Genetic diversity of Duffy binding protein 2 region II of Plasmodium cynomolgi from wild macaques in Peninsular Malaysia

@#Recent reports of natural human infection by Plasmodium cynomolgi indicate the increased risk of zoonotic transmission by this simian parasite. The P. cynomolgi Duffy binding protein 2 (PcDBP2) has a potential role in the invasion pathway of host erythrocytes, and it is a possible vaccine candidate against cynomolgi malaria. This study investigates the genetic diversity, haplotypes, and natural selection of PcDBP2 region II from isolates collected from wild macaques in Peninsular Malaysia. Blood samples from 50 P. cynomolgi-infected wild macaques were used in the study. Genomic DNA extracted from the blood samples was used as template for PCR amplification of the PcDBP2 region II. The amplicons were cloned into a plasmid vector and sequenced. MEGA X and DnaSP ver.6.12.03 programmes were used to analyse the DNA sequences. A genealogical relationship of PcDBP2 region II were determined using haplotype network tree on NETWORK ver.10.2. Result showed high genetic diversity (ð = 0.017 ± 0.002; Hd = 1.000 ± 0.001) of the PcDBP2 region II. The Z-test indicates a purifying selection, with population expansion as shown in Tajima’s D analysis. A total of 146 haplotypes of PcDBP2 region II were observed. Phylogenetic tree analysis showed that these haplotypes were grouped into three allelic types (136 for Strain B type, 9 for Berok type, and 1 recombinant type). In the haplotype network, PcDBP2 region II revealed no geographical groupings but was divided into two distinct clusters.

Genetic relatedness and its causal role in the evolution of insect societies

It has been proposed that age reprogramming enables old cells to be rejuvenated without passage through an embryonicstage (Singh and Zacouto in J. Biosci. 35 315–319, 2010). As such, age reprogramming stands apart from the inducedpluripotent stem (iPS) and nuclear transfer-embryonic stem (NT-ES) cell therapies where histo-compatible cells are produced only after passage through an embryonic stage. It avoids many of the disadvantages associated with iPS and NT-EScell therapies. Experimental evidence in support of age reprogramming is burgeoning. Here, we discuss possible newapproaches to enhance age reprogramming, which will have considerable benefits for regenerative therapies.

Genetic characterisation of the erythrocyte-binding protein (PkβII) of Plasmodium knowlesi isolates from Malaysia

Plasmodium knowlesi contributes to the majority of human malaria incidences in Malaysia. Its uncontrollable passage among the natural monkey hosts can potentially lead to zoonotic outbreaks. The merozoite of this parasite invades host erythrocytes through interaction between its erythrocyte-binding proteins (EBPs) and their respective receptor on the erythrocytes. The regionII of P. knowlesi EBP, P. knowlesi beta (PkβII) protein is found to be mediating merozoite invasion into monkey erythrocytes by interacting with sialic acid receptors. Hence, the objective of this study was to investigate the genetic diversity, natural selection and haplotype grouping of PkβII of P. knowlesi isolates in Malaysia. Polymerase chain reaction amplifications of PkβII were performed on archived blood samples from Malaysia and 64 PkβII sequences were obtained. Sequence analysis revealed length polymorphism, and its amino acids at critical residues indicate the ability of PkβII to mediate P. knowlesi invasion into monkey erythrocytes. Low genetic diversity (π = 0.007) was observed in the PkβII of Malaysia Borneo compared to PeninsularMalaysia (π = 0.015). The PkβII was found to be under strong purifying selection to retain infectivity in monkeys and it plays a limited role in the zoonotic potential of P. knowlesi. Its haplotypes could be clustered into Peninsular Malaysia and Malaysia Borneo groups, indicating the existence of two distinct P. knowlesi parasites in Malaysia as reported in an earlier study.

