A genomic parasite in the evolution of metazoan development.

It is a challenge to understand how development emerged as a mechanism to dismantle and dismiss the intromission of foreign parasites in order to consolidate a higher-level multicellular unit of selection where more heritable variations in fitness, required for complex organization, can be procured. Levels in biological hierarchy genes, networks of genes, chromosomes, cells, organisms, etc., possess heritable variations in fitness to varying degrees, and as such, they function as units of selection in the evolutionary process [Lewontin, (1970). The units of selection. Annu. Rev. Ecol. Syst. 1: 1-18]. To proceed from each of these levels to the next constitutes a major transition in evolutionary history. When analyzing the splendid road epitomized by these transitions in units of selection, it is possible to conceive three processes: firstly, the molecular "recognition" of the "convenience" of exchanging the higher energy cost of cooperating cells with more fitness than single-cell selection (after that first recognition the emergence of cooperation among cells is possible); secondly, the establishment of the mechanisms to regulate conflict, and finally, the regulation of cell differentiation and compartmentalization.

From unicellularity to multicellularity - molecular speculations about early animal evolution.

A morphological, physiological, developmental, and genetic organization of great complexity ineluctably unfolded from relatively simple phenomena invested with enormous potential. Sometime long ago in the Protererozoic times, parasitic invasions caused lower evolutionary levels to integrate into higher-level selection. Therefore, we have a multi-level selection problem that ultimately revolves around the question of how natural selection among lower-level units acts to create higher-level units of selection, in which Darwinian competition among replicators ceases to be the foremost force. The first level relinquishes its independence for the benefit of a higher-level cooperative force that is now the criterion of fitness for the new transition in the evolutionary process.

From geochemistry and biochemistry to prebiotic evolution...we necessarily enter into Gánti's fluid automata.

The present study is just an overview of the opening of the geochemical stage for the appearance of life. But that opening would not have been sufficient for the intellectual discovery of the origin of life! The excellent works and many commendable efforts that advance this explanation have not shown the fundamental elements that participate in the theoretical frame of biological evolution. The latter imply the existence of evolutionary transitions and the production of new levels of organization. In this brief analysis we do not intend to introduce the audience to the philosophy of biology. But we do expect to provide a modest overview, in which the geochemical chemolithoautotrophic opening of the stage should be seen, at most, as the initial metabolism that enabled organic compounds to follow the road where a chemical fluid machinery was thus able to undertake the more "sublime" course of organic biological evolution. We think that Tibor Gánti's chemoton is the most significant contribution to theoretical biology, and the only course now available to comprehend the unit of evolution problem without the structuralist and functionalist conflict prevalent in theoretical biology. In our opinion Gánti's chemoton theory travels to the "locus" where evolutionary theory dares to extend itself to entities at many levels of structural organization, beyond the gene or the group above. Therefore, in this and subsequent papers on the prebiotic conditions for the eventual appearance of the genetic code, we explore the formation and the presence of metal sulfide minerals, from the assembly of metal sulfide clusters through the precipitation of nanocrystals and the further reactions resulting in bulk metal sulfide phases. We endeavor to characterize pristine reactions and the modern surfaces, utilizing traditional surface science techniques and computational methods. Moreover, mechanistic details of the overall oxidation of metal sulfide minerals are set forth. We hope that this paper will lead our audience to accept that in a chemically oscillating system the chemoton is a model fluid state automaton capable of growth and self-reproduction. This is not simply a matter of transmitting a pattern, as in inorganic crystals; such self-reproduction must be more complex than crystal growth. Indeed that is what Gánti's theoretical and abstract model offers to us all: we finally have a philosophy of evolutionary units in theoretical biology.

Population genetics in the American tropics : XI. Seasonal and temporal variations in relative frequencies of species belonging to the Willistoni group in Colombia.

The authors examined seasonal and plant food preferences of members of Drosophila willistoni group in three different ecosystems in Colombia. The results show that there are seasonal preferences as well as food preferences. Furthermore, there exist clear cut temporal (hours of the day) selection which would make possible the sympatric exploitation of equal ecological niches. Comparisons with melanogaster species and with obscura species group are also made.

Population genetics in the American Tropics XVI. Data on partial dominance of recessives in Drosophila willistoni.

Through a series of genetic load studies made on 1) samples of Drosophila willistoni from two sites in Mesitas, Colombia, it was found that the relative contributions to the total, subvital and lethal loads reflect lethal equivalences (B/A) ratios which support more the balancing theory of population structure than the neutralist theory. Moreover, measurements of population size have revealed the existance of very small demes in local populations. Under such conditions we have calculated extremely small lethal equivalence ratios in demes where probably a great deal of consanguinity takes place. We are aware that under these conditions B/A ratios cannot be very good monitors of random load measurements and, therefore, suggest a change in the mathematical formulation that take into consideration the existance of small populations.Furthermore, it appears plausible that the degree of penetrance in the heterozygous condition changes as the population structure changes. We speculate that natural populations may have unknown selective mechanisms capable of guiding unknown dominance modifiers according to the intensity of selection.

Population genetics in the American Tropics : 18. The genetic structure of peripheral Drosophila pseudoobscura from Colombia.

There are several Colombian populations of Drosophila pseudoobscura which have begun to show divergence. The temporal samples of Torobarroso, one of the local populations identified, demonstrate genetic "resourcefulness" and selective opportunism by fluctuating mortality. The data suggest that both balanced selection and mutational origin are necessary to account for the frequencies of drastic genes encountered. In genetic isolates there seems to exist alternatively a mutational component and a balanced - selection component. These components overcome the damage in the first instance and in the second instance, profit from the recessive load.

