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Multiple-line inference of selection on quantitative traits  [PDF]
Nico Riedel,Bhavin S. Khatri,Michael L?ssig,Johannes Berg
Quantitative Biology , 2014, DOI: 10.1534/genetics.115.178988
Abstract: Trait differences between species may be attributable to natural selection. However, quantifying the strength of evidence for selection acting on a particular trait is a difficult task. Here we develop a population-genetic test for selection acting on a quantitative trait which is based on multiple-line crosses. We show that using multiple lines increases both the power and the scope of selection inference. First, a test based on three or more lines detects selection with strongly increased statistical significance, and we show explicitly how the sensitivity of the test depends on the number of lines. Second, a multiple-line test allows to distinguish different lineage-specific selection scenarios. Our analytical results are complemented by extensive numerical simulations. We then apply the multiple-line test to QTL data on floral character traits in plant species of the Mimulus genus and on photoperiodic traits in different maize strains, where we find a signatures of lineage-specific selection not seen in a two-line test.
Effect of Individual Selection System of Parental Pure Lines on Productive Traits of Six Hybrids of Silkworm
Hossein Hojatpour,Abolghasem Lavvaf,Alireza Seidavi,Ehsan Hajian,Tarlan Farahvash
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.1246.1254
Abstract: In order to study effect of individual selection system of parental pure lines (31, 32, 103, 104, 107 and 110) on productive traits of six hybrids (31x32, 32x31, 103x104, 104x103, 107x110 and 110x107) of resulted offspring from faraway crossing during fourth generation, these six parental pure lines of Iran silkworm were recorded individually and forty males and forty females through cocoon weight in each of these six parental pure lines selected. Then, for each of these six lines along with selection group, a control group includes of average same as society as base society was considered. Lines based on conditions over reproductive line system of lines, Iran silkworm grand and mother in continues three generations as pure lines were maintained and trained and intra hybrids during each generation without any re-selection was carried out. Then, in fourth generation with breeding between parental lines, six types of larvae egg commercial hybrid, each one in two types of selective and random were produced. These twelve hybrids each one in the form of four repetitions, ere trained and their performance (selective and random hybrid) were recorded and compared. Finally, the results of individual selection system of parental pure lines on performance of theses offspring hybrids were analysed. For doing this, data was recorded by Excel software and the data mean based on completely random program by use of t-student test by SAS software were analysed and calculated. Then, performance (data mean) of obtained hybrids resulted from crossing parental pure lines by Duncan test were compared. Obtained results of mean comparison of each trait (performance) between (selective and control group) resulted hybrids of simple six parental pure lines studied showed that individual selection among each of these parental pure lines, a total (whole of these six lines) of four traits of eleven traits studied in this study have meaningful effect (statistically). For cocoon weight that resulted to 10000 larvae in 104x103 hybrid and 103x104 hybrid, a meaningful difference was observed. For traits of double cocoon number and double cocoon percentage in 103x104 hybrid, no meaningful difference was observed. For cocoon number produced in 104x103, meaningful difference was observed. Results showed that except in three hybrids 32x31, 107x110 and 110x107 in other produced and studied hybrids in this study, meaningful difference for some trait (total of four traits) were obtained.
Life History Trade-Offs and Relaxed Selection Can Decrease Bacterial Virulence in Environmental Reservoirs  [PDF]
Lauri Mikonranta, Ville-Petri Friman, Jouni Laakso
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043801
Abstract: Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a result, opportunistic pathogens are likely to experience conflicting selection pressures across different environments, and this could affect their virulence through life-history trait correlations. We studied these correlations experimentally by exposing an opportunistic bacterial pathogen Serratia marcescens to its natural protist predator Tetrahymena thermophila for 13 weeks, after which we measured changes in bacterial traits related to both anti-predator defence and virulence. We found that anti-predator adaptation (producing predator-resistant biofilm) caused a correlative attenuation in virulence. Even though the direct mechanism was not found, reduction in virulence was most clearly connected to a predator-driven loss of a red bacterial pigment, prodigiosin. Moreover, life-history trait evolution was more divergent among replicate populations in the absence of predation, leading also to lowered virulence in some of the ‘predator absent’ selection lines. Together these findings suggest that the virulence of non-obligatory, opportunistic bacterial pathogens can decrease in environmental reservoirs through life history trade-offs, or random accumulation of mutations that impair virulence traits under relaxed selection.
