selection
oracknows | November 24, 2014(Orac note: I was away at Skepticon over the weekend, where I gave a talk entitled The Central Dogma of Alternative Medicine. (When the talk’s up on YouTube, I’ll provide a link, of course.) Because of all the fun and travel delays I didn’t get a chance to turn my slides and notes into a blog post yet. Also, I’m on vacation this week. However, this gives me the opportunity to resurrect a blog post from 2007, because I think the concept is interesting. I even use it in a slide that shows up in many of my talks (above). I’ve updated dead links and added some text to include relevant links to…
razib | February 27, 2010The Genetics of Human Adaptation: Hard Sweeps, Soft Sweeps, and Polygenic Adaptation:
There has long been interest in understanding the genetic basis of human adaptation. To what extent are phenotypic differences among human populations driven by natural selection? With the recent arrival of large genome-wide data sets on human variation, there is now unprecedented opportunity for progress on this type of question. Several lines of evidence argue for an important role of positive selection in shaping human variation and differences among populations. These include studies of comparative…
razib | February 20, 2010An interesting exchange in Nature on ways to conceptualize the evolution of virulence. First, Adaptation and the evolution of parasite virulence in a connected world:
Adaptation is conventionally regarded as occurring at the level of the individual organism, where it functions to maximize the individual's inclusive fitness...However, it has recently been argued that empirical studies on the evolution of parasite virulence in spatial populations show otherwise...In particular, it has been claimed that the evolution of lower virulence in response to limited parasite dispersal...provides proof…
razib | February 6, 2010A few days ago I discussed a new paper which explores the patterns of natural selection in the genome of the X chromosome. As you know the X is "carried" disproportionately by females, as males have only one copy, so it offers up an interesting window into evolutionary dynamics (see The Red Queen for a popular treatment). Today Dienekes points me to a new paper in Genome Biology which puts the focus on the X chromosome again, Characterization of X-Linked SNP genotypic variation in globally-distributed human populations:
Background
The transmission pattern of the human X chromosome reduces its…
razib | January 7, 2010Update: Must read post from p-ter.
A Composite of Multiple Signals Distinguishes Causal Variants in Regions of Positive Selection:
The human genome contains hundreds of regions whose patterns of genetic variation indicate recent positive natural selection, yet for most the underlying gene and the advantageous mutation remain unknown. We developed a method, Composite of Multiple Signals (CMS), that combines tests for multiple signals of selection and increases resolution by up to 100-fold. Applying CMS to candidate regions from the International Haplotype Map, we localized population-specific…
razib | December 7, 2009
Well, I don't quite know about that, but that's the sort of take-away from a new paper in PLoS Biology which looks at the downsides of female attractiveness. A Cost of Sexual Attractiveness to High-Fitness Females:
Adaptive mate choice by females is an important component of sexual selection in many species. The evolutionary consequences of male mate preferences, however, have received relatively little study, especially in the context of sexual conflict, where males often harm their mates. Here, we describe a new and counterintuitive cost of sexual selection in species with both male mate…
razib | April 29, 2009Haplotypic Background of a Private Allele at High Frequency in the Americas:
Recently, the observation of a high-frequency private allele, the 9-repeat allele at microsatellite D9S1120, in all sampled Native American and Western Beringian populations has been interpreted as evidence that all modern Native Americans descend primarily from a single founding population. However, this inference assumed that all copies of the 9-repeat allele were identical by descent and that the geographic distribution of this allele had not been influenced by natural selection. To investigate whether these…
razib | March 25, 2009Dan MacArthur already posted some of the supplementary figures from Signals of recent positive selection in a worldwide sample of human populations, but he didn't put up one that I thought was really striking. The text:
First, there is extensive sharing of extreme iHS and XP-EHH signals between Europe, the Middle East, and Central Asia, while overlap between other regions is much more limited. In fact, 44% of the genomic segments in the 1% tail of iHS in Europe fall in the 5% tail for both the Middle East and Central Asia (89% are shared between Europe and at least one of these two), while…
razib | March 25, 2009Nick Wade in The New York Times has a piece on a review on the relationships between male competition, signaling and sexual selection. If the topic interests you I strongly recommend Animal Signals, John Maynard Smith's last book.
razib | March 24, 2009Genetic Future's summary of Signals of recent positive selection in a worldwide sample of human populations is an excellent complement to mine. Highly recommended.
razib | March 24, 2009John Hawks & Daniel MacArthur have already pointed to a new paper in Genome Research, Signals of recent positive selection in a worldwide sample of human populations. As Dan notes, it's Open Access, so you can read the PDF yourself. That being said, "Just read it!" might be somewhat a tall order if you don't have some background, so make sure to read the papers at this link. In particular the paper refers to two tests for detecting natural selection which utilize haplotype structure, integrated haplotype score (iHS) and cross population extended haplotype