speciation

From Chris Woolston at Nature: Researchers previously split giraffes into several subspecies on the basis of their coat patterns and where they lived. Closer inspection of their genes, however, reveals that giraffes should actually be divided into four distinct lineages that don’t interbreed in the wild, researchers report on 8 September in Current Biology1. Previous genetic studies2 have suggested that there were discrete giraffe populations that rarely intermingled, but this is the first to detect species-level differences, says Axel Janke, a geneticist at Goethe University in Frankfurt, Germany, and the study’s senior author. “It was an amazing finding,” he says. He notes that giraffes are highly mobile, wide-ranging animals that would have many chances to interbreed in the wild if Read More ›

At PLOSOne, What Is Speciation? Abstract: Concepts and definitions of species have been debated by generations of biologists and remain controversial. Microbes pose a particular challenge because of their genetic diversity, asexual reproduction, and often promiscuous horizontal gene transfer (HGT). However, microbes also present an opportunity to study and understand speciation because of their rapid evolution, both in nature and in the lab, and small, easily sequenced genomes. Here, we review how microbial population genomics has enabled us to catch speciation “in the act” and how the results have challenged and enriched our concepts of species, with implications for all domains of life. We describe how recombination (including HGT and introgression) has shaped the genomes of nascent microbial, animal, and Read More ›

As New Scientist tells it, “Red wolf may lose endangered status because it’s just a hybrid”: The red wolf, a critically endangered species living in the south-eastern US, may be nothing more than a hybrid between coyotes and the grey wolf, a new study suggests. If so, it may lose its conservation status and protection, given that US legislation does not protect hybrids. This could lead to loss of an important evolutionary lineage, because the red wolf is the only living repository of genes from the grey wolves that were driven near extinction in the south-eastern states by trapping and agricultural development. More. Shocka: Everyone knew that about the red wolf. There is usually  no critical reason to protect hybrids except Read More ›

From ScienceDaily: Earth could contain nearly 1 trillion species, with only one-thousandth of 1 percent now identified, according to a study from biologists. The estimate is based on the intersection of large datasets and universal scaling laws. Scaling laws, like those discovered by the IU scientists, are known to accurately predict species numbers for plant and animal communities. For example, the number of species scales with the area of a landscape. “Until now, we haven’t known whether aspects of biodiversity scale with something as simple as the abundance of organisms,” Locey said. “As it turns out, the relationships are not only simple but powerful, resulting in the estimate of upwards of 1 trillion species.” The study’s results also suggest that Read More ›

Here: Dozens of genes found in humans today have been traced to Neanderthals and Denisovans. They made their way into the human species when some of our direct ancestors mated with ancient lineages that are now extinct. Interbreeding like this happened in Africa and in Eurasia, producing many human hybrids – you can read more about them here. Recent genetic decoding has revealed that it partly accounts for differences in our physical appearance – things like skin and hair colour – and affects our health. More. One must pay to read anything significant, and one senses that we’re not going to hear why, exactly, those other groups are somehow classified as not “the human species.” Because if they are, the Read More ›

DNA proves it, say researchers. From ScienceDaily: New research examining the DNA of North American mammoths challenges the way we categorize a species. Several species of mammoth are thought to have roamed across the North American continent. The new study results show that while mammoths clearly evolved differences in their physical appearance to deal with different environments, it did not prohibit them from cross-breeding and producing healthy offspring. Paper. (public access) – Dan Fisher et al. Mammuthus Population Dynamics in Late Pleistocene North America: Divergence, Phylogeography and Introgression. Frontiers in Ecology and Evolution, April 2016 DOI: 10.3389/fevo.2016.00042 … A species can be defined as a group of similar animals that can successfully breed and produce fertile offspring. By using differences Read More ›

From Ansel Payne at Nautilus: Why Do Taxonomists Write the Meanest Obituaries? The open nature of the science of classification virtually guarantees fights. Well, “speciation” has been a mess forever. No one can define it but it is the basis of Darwinian evolution. On the other hand, maybe that works. Still, one wouldn’t have expected this, necessarily: For starters, there’s the problem of classification itself. Ever since Darwin gave us a framework for understanding common descent, the search has been on for a natural classification, an arrangement of nested groups, or taxa, that accurately reflects evolutionary relationships. In this scheme, a classification functions as an explicit evolutionary hypothesis—to say that five species form a genus is also to say that Read More ›

