, the microsatellite mTcCIR35 explained 35.5% of the phenotypic variation in resistance. This marker is being used for marker-assisted selection in Scavina-6 progenies, including those selected in private plantations, as an auxiliary tool to the phenotypic selection.

RESUMO -Avaliou-se a utilização de marcadores microssatélites para acelerar a recuperação do genoma recorrente, em programas de retrocruzamento em milho. Uma linhagem com elevada capacidade geral de combinação para produtividade de grãos e alta inserção da espiga (L11) foi utilizada como genitor recorrente e uma linhagem com baixa inserção da espiga e baixa produtividade de grãos em cruzamento (L13) foi utilizada como genitor doador. A seleção fenotípica para baixa inserção de espiga foi realizada por dois ciclos de retrocruzamento e a recuperação do genoma do genitor recorrente nas plantas selecionadas foi monitorada utilizando-se marcadores SSR. Procurou-se, neste trabalho, comparar a recuperação do genoma recorrente em progênies de retrocruzamento selecionadas para baixa inserção da espiga, com e sem seleção assistida por marcadores. Para esse propósito, foi avaliada a produtividade de grãos dessas progênies em cruzamentos topcrosses, com uma linhagem testadora (L161), em três locais. Os resultados indicaram que os marcadores SSR foram eficientes na identificação de indivíduos com maior proporção de recuperação do genoma recorrente nos dois ciclos iniciais de retrocruzamento, permitindo um ganho de até três ciclos, se comparada com a recuperação esperada no retrocruzamento convencional. A seleção fenotípica para a baixa inserção da espiga foi eficiente, embora não tenha havido uma completa recuperação do fenótipo do genitor doador (L13), após dois ciclos de retrocruzamento. Foram obtidos híbridos topcrosses de progênies derivadas do retrocruzamento assistido mais produtivos e com inserção de espiga mais baixa que o híbrido topcross da linhagem recorrente. No entanto, as condições experimentais não permitiram concluir sobre a utilização da produtividade de grãos em híbridos topcrosses, na avaliação da recuperação do genoma recorrente, em programas de retrocruzamento em milho.

Cross validation (CV) and validation with an independent sample (IV) are new biometric approaches in QTL analysis to obtain unbiased estimates of QTL effects and the proportion of the genetic variance explained by the detected marker-QTL association (p). Our objective with these methods was to obtain a realistic picture on the prospects of marker-assisted selection (MAS) for improving the resistance of maize against the tropical stem borer species Diatraea grandiosella (SWCB) and Diatraea saccharalis (SCB). Published QTL mapping studies on leaf-damage ratings (LDR) with populations of F 2:3 lines and recombinant inbred lines (RIL) from crosses CML131×CML67 and Ki3× CML139 of tropical maize inbreds were re-analyzed with CV and IV. With CV, the reduction in p for LDR compared to p obtained with the whole data set varied between 41.0 and 79.6% in the populations of F 2:3 lines and between 30.1 and 65.2% in the two populations of RIL. Estimates of p for SCB LDR were similar for CV and IV. For SWCB LDR, p estimates obtained with IV were larger than those obtained with CV in CML131× CML67. The reverse was observed for Ki3×CML139. Under the assumption of identical selection intensities, and based on the re-estimates of p, MAS using only molecular marker information is less-efficient than conventional phenotypic selection (CPS). MAS combining marker and phenotypic data increases the relative efficiency by only 4% in comparison to CPS. In conclusion, MAS for improving SWCB and SCB LDR seems notpromising unless additional QTLs with proven large ef-fects are available or the costs of marker assays are considerably reduced.

Bayesian analysis via Gibbs sampling, restricted maximum likelihood (REML), and Method R were used to estimate variance components for several models of simulated data. Four simulated data sets that included direct genetic effects and different combinations of maternal, permanent environmental, and dominance effects were used. Parents were selected randomly, on phenotype across or within contemporary groups, or on BLUP of genetic value. Estimates by Bayesian analysis and REML were always empirically unbiased in large data sets. Estimates by Method R were biased only with phenotypic selection across contemporary groups; estimates of the additive variance were biased upward, and all the other estimates were biased downward. No empirical bias was observed for Method R under selection within contemporary groups or in data without contemporary group effects. The bias of Method R estimates in small data sets was evaluated using a simple direct additive model. Method R gave biased estimate...