Comparison of Response to Selection in Three Commercial Pure Lines of Silkworm in Spring and Autumn Seasons
Ehsan Hajian,Alireza Seidavi,Abolghasem Lavvaf
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2011.1299.1308
Abstract: An experiment was done in order to comparison of response to selection in three commercial pure lines of silkworm in spring and autumn seasons. Base population in each line consists of two selective and randomly groups. Selective group to each of the studied lines, superior 40 cocoon male and 40 cocoon female based on single cocoon weight after single recording of the three cocoon weight traits, cocoon shell weight and cocoon shell percentage of the population was selected 3P and another random mating were given. Random group (control) related to each of the studied lines, 40 male cocoon and 40 female cocoons randomly selected without any recording of the mentioned traits among 3P population had been gathered and crossed. In the first generation of the 40 produced larvae eggs categories in each group of each line, 8 categories with hatched percentage and suitable fertility for breeding were hatched. Thus each group consisted of 8 families in each line of brothers and sisters (with a parent). All the first generation, data files consist of 2400 records for each of three traits (800 records per line). Finally among the 8 families per group in each line 40 male cocoons and 40 female cocoons were crossed randomly to produce 40 larvae eggs categories of next generation. Breeding process and producing row data in second generation or 2p and third generation or p was done as the same as the first generation. All data files in all lines contain 7680 records from each of the three traits were studied (2560 records in each line). It should be noted that only selected population in all lines was done just in vase population and all crossing in nest generations were carried out randomly. According to information available to separate spring and fall seasons, the effects of data were separated and the response to selection separately for each season, were recorded and saved in the computer. Separation of effects in spring and fall seasons and compare responses to a choice of three lines of the above actions seaso effect showed that spring effects on three traits of 27 trait and autumn effect on four traits of these traits was significant statistically. Individual selection performance comparisons in base population of above three commercial lines based on cocoon weight and response to selected three lines for 27 traits examined in this study showed that spring effect on three traits of 27 studied traits is significant and the autumn on the four traits have significant effects. Spring effect on three traits in the pupae vitality percentage in middle cocoons, larvae duration and the un-hatched eggs number, the autumn on four traits was significant effects. Spring effect on three traits of pupae vitality percentage in middle cocoon, larvae duration and un-hatched eggs number was significant. Autumn effect on three traits of pupae vitality percentage in best cocoon, best cocoon percentage, middle cocoon percentage and un-hatched eggs number was significant.
forqs: Forward-in-time Simulation of Recombination, Quantitative Traits, and Selection  [PDF]
Darren Kessner,John Novembre
Quantitative Biology , 2013,
Abstract: forqs is a forward-in-time simulation of recombination, quantitative traits, and selection. It was designed to investigate haplotype patterns resulting from scenarios where substantial evolutionary change has taken place in a small number of generations due to recombination and/or selection on polygenic quantitative traits. forqs is implemented as a command- line C++ program. Source code and binary executables for Linux, OSX, and Windows are freely available under a permissive BSD license.
Effects on some immunological traits after crossing three rabbit breeds in Egypt
Mahmoud S. El-Tarabany,Khairy M. El-Bayoumi
Veterinaria Italiana , 2010,
Abstract: The authors evaluate the effect of crossing three purebred rabbit breeds in a complete 3 × 3 diallel crossbreeding experiment (New Zealand White, V-line and Gabali) on certain immunological traits, including IgG titre. Sheep red blood cells (SRBCs) were administered at 8 weeks of age and boosted at 10 weeks of age. V-line/Gabali crossbreeds gave the highest significant (p<0.05) level of serum total protein at 8 and 12 weeks of age (4.71 and 7.70 g/dl, respectively). Its reciprocal crossbreed Gabali/V-line resulted in the highest estimate of serum globulin at 8 weeks of age (2.07 g/dl). V-line/Gabali crossbreeds showed the highest positive heterosis percentage (H%) of total protein, albumin and globulin at 8 weeks of age (27.98, 30.28 and 25.00, respectively). However, its reciprocal crossbreeds, Gabali/V-line, revealed negative estimates for total protein and albumin at the same age (–4.07 and –29.80). V-line/Gabali crossbreeds gave the highest titre (3.167) and positive H% (0.69) of IgG to the second dose of SRBCs. On the contrary, the highest negative estimate to the second dose was recorded in Gabali/New Zealand White crossbreeds (–2.49). Using the Gabali breed as the female line gave superior results for most immunological parameters.