From unicellularity to multicellularity - molecular speculations about early animal evolution

A morphological, physiological, developmental, and genetic organization of great complexity ineluctably unfolded from relatively simple phenomena invested with enormous potential. Sometime long ago in the Protererozoic times, parasitic invasions caused lower evolutionary levels to integrate into higher-level selection. Therefore, we have a multi-level selection problem that ultimately revolves around the question of how natural selection among lower-level units acts to create higher-level units of selection, in which Darwinian competition among replicators ceases to be the foremost force. The first level relinquishes its independence for the benefit of a higher-level cooperative force that is now the criterion of fitness for the new transition in the evolutionary process.

From geochemistry and biochemistry to prebiotic evolution... we necessarily enter into Gánti's fluid automata

The present study is just an overview of the opening of the geochemical stage for the appearance of life. But that opening would not have been sufficient for the intellectual discovery of the origin of life! The excellent works and many commendable efforts that advance this explanation have not shown the fundamental elements that participate in the theoretical frame of biological evolution. The latter imply the existence of evolutionary transitions and the production of new levels of organization. In this brief analysis we do not intend to introduce the audience to the philosophy of biology. But we do expect to provide a modest overview, in which the geochemical chemolithoautotrophic opening of the stage should be seen, at most, as the initial metabolism that enabled organic compounds to follow the road where a chemical fluid machinery was thus able to undertake the more [quot ]sublime[quot ] course of organic biological evolution. We think that Tibor Gánti's chemoton is the most significant contribution to theoretical biology, and the only course now available to comprehend the unit of evolution problem without the structuralist and functionalist conflict prevalent in theoretical biology. In our opinion Gánti's chemoton theory travels to the [quot ]locus[quot ] where evolutionary theory dares to extend itself to entities at many levels of structural organization, beyond the gene or the group above. Therefore, in this and subsequent papers on the prebiotic conditions for the eventual appearance of the genetic code, we explore the formation and the presence of metal sulfide minerals, from the assembly of metal sulfide clusters through the precipitation of nanocrystals and the further reactions resulting in bulk metal sulfide phases. We endeavor to characterize pristine reactions and the modern surfaces, utilizing traditional surface science techniques and computational methods. Moreover, mechanistic details of the overall...

Conflicting genomes, the demic theory & biodiversity

O darwinismo centrado nos organismos, para usar fenótipos diretos para medir os efeitos da seleçäo natural, requer harmonia e coerência uniforme do genoma, além de populaçöes de grande tamanho. Contudo, o darwinismo moderno, centrado no gene, tem encontrado novas interpretaçöes para dados que falam de incoerência e desarmonia genômica. Como resultado dessas duas posiçöes conflitantes, uma crise conceitual nasceu na Biologia. Minha posiçäo é que a presença de demes de diminuto tamanho, é importante para gerar divergências e crise fenotípica; além disso, a presença de genomas parasitas, como em vermes acantocéfalos, que chegam a manipular comportamentos suicidas em seus hospedeiros; distorcedores de segregaçäo que alteram a meiose e as taxas mendelianas; genes egoístas e cromossomas inteiros egoístas, tais como no caso de cromossomos B do gafanhoto; elementos P da Drosophila; cromossomos Y que manipulam as taxas sexuais, fazendo com que os machos sejam mais freqüentes, como no "drive" ligado ao X de Hamilton; e genes estratégia macho e fora-da-lei säo exemplos eloqüentes da presença de genomas conflitantes reais e de uma coerência fenotípica e harmonia genômica näo uniformes. Assim, nós propomos que a incoerência e a desarmonia em geral geram desordem, mas também geram mais biodiversidade e criatividade. Finalmente, se os genes podem manipular a seleçäo natural, eles podem multiplicar as mutaçöes ou as características indesejáveis e mesmo as letais ou deletérias, daí o acúmulo de cargas genéticas. Genes fora-da-lei podem mudar o que é conveniente adaptativamente, mesmo no sentido do carácter que se afasta do ótimo. O ótimo pode ser "negociado" entre as variantes näo apenas porque os efeitos pleiotrópicos assim o exigem, mas também, em alguns casos, porque genes egoístas ou fora-da-lei ou elementos P ou manipulaçäo fenótipica externa assim o requerem. Com o darwinismo organísmico, o genoma na populaçäo e no indivíduo era considerado como agindo harmoniosamente sem conflitos e os genótipos caminhavam em direçäo a uma maior adaptabilidade. O darwinismo moderno tem uma visäo centrada no gene, em que os genes, como objetos da seleçäo natural, podem mudar em dissonância no sentido que beneficia sua multiplicaçäo. Assim, existem maiores oportunidades para os genomas que estäo em permanente conflito.

La crisis poblacional / Population crisis

Con una visión Genética se analiza el vertiginoso crecimiento poblacional que presenta la especie humana y las repercusiones en su fertilidad y en las demás instancias fisiológicas, sico-sociales, de comportamiento del espacio físico, con sus consecuencias culturales y ambientales. Plantea la necesidad de que cada uno de los paises del mundo ejecuten políticas poblacionales con el fin de incrementar un control natal que logre una tasa de crecimiento cero, para optimizar las características genéticas fisiológicas, nutricionales, evolutivas y de recursos del hombre