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Search Results: 1 - 10 of 420548 matches for " Paul M. Brakefield "
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Bringing Evo Devo to Life
Paul M. Brakefield
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0030340
Abstract:
Bringing Evo Devo to Life
Paul M Brakefield
PLOS Biology , 2005, DOI: 10.1371/journal.pbio.0030340
Abstract:
Single locus affects embryonic segment polarity and multiple aspects of an adult evolutionary novelty
Suzanne V Saenko, Paul M Brakefield, Patrícia Beldade
BMC Biology , 2010, DOI: 10.1186/1741-7007-8-111
Abstract: We show that three mutations affecting eyespot size and/or colour composition in Bicyclus anynana butterflies occurred in the same locus, and that two of them are embryonic recessive lethal. Using surgical manipulations and analysis of gene expression patterns in developing wings, we demonstrate that the effects on eyespot morphology are due to changes in the epidermal response component of eyespot induction. Our analysis of morphology and of gene expression in mutant embryos shows that they have a typical segment polarity phenotype, consistent with the mutant locus encoding a negative regulator of Wingless signalling.This study characterizes the segregation and developmental effects of alleles at a single locus that controls the morphology of a lineage-specific trait (butterfly eyespots) and a conserved process (embryonic segment polarity and, specifically, the regulation of Wingless signalling). Because no gene with such function was found in the orthologous, highly syntenic genomic regions of two other lepidopterans, we hypothesize that our locus is a yet undescribed, possibly lineage-specific, negative regulator of the conserved Wnt/Wg pathway. Moreover, the fact that this locus interferes with multiple aspects of eyespot morphology and maps to a genomic region containing key wing pattern loci in different other butterfly species suggests it might correspond to a 'hotspot' locus in the diversification of this novel trait.The origin and diversification of novel morphological traits, such as angiosperm flowers, bird feathers, insect wings, or beetle horns, have always fascinated biologists and laymen alike and are currently a key theme in evolutionary developmental biology [1,2]. Novelties arise during the evolution of a lineage and perform new functions within its ecology [3]. While the ecological and evolutionary factors that promote the diversification of such traits have been studied for some time (e.g., [4,5]), it is only more recently that the genetic and de
Mitochondrial DNA Signature for Range-Wide Populations of Bicyclus anynana Suggests a Rapid Expansion from Recent Refugia
Maaike A. de Jong, Niklas Wahlberg, Marleen van Eijk, Paul M. Brakefield, Bas J. Zwaan
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021385
Abstract: This study investigates the genetic diversity, population structure and demographic history of the afrotropical butterfly Bicyclus anynana using mitochondrial DNA (mtDNA). Samples from six wild populations covering most of the species range from Uganda to South Africa were compared for the cytochrome c oxidase subunit gene (COI). Molecular diversity indices show overall high mtDNA diversity for the populations, but low nucleotide divergence between haplotypes. Our results indicate relatively little geographic population structure among the southern populations, especially given the extensive distributional range and an expectation of limited gene flow between populations. We implemented neutrality tests to assess signatures of recent historical demographic events. Tajima's D test and Fu's FS test both suggested recent population growth for the populations. The results were only significant for the southernmost populations when applying Tajima's D, but Fu's FS indicated significant deviations from neutrality for all populations except the one closest to the equator. Based on our own findings and those from pollen and vegetation studies, we hypothesize that the species range of B. anynana was reduced to equatorial refugia during the last glacial period, and that the species expanded southwards during the past 10.000 years. These results provide crucial background information for studies of phenotypic and molecular adaptation in wild populations of B. anynana.
