Search results for "Biological Evolution"
showing 10 items of 522 documents
The pallial amygdala of amniote vertebrates: evolution of the concept, evolution of the structure
2002
Embryological studies indicate that the amygdala includes pallial structures, namely the cortical amygdala (olfactory and vomeronasal) and the basolateral complex deep to it. In squamate reptiles, the cortical amygdala includes secondary olfactory (the ventral anterior amygdala) and vomeronasal centres (the nucleus sphericus). In birds, the situation is far less clear, due to the relative underdevelopment of the chemosensory systems. The basolateral amygdala of squamate reptiles includes two ventropallial structures: the posterior dorsal ventricular ridge and the lateral amygdala. Like their mammalian counterparts, these centres give rise to glutamatergic projections to the striatal (centro…
Man's strategy in domestication - a synthesis of new research trends.
1976
The minimum brain size possible in the relevant wild species and certain colour types which, because of alterations in the neurotransmitter system caused by the respective colour genes, are related to behavioural traits diverging from the wild animal's norm appear to be first-rate bases for domestication either separately or in combination.
Assessing the root of bilaterian animals with scalable phylogenomic methods.
2009
A clear picture of animal relationships is a prerequisite to understand how the morphological and ecological diversity of animals evolved over time. Among others, the placement of the acoelomorph flatworms, Acoela and Nemertodermatida, has fundamental implications for the origin and evolution of various animal organ systems. Their position, however, has been inconsistent in phylogenetic studies using one or several genes. Furthermore, Acoela has been among the least stable taxa in recent animal phylogenomic analyses, which simultaneously examine many genes from many species, while Nemertodermatida has not been sampled in any phylogenomic study. New sequence data are presented here from org…
The diversity and evolution of chelicerate hemocyanins
2012
Abstract Background Oxygen transport in the hemolymph of many arthropod species is facilitated by large copper-proteins referred to as hemocyanins. Arthropod hemocyanins are hexamers or oligomers of hexamers, which are characterized by a high O2 transport capacity and a high cooperativity, thereby enhancing O2 supply. Hemocyanin subunit sequences had been available from horseshoe crabs (Xiphosura) and various spiders (Araneae), but not from any other chelicerate taxon. To trace the evolution of hemocyanins and the emergence of the large hemocyanin oligomers, hemocyanin cDNA sequences were obtained from representatives of selected chelicerate classes. Results Hemocyanin subunits from a sea s…
Charles Darwin and the Origin of Life
2009
When Charles Darwin published The Origin of Species 150 years ago he consciously avoided discussing the origin of life. However, analysis of some other texts written by Darwin, and of the correspondence he exchanged with friends and colleagues demonstrates that he took for granted the possibility of a natural emergence of the first life forms. As shown by notes from the pages he excised from his private notebooks, as early as 1837 Darwin was convinced that “the intimate relation of Life with laws of chemical combination, & the universality of latter render spontaneous generation not improbable”. Like many of his contemporaries, Darwin rejected the idea that putrefaction of preexisting organ…
Decreasing Phanerozoic extinction intensity as a consequence of Earth surface oxygenation and metazoan ecophysiology
2021
The decline in background extinction rates of marine animals through geologic time is an established but unexplained feature of the Phanerozoic fossil record. There is also growing consensus that the ocean and atmosphere did not become oxygenated to near-modern levels until the mid-Paleozoic, coinciding with the onset of generally lower extinction rates. Physiological theory provides us with a possible causal link between these two observations-predicting that the synergistic impacts of oxygen and temperature on aerobic respiration would have made marine animals more vulnerable to ocean warming events during periods of limited surface oxygenation. Here, we evaluate the hypothesis that chang…
Critics and Criticisms of the Modern Synthesis: the Viewpoint of a Philosopher
1990
International audience
A mathematical method for determining genome divergence and species delineation using AFLP.
2002
The delineation of bacterial species is presently achieved using direct DNA-DNA relatedness studies of whole genomes. It would be helpful to obtain the same genomically based delineation by indirect methods, provided that descriptions of individual genome composition of bacterial genomes are obtained and included in species descriptions. The amplified fragment length polymorphism (AFLP) technique could provide the necessary data if the nucleotides involved in restriction and amplification are fundamental to the description of genomic divergences. Firstly, in order to verify that AFLP analysis permits a realistic exploration of bacterial genome composition, the strong correspondence between …
Epistatic interactions between pterin and carotenoid genes modulate intra-morph color variation in a lizard.
2021
Color polymorphisms have become a major topic in evolutionary biology and substantial efforts have been devoted to the understanding of the mechanisms responsible for originating such colorful systems. Within-morph continuous variation, on the other hand, has been neglected in most of the studies. Here, we combine spectrophotometric/visual modeling and genetic data to study the mechanisms promoting continuous variation within categorical color morphs of Podarcis muralis. Our results suggest that intra-morph variability in the pterin-based orange morph is greater compared to white and yellow morphs. We also show that continuous variation within the orange morph is partially discriminable by …
Silent rain: does the atmosphere-mediated connectivity between microbiomes influence bacterial evolutionary rates?
2020
ABSTRACT Air carries a vast number of bacteria and viruses over great distances all the time. This leads to continuous introduction of foreign genetic material to local, established microbial communities. In this perspective, I ask whether this silent rain may have a slowing effect on the overall evolutionary rates in the microbial biosphere. Arguably, the greater the genetic divergence between gene ‘donors’ and ‘recipients’, the greater the chance that the gene product has a deleterious epistatic interaction with other gene products in its genetic environment. This is due to the long-term absence of check for mutual compatibility. As such, if an organism is extensively different from other…