Natural selection

Though he helped develop it. Recently, a problem has arisen round efforts to create a synthetic cell.  Gerald Joyce, now of the Salk Institute, helped NASA come up with a very widely used definition of life, “Life is a self-sustained chemical system capable of undergoing Darwinian evolution.” But, as medicl historian Rebecca Wilbanks explains at Aeon, In 2009, after decades of work, Joyce’s group published a paper in which they described an RNA molecule that could catalyse its own synthesis reaction to make more copies of itself. This chemical system met Joyce’s definition of life. But nobody wanted to claim that it was alive. We’d certainly have heard about it if they had. But Joyce no longer seems satisfied with that definition. For Read More ›

Researchers Iranzo and Koonin ask: Typically, natural selection results in deletions of harmful genes, so the main question is, why hasn’t natural selection wiped out genetic parasites? They mean “transposons, plasmids, viruses” etc., that offer no benefit to the hosts. They offer a hypothesis: In a new study published in EPL, researchers Jaime Iranzo and Eugene V. Koonin at the National Institutes of Health in Bethesda, Maryland, have found that horizontal gene transfer may be one of the keys to understanding the persistence and spread of genetic parasites over evolutionary timescales. In horizontal gene transfer (HGT), genetic information is transferred to an organism by a variety of mechanisms other than the traditional parent-to-offspring process of transferring DNA. For example, an Read More ›

From ScienceDaily: Research on evolution typically focuses on the importance of social interactions, including parent-offspring bonding, competition for resources, and courtship and mating rituals. But Nathan Bailey at the University of St Andrews in Scotland and his colleague Allen Moore at the University of Georgia realized that isolation must then be an extreme condition worthy of equal attention. “The environment an animal experiences can influence which genes it expresses, when, and how much, so conditions of social isolation might cause expression of different traits,” says Bailey. “This in turn could affect responses to natural selection in terms of survival and reproduction, which has evolutionary consequences. For some species, it might even mean that temporary social isolation is favorable.” The invasive Read More ›

From ScienceDaily: Susanne Åkesson, a biologist at Lund University in Sweden, refutes the theory that zebras have striped fur to stay cool in the hot sun. That hypothesis is wrong, she and her colleagues show in a study recently published in Scientific Reports. There has been an ongoing discussion among researchers, dating back to Darwin, on why zebras have their signature black and white stripes. One of several theories is that it keeps them cool in the sunshine. The black stripes get warmer than the white areas, and the theory states that this creates small vortexes when the hotter air above the dark fur meets the cooler air above the white fur. According to the theory these vortexes works as Read More ›

What? We have been told that natural selection acting on random mutations explains diversity! From ScienceDaily: For years, it was assumed other nematodes’ neurons were similar to those of C. elegans, until researchers at the University of Illinois demonstrated the vast diversity in neuronal anatomy present across species. Now Nathan Schroeder, assistant professor in the Department of Crop Sciences at U of I and leader of the previous study, has shown that gonad development also varies in other nematodes relative to C. elegans. Specifically, he and graduate student Hung Xuan Bui focused on Steinernema carpocapsae, a nematode used in insect biocontrol applications in lawns and gardens. The gonads in all nematodes develop within a structure called the gonad arm, a Read More ›

Readers have written to ask why Wolf-Ekkehard Lönnig’s book, The Evolution of the Long-Necked Giraffe: (Giraffa camelopardalis L.) What do we really know? Testing the Theories of Gradualism, Macromutation, and Intelligent Design, is no longer available on Amazon: “Darwin (1871) and many African folk legends before him […] proposed a simple but powerful explanation for the large and elongated shape. Long necks allowed giraffe to outreach presumed competitors, particularly during dry-season bottlenecks when leaves become scarce; (Simmons and Scheepers). However, this old African folk legend which is still commonly taught in high schools, fails to explain, among other things, the size differences between males and females. Giraffe cows are up to 1.5 meters shorter than the giraffe bulls, not to Read More ›

From W. Ford Doolittle and S. Andrew Inkpen at PNAS: Many practicing biologists accept that nothing in their discipline makes sense except in the light of evolution, and that natural selection is evolution’s principal sense-maker. But what natural selection actually is (a force or a statistical outcome, for example) and the levels of the biological hierarchy (genes, organisms, species, or even ecosystems) at which it operates directly are still actively disputed among philosophers and theoretical biologists. Most formulations of evolution by natural selection emphasize the differential reproduction of entities at one or the other of these levels. Some also recognize differential persistence, but in either case the focus is on lineages of material things: even species can be thought of Read More ›

