extinction

From PhysOrg this morning, in a study using “DNA bar-codes” (mitochondrial DNA, using a specific gene COI) and conducted around the world, here’s the verdict: The study’s most startling result, perhaps, is that nine out of 10 species on Earth today, including humans, came into being 100,000 to 200,000 years ago. “This conclusion is very surprising, and I fought against it as hard as I could,” Thaler told AFP. The scientists can’t figure out what might have caused this. They ask: Was there some catastrophic event 200,000 years ago that nearly wiped the slate clean? Maybe a “flood”? About “bar-codes” there’s this: On the one hand, the COI gene sequence is similar across all animals, making it easy to pick Read More ›

From ScienceDaily: With individuals weighing in at more than 140 pounds, the critically endangered Chinese giant salamander is well known as the world’s largest amphibian. But researchers reporting in the journal Current Biology on May 21 now find that those giant salamanders aren’t one species, but five, and possibly as many as eight. The bad news as highlighted by another report appearing in the same issue is that all of the salamanders — once thought to occur widely across China — now face the imminent threat of extinction in the wild, due in no small part to demand for the amphibians as luxury food. … “We were not surprised to discover more than one species, as an earlier study suggested, Read More ›

From ScienceDaily: The evolution of wild species, adapting them to human management practices, can cause localised extinctions when those practices rapidly change. And in a new study published in Nature, Professors Michael C. Singer and Camille Parmesan have used more than 30 years of research to fully document an example of this process. A large, isolated population of a North American butterfly evolved complete dependence on an introduced European weed to the point where the continued existence of the butterfly depended on the plant’s availability. The insects then became locally extinct when humans effectively eliminated that availability, confirming a prediction made by the same authors in a 1993 Nature paper. Thus the advent of cattle ranching more than 100 years Read More ›

From ScienceDaily: The lengths that some males go to attract a mate can pay off in the short-term. But according to a new study from scientists at the Smithsonian’s National Museum of Natural History (NMNH), extravagant investments in reproduction also have their costs. By analyzing the fossils of thousands of ancient crustaceans, a team of scientists led by NMNH paleontologist Gene Hunt has found that devoting a lot of energy to the competition for mates may compromise species’ resilience to change and increase their risk of extinction. Hunt, NMNH postdoctoral fellow M. João Fernandes Martins, and collaborators at the College of William and Mary and the University of Southern Mississippi reported their findings April 11, 2018, in the journal Nature. Read More ›

From Andrew Porterfield at the Genetic Literacy Project: idea called “genetic load” was developed in the 1930s by famed biologist J.B.S. Haldane, referring to any genome that had increasing numbers of deleterious mutations. The more mutations in a population, the more likely that members of that population couldn’t survive, ultimately threatening the fitness of that population. With enough mutations, a group couldn’t adapt as well to environments, and members would die off. Thus, there’s a limit to natural selection. Now, for some evolutionary biologists, the concept of genetic load has resurfaced as a genuine concern. … He doesn’t think it’s that big a concern. One problem is that modern sequencing has produced much more data, and shown us so many Read More ›

From Phoebe Weston at the Daily Mail, who offers a convenient bullet point format: Revealed: The worrying state of Earth’s species in numbers as scientists warn the sixth mass extinction is here and wildlife is in a ‘global crisis’ Two species of vertebrate, animals with a backbone, have gone extinct each year Currently more than a quarter of mammals are threatened with extinction There are an estimated 8.7 million plant and animal species on our planet About 86% of land species and 91% of sea species remain undiscovered Starting Saturday, a comprehensive, global appraisal of the damage, and what can be done to reverse it, will be conducted in Colombia More. The problem is, if we takes ecology seriously, how Read More ›

But the giraffe turned out to be four species. From ScienceDaily: Evolutionary biologists have now discovered that the Pygmy Marmoset — the world’s smallest monkey — is not one species but two. Weighing in at just 100 grams — roughly the size of a large tomato — the insect-eating primate was first described scientifically in 1823 by German naturalist Johann Spix as Cebuella pygmaea, with a sub-species subsequently found. Now a team led by the University of Salford, using the latest techniques in genomics and phylogenetics, have established proof of two clades or branches of pygmy marmosets, that have diverged from one another around 2 — 3 million years ago. The study was restricted to monkeys in the Brazilian Amazon, Read More ›

Ah, start the day with fond memories. Most people who were kids in the mid-twentieth century grew up with the icons of horse evolution, starting with grubby little Eohippus and ending with Black Beauty. Of course, the story didn’t need to be true and as Jonathan Wells pointed out in Icons of Evolution, it wasn’t really true, at least not in a factual way. It was more the idea of evolution that was supposed to sink in for us. As CS Lewis has pointed out, Darwinian evolution was a great story, not necessarily to be confused with facts of nature. Meanwhile, at ScienceDaily: There are no such things as “wild” horses anymore. Research published in Science today overturns a long-held Read More ›