Two cucumber recombinant inbred lines (RILs) differing in plant habit were crossed and progeny self-pollinated to produce F 3 individuals upon which phenotypic selection was practiced to identify a base population which in turn underwent either two cycles of MAS or random mating without selection (RAN). MAS and RAN were practiced to produce F 4 and F 5 progeny sets. RIL, crossing parents, and F 3-F 5 progeny sets were then evaluated under replicated field conditions for fruit yield and quality (L:D and E:T) to evaluate gain from selection (DG). The broad-sense heritability (h 2 B) over cycles (C) of selection ranged 0.22-0.45, 0.09-0.20, and 0.11-0.15 for yield, L:D, and E:T, respectively. Although one cycle of PHE selection followed by MAS was effective in conserving the performance of the traits examined during inbreeding, progeny performance during RAN fluctuated (F 4-F 5 generation; C 2). Lack of DG during advanced generations (F 4-F 5) of MAS was likely due to allelic fixation and/or optimized epistatic complementation.

The traditional narrow focus on male mate competition in studies of mammalian mating strategies has been successful in explaining many conspicuous outcomes of sexual selection. However, focusing on ungulates, I here review increasing evidence that a comprehensive understanding of sexually selected adaptations requires consideration of a broader range of sex roles, particularly those relating to female behaviour. I show how mate competition and mate choice in both sexes can interact and often lead to intra-and intersexual conflicts and sometimes also cooperation. By causing phenotypic selection, these behavioural interactions can shape evolution although the outcome depends on genetic constraints. I conclude that to advance the understanding of mammalian mating systems we must broaden our conceptual framework from being largely focused on male competitive strategies to encompass coevolutionary dynamics between the mating strategies of both sexes. Future challenges include clarifying (1) the ecological basis for the inter-and intraspecific diversity in sex roles, (2) the condition-dependence of female mating strategies, and (3) the ultimate causes of mate competition and promiscuity in females.

Flowers emit a large variety of floral signals that play a fundamental role in the communication of plants with their mutualists and antagonists. We investigated phenotypic selection on floral scent and floral display using the rewarding orchid species Gymnadenia odoratissima. We found positive directional selection on inflorescence size, as well as positive and negative selection on floral scent compounds. Structural equation modeling showed that ''active'' compounds, i.e. those that were shown in earlier investigations to be detected by pollinator insects, were positively linked to fitness, whereas ''non-active'' were negatively linked to fitness. Our results suggest that different patterns of selection impact on different scent compounds, which may relate to the functions of compounds for attracting/deterring insects.

Hasta fechas muy recientes, la mayoría de los estudios teóricos y empíricos sobre la evolución de la relación entre las plantas y sus polinizadores han asumido que estos sistemas están altamente especializados, es decir, cada especie vegetal es visitada por sólo unos cuantos polinizadores relacionados filogenéticamente como fruto de la selección impuesta por ellos. La omnipresencia de especialización se ha derivado de aceptar el principio del polinizador más eficiente, según el cual una planta debe especializarse en el polinizador más eficaz y/o más abundante cuando su disponibilidad es predecible. Muchos estudios han encontrado realmente que los polinizadores ejercen selección fenotípica sobre rasgos reproductivos de las plantas. Sin embargo, igual de evidente es el hecho de que muchas especies vegetales son polinizadas por conjuntos numerosos y taxonómicamente diversos de polinizadores. Estas observaciones sugieren que en realidad los sistemas de polinización son generalistas. La generalización es producida y mantenida por varios factores ecológicos entre los que destacan la variación espacial y la fluctuación temporal de la identidad de los polinizadores más importantes, la similitud en la eficiencia y preferencia por los rasgos florales por parte de polinizadores diferentes, la existencia de factores externos que reducen la capacidad de los polinizadores de afectar al fitness de la planta, y la existencia de selección indirecta.