From ScienceDaily: Many tame domesticated animals have a different appearance compared to their relatives in the wild, for example white patches in their fur or shorter snouts. Researchers have now for the first time shown that wild house mice develop the same visible changes — without selection, as a result of exposure to humans alone. The significant part of the story is that the mice were not exposed to any kind of selection other than free handouts (although one suspects that mouse predators may have avoided the barn due to the common presence of humans). A team of researchers led by Anna Lindholm from the Department of Evolutionary Biology and Environmental Studies at UZH has now also observed this phenomenon Read More ›

From William Basenerand John Sanford at The Skeptical Zone: Joe Felsenstein and Michael Lynch (JF and ML) wrote a blog post, “Does Basener and Sanford’s model of mutation vs selection show that deleterious mutations are unstoppable?” Their post is thoughtful and we are glad to continue the dialogue. This is the first part of a response to their post, focusing on the impact of R. A. Fisher’s work. Paper. R. A. Fisher was one of the three founders of population genetics, and is considered by many to be the first and primary founder. His Fundamental Theorem of Natural Selection contributed significantly to a “revival of Darwinism” (see Koonin quote above and Wikipedia). His theorem has been considered by many a Read More ›

From Nancy Pearcey, author of Love Thy Body: Answering Hard Questions about Life and Sexuality, at CNS: What Was Darwin’s ‘Original’ Thought? Original thinking? The truth is that there was little about Darwin’s scientific theory that was original—and the part that was original was not scientific. The idea that organisms undergo minor variations was not original. For millennia, farmers and breeders have known that they could induce minor changes in a breeding population (typically a species or genus). This process also happens in nature, where it is called microevolution. What was original was Darwin’s proposal that the same minor variations might accumulate via undirected natural selection to originate completely new organs and body plans (generating higher taxonomic categories such as Read More ›

By evolutionary biologist Kevin Laland, who seems to have adopted that role: Evolution unleashed: Is evolutionary science due for a major overhaul – or is talk of ‘revolution’ misguided? If you are not a biologist, you’d be forgiven for being confused about the state of evolutionary science. Modern evolutionary biology dates back to a synthesis that emerged around the 1940s-60s, which married Charles Darwin’s mechanism of natural selection with Gregor Mendel’s discoveries of how genes are inherited. The traditional, and still dominant, view is that adaptations – from the human brain to the peacock’s tail – are fully and satisfactorily explained by the natural selection (and subsequent inheritance). Yet as novel ideas flood in from genomics, epigenetics and developmental biology, Read More ›

From ScienceDaily: Bacteria not only develop resistance to antibiotics, they also can pick it up from their rivals. In a recent publication in Cell Reports, Researchers from the Biozentrum of the University of Basel have demonstrated that some bacteria inject a toxic cocktail into their competitors causing cell lysis and death. Then, by integrating the released genetic material, which may also carry drug resistance genes, the predator cell can acquire antibiotic resistance. … The predator bacteria take up the released DNA fragments. If these fragments carry certain drug resistance genes, the specific resistance can be conferred upon the new owner. As a result, the antibiotic is no longer effective and the bacterium can reproduce largely undisturbed. Pathogens with such abilities Read More ›

  Did Darwin really explain the origin of species?   My quote of the month is now up on my blog. This is an interesting one as it comes from an evolutionary biologist and critic of ID. I also focus on comments of a similar nature that have been made in more recent years. Surprise, surprise, Darwin’s work isn’t all it is cracked up to be.                                                H. Allen Orr on Darwin’s Failure    

From evolutionary biologist Richard O. Prum at the New York Times: Are These Birds Too Sexy to Survive? Natural selection can’t explain this. Wow. Careers have been wrecked over such departures from dogma. Most biologists believe that these mechanisms always work in concert — that sex appeal is the sign of an objectively better mate, one with better genes or in better condition. But the wing songs of the club-winged manakin provide new insights that contradict this conventional wisdom. Instead of ensuring that organisms are on an inexorable path to self-improvement, mate choice can drive a species into what I call maladaptive decadence — a decline in survival and fecundity of the entire species. It may even lead to extinction. Read More ›

There has been quite a controversy over the past few years over whether the extended evolutionary synthesis is a replacement of the modern synthesis or a refinement of it.
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