Evolution
Giant Viruses Are Ancient Living Organisms
14/09/12 13:17 Filed in: Laboratory Equipment
Gustavo Caetano-Anollés at the Univ. of Illinois Crop Sciences and Institute for Genomic Biology and his colleagues completed a study of giant viruses that supports the idea that viruses are ancient living organisms that may have arisen from a fourth branch of life, alongside bacteria, archaea and eukarya. The researchers conducted a census of all the protein folds occurring in more than 1,000 organisms representing bacteria, viruses, the microbes known as archaea and all other living things, and found that the genomes of some giant viruses exceeded the genetic endowments of the simplest bacteria. S. Pelech envisions that giant viruses evolved from invasive bacteria that eventually become mobile parasites that utilized the proteins encoded by their hosts to facilitate their own replication. Consequently, it is not necessary to invoke the existence of a fourth branch of life that predated or co-existed with the three known superkingdoms to explain their ubiquitous presence. Read More...
Strength in Numbers
08/08/12 12:57 Filed in: GenomeWeb Daily Scan
University of Chicago in Illinois' Tim Wootton and Cathy Pfister suggest that sheer numbers are more important than genetic diversity for preserving species threatened with extinction based on their 12 years of breeding studies of the sea palm Postelsia. Genetic diversity did not influence the odds of a population's survival, whereas the size of the population was more critical. S. Pelech points out that preservation of habitat that is rich in biological diversity seems to be the best solution to ensure survival of most species facing extinction today due to their interdependence. He notes that there are many examples, including humans and whales, where genetic diversity appears to be less critical for avoiding extinction than population size. When one looks closely at the various genes encoded in diverse animal species, the number of genes and their nucleotide sequences are remarkably similar. It seems that phenotypic differences arise primarily from where and when the proteins encoded from these genes are produced. Read More...
The Evolution of Evolution
02/07/10 21:19 Filed in: GenomeWeb Daily Scan
Dan Jones at the New Scientist wondered whether the capacity for evolutionary innovation is built into the fabric of life and if such "evolvability" is reflected in an organism's ability to adapt to its environment that can be passed down to subsequent generations. S. Pelech proposes that enhancements of one or more levels of "hierarchical intelligence" - molecular, cellular or social - may play a central role in the development of evolvability. Read More...
Ain't Nothing Gonna Break My Stride
20/07/10 15:19 Filed in: GenomeWeb Daily Scan
Nicholas Wade at the New York Times highlighted some studies that point to natural selection-driven, relatively recent genetic changes in human groups. S. Pelech points out that selective breeding in a relatively small number of generations can lead to profound changes in the appearance and physiology in animals, and eventually we will likely be genetically engineering human genomes to get rid of deleterious mutations and make further improvements, including adaptation to alien environments and cyborg acclimation. Read More...
George Williams Dies
16/09/10 18:30 Filed in: GenomeWeb Daily Scan
Evolutionary biologist George Williams, who died at 83 years of age in 2010, was widely regarded by peers in his field as one of the most influential and incisive evolutionary theorists of the 20th century and advanced the argument that natural selection works at the level of the gene and individual. S. Pelech argues it would be a mistake to believe that natural selection works simply at the level of the gene and individual, but that eusociality plays as much if not a greater role than the individual. The concept of the gene as being the basic unit of natural selection arises from the bigotry of those that hold a strong genopocentric perspective. Read More...
Evolution of a Fruit Fly, Evolution of a Human
22/09/10 18:19 Filed in: GenomeWeb Daily Scan
Researchers at UC Irvine have published research results with fruit flies that confirm the so-called "soft sweep" theory of evolutionary that the exploitation of small differences in many different genes were responsible for the emergence of new traits, rather that a large mutation in single genes. "If complex traits, including susceptibility to disease, are influenced by tens or hundreds of genes, then treatments targeted to single genes won't be very effective". S. Pelech questions the applicability of studies with flies that can bred after 8.5 days with humans that must be about 12 years old before they are capable of reproduction, but notes that it is already well appreciated that many genes influence complex traits, and susceptibility to diseases does not arise from just a few genes. Read More...
Genotype-Phenotype Correlations Confer 'Chaotic' Evolution
21/11/10 03:24 Filed in: GenomeWeb Daily Scan
Keith Bennett at Queen's University Belfast examined the burgeoning "chaos theory of evolution," and argues that the connection between environmental change and evolutionary change is weak, which is not what might have been expected from Darwin's hypothesis, and that macroevolution may, over the longer-term, be driven largely by internally generated genetic change, not adaptation to a changing environment. S. Pelech comments that it would be unwise to under-estimate the impact of a rapidly changing environment on evolution, including the rapid disappearance of dinosaurs following an asteroid impact 65 million years ago or as a consequence of human activity today. Read More...
Evolution in Action
28/06/11 14:34 Filed in: GenomeWeb Daily Scan
Bob Holmes at the New Scientist described the work of Dr. William Ratcliff and his colleagues at the University of Minnesota in St. Paul to select unicellular brewer's yeast that clump into a "snowflake" form as a model to study the evolution of single-celled organisms to multicellularity. After several hundred generations of selection, the yeast snowflakes began to show reproductive properties with some cells undergoing cell death to provide weak points for other cells to break off, allowing the snowflake to create offspring while leaving the clump strong enough to survive. S. Pelech points out that yeast like Saccharomyces cerevisiae are well known to naturally form pseudohyphal filaments depending on the nutrient conditions in their environment, so the formation of cell aggregates is already an inherent property of these types of fungi. The fact that some cells in Dr. Ratcliff's "snowflakes" die, most likely from competition for food and toxic products produced by neighbouring cells, is hardly a measure of cooperation amongst cells for the survival of the colony. Read More...