The proboscis of male elephant seals (Mirounga Gray, 1827) has been suggested as an example of a secondary sexual trait since Darwin. There has been much speculation about its social function (e.g., optical signal of breeding status, amplification of vocalizations, cue for female choice). However, it has never been studied in detail, probably because its fleshy nature makes measurement difficult. In this paper, we employ photogrammetry to measure the proboscis and facial morphology of a large sample of wild, unrestrained, displaying male southern elephant seals (Mirounga leonina (L., 1758)). We describe ontogeny and allometry of the proboscis and analyze current phenotypic selection pressures on proboscis traits. We discuss the potential role of the proboscis in optical and acoustic signaling of male resource-holding potential and status. We demonstrate that proboscis size is positively correlated with age and body size independently, and that it is currently under a positive sexual selection pressure when the effect of selection on body size is removed. We suggest that selection on proboscis size is functionally related to the emission of agonistic vocalizations.

Molecular markers (RAPD, AFLP and microsatellites) were used to generate a linkage map and to identify QTLs associated to witches' broom (Crinipellis perniciosa) resistance in cacao (Theobroma cacao), using 82 individuals of an F2 population derived from the clones ICS-1 (susceptible) and Scavina-6 (resistant). Fifteen evaluations of the number of brooms have been carried out in six years (1997–2002). In order to increase the precision and accuracy in the measures of resistance, each F2 plant was cloned in three replications in a randomized block design with single-tree plots and evaluated over 2 years. Three hundred and forty-two markers were obtained, being 33 microsatellites, 77 AFLPs and 232 RAPDs. The distribution of the number of brooms in the F2 population was skewed to resistance, suggesting the involvement of major genes controlling resistance and the repeatability estimated for resistance was 44%. A strong putative QTL was detected as being related to witches' broom resistance. Associated to this QTL, the microsatellite mTcCIR35 explained 35.5% of the phenotypic variation in resistance. This marker is being used for marker-assisted selection in Scavina-6 progenies, including those selected in private plantations, as an auxiliary tool to the phenotypic selection.

A method is presented for the selection of parents with the aim of obtaining improved genotypes in the progeny of a cross. The procedure is designed to select in several unrelated traits simultaneously and is based on the selection of molecular markers that are linked to QTLs. The method was compared with conventional phenotypic selection in simulation experiments for a number of genetic structures underlying the traits and several types of parental populations. Although the method in general provides good results, some of the underlying assumptions may be violated quite easily, thereby reducing the applicability of the procedure in practice.

A mathematical approach to interactions between genotypes and phenotypes in a multilocus multiallele population is developed. No a priori information on a fitness function is required. In particular, some structural definitions of epistasis and the position effect are given in terms of a decomposition of phenotypical structures. On this base a distance to the additive nonepistasis is introduced and an explicit formula for it is obtained. A class of phenotypical structures including multilocus dominance is described in terms of directed graphs. The evolutionary equations are adjusted to a fitness function compatible with a phenotypical structure. Some results on the finiteness of the equilibria set are presented.

Use of DNA-based markers can accelerate cultivar development in variable cultivation environments since, in contrast to phenotype, DNA markers are environment-independent. In an effort to elucidate the genetic basis of genotype-by-environment interaction (G • E) for yield of rice (Oryza sativa L.), the associations between 139 AFLP markers and grain yield were determined for rice grown in fresh water (EC of 0.65 dS m-1) and saline conditions (EC of 4-8 dS m-1) with 0 kg ha-1 or 100 kg ha-1 nitrogen fertilizer in the years 2000 and 2001. A population

We examine the hierarchical geographic structure of the interaction between a plant, Helleborus foetidus, and its floral herbivores and pollinators (interactors). Six populations from three distant regions of the Iberian Peninsula were used to examine intra-and interregional variation in plant traits, interactors and plant fecundity, and to compare, through selection gradient and path analyses, which traits were under selection, and which interactors were responsible for differential selection. Geographic and temporal congruency in interactormediated selection was further tested using a recent analytical approach based on multi-group comparison in Structural Equation Models. Most plant traits, interactors and fecundity differed among regions but not between populations. Similarly, the identity of the traits under selection, the selection gradients (strength and/or the direction of the selection) and the path coefficients (identifying the ecological basis for selection) varied inter-but not intraregionally. Results show a selection mosaic at the broad scale and, for some traits, a link of differential selection to trait differentiation.