Low Levels of Polymorphisms and Negative Selection in Plasmodum knowlesi Merozoite Surface Protein 8 in Malaysian Isolates

Human infections due to the monkey malaria parasite Plasmodium knowlesi is increasingly being reported from most Southeast Asian countries specifically Malaysia. The parasite causes severe and fatal malaria thus there is a need for urgent measures for its control. In this study, the level of polymorphisms, haplotypes and natural selection of full-length pkmsp8 in 37 clinical samples from Malaysian Borneo along with 6 lab-adapted strains were investigated. Low levels of polymorphism were observed across the full-length gene, the double epidermal growth factor (EGF) domains were mostly conserved, and non-synonymous substitutions were absent. Evidence of strong negative selection pressure in the non-EGF regions were found indicating functional constrains acting at different domains. Phylogenetic haplotype network analysis identified shared haplotypes and indicated geographical clustering of samples originating from Peninsular Malaysia and Malaysian Borneo. This is the first study to genetically characterize the full-length msp8 gene from clinical isolates of P. knowlesi from Malaysia; however, further functional characterization would be useful for future rational vaccine design.

Epidemias e colapso demográfico no México e nos Andes do século XVI: contribuições da biologia evolutiva / Epidemics and demographic collapse in Mexico and the Andes in the sixteenth century: contributions from evolutionary biology

Resumo Discute as epidemias no colapso demográfico de ameríndios no México e na América Andina após a chegada dos espanhóis. A partir das categorias de Ernst Mayr de causas distantes (ou evolutivas) e próximas (ou funcionais), argumenta-se que causas distantes, como causas genéticas, que conferiram resistência imunológica aos espanhóis, manifestaram-se em um cenário muito estratificado, provocando a destruição de incas e astecas. Interpretações recentes do projeto colonialista europeu buscam minimizar a importância das epidemias ou matizá-las com fatores sociais, econômicos e políticos, interpretados aqui como causas próximas. Defendemos que somente pela articulação dessas duas categorias é possível entender a importância das epidemias na conquista espanhola da América Latina.

Abstract The role of epidemics in the demographic collapse of the Amerindians in Mexico and Andean America after the arrival of the Spanish is discussed. Ernst Mayr's categories of ultimate (or evolutionary) and proximal (or functional) causes are used to argue that ultimate causes, such as genetics, which gave the Spanish immunological resistance, were manifested in a very stratified setting, triggering the destruction of the Incas and Aztecs. Recent interpretations of colonization have played down the importance of epidemics or combined them with social, economic, and political factors, interpreted here as proximate causes. We understand that only by articulating these two categories can the importance of epidemics in the Spanish conquest of Latin America be understood.

Genetic Diversity and Natural Selection in 42 kDa Region of Plasmodium vivax Merozoite Surface Protein-1 from China-Myanmar Endemic Border

Plasmodium vivax merozoite surface protein-1 (PvMSP1) gene codes for a major malaria vaccine candidate antigen. However, its polymorphic nature represents an obstacle to the design of a protective vaccine. In this study, we analyzed the genetic polymorphism and natural selection of the C-terminal 42 kDa fragment within PvMSP1 gene (Pv MSP142) from 77 P. vivax isolates, collected from imported cases of China-Myanmar border (CMB) areas in Yunnan province and the inland cases from Anhui, Yunnan, and Zhejiang province in China during 2009–2012. Totally, 41 haplotypes were identified and 30 of them were new haplotypes. The differences between the rates of non-synonymous and synonymous mutations suggest that PvMSP142 has evolved under natural selection, and a high selective pressure preferentially acted on regions identified of PvMSP133. Our results also demonstrated that PvMSP142 of P. vivax isolates collected on China-Myanmar border areas display higher genetic polymorphisms than those collected from inland of China. Such results have significant implications for understanding the dynamic of the P. vivax population and may be useful information towards China malaria elimination campaign strategies.

The levels of selection debate: taking into account existing empirical evidence / El debate sobre niveles de selección: teniendo en cuenta la evidencia empírica existente

For over five decades the dominant neo-Darwinian view is that natural selection acts only at the genic and organismal levels, but the ignored empirical evidence of multilevel selection occurring in nature obtained over the last fifty years does not agree with it. A long exchange of mathematical and theoretical arguments about the levels at which natural selection acts constitutes what is known as the 'levels of selection debate'. The large amount of empirical evidence, studied by quantitative genetics means, specifically contextual analysis, indicates that natural selection acts on levels of the biological hierarchy above and below that of the gene and organism, from the molecular to the ecosystem level, thus supporting what is called the multilevel selection theory. Beyond theoretical arguments, if empirical evidence for multilevel selection and contextual analysis results are carefully examined, the debate on the levels of selection is easily resolved: natural selection occurs in nature at different levels of biological hierarchy. This text provides an overview of such empirical evidence.

