Evolution

the 47-million-year-old Darwinius masillae fossil that was celebrated last year as a so-called 'missing link' between humans and early primates is actually a forebearer of modern-day lemurs and lorises, according to two papers in the Journal of Human Evolution and PNAS. Researchers note in one article published in the Journal of Human Evolution that Darwinius masillae is not a haplorhine primate like humans, apes and monkeys, as the 2009 research claimed. They also note that the article on Darwinius published last year ignores two decades of published research showing that similar fossils are…

Researchers analyzing mitochondrial DNA extracted from a polar bear fossil discovered in Norway in 2004 say the species is relatively young, splitting off from brown bears approximately 150,000 years ago and rapidly evolving during the late Pleistocene. The findings are published in the Proceedings of The National Academy of Sciences "Very few polar bear fossils have been found, leading to widely varying estimates of exactly when and how polar bears evolved," explains Øystein Wiig, polar bear expert and co-author at the University of Oslo's Natural History Museum. "Because polar bears live on…

Promiscuous females may be the key to a species' survival, according to new research published today in Current Biology. The study may explain why females of most species have multiple mates, despite this being more risky for the individual. Known as 'polyandry' among scientists, the phenomenon of females having multiple mates is shared across most animal species, from insects to mammals. This study suggests that polyandry reduces the risk of populations becoming extinct because of all-female broods being born. This can sometimes occur as a result of a sex-ratio distortion (SR) chromosome,…

Researchers who observed viruses as they evolved to infect bacteria say they have confirmed the Red Queen Hypothesis, the idea that competing species drive molecular evolution through natural selection for adaptation and counter-adaptation. The team used high-throughput DNA sequencing technology to sequence thousands of virus genomes. They found that when the bacteria could evolve defenses, the viruses evolved at a quicker rate and generated greater diversity, compared to situations where the bacteria were unable to adapt to the viral infection. The results are published in Nature. First put…

Life can be brutal for yeast in the wild. You don't know where your next meal is coming from or what form it's going to take. The key to being a successful yeast is to be metabolically agile, able to switch your metabolic state quickly based on the food source that's currently available on the bark of an oak tree or in the leaf litter of a forest floor. So yeast, especially the set of species related to baker's yeast, have various networks of genes that specialize in making a meal out of different sugars. A yeast has to detect, pump in, and break down various sugars like sucrose, galactose,…

Writing in the Proceedings of The National Academy of Sciences, Harvard University researchers say they have demonstrated that simple changes in beak length and depth can explain the important morphological diversity of all beak shapes within the famous genus Geospiza. Broadly, the work suggests that a few, simple mathematical rules may be responsible for complicated biological adaptations. Using digitization techniques, researchers found that 14 distinct beak shapes, that at first glance look unrelated, could be categorized into three broader, group shapes. Despite the striking variety of…

Assorted creationists claim variously that creation theories are falsifiable and that evolutionary theories are not falsifiable. Here, I want to quickly point out a few flaws that I see in their arguments. I will discuss these issues in a more general manner in another post that I am currently writing. Creationism is falsifiable: This essay from the Discovery Institute provides two arguments, neither of which are satisfying. First, they look at the idea of irreducible complexity (IC, a component of Intelligent Design theory), and claim that it can be falsified by finding an evolutionary…

A new study in PNAS of the side-blotched lizard (Uta stansburiana) may bolster the idea that 'morphs', morphologically distinct types often found within species, could be the raw material for speciation. Previous research has shown that competition among male side-blotched lizards takes the form of a rock-paper-scissors game in which each mating strategy beats and is beaten by one other strategy. Males with orange throats can take territory from blue-throated males because they have more testosterone and body mass. As a result, orange males control large territories containing many females…

Natural selection – the force that drives evolution – acts not only on whole organisms and individual genes, but also on gene networks, according to a new study appearing in Nature this week.The finding suggests that natural selection is both more powerful and more complex than scientists recognized. Researchers found that a close relative of brewer's yeast, Saccharomyces kudriavzevii, exists in two very different states: one that can efficiently digest the sugar galactose and one that cannot. Galactose is a natural sugar found in milk and many fruits and legumes. The variant found in…

Biologists have struggled for many years to comprehend the relationships among the major groups of arthropods. Now, a team of researchers has completed new analysis of the evolutionary relationships among arthropods, which may answer many questions that defied previous attempts to unravel how these creatures were connected. The study will appear in Nature later this month. There are millions of distinct species of arthropods, including all the insects, crustaceans, millipedes, centipedes, spiders, and a host of other animals, all united by having a hard external shell and jointed legs. They…