Application of Marker-Assisted Selection in Crop Breed- ing. Muhammad Azrai. DNA-based technology has dramat- ically enhanced the efficiency of plant breeding, especially when selections are to be done under unfavourable condi- tions. Although significant strides have been made in crop improvement trough phenotypic selections for ergonomic- ally important traits, this often encounters considerable diffi- culties, particularly those posed by genotype x environment interactions. Besides testing procedure may be many times difficult, unreliable or expensive due to the nature of the target traits (e.g. abiotic and biotic stresses) or the target environment. The most widespread use of Marker Assisted Selection (MAS) to date is to assist backcrossing of major gene already proven elite cultivars. If individual genes or Quantitative Trait Loci (QTL) significantly influencing spe- cific target traits can be identified based on their linkage to molecular markers, the efficiency of incorporati...

Patterns of selection are widely believed to differ geographically, causing adaptation to local environmental conditions. However, few studies have investigated patterns of phenotypic selection across large spatial scales. We quantified the intensity of selection on morphology in a monogamous passerine bird, the barn swallow Hirundo rustica, using 6495 adults from 22 populations distributed across Europe and North Africa. According to the classical Darwin-Fisher mechanism of sexual selection in monogamous species, two important components of fitness due to sexual selection are the advantages that the most attractive males acquire by starting to breed early and their high annual fecundity. We estimated directional selection differentials on tail length (a secondary sexual character) and directional selection gradients after controlling for correlated selection on wing length and tarsus length with respect to these two fitness components. Phenotype and fitness components differed significantly among populations for which estimates were available for more than a single year. Likewise, selection differentials and selection gradients differed significantly among populations for tail length, but not for the other two characters. Sexual selection differentials differed significantly from zero across populations for tail length, particularly in males. Controlling statistically for the effects of age reduced the intensity of selection by 60 to 81%, although corrected and uncorrected estimates were strongly positively correlated. Selection differentials and gradients for tail length were positively correlated between the sexes among populations for selection acting on breeding date, but not for fecundity selection. The intensity of selection with respect to breeding date and fecundity were significantly correlated for tail length across populations. Sexual size dimorphism in tail length was significantly correlated with selection differentials with respect to breeding date for tail length in male barn swallows across populations. These findings suggest that patterns of sexual selection are consistent across large geographical scales, but also that they vary among populations. In addition, geographical patterns of phenotypic selection predict current patterns of phenotypic variation among populations, suggesting that consistent patterns of selection have been present for considerable amounts of time.

The relative strength of different types of directional selection has seldom been compared directly in natural populations. A recent meta-analysis of phenotypic selection studies in natural populations suggested that directional sexual selection may be stronger in magnitude than directional natural selection, although this pattern may have partly been confounded by the different time scales over which selection was estimated. Knowledge about the strength of different types of selection is of general interest for understanding how selective forces affect adaptive population divergence and how they may influence speciation. We studied divergent selection on morphology in parapatric, natural damselfly (Calopteryx splendens) populations. Sexual selection was stronger than natural selection measured on the same traits, irrespective of the time scale over which sexual selection was measured. Visualization of the fitness surfaces indicated that population divergence in overall morphology i...