Por más de cinco décadas la visión neo-darwinista dominante de la selección natural es que esta actúa únicamente a nivel génico y organísmico, pero la ignorada evidencia empírica de selección multinivel ocurriendo en la naturaleza obtenida durante los últimos cincuenta años no es consecuente. Un largo intercambio de argumentaciones matemáticas y teóricas sobre los niveles en los que actúa la selección natural constituye lo que se denomina como el "debate de los niveles de selección". La gran cantidad de evidencia empírica, estudiada mediante métodos de genética cuantitativa, específicamente el análisis contextual, indica que la selección natural actúa en niveles de la jerarquía biológica por encima y por debajo del nivel del gen y organismo, desde el nivel molecular hasta el ecosistémico, apoyando así lo que se denomina la teoría de selección multinivel. Más allá de argumentos teóricos, si se examina cuidadosamente la evidencia empírica de selección multinivel y los resultados del análisis contextual, se resuelve de forma sencilla el debate de los niveles de selección: la selección natural ocurre en la naturaleza en diferentes niveles de la jerarquía biológica. Este texto ofrece una revisión general de dicha evidencia empírica.

Evolutionary change and phylogenetic relationships in light of horizontal gene transfer.

Horizontal gene transfer has, over the past 25 years, become a part of evolutionary thinking. In the present paper I discuss horizontal gene transfer (HGT) in relation to contingency, natural selection, evolutionary change speed and the Tree-of-Life endeavour, with the aim of contributing to the understanding of the role of HGT in evolutionary processes. In addition, the challenges that HGT imposes on the current view of evolution are emphasized.

Especiação e seus mecanismos: histórico conceitual e avanços recentes / Speciation and its mechanisms: conceptual background and recent advances

Apresenta uma abordagem histórica sobre conceitos gerais de especiação e seus mecanismos, a partir das ideias primordiais até as teorias mais recentes que visam elucidar a origem da biodiversidade. Sabe-se que especiação é um tema polêmico e complexo que abrange praticamente todas as linhas de pesquisa dentro da biologia, além da geologia e da paleontologia. O objetivo principal do artigo é clarificar os conceitos teóricos sobre a origem das espécies animais, na ordem cronológica em que foram estabelecidos, ao longo do desenvolvimento da biologia evolutiva como ciência.

This paper presents a historical approach on general concepts of speciation and its mechanisms, from the primordial ideas to the most recent theories that seek to elucidate the origin of biodiversity. It is common knowledge that speciation is a controversial and complex issue that encompasses virtually all the lines of research of biology, in addition to geology and paleontology. The main objective of the paper is to clarify the theoretical concepts on the origin of the animal species, in the chronological order in which they became established throughout the whole of the development of evolutionary biology as a science.

Measuring opportunity for natural selection: Adaptation among two linguistically cognate tribes inhabiting two eco-situations of North-East India.

BACKGROUND: Numerous literature on the migration of Mishings point out to the fact that the Mishing and the Minyong are two culturally and linguistically cognate tribes that co-existed in the same ecology in the hills of Arunachal Pradesh. The Mishing tribe after migration, now inhabits flood-prone areas of Brahmaputra valley of Assam. AIM: The study aims to measure the adaptation process of these two cognate tribes inhabiting two different ecologies at present: Hills and plains by calculating the index of selection intensity by Crow’s and Johnston and Kensinger’s formulae. MATERIALS AND METHODS: The reproductive histories of 77 Mishing mothers of completed fertility inhabiting a flood affected village of Assam and 74 Minyong mothers inhabiting a hilly village of Arunachal Pradesh are selected. RESULTS AND DISCUSSION: The Minyongs show higher average fertility than the Mishings. The proportion of embryonic death is higher, and child death is lower among the Mishings (0.1661; 0.1623) than the Minyongs (0.1319; 0.2238). The index of selection due to mortality component is contributing more toward the total index of selection in both the tribes. CONCLUSION: The contribution of mortality component is sizeable to the total selection like many other tribes of North-East India. Higher proportion of embryonic deaths among the Mishings infers that the causes are mostly biological whereas, the higher proportion of child deaths among the Minyongs infers that the causes are mostly socio-cultural.