Differences in the selection response of serially repeated color pattern characters: Standing variation, development, and evolution
Cerisse E Allen, Patrícia Beldade, Bas J Zwaan, Paul M Brakefield
BMC Evolutionary Biology , 2008, DOI: 10.1186/1471-2148-8-94
Abstract: Here we focus on two ecologically relevant features of butterfly wing color patterns, eyespot size and color composition, which are similarly and strongly correlated across the serially repeated eyespots. Though these two characters show similar patterns of standing variation and covariation within a population, they differ in key features of their underlying development. We targeted pairs of eyespots with artificial selection for coordinated (concerted selection) versus independent (antagonistic selection) change in their color composition and size and compared evolutionary responses of the two color pattern characters.The two characters respond to selection in strikingly different ways despite initially similar patterns of variation in all directions present in the starting population. Size (determined by local properties of a diffusing inductive signal) evolves flexibly in all selected directions. However, color composition (determined by a tissue-level response to the signal concentration gradient) evolves only in the direction of coordinated change. There was no independent evolutionary change in the color composition of two eyespots in response to antagonistic selection. Moreover, these differences in the directions of short-term evolutionary change in eyespot size and color composition within a single species are consistent with the observed wing pattern diversity in the genus.Both characters respond rapidly to selection for coordinated change, but there are striking differences in their response to selection for antagonistic, independent change across eyespots. While many additional factors may contribute to both short- and long-term evolutionary response, we argue that the compartmentalization of developmental processes can influence the diversification of serial repeats such as butterfly eyespots, even under strong selection.Despite the diversity of animal form in nature, a limited range of phenotypes is often observed [1-3]. Stasis, convergence, and limit
Cytogenetic Characterization and AFLP-Based Genetic Linkage Mapping for the Butterfly Bicyclus anynana, Covering All 28 Karyotyped Chromosomes
Arjen E. Van't Hof, Franti?ek Marec, Ilik J. Saccheri, Paul M. Brakefield, Bas J. Zwaan
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003882
Abstract: Background The chromosome characteristics of the butterfly Bicyclus anynana, have received little attention, despite the scientific importance of this species. This study presents the characterization of chromosomes in this species by means of cytogenetic analysis and linkage mapping. Methodology/Principal Findings Physical genomic features in the butterfly B. anynana were examined by karyotype analysis and construction of a linkage map. Lepidoptera possess a female heterogametic W-Z sex chromosome system. The WZ-bivalent in pachytene oocytes of B. anynana consists of an abnormally small, heterochromatic W-chromosome with the Z-chromosome wrapped around it. Accordingly, the W-body in interphase nuclei is much smaller than usual in Lepidoptera. This suggests an intermediate stage in the process of secondary loss of the W-chromosome to a ZZ/Z sex determination system. Two nucleoli are present in the pachytene stage associated with an autosome and the WZ-bivalent respectively. Chromosome counts confirmed a haploid number of n = 28. Linkage mapping had to take account of absence of crossing-over in females, and of our use of a full-sib crossing design. We developed a new method to determine and exclude the non-recombinant uninformative female inherited component in offspring. The linkage map was constructed using a novel approach that uses exclusively JOINMAP-software for Lepidoptera linkage mapping. This approach simplifies the mapping procedure, avoids over-estimation of mapping distance and increases the reliability of relative marker positions. A total of 347 AFLP markers, 9 microsatellites and one single-copy nuclear gene covered all 28 chromosomes, with a mapping distance of 1354 cM. Conserved synteny of Tpi on the Z-chromosome in Lepidoptera was confirmed for B. anynana. The results are discussed in relation to other mapping studies in Lepidoptera. Conclusions/Significance This study adds to the knowledge of chromosome structure and evolution of an intensively studied organism. On a broader scale it provides an insight in Lepidoptera sex chromosome evolution and it proposes a simpler and more reliable method of linkage mapping than used for Lepidoptera to date.
The combined effect of two mutations that alter serially homologous color pattern elements on the fore and hindwings of a butterfly
Antónia Monteiro, Bin Chen, Lauren C Scott, Lindsey Vedder, H Joop Prijs, Alan Belicha-Villanueva, Paul M Brakefield
BMC Genetics , 2007, DOI: 10.1186/1471-2156-8-22
Abstract: Missing removes or greatly reduces the size of two of the hindwing eyespots from the row of seven eyespots, with no detectable effect on the rest of the wing pattern. Offspring carrying a single Missing allele display intermediate sized eyespots at these positions. Spotty has the opposite effect of Missing, i.e., it introduces two extra eyespots in homologous wing positions to those affected by Missing, but on the forewing. When Missing is combined with Spotty the size of the two forewing eyespots decreases but the size of the hindwing spots stays the same, suggesting that these two mutations have a combined effect on the forewing such that Missing reduces eyespot size when in the presence of a Spotty mutant allele, but that Spotty has no effect on the hindwing. Missing prevents the complete differentiation of two of the eyespot foci on the hindwing. We found no evidence for any linkage between the Distal-less and Missing genes.The spontaneous mutation Missing controls the differentiation of the signaling centers of a subset of the serial homologous eyespots present on both the fore and the hindwing in a dose-dependent fashion. The effect of Missing on the forewing, however, is only observed when the mutation Spotty introduces additional eyespots on this wing. Spotty, on the other hand, controls the differentiation of eyespot centers only on the forewing. Spotty, unlike Missing, may be under Ubx gene regulation, since it affects a subset of eyespots on only one of the serially homologous wings.Modularity of body plans, and of serially repeated structures is widespread in the animal kingdom [1]. Examples of modular structures include vertebrae [2], teeth [3], limbs [4], digits [5], arthropod body segments [6], C. elegans terminal rays [7], insect fore and hindwings [8-10], and butterfly eyespot patterns [11-13]. One of the key questions driving research in the field of modularity is to understand how such modules acquire the ability to differentiate into more or less