Evaluation of root traits in rainfed lowland rice is very difficult. Molecular genetic markers could be used as an alternative strategy to phenotypic selection for the improvement of rice root traits. This research was undertaken to map QTLs associated with five root traits using RFLP and AFLP markers. Recombinant inbred lines (RILs) were developed from two indica parents, IR58821-23-B-1-2-1 and IR52561-UBN-1-1-2, that were adapted to rainfed lowland production systems. Using wax-petrolatum layers to simulate a hardpan in the soil, 166 RILs were evaluated for total root number (TRN), penetrated root number (PRN), root penetration index (RPI, the ratio of PRN to TRN), penetrated root thickness (PRT) and penetrated root length (PRL) under greenhouse conditions during the summer and the fall of 1997. A genetic linkage map of 2022 cM length was constructed comprising 303 AFLP and 96 RFLP markers with an average marker space of 5.0 cM. QTL analysis via interval mapping detected 28 QTLs for these five root traits, which were located on chromosomes 1, 2, 3, 4, 6, 7, 10 and 11. Individual QTLs accounted for between 6 and 27% of the phenotypic variation. Most of the favorable alleles were derived from the parent IR58821-23-B-1-2-1, which was phenotypically superior in root traits related to drought resistance. Three out of six QTLs for RPI were detected in both summer and fall experiments and they also were associated with PRN in both experiments. Out of eight QTLs for RPT, five were common in both seasons. Two genomic regions on chromosome 2 were associated with three root traits (PRN, PRT and RPI), whereas three genomic regions on chromosomes 2 and 3 were associated with two root traits (PRT and RPI). Two QTLs affecting RPI and two QTLs affecting PRT were also found in similar genomic regions in other rice populations. The consistent QTLs across genetic backgrounds and the common QTLs detected in both experiments should be good candidates for marker-assisted selection toward the incorporation of root traits in a drought resistance breeding program, especially for rainfed lowland rice.

In this work, Potato virus Y (PVY) resistant potatoes were generated using an environmentally safe construct. For this purpose, a 'shooter' mutant Agrobacterium-based transformation system was used. The isopentenyl transferase gene (ipt) present on the Ti plasmid of 'shooter' strains enhances shoot regeneration and can be used as a phenotypic selection marker. The introduced marker-free binary vector carried a hairpin construct derived from the coat protein gene of PVY-NTN strain in order to induce gene silencing. Transformation resulted in high regeneration rates (1.4-5.7 shoots per explant). With pre-selection for the ipt + phenotype the transformation frequency was 24-53%, while without selection 12-28% of the shoots were PCR positive. The presence of the transgene was verified by Southern hybridization. In 16 of 31 challenged transformant lines PVY could be detected neither by RT-PCR nor by back inoculation. A 62.5% of these resistant lines proved to be also ipt-free. This transformation system was reproducible in four potato cultivars, suggesting that it could easily be adapted for other species.

Extraordinary floral variation is common among some orchids that employ deception to attract pollinators. This variation may be maintained by frequency-dependent selection where rare phenotypes are preferred. Over a 2-yr period, 1993-1994, we monitored the reproductive success of Tolumnia variegata, an obligately outcrossing epiphytic orchid, at three localities in Puerto Rico that differed in pollinator service. Plants varied in floral morphology and fragrance characteristics. Artificial arrays of varying frequencies of scentless and fragrant phenotypes were established to test for frequency-dependent selection. Where pollinators were rare (Cambalache, range of census average ϭ 0-0.2 bees/h), 0.9-1.2% of the flowers were effectively visited (pollinarium removals and pollinations). At Tortuguero where 0.4-1.1 bees/h were observed, 4-9.2% of the flowers were visited. At Piñones where bees were the most abundant (1.4-5.2bees/h), 20.9-25.0% of the flowers were visited. A significant portion of the variance in all measures of reproductive success (male, female, and combined) was explained by differences among populations, which we attribute mostly to variation in pollinator abundance. Neither the fragrance phenotype nor its frequency had a significant effect on success as revealed by a split-plot ANOVA. There was a significant interaction between population and phenotypic frequencies in all our measures of reproductive success, but only for the 1994 flowering season. Thus, variation in floral fragrance phenotypes is not likely maintained by frequency-dependent selection. High levels of variation remain unexplained.