Upstream guppies (Poecilia reticulata, Peters, 1859) go against the flow / Gupies (Poecilia reticulata, Peters, 1859) de áreas de cabeceira se posicionam contra a corrente

Guppies (Poecilia reticulata Peters 1859) in lakes and from captive-bred populations are predicted to show little rheotaxis compared to conspecifics in a stream environment that are regularly exposed to flash floods associated with involuntary downstream migration. Here we test this hypothesis using an artificial stream, examining guppies of two wild riverine populations, one lake population, and one ornamental strain. Guppies from the most upstream riverine habitat show the most pronounced rheotaxis and are less likely to be swept downstream during flooding events. However, there is no significant difference between guppies from the lowland riverine habitat, the Pitch Lake and ornamental strain. We propose that station-keeping behaviours are most strongly selected in the upstream population because large spatial differences exist in ecology and environment between up- and downstream habitats. Given that these sites are separated by barrier waterfalls that prevent compensatory upstream migration, natural selection operates particularly strong against upstream guppies that have been displaced downstream during flooding events.

Populações de guppies (Poecilia reticulata Peters) que vivem em lagos e em cativeiro podem demonstrar menos reotaxia em comparação com populações que habitam rios e que estão frequentemente expostas a enchentes e que provocam a migração involuntária para jusante. Neste trabalho, vamos testar esta hipótese num rio artificial utilizando guppies de duas populações selvagens que habitam em rios, uma população que habita em lagos, e uma linhagem ornamental. Os resultados demonstram que os guppies de rios que provêm de localidades a montante demonstram maior reotaxia, diminuindo assim probabilidade de serem arrastados para jusante em períodos de enchentes. No entanto, não foram encontradas diferenças significativas entre guppies de localidades a jusante, do lago Pitch ou ornamentais. Este resultado pode dever-se ao facto de existirem grandes diferenças ecológicas entre os habitats localizados a jusante e a montante dos rios. Devido ao facto de estas localidades estarem separadas por cachoeiras, impossibilitando a migração rio-acima, a seleção natural poderá estar a actuar contra guppies que sejam arrastados rio abaixo durantes os períodos de cheias.

Alfred Russel Wallace and the elimination of the unfit.

The differences between Charles Darwin’s and Alfred Russel Wallace’s theories of natural selection have been discussed for many years, with particular attention to their varying thoughts on sexual selection, whether competition occurs primarily between individuals or varieties, and how human consciousness evolves. Potentially the most important difference between their respective points of view has, however, been largely overlooked. Darwin’s natural selection, later characterized as the ‘survival of the fittest,’ contains an ‘adaptation results in adaptations’ logic that some have criticized as tautological (Lewontin 1984) or even teleological (Reiss 2009). This inelegancy has been tolerated because the theory’s stated premises (i.e. the presence of a limited resource base, coupled with variation within populations and the potential for procreation to the point of superabundance) remain as unassailable now as they were originally. In a paper in the journal Complexity (Smith 2012), however, I argue that Wallace’s conceptualization, focusing on an elimination (or extermination) of the unfit driving mechanism, might represent a better vehicle for relating natural selection to other evolution-related phenomena such as mass extinction, divergence, speciation and the origins of variation itself. Wallace’s natural selection emphasizes ecological interactions. Bateson (1972) noted his use of the steam engine governor analogy as a means of describing its operation in the famous essay ‘On the tendency of varieties to depart indefinitely from the original type’ (Wallace 1858; see excerpt below), and went so far as to interpret Wallace’s thinking (see first quotation below) as the first example of cybernetic modelling. One immediate benefit of this kind of thinking is that it becomes easier to differentiate selection for domestication from ‘natural’ selection: in the former, the ideal of fitness is a predetermined one and is deliberately selected for, whereas in the latter, removal is not predetermined, leaving successful adaptation a function of environmental engagement – of whatever sort. Importantly, such engagement can then be considered in independently conceived ecological and biogeographical terms, thus focusing on assembly rules and eliminating the tautological trap. Darwin, by contrast, once stated: ‘It is a beautiful part of my theory, that domesticated races of organics are made by precisely same means as species – but latter far more perfectly and infinitely slower’ (Darwin 2002). Further discussion of this matter can proceed elsewhere. As a first step, however, it is essential workers at least come to grips with the idea that Wallace really did think in ‘elimination of the unfit’ terms, and consider how this framework might lead us in new directions. To that end I have compiled a set of excerpts from Wallace’s writings that should leave few doubts on that score: The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure soon to follow. (Wallace 1858, p 62) Natural selection . . . does not so much select special variations as exterminate the most unfavourable ones. (from a famous 1866 letter to Darwin reproduced in Marchant 1916) In the case of butterflies the argument becomes even stronger, because the fertility is so much greater, and the weeding out of the unfit takes place, to a great extent, in the egg and larvæ state. (Wallace 1877, p 405).

