Convergent evolution

Just how lamprey sex is determined is unclear. From Erin Ross at Nature: A team led by biologist Nick Johnson, at the US Geological Survey in Millersburg, Michigan, identified lamprey habitats in and near streams leading to the Great Lakes. Some areas were productive, with lots of food, whereas others were unproductive sites with little food. After taking measures to ensure no wild lamprey were present, they released between 1,500 and 3,000 wire-tagged larval lamprey into each of the study sites. The researchers recaptured the tagged lamprey and checked their sex after the larvae had metamorphosed into adults and migrated upstream. They found that lamprey in productive streams with lots of food were larger, reached maturity earlier and were more Read More ›

Part two of my series looking at Jeffrey Koperski’s paper ‘Two Bad Ways to Attack Intelligent Design and Two Good Ones’ is now up on my blog. This one is quite in depth, but a couple of interesting issues come up along the way. I examine the concept of soft and hard anomalies in scientific theories and how they might affect theory change. I then look at the claim that ID’s scientific core is too meagre to be considered serious science. The final objection I analyse is the claim that ID violates a metatheoretic shaping principle known as scientific conservatism. In part one of this series looking at Jeffrey Koperski’s paper, Two Bad Ways to Attack Intelligent Design and Two Read More ›

From ScienceDaily: Marauding across the tropical forest floor, aggressive army ant colonies harbor hidden enemies within their ranks. The impostors look and smell like army ants, march with the ants, and even groom the ants. But far from being altruistic nest-mates, these creatures are parasitic beetles, engaged in a game of deception. Through dramatic changes in body shape, behavior, and pheromone chemistry, the beetles gain their hostile hosts’ acceptance, duping the ants so they can feast on the colony brood. This phenomenon did not evolve just once. Instead, these beetles arose at least a dozen separate times from non-ant-like ancestors. This discovery, published March 9 in Current Biology, provides evidence that evolution has the capacity to repeat itself in an Read More ›

From ScienceDaily: Dolphins and crocodiles now live in rivers and oceans, but each evolved from land-based animals. Feeding in water has many new challenges. This new study shows that despite being separated by 300 million years, dolphins and crocodiles found comparable solutions to these problems, and evolved skull shapes that are remarkably similar. “Our results suggest the remarkable similarity between some crocodilians and toothed whales is driven by what they eat rather than where they live,” said lead author Mr Matthew McCurry from the Monash School of Biological Sciences. Previously no rigorous attempt had been made to show how similar the head shapes of dolphins and crocodiles really are. It had been thought that aspects such shallow seas or rivers Read More ›

From ScienceDaily: Euchambersia was a dog-sized pre-mammalian reptile living 260 million years ago in a deadly South African environment: Living in the Karoo, near Colesberg in South Africa, the Euchambersia developed a deep and circular fossa, just behind its canine teeth in the upper jaw, in which a deadly venomous cocktail was produced, and delivered directly into the mouth through a fine network of bony grooves and canals. “This is the first evidence of the oldest venomous vertebrate ever found, and what is even more surprising is that it is not in a species that we expected it to be, ” says Dr Julien Benoit, researcher at the Bernard Price Institute for Palaeontological Research at the University of the Witwatersrand in Read More ›

From Juliet Lamb at J-Stor: Take the Giant Panda, for example. Watch a panda eat, and you’ll notice the thumb-like appendage that helps it hold onto bamboo stalks. The panda’s thumb isn’t actually a thumb; it’s an elongated wrist bone that opposes the five true fingers of the panda’s hand, allowing it to grip and manipulate the delicate bamboo stalks that form the majority of its diet. For an enormous organism like a panda to survive on an energy-poor resource like bamboo, most of which is composed of indigestible fiber, maximizing eating efficiency is key. Without gripping abilities, pandas would require more effort to consume less bamboo, compromising their ability to meet their energy needs. The misleadingly named Red Panda Read More ›

A reader draws our attention to Prof. Eric Arnoy’s comments at Calvin College, BiochemistryII: The reduction of nitrogen to ammonia, known as nitrogen fixing, is vital to agriculture: N2 + 3H2 → 2NH3 The bacteria that perform this job for plants are symbionts with th plants, exchanging ammonia for energy. The plant provides leghemoglobin to bind the oxygen. Now, here’s the interesting part: Leghemoglobin is part of the globin protein family and resembles the mammalian oxygen-binding protein myoglobin in structure, though the sequences differ greatly. But how is that? Arnoy writes, Furthermore, myoglobin is not found in plants, so it would be a stretch to suggest that leghemoglobin arose from myoglobin. Instead, what we see here is a wonderful example Read More ›

From ScienceDaily: “For the first time ever, we looked at the evolution of venom across all fishes,” said lead author William Leo Smith, assistant curator at the University of Kansas Biodiversity Institute. “Nobody had attempted to look across all fishes. Nobody had done sharks or included eels. Nobody had looked at them all and included all fishes in an evolutionary tree at the same time.” … According to Smith, the 18 independent evolutions of venom each pose an opportunity for drug makers to derive therapies for a host of human ailments. “Fish venoms are often super complicated, big molecules that have big impact,” he said. “Venom can have impacts on blood pressure, cause local necrosis, breakdown of tissue and blood, Read More ›