Gestational diabetes mellitus (GDM) is a heterogeneous group of disorders in which diabetes or glucose intolerance is first diagnosed during pregnancy. Gestational diabetic patients include those with previously undiagnosed Type I (insulin-dependent) diabetes mellitus, Type II (non-insulin-dependent) diabetes mellitus, impaired glucose tolerance and specific defined monogenic subgroups in addition to pregnancy-induced glucose intolerance which reverses after delivery. The clinical course of patients with GDM varies considerably, both during and after pregnancy, reflecting the different causes.

Pollination syndromes suggest that convergent evolution of floral traits and trait combinations reflects similar selection pressures. Accordingly, a pattern of selection on floral traits is expected to be consistent with increasing the attraction and pollen transfer of the important pollinator. We measured individual variation in six floral traits and yearly and lifetime total plant seed and fruit production of 758 plants across nine years of study in natural populations of Ruby-Throated Hummingbird-pollinated Silene virginica. The type, strength, and direction of selection gradients were observed by year, and for two cohorts selection was estimated through lifetime maternal fitness. Positive directional selection was detected on floral display height in all years of study and stigma exsertion in all years but one. Significant quadratic and correlational selection gradients were rare. However, a canonical analysis of the gamma matrix indicated nonlinear selection was common; if significant curvature was detected it was convex with one exception. Our analyses demonstrated selection favored trait combinations and the integration of floral features of attraction and pollen transfer efficiency that were consistent with the hummingbird pollination syndrome.

A strategy combining single backcrossing with selected bulk breeding has been successfully used in wheat improvement at CIMMYT to introgress rust resistant genes from donor parents to elite adapted cultivars. In this research, the efficiency of this breeding strategy was compared to other crossing and selection strategies through computer simulation. Results indicated this breeding strategy has advantages in retaining or improving the adaptation of the recurrent parents, and at the same time transferring most of the desired donor genes in a wide range of scenarios. Two rounds of backcrossing have advantages when the adaptation of donor parents is much poorer than that of the adapted parents, but the advantage of three rounds of backcrossing over two rounds is minimal. We recommend using the single backcrossing breeding strategy (SBBS) when three conditions are met: (1) multiple genes govern the phenotypic traits to be transferred from donor parents to adapted parents, (2) the donor parents have some favorable genes that may contribute to the improvement of adaptation in the recipient parents, and (3) conventional phenotypic selection is being applied, or individual genotypes cannot be precisely identified. We envisage that all three conditions commonly exist in modern breeding programs, and therefore believe that SBBS could be applied widely. However, we do not exclude the use of repeated backcrossing if the transferred genes can be precisely identified by closely linked molecular markers, and the donor parents have extremely poor adaptation.

Expression of additive and dominance effects during development of forest trees species is poorly documented. A set of 10 subpopulations, generated from factorial mating amongst subsets of 88 females and 107 males representing 684 families and 37,206 individual trees, was used to estimate variance components between 4 and 65 months in a Eucalyptus urophylla * grandis breeding population. The variance components were significantly different from zero for female, male and female-by-male interaction effects for height and circumference. The results, from the set of experiments, stressed the huge dispersion of variance component estimates among subpopulations. The trends were modelled using linear and nonlinear models. The trends in additive, dominance and environmental variances with age showed three phases corresponding to the stage of competition during stand development. No significant trend was observed for the coefficients of variation of these three effects. The dominance to additive variance ratio did not show specific age-related trends and was close to 1.2 during the growth period. The additive, dominance and environmental correlations between height and circumference were higher than 0.8 after 24 months. A similar age-related trend was observed for the additive and dominance effects. These results emphasise the significant role of dominance in the genetic control of growth traits. They differ from the majority of studies of pines, where additive variance is preponderant, but are similar to those of other eucalyptus studies. In the context of Congolese breeding strategy, this can be explained by the phenotypic selection of parents constituting the breeding population and/or the expression of overdominance in eucalyptus hybrid populations planted in marginal zones.