The Selection Metaphor: The Concepts of Metacontingencies and Macrocontingencies Revisited / La metáfora de la selección: una revisión de los conceptos de metacontingencia y macrocontingencia

Las explicaciones tradicionales de la conducta cultural se fundamentan en una perspectiva seleccionista. Sin embargo, varias discusiones teóricas se han preguntado sobre la misma y sobre la identificación de unidades de selección. Argumentaré que, si bien las propuestas centrales de Glenn constituyen una extensión valiosa de los principios operantes, el enfoque seleccionista ha entorpecido el desarrollo conceptual y empírico de la teoría. Se presenta un examen de las nociones fundamentales de la teoría de la evolución cultural; específicamente, una revisión de los conceptos de metacontingencias, contingencias conductuales entrelazadas, macrocontingencias y productos agregados, en términos de su contribución a una explicación válida y significativa del comportamiento cultural. Se sugiere que se requieren análisis experimentales funcionales para identificar el control de la conducta por parte de contingencias individuales o grupales, incluyendo los productos acumulados y agregados.

Current mainstream accounts of cultural behavior are strongly founded on a selectionist perspective. However, more than a few theoretical discussions have emerged regarding the appropriateness of the subject matter and the identification of units of selection. I argue that although Glenn's central formulations constitute a valuable extension of operant principles, the selectionist approach has hindered the theory's conceptual and empirical development. An examination of the fundamental notions included in the theory of cultural evolution is presented. Specifically, we review the concepts of metacontingencies, interlocking behavioral contingencies, macrocontingencies, and aggregate products in terms of their contribution to a valid and significant account of cultural behavior. It is suggested that experimental functional analyses are required to identify control of behavior by local contingencies or group consequences including cumulative and aggregate products.

Los nuevos pilaees de la teoría evolutiva a la luz de la genómica / New Pillars of Evolutionary Theory in the Light of Genomics

La teoría de evolución de Darwin se ha constituido en uno de los pilares fundamentales de la biología. Algunos supuestos de dicha teoría han sido complementados con las bases genéticas de la herencia dando origen a la teoría moderna o sintética de la evolución. En los últimos años se han logrado grandes avances en el área de secuenciación y análisis de genomas completos que han aportado elementos para debatir varios de los postulados darwinistas de la evolución. La demostración de procesos de duplicación de genes y de genomas completos, la transferencia horizontal de genes y la teoría endosimbiótica cuestionan la idea de cambio evolutivo como un proceso de acumulación de pequeños cambios a través del tiempo geológico. La evidencia de la selección neutral en el contexto genómico pone de manifiesto otros mecanismos de evolución, que no necesariamente van acompañados de un programa adaptacionista ni con la idea de progreso. En este artículo se presentan estos y otros conceptos adicionales tales como la regulación génica y los mecanismos moleculares del desarrollo y del ambiente como puntos de partida para el planteamiento de una teoría evolutiva incluyente y acorde a los conocimientos actuales.

The evolutionist theory proposed by Darwin is one of the fundamental pillars in biology. Darwin’s theory was solidified with the Modern synthesis of evolutionary biology thanks to the rediscovery of Mendel’s work, which laid the genetic basis of heredity. In recent years, great progress has been acquired in the sequencing and analyses of complete genomes, which have provided several elements to discuss some Darwinists tenets of evolution. The evidence of gene duplication and whole-genome duplication, the horizontal gene transfer and the endosymbiosis process question the idea that evolution proceeds through the gradual accumulation of infinitesimally small random changes. The new evidence of neutral selection on the genomics context reveals other mechanisms of evolution not necessarily related with the idea of progress or with an adaptationist program as was originally stated by the Darwin’s theory. In this paper, I present these and other concepts such as gene regulation, molecular mechanisms of development and some environmental aspects (epigenesis and phenotypic plasticity) as starting points to think in the necessity to update the evolutionary theory which in my opinion should be more inclusive, pluralistic and consistent with our current knowledge.