Evolutionary history of the recruitment of conserved developmental genes in association to the formation and diversification of a novel trait
Leila T Shirai, Suzanne V Saenko, Roberto A Keller, Maria A Jerónimo, Paul M Brakefield, Henri Descimon, Niklas Wahlberg, Patrícia Beldade
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-21
Abstract: We investigated the evolutionary history of the recruitment and co-recruitment of four conserved transcription regulators to the larval wing disc region where circular pattern elements develop. The co-localization of Antennapedia, Notch, Distal-less, and Spalt with presumptive (eye)spot organizers was examined in 13 butterfly species, providing the largest comparative dataset available for the system. We found variation between families, between subfamilies, and between tribes. Phylogenetic reconstructions by parsimony and maximum likelihood methods revealed an unambiguous evolutionary history only for Antennapedia, with a resolved single origin of eyespot-associated expression, and many homoplastic events for Notch, Distal-less, and Spalt. The flexibility in the (co-)recruitment of the targeted genes includes cases where different gene combinations are associated with morphologically similar eyespots, as well as cases where identical protein combinations are associated with very different phenotypes.The evolutionary history of gene (co-)recruitment is consistent with both divergence from a recruited putative ancestral network, and with independent co-option of individual genes. The diversity in the combinations of genes expressed in association with eyespot formation does not parallel diversity in characteristics of the adult phenotype. We discuss these results in the context of inferring homology. Our study underscores the importance of widening the representation of phylogenetic, morphological, and genetic diversity in order to establish general principles about the mechanisms behind the evolution of novel traits.The origin and diversification of novel traits are central and longstanding issues in evolutionary biology [1]. Evolutionary novelties are lineage-restricted traits often associated with new adaptive functions [1,2]. Compelling examples include angiosperm flowers, beetle horns, bird feathers, and butterfly wing color patterns. Studies in evolutionary dev
The Male Sex Pheromone of the Butterfly Bicyclus anynana: Towards an Evolutionary Analysis
Caroline M. Nieberding, Helene de Vos, Maria V. Schneider, Jean-Marc Lassance, Natalia Estramil, Jimmy Andersson, Joakim B?ng, Erik Hedenstr?m, Christer L?fstedt, Paul M. Brakefield
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002751
Abstract: Background Female sex pheromones attracting mating partners over long distances are a major determinant of reproductive isolation and speciation in Lepidoptera. Males can also produce sex pheromones but their study, particularly in butterflies, has received little attention. A detailed comparison of sex pheromones in male butterflies with those of female moths would reveal patterns of conservation versus novelty in the associated behaviours, biosynthetic pathways, compounds, scent-releasing structures and receiving systems. Here we assess whether the African butterfly Bicyclus anynana, for which genetic, genomic, phylogenetic, ecological and ethological tools are available, represents a relevant model to contribute to such comparative studies. Methodology/Principal Findings Using a multidisciplinary approach, we determined the chemical composition of the male sex pheromone (MSP) in the African butterfly B. anynana, and demonstrated its behavioural activity. First, we identified three compounds forming the presumptive MSP, namely (Z)-9-tetradecenol (Z9-14:OH), hexadecanal (16:Ald ) and 6,10,14-trimethylpentadecan-2-ol (6,10,14-trime-15-2-ol), and produced by the male secondary sexual structures, the androconia. Second, we described the male courtship sequence and found that males with artificially reduced amounts of MSP have a reduced mating success in semi-field conditions. Finally, we could restore the mating success of these males by perfuming them with the synthetic MSP. Conclusions/Significance This study provides one of the first integrative analyses of a MSP in butterflies. The toolkit it has developed will enable the investigation of the type of information about male quality that is conveyed by the MSP in intraspecific communication. Interestingly, the chemical structure of B. anynana MSP is similar to some sex pheromones of female moths making a direct comparison of pheromone biosynthesis between male butterflies and female moths relevant to future research. Such a comparison will in turn contribute to understanding the evolution of sex pheromone production and reception in butterflies.
Suicide Rates in U.S. Presidential Election Years: 2008, 2012 and 2016  [PDF]
Paul M. Sommers
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.68003
Abstract: The author examines age-group specific suicide rates by state in the United States presidential election years of 2008, 2012 and 2016. For each election year, the states are divided into blue states (whose voters chose the Democratic Party presidential candidate) and red states (whose voters chose the Republican Party presidential candidate). While suicide rates have trended higher in all states, the differences in mean suicide rates in 2012 (when Democrat Barack Obama was re-elected) were significantly higher in red states than they were in blue states for every age group but adults 55 to 64 years of age. In 2016, when the Republican Party re-captured the White House late in the year, mean differences were notably higher in red states than in blue states among adults between 25 and 54 years of age.
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