Asks Jon Tennant at Paleo Community: Further to the dinosaur document dump (a fair bit of news and views recently, about the late and the great): Why are there so many bird species around today, when we have relatively so few dinosaurs in the fossil record? This disparity is even more extreme when you consider that while non-avian dinosaurs were around for about 170 million years, there were only ever about 800 or so species of dinosaur, based on current records. The actual number fluctuates through time, as new species are discovered, and others are shown to be invalid through research broadly known as ‘taxonomy’. One problem is with the difference between what existed and what gets preserved and another Read More ›

From ScienceDaily: Researchers recently discovered that alligators and related crocodilian species have a previously unknown second jaw joint that helps to distribute the extreme force of their bite, which is the most powerful of any living animal. The finding raises new questions about the evolution of our own meager-by-comparison jaws and could potentially lead to a better understanding of common jaw disorders. When we discovered that crocs had built this new jaw joint, it made us re-evaluate how mammals actually evolved our jaw joint and reinterpret what we thought we knew about where parts of our jaw joint came from,” said Casey Holliday, Ph.D., assistant professor of anatomy at the University of Missouri, who led the research. “It’s one of Read More ›

From ScienceDaily: Researchers discover sophisticated alarm signaling in a primitive insect Many insect species respond to danger by producing chemical alarm signals, or alarm pheromones, to inform others. In a recent study, investigators found that their alarm may be even be context dependent. The researchers discovered that larvae of the Western Flower Thrips produce an alarm pheromone whose composition of 2 chemicals, decyl acetate and dodecyl acetate, varies with the level of danger they face. When pheromone is excreted with a predator present but not attacking, the percentage of dodecyl acetate increases, whereas when a predator does attack, the percentage of dodecyl acetate is low. “This type of communication was so far only known from vocal alarm calling in mammals, Read More ›

Worrying on behalf of the Sixth Great Extinction, Patrick Monahan at Science: … That’s why Roy Plotnick, a paleontologist at the University of Illinois, Chicago, and lead author of the study, thinks about far-flung scenarios involving future paleontologists. “We really need to look at modern day extinctions as if they were in the fossil record already, in order to make a comparison,” he says. So he and his colleagues searched fossil databases for modern mammal species—both those threatened by extinction and those that aren’t—to see how many modern extinctions would be detectable by relying only on fossils. Humans have recorded fossils for just 9% of the world’s threatened modern mammal species, the team reports this month in Ecology Letters. Nonthreatened Read More ›

From Nature News: The pupfish has evolved distinct differences from related species that live nearby, including reduced aggression, larger eyes and missing pelvic fins. But Many researchers thought that the fish species had been isolated in its cavern from around 13,000 years ago — the last time major flooding occurred in the region. But Christopher Martin, an evolutionary biologist at the University of North Carolina, Chapel Hill, and his colleagues say that genetic sequencing suggests that the pupfish became trapped in Devils Hole somewhere between 105 and 830 years ago — and since then has continued to exchange genes with neighbouring populations of pupfish species. “That was the big surprise,” says Martin. “Every few hundred years there’s a fish or Read More ›

From New Scientist: Why one lake contains more than 1000 species of the same fish One thousand species of the “same fish” in Lake Malawi? We used to think the word “species” meant something. The huge number of closely related species living together has meant they feature prominently in models of species diversification. But what made them so diverse has remained a mystery. Some think environmental forces drove the diversification, others that the underlying cause was biological, says Scholz. For example, some females are colour-blind to males that are a different colour to them, which can drive sexual isolation between different groups of fish. In humans, we call that  behaviour “demography.” People who don’t speak the same language or move Read More ›

From Science Daily: Researchers at Michigan State University, with the help of some stickleback fish, have shown that intense competition among males most definitely has a big say in creating new species. The results, featured in the January issue of Ecology Letters, also show that such competition can reverse the process, actually erasing boundaries between species. “Our paper is of special interest because this is the first time that researchers have shown that intense competition between males for the chance to mate with females can have this kind of influence on splitting populations in two or fusing them together,” said Janette Boughman, MSU integrative biologist and the paper’s senior author.More. Good heavens, not the threespine sticklebacks again? Two stories blew Read More ›

Well, that’s one way of looking at it. From New Scientist: Some thought it was impossible. But a population of stickleback fish that breed in the same streams is splitting into two separate species before our eyes, and at rapid speeds. Three-spine sticklebacks were introduced to Lake Constance in Switzerland around 150 years ago – a blink of an eye in evolutionary terms. But since then, the fish have begun splitting into two separate types: one that lives in the main lake (pictured above left, female top, male in breeding colours below), and another that lives in the streams that flow into it (above right). The main lake dwellers are bigger, with longer spines and tougher armour. In theory, these Read More ›