Extinct animals? Pos-Darwinista writes to draw our attention to Theo Murphy International scientific meeting organised by Dr Rob Knell, Dr Dave Hone and Professor Doug Emlen [May 9-10 2018] Sexual selection is potentially an important driver of macroevolutionary processes like speciation and extinction, but this has rarely been tested using the fossil record. This meeting will bring biologists and palaeontologists together to discuss sexual selection’s role in macroevolution, how to detect it in extinct animals and how to measure its influence on the history of life across geological time. One thing about studying sexual selection in extinct animals, we may never be able to find out if we are wrong. Sexual selection was Darwin’s other Really Big Theory of how evolution happens, Read More ›

We’ll probably never know what dinos were really like inthe sense that we can know what horses are like but we learn from Will Tattersdill at H-Sci-Med-Tech about the different ways we have understood them. Reviewing Dinosaurs Ever Evolving: The Changing Face of Prehistoric Animals in Popular Culture by Allen A. Debus, (1926–2009), he writes If you are interested in the history of dinosaurs in popular culture, Debus is an author you simply cannot ignore. He has written copiously on the “imaginative impact” of dinosaurs, and he is clearly on to something when he proposes to offer “an alternate history” of their evolution (pp. 265, 3)—a history written not across the geological ages of the Mesozoic (Triassic, Jurassic, Cretaceous) but Read More ›

Along with massive but not total extinction of many other life forms. From Laura Geggel at LiveScience: The 2 minutes of darkness caused by the total solar eclipse earlier this week may seem momentous, but it’s nothing compared with the prolonged darkness that followed the dinosaur-killing asteroid that collided with Earth about 65.5 million years ago, a new study finds. When the 6-mile-wide (10 kilometers) asteroid struck, Earth plunged into a darkness that lasted nearly two years, the researchers said. This darkness was caused, in part, by tremendous amounts of soot that came from wildfires worldwide. Without sunlight, Earth’s plants couldn’t photosynthesize, and the planet drastically cooled. These two key factors likely toppled global food chains and contributed to the Read More ›

From ScienceDaily: Daniel Whitmire, a retired astrophysicist who teaches mathematics at the University of Arkansas, once thought the cosmic silence indicated we as a species lagged far behind. “I taught astronomy for 37 years,” said Whitmire. “I used to tell my students that by statistics, we have to be the dumbest guys in the galaxy. After all we have only been technological for about 100 years while other civilizations could be more technologically advanced than us by millions or billions of years.” Recently, however, he’s changed his mind. By applying a statistical concept called the principle of mediocrity — the idea that in the absence of any evidence to the contrary we should consider ourselves typical, rather than atypical — Read More ›

From Casey Smith at National Geographic: In essence, the researchers say, only the death of the sun will ultimately lead to the total extinction of life on Earth, including tardigrade [water bears]. “It seems that life, once it gets going, is hard to wipe out entirely,” Sloan says. “Huge numbers of species, or even entire genera, may become extinct, but life as a whole will go on.” And that’s an encouraging message for scientists seeking signs of life beyond our planetary shores. “Tardigrades are as close to indestructible as it gets on Earth,” Alves Batista says, “but it’s possible that there are other resilient species examples elsewhere in the universe.” More. Provided, that is, it can get started there. Someone should tell Read More ›

From Laura Geggel at LiveScience: The road to bringing back the mammoth — a giant that went extinct at the end of the last ice age — is filled with barriers.More. Of the eleven hurdles Geggel cites, here’s Even if pieces of preserved ancient DNA are uncovered, they might be contaminated with foreign DNA from fungus, bacteria, plants, animals and even from humans handling it for research purposes. This DNA contamination can make it difficult for researchers to know which DNA molecule belongs to the animal, and which is from contamination, especially if the extinct animal doesn’t have a living relative whose DNA can serve as a roadmap, Shapiro wrote. John Hawk noted back in February that the breathless predictions Read More ›

Animals we thought were extinct sometimes aren’t. From Julia Brown at New Scientist: Will Bill Laurance and his team find Tasmanian tigers lurking in Australia’s remote Cape York peninsula? Numerous animals that were thought to be extinct have recently been rediscovered. Here are our top five species that came back from the dead – and two more that might also have been written off too soon. More. This subject has heated up recently on account of possible sightings of the Tasmanian wolf (tiger), a marsupial that was believed to have gone extinct in the last century. Possibly, current technology would help us determine the chances that an actual species has actually gone extinct. The fact that one hasn’t seen any Read More ›