$f(T)$ models with phantom divide line crossing  [PDF]
Puxun Wu,Hongwei Yu
Physics , 2010, DOI: 10.1140/epjc/s10052-011-1552-2
Abstract: In this paper, we propose two new models in $f(T)$ gravity to realize the crossing of the phantom divide line for the effective equation of state, and we then study the observational constraints on the model parameters. The best fit results suggest that the observations favor a crossing of the phantom divide line.
Crossing the Phantom divide line in the Chaplygin gas model  [PDF]
H. Mohseni Sadjadi
Physics , 2009, DOI: 10.1016/j.physletb.2010.03.011
Abstract: The role of the interaction in reaching and crossing the phantom divide line in the Chaplygin gas model is discussed. We obtain some necessary properties of the interaction that allow the model to arrive at or cross the phantom divide line. We show that these properties put some conditions on the ratio of dark matter to dark energy density in the present epoch.
Effects of Selection for Honey Bee Worker Reproduction on Foraging Traits  [PDF]
Benjamin P. Oldroyd,Madeleine Beekman
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0060056
Abstract: The “reproductive ground plan” hypothesis (RGPH) proposes that reproductive division of labour in social insects had its antecedents in the ancient gene regulatory networks that evolved to regulate the foraging and reproductive phases of their solitary ancestors. Thus, queens express traits that are characteristic of the reproductive phase of solitary insects, whereas workers express traits characteristic of the foraging phase. The RGPH has also been extended to help understand the regulation of age polyethism within the worker caste and more recently to explain differences in the foraging specialisations of individual honey bee workers. Foragers that specialise in collecting proteinaceous pollen are hypothesised to have higher reproductive potential than individuals that preferentially forage for nectar because genes that were ancestrally associated with the reproductive phase are active. We investigated the links between honey bee worker foraging behaviour and reproductive traits by comparing the foraging preferences of a line of workers that has been selected for high rates of worker reproduction with the preferences of wild-type bees. We show that while selection for reproductive behaviour in workers has not altered foraging preferences, the age at onset of foraging of our selected line has been increased. Our findings therefore support the hypothesis that age polyethism is related to the reproductive ground plan, but they cast doubt on recent suggestions that foraging preferences and reproductive traits are pleiotropically linked.
Effects of Selection for Honey Bee Worker Reproduction on Foraging Traits  [PDF]
Benjamin P Oldroyd ,Madeleine Beekman
PLOS Biology , 2008, DOI: 10.1371/journal.pbio.0060056
Abstract: The “reproductive ground plan” hypothesis (RGPH) proposes that reproductive division of labour in social insects had its antecedents in the ancient gene regulatory networks that evolved to regulate the foraging and reproductive phases of their solitary ancestors. Thus, queens express traits that are characteristic of the reproductive phase of solitary insects, whereas workers express traits characteristic of the foraging phase. The RGPH has also been extended to help understand the regulation of age polyethism within the worker caste and more recently to explain differences in the foraging specialisations of individual honey bee workers. Foragers that specialise in collecting proteinaceous pollen are hypothesised to have higher reproductive potential than individuals that preferentially forage for nectar because genes that were ancestrally associated with the reproductive phase are active. We investigated the links between honey bee worker foraging behaviour and reproductive traits by comparing the foraging preferences of a line of workers that has been selected for high rates of worker reproduction with the preferences of wild-type bees. We show that while selection for reproductive behaviour in workers has not altered foraging preferences, the age at onset of foraging of our selected line has been increased. Our findings therefore support the hypothesis that age polyethism is related to the reproductive ground plan, but they cast doubt on recent suggestions that foraging preferences and reproductive traits are pleiotropically linked.
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