The evolutionary origin of complex features

A long-standing challenge to evolutionary theory has been whether it can explain the origin of complex organismal features. We examined this issue using digital organisms—computer programs that self-replicate, mutate, compete and evolve. Populations of digital organisms often evolved the ability to perform complex logic functions requiring the coordinated execution of many genomic instructions. Complex functions evolved by building on simpler functions that had evolved earlier, provided that these were also selectively favoured. However, no particular intermediate stage was essential for evolving complex functions. The first genotypes able to perform complex functions differed from their non-performing parents by only one or two mutations, but differed from the ancestor by many mutations that were also crucial to the new functions. In some cases, mutations that were deleterious when they appeared served as stepping-stones in the evolution of complex features. These findings show how complex functions can originate by random mutation and natural selection

Ontogeny tends to recapitulate phylogeny in digital organisms

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. . abstract: Biologists have long debated whether ontogeny recapitulates phylogeny and, if so, why. Two plausible explanations are that (i) changes to early developmental stages are selected against because they tend to disrupt later development and (ii) simpler structures often precede more complex ones in both ontogeny and phylogeny if the former serve as building blocks for the latter. It is difficult to test these hypotheses experimentally in natural systems, so we used a computational system that exhibits evolutionary dynamics. We observed that ontogeny does indeed recapitulate phylogeny; traits that arose earlier in a lineage's history also tended to be expressed earlier in the development of individuals. The relative complexity of traits contributed substantially to this correlation, but a significant tendency toward recapitulation remained even after accounting for trait complexity. This additional effect provides evidence that selection against developmental disruption also contributed to the conservation of early stages in development

A multidisciplinary consensus on the morphological and functional responses to immunotherapy treatment

The implementation of immunotherapy has radically changed the treatment of oncological patients. Currently, immunotherapy is indicated in the treatment of patients with head and neck tumors, melanoma, lung cancer, bladder tumors, colon cancer, cervical cancer, breast cancer, Merkel cell carcinoma, liver cancer, leukemia and lymphomas. However, its efficacy is restricted to a limited number of cases. The challenge is, therefore, to identify which subset of patients would benefit from immunotherapy. To this end, the establishment of immunotherapy response criteria and predictive and prognostic biomarkers is of paramount interest. In this report, a group of experts of the Spanish Society of Medical Oncology (SEOM), the Spanish Society of Medical Radiology (SERAM), and Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM) provide an up-to-date review and a consensus guide on these issues

Identification of novel loci associated with gastrointestinal parasite resistance in a Red Maasai x Dorper backcross population

Gastrointestinal (GI) parasitic infection is the main health constraint for small ruminant production, causing loss of weight and/or death. Red Maasai sheep have adapted to a tropical environment where extreme parasite exposure is a constant, especially with highly pathogenic Haemonchus contortus. This breed has been reported to be resistant to gastrointestinal parasite infection, hence it is considered an invaluable resource to study associations between host genetics and resistance. The aim of this study was to identify polymorphisms strongly associated with host resistance in a double backcross population derived from Red Maasai and Dorper sheep using a SNP-based GWAS analysis. The animals that were genotyped represented the most resistant and susceptible individuals based on the tails of phenotypic distribution (10% each) for average faecal egg counts (AVFEC). AVFEC, packed cell volume (AVPCV), and live weight (AVLWT) were adjusted for fixed effects and co-variables, and an association analysis was run using EMMAX. Revised significance levels were calculated using 100,000 permutation tests. The top five significant SNP markers with - log10 p-values >3.794 were observed on five different chromosomes for AVFEC, and BLUPPf90/PostGSf90 results confirmed EMMAX significant regions for this trait. One of these regions included a cluster of significant SNP on chromosome (Chr) 6 not in linkage disequilibrium to each other. This genomic location contains annotated genes involved in cytokine signalling, haemostasis and mucus biosynthesis. Only one association detected on Chr 7 was significant for both AVPCV and AVLWT. The results generated here reveal candidate immune variants for genes involved in differential response to infection and provide additional SNP marker information that has potential to aid selection of resistance to gastrointestinal parasites in sheep of a similar genetic background to the double backcross population

God of the Gaps: The Argument from Ignorance and the Limits of Methodological Naturalism

W niniejszym eseju skoncentruję się na dwóch ważnych aspektach filozoficznego bagażu, który dźwigany jest w każdej dyskusji o stworzeniu i ewolucji. Oba te aspekty związane są z zagadnieniami natury metodologii naukowej. Pierwszy odnosi się do twierdzenia kreacjonistów, że ich hipoteza stworzenia powinna być uznana nie tylko za prawowitą naukową alternatywę dla teorii ewolucji, ale być może nawet za alternatywę lepszą. Drugi aspekt związany jest z ich twierdzeniem, że nauka, z racji stosowanych w niej metod, sama jest "panującą religią" i to o charakterze ateistycznym. Oba te twierdzenia są bezpodstawne. Negatywna kreacjonistyczna krytyka teorii ewolucji jest chybiona - kreacjoniści nie zaproponowali niczego, co choć w najmniejszym stopniu zasługiwałoby na miano pozytywnej naukowej alternatywy dla teorii ewolucji, a tylko wysuwają argument z niewiedzy. Wnioskowanie o projekcie nie potwierdza istnienia transcendentnego projektanta - niezależnie od tego, czy wnioskowanie to interpretowane jest jako argument z analogii, wniosko-wanie do najlepszego wyjaśnienia, czy też jako argument eliminacyjny. Ostatecznie okazuje się, że jest to jedynie błędny argument z Boga w lukach wiedzy. Teza kreacjonistów, że metoda naukowa jest dogmatycznie ateistyczna, także jest bezzasadna. Nauka, we właściwym rozumieniu, nie jest "panującą" religią, lecz zachowuje religijną neutralność.In this essay I will focus on two important aspects of the philosophical baggage that is carried along in any discussion of the creation/evolution issue. Both involve questions about the nature of scientific methodology. The first deals with creationists’ contention that their creation hypothesis ought to be recognized not only as a legitimate scientific alternative to evolution but perhaps even a better alternative. The second deals with their contention that science, because of its methods, is itself an „established religion”, and an atheist religion at that. In both cases, these contentions are unjustified. Creationists’ negative attacks upon evolution miss their mark — they have not advanced anything close to a positive scientific alternative to evolution, but have simply given an argument form ignorance. The design inference fails to confirm a transcendent designer — whether it is interpreted as an argument by analogy, an inference to the best explanation, or an eliminative argument. In the end, their version is no more than a spurious god-of-the-gaps argument. Creationists’ attack upon scientific method as being dogmatically atheistic is also misplaced. Science, properly understood, is not an „established” religion. It is indeed religiously neutral