From ScienceDaily: The Australian National University (ANU) study found that by living in the same habitat, pythons and boas evolved independently to look similar. This happened at least five times in different habitats. Aquatic pythons look like aquatic boas, burrowing pythons look like borrowing boas and tree-dwelling pythons look like tree-dwelling boas. … Other famous examples of convergent evolution are sharks and dolphins, which are not related but have evolved similar body plans. Similarly, the extinct Tasmanian Tiger, a marsupial mammal, and the wolf, a placental mammal, evolved similar body plans. Esquerre attempts to pin all this on natural selection (Darwinism) and adaptation, then admits: not all evolution was driven by natural selection, but examples such as pythons and boas Read More ›

From ScienceDaily: Long-snouted crocodylians in South America, India evolved separately to adopt river-dwelling lifestyle, protruding eyes The 13-million-year-old fossils of an extinct crocodylian, named ‘the storyteller,’ suggest that South American and Indian species evolved separately to acquire protruding, ‘telescoped’ eyes for river-dwelling, according to a study published April 20, 2016 in the open-access journal PLOS ONE by Rodolfo Salas-Gismondi from the University de Montpellier, France, and colleagues. Paper. (public access) More. Parallel evolution from ScienceDaily: One of the most spectacular examples of parallel evolution is provided by the two main branches of the mammals, the placentals and marsupials, which have followed independent evolutionary pathways following the break-up of land-masses such as Gondwanaland roughly 100 million years ago. … While some Read More ›

From ScienceDaily: By poring over the fossilized skulls of ancient wildebeest-like animals (Rusingoryx atopocranion) unearthed on Kenya’s Rusinga Island, researchers have discovered that the little-known hoofed mammals had a very unusual, trumpet-like nasal passage similar only to the nasal crests of lambeosaurine hadrosaur dinosaurs. The findings reported in the Cell Press journal Current Biology on February 4 offer “a spectacular example” of convergent evolution between two very distantly related taxa and across tens of millions of years, the researchers say. “The nasal dome is a completely new structure for mammals– it doesn’t look like anything you could see in an animal that’s alive today,” says Haley O’Brien of Ohio University, Athens. “The closest example would be hadrosaur dinosaurs with half-circle Read More ›

From Eurekalert: Birds and humans look different, sound different and evolved completely different organs for voice production. But now new research published in Nature Communications reveals that humans and birds use the exact same physical mechanism to make their vocal cords move and thus produce sound. “Science has known for over 60 years that this mechanism – called the myoelastic-aerodynamic theory, or in short the MEAD mechanism- drives speech and singing in humans. We have now shown that birds use the exact same mechanism to make vocalizations. MEAD might even turn out to be a widespread mechanism in all land-dwelling vertebrates”, says lead author of the paper, Associate Professor Dr. Coen Elemans, Department of Biology, University of Southern Denmark. The Read More ›

Despite evolutionary distance, researchers say. From ScienceDaily: Ever wonder how animals see the world? New research suggests that animals, or mammals at least, see the world the same way humans do. In a study published in the Nov. 25th issue of Biology Letters, researchers from Japan and France report that the eye view of ponies, dolphins, chimps, and humans are surprisingly similar despite having evolved in different environments. … In the study, the researchers used touchscreens to test the visual perception of three ponies: Ponyo, Nemo, and Thomas. The ponies were shown two shapes on the touchscreen, one of which the researchers arbitrarily decided was correct. The ponies received a carrot piece as a reward when they tapped their muzzle Read More ›

From BBC News : Tarantulas have evolved almost exactly the same shade of vibrant blue at least eight separate times. That is the conclusion of a study by US biologists, exploring how the colour is created in different tarantula species. The hue is caused by tiny structures inside the animals’ hairs, but those shapes vary across the family tree. This suggests, the researchers say, that the striking blue is not driven by sexual selection – unlike many other bright colours in the animal kingdom. This argument is also supported by the fact that tarantulas have poor colour vision, and do not appear to show off their hairy blue body parts during courtship. More. The researchers think that the blue colour Read More ›

From New Scientist: Sometimes evolution just doesn’t have a choice. Reptiles have evolved to resist toad poisons four separate times, and each time they have made precisely the same biochemical changes to do it. What’s more, an even wider range of animals show similar adaptations in response to these toxins, giving us by far the most extensive illustration of so-called convergent evolution to date. “so-called” convergent evolution? Yup. That’s what it is called. Gotta problem with that? This striking convergence on a few evolutionary outcomes probably occurs because sodium channels play such a critical role in cells. “There are very few options for a gene to modify itself to develop resistance without impairing function,” says Casewell. “It suggests that in Read More ›