Small scale tree domestication, tree breeding and genetic conservation activities face different challenges compared to large and highly developed programs. There are various economical and logistical constraints as listed below, particularly in developing countries. In general, there is not sufficient financial support or land to develop rigorous and largescale tree breeding programs for many forest tree species The scale (and cost) of the improvement program should be customized to the (financial and planting) capacities of the end users, or the cultivation range of the species. Most countries have to deal with multiple species Some countries have forest land with steep slopes and low fertility land. Progeny testing is costly and physically challenging. In most instances, conventional tree breeding is not appropriate. Conservation of genetic resources of minor species may require different strategy compared to widely used forest tree species To address problems outlined above, an international meeting was held on October 9-13, 2006, in Belek, Antalya, Turkey. The topics included the following: Low-cost domestication, breeding and testing strategies Economic analysis of small scale forest tree breeding and gene conservations strategies in reducing the cost? Use of molecular markers and biotechnology in designing and implementing cost efficient breeding and gene conservation programs The role of in-vitro / vegetative propagation in design and implementation of cost efficient breeding programs, the role of clonal testing and selection Low-cost gene conservation strategies Tree selection, domestication and improvement for agroforestry. This booklet contains the program and the abstracts of the presentations at the meeting. The full versions of the presentations will be available soon at the congress website, and will remain there for about six months (until June 30 th 2007).

Background. In order to properly direct the breeding work of cultivars of a given potato earliness group it is necessary to know the range of variability and relationships between their characteristics, both in a given
year and between years. Therefore, the purpose of this study was to determine the structure of the variability of the quantitative traits of mid-early potato cultivars, which would facilitate in selecting cultivars with the highest stability of the desired characteristics.
Material and methods. The analysis was based on a strict field experiment carried out in the years 2010-2012 at the Experimental Station in Uhnin (Lublin Province), (51°34' N; 23°02' E), on lessive soil, slightly acidic. The experiment was performed in randomized blocks in three repetitions. Eighteen potato cultivars were studied, four very early cultivars and six early cultivars. Cultivation techniques were conducted in accordance with the principles of Good Agricultural Practice and conservation measures in line with the recommendations of the IOR-PIB. Organic fertilizers and minerals for potato were at the same level each
year (20 Mg·ha-1 white mustard for ploughing, 90 kg N, 39.3 kg P, and 112.0 kg K·ha-1.
Results. The dominant role in the variability of tuber yield and its structure was played by the interaction between the cultivar and the environment (3.2%-92.7%). Genotype accounted for 2.9%-27.9% of variance in the total variance of the studied characteristics, and the test conditions for 3.7%-73.9%. Interaction between the genotype and the environment was the most conducive to: total yield, commercial yield, yield of seed potatoes, and proportion of tuber mass of <4, 5-6 and >6 cm in diameter. It did not, however, significantly affect the number of shoots per plant. The most stable characteristic of the activity of the tested cultivars was mass proportion of commercial tubers, and the most variable one was their yield. Conclusion. Analysis of the main components identified five groups of cultivars with specific characteristics that can be used in decision-making in the breeding of new cultivars.

The advent of molecular markers as a tool to aid selection has provided plant breeders with the opportunity to rapidly deliver superior genetic solutions to problems in agricultural production systems. However, a major constraint to the implementation of marker-assisted selection (MAS) in pragmatic breeding programs in the past has been the perceived high relative cost of MAS compared to conventional phenotypic selection. In this paper, computer simulation was used to design a genetically effective and economically efficient marker-assisted breeding strategy aimed at a specific outcome. Under investigation was a strategy involving the integration of both restricted backcrossing and doubled haploid (DH) technology. The point at which molecular markers are applied in a selection strategy can be critical to the effectiveness and cost efficiency of that strategy. The application of molecular markers was considered at three phases in the strategy: allele enrichment in the BC1F1 population, gene selection at the haploid stage and the selection for recurrent parent background of DHs prior to field testing. Overall, incorporating MAS at all three stages was the most effective, in terms of delivering a high frequency of desired outcomes and at combining the selected favourable rust resistance, end use quality and grain yield alleles. However, when costs were included in the model the combination of MAS at the BC1F1 and haploid stage was identified as the optimal strategy. A detailed economic analysis showed that incorporation of marker selection at these two stages not only increased genetic gain over the phenotypic alternative but actually reduced the over all cost by 40%.