Differences in predatory pressure on terrestrial snails by birds and mammals.

The evolution of shell polymorphism in terrestrial snails is a classic textbook example of the effect of natural selection in which avian and mammalian predation represents an important selective force on gene frequency. However, many questions about predation remain unclear, especially in the case of mammals. We collected 2000 specimens from eight terrestrial gastropod species to investigate the predation pressure exerted by birds and mice on snails. We found evidence of avian and mammalian predation in 26.5% and 36.8% of the shells. Both birds and mammals were selective with respect to snail species, size and morphs. Birds preferred the brown-lipped banded snail Cepaea nemoralis (L.) and mice preferred the burgundy snail Helix pomatia L. Mice avoided pink mid-banded C. nemoralis and preferred brown mid-banded morphs, which were neglected by birds. In contrast to mice, birds chose larger individuals. Significant differences in their predatory pressure can influence the evolution and maintenance of shell size and polymorphism of shell colouration in snails.

La selección nauural y los cultivos transgénicos: ¿un hiato darwinisaa? / Natural Selection and Transgenic Crops: A Darwinian Hiatus?

En diciembre de 2008, se reportaron 125 millones de hectáreas de variedades transgénicas de soya, maíz, algodón y canola, sembradas en 23 países de los cinco continentes. Estas variedades fueron transformadas con genes de origen procariote, que les confieren la capacidad de resistir el ataque de insectos lepidópteros o tolerar dosis comerciales de herbicidas. Desde el inicio de la ingeniería genética, se ha planteado la pregunta de si estos organismos, liberados de manera masiva en los agroecosistemas, pueden causar efectos ambientales negativos en el mediano plazo, o efectos evolutivos desastrosos en el largo plazo. Una manera de analizar este problema, es considerar si pueden escapar a la selección natural darwinista, por el hecho de haberse introducido genes foráneos mediante manipulación humana. Para ello, se estudia la literatura disponible sobre el flujo de genes, desde los cultivos modificados hacía sus parientes silvestres estrechamente relacionados. Existe evidencia empírica de la hibridación entre materiales mejorados por métodos convencionales (hibridación, retrocruces, selección) o biotecnológicos (transferencia de genes foráneos) y parientes silvestres estrechamente relacionados. En todo caso, los efectos de estas hibridaciones dependen de la interacción entre el gen transferido y la planta silvestre pariente de la planta hospedera, en el ecosistema particular en que ocurra. El mayor efecto ambiental y evolutivo, es el resultado de la introgresión del transgen en el pariente silvestre, proceso que implica la estabilización del transgen en el genoma hospedero, resultado de sucesivas generaciones de hibridación y retrocruce. La introgresión depende más de la naturaleza del gen, y del lugar que ocupa en el genoma donante, que del mecanismo de introducción en dicho parental. No se han reportado efectos negativos sobre la diversidad genética de las especies transformadas, ni sobre el ambiente o los consumidores. En el contexto de la evidencia analizada, parecería que los cultivos transgénicos no escapan a la selección natural darwinista, sin embargo es muy temprano en términos evolutivos para llegar a una conclusión sobre este asunto.

In December 2008, 125 million hectares of transgenic varieties of soybean, corn, cotton and canola, were reported planted in 23 countries on five continents. These varieties were transformed with genes of prokaryote origin, rendering them resistant to lepidopteran insects attack or toleratant to commercial herbicides. Since the beginning of genetic engineering, the question whether mass release of these crops in agroecosystems, can cause either negative environmental effects in the medium term or evolutionary effects in the long term, has been raised. One way of analyzing this problem is to consider whether they can escape Darwinian natural selection, because foreign genes have been introduced through human manipulation. To this end, I study the available literature on gene flow from modified crops to their wild closely related relatives. There is empirical evidence of hybridization between improved materials, by both conventional methods (hybridization, backcross, selections) and biotechnological (transfer of foreign genes), and closely related wild relatives. In any case, the effects of these hybrids depend on the interaction between the transferred gene and the wild relative, the particular ecosystem in which it occurs. The biggest environmental and evolutionary impact is the result of introgression of a transgene in the wild relative, a process that involves stabilization of the transgene in the host genome, as a result of successive generations of hybridization and backcrossing. The introgression depends more upon the nature of the gene and its localization in the donnor s genome, than on the mechanism of introduction. No negative effects on the genetic diversity of species genetically modified, have been reported, neither on the environment or consummers. In the context of the evidence discussed, it appears s if genetic modified crops do not escape Darwinian natural selection, however it is very early in evolutionary terms to reach a conclusion on this matter.

Darwin o el faloo conflicto entre la teoría de a selección natural y la hipóteesis de la pangénesis / Darwin or the False Conflict Between the Theory of Natural Selection and the Hypotheses Pangenesis

Teniendo como objetivo buscar una compresión más integral de la obra de Darwin, presento una reflexión sobre el desarrollo de sus ideas, resaltando las influencias que la visión mecánica de la naturaleza, el lamarckismo y las teorías recapitulacionistas alemanas, ejercieron sobre él. Se destaca la originalidad de la teoría de la selección natural surgida por comparación con el cruce dirigido y fundamentada en una interpretación de la naturaleza como sistema económico donde se aplica la ley de población de Malthus. Sin embargo, la preocupación de Darwin por el origen de la variación lo llevó a considerar el carácter complejo de este problema y en particular, lo relacionado con la influencia del medio ambiente en la variación evolutiva. En este contexto se destaca la importancia histórica que tiene su fallida presentación de la hipótesis de la pangénesis. Para concluir se muestra que a pesar de que el concepto de evolución por selección natural presupone la existencia de variaciones individuales azarosas, Darwin continuó con su intento obstinado de encontrar las leyes de la variación, las cuales creyó haber explicado mediante esta hipótesis.

In order to provide a more integral view of Darwin’s work, I present the development of his ideas, showing the influence of the mechanical view of nature on one hand, and the Lamarckian recapitulationism on the other. The originality of the theory of evolution by natural selection is highlighted, while showing its connection with the analogy with breeders directed crosses and its theoretical justification inspired in Mathus population theory. However, it is explained how Darwin’s concern with the problem of the origin of evolutionary variations led him to consider the role of the environment in the production of variants. In this context it is explained the historical importance of his ill-fated hypothesis of pangenesis. To conclude, it is shown that though the concept of evolution by natural selection assumes the randomness of individual variations, Darwin nevertheless pursued his stubborn search for the laws of variations that he believed to have accounted for with this hypothesis.

Darwin y la impssibilidad de causas finales en la bollogía / Darwin and the Impossibility of Final Causes in Biology

La teoría de la selección natural propuesta por Charles Darwin en su obra El origen de las especies no solo colocó las bases para una explicación coherente de los hechos fundamentales de la biología (el origen común de los seres vivos, la diversidad de individuos y especies y la transmisión de características hereditarias), sino que además introdujo maneras nuevas de hacer filosofía. La teoría de la selección natural hace superflua cualquier posibilidad de apelar a explicaciones de tipo finalista en la ciencia. Desde Aristóteles se conocen cuatro tipos de causa: la material, la formal, la eficiente y la final. Aunque la causa eficiente es el paradigma de explicación por exce-lencia de las ciencias naturales, la causa final sigue desempeñando un papel explicativo, por cuanto parece estar arraigada en nuestra estructura humana de pensamiento y la tendencia a presentar explicaciones finalistas sigue siendo recalcitrante. Quizá por estar los seres humanos tan familiarizados con la complejidad inherente a los procesos de diseño en las artes y en la técnica y quizá por la circunstancia de que los seres humanos organizamos casi todas nuestras acciones en torno a propósitos, es decir, a la definición de unos fines para los cuales buscamos unos medios, suponemos por vía de analogía que la naturaleza en su complejidad exige la presencia y acción de un diseñador inteligente. Kant en la Crítica de la facultad de juzgar hace una defensa del carácter "irrenunciable al género humano" de este modelo explicativo. Para contro-vertir esta opinión milenaria, me apoyaré, en investigaciones recientes de Richard Dawkins y de otros biólogos contemporáneos para mostrar con la evolución de ojos en la naturaleza que el surgimiento de órganos de alta complejidad puede ser explicado sin problema con la teoría de la selección natural propuesta por Darwin en 1859.

Darwin’s theory of natural selection in The Origin of Species not only laid the fundamental elements for a persuasive explanation of biological facts (as the common origin of all living beings, the rich diversity of individuals and species and partially the transmission of hereditary characters), but rather it introduces new forms for doing philosophy. The theory of natural selection leaves no room for final explanations and causes in the natural sciences. Since Aristotle there are four types of causes: material, formal, efficient and final. The efficient cause is since the 17th century the established model of explanation in natural science. However the final cause type of explanation seems to be well rooted in the structure of our human understanding. As creative artists, as craft designers, as lawgivers in societies, human beings are fully conscious that complexity in organization requires previous intelligence. As free rational beings we tend to organize most of our actions as purposive in terms of selecting ends and means. As I will show we suppose wrongly by way of analogy that the explanation of complexity in nature likewise requires the presence and the action of an intelligent being. Kant in his Kritik der Urteilskraft defended that this model of explanation seems to be "unrejectable for human beings". With an analysis of contemporary research work done by Richard Dawkins and others on the evolution of eyes in nature, I will show that in 1859 Darwin´s theory of natural selection demolished this millenary way of thinking, in which final cause has a place for explanation in natural science.

Evolutionary insights into duffy gene in mammalian taxa with comparative genetic analysis.

Background & objectives: Evolutionary analyses of genes conserved across taxa are keys to understand the complexity of gene and genome variation. Since malaria is a highly infectious human disease and its susceptibility in human is genetically controlled, characterization and evolutionary analyses of such genes are of prime importance to understand genetic mechanisms of disease susceptibility. In the present study we have characterized and performed comparative genomic analyses of the human Duffy gene responsible for malaria pathogenesis in nine different mammalian taxa. Methods: DNA sequences of human duffy gene were downloaded from public domain and have been characterized in detail and compared with eight other different mammalian taxa (Pan troglodytes, Macaca mulatta, Pongo pygmaeus, Rattus norvegicus, Mus musculus, Monodelphis domestica, Bos taurus and Canis familiaris). Comparative and evolutionary analyses were performed using statistical software and tools. Results: We observed that the genetic architecture of this gene was entirely different across all the nine taxa and a close similarity between Homo sapiens and Pan troglodytes (chimpanzee) was evident for several aspects of this gene. Comparisons on several aspects, such as ratio of coding and non-coding regions, total gene length number and size of introns and difference of number of nucleotides in human and chimpanzees have revealed interesting features. Phylogenetic inferences based on the Duffy gene among nine different taxa were found to be different than other genes previously studied. Interpretation & conclusion: Most remarkably, human and chimpanzee were only 0.75% different in this gene. The results were discussed on the similarities between human and chimpanzee and gain of introns in human-chimpanzee clade with an inference on the role of evolutionary forces (mainly natural selection) in maintaining such variations across closely-related mammalian taxa.

Why Darwin rejected intelligent design.

Natural Theology is constructed around the analogy of a watchmaker, a metaphor borrowed from previous advocates of the design doctrine. Imagine, Paley suggests, that you are walking across a heath and suddenly encounter a watch lying on the ground. After close inspection of the watch, you would be compelled to conclude that such an intricate device could not have been constructed otherwise in order for it to work. It is only reasonable to assume “that the watch must have had a maker; that there must have existed, at some time and at some place or other, an artifi cer or artifi cers who formed it for the purpose which we fi nd it actually to answer; who comprehended its construction, and designed its use” (1802:3–4). In the case of living organisms Paley continued, the evidence for design is even stronger “in a degree which exceeds all computation” (1802:19), and he concluded: “The marks of design are too strong to be got over. Design must have had a designer. That designer must have been a person. That person is GOD” (1802:473). The efforts by Ray, Paley, and others to unite natural history with theology were among the inducements that inclined Darwin, at the age of eighteen, to look favourably on a career in the church. Sent by his father two years earlier to study medicine at Edinburgh University, Darwin had found himself uninspired by this profession and revolted by the sight of operations, which at that time were conducted without the benefi t of anesthesia. Worried that his son might turn into “an idle sporting man,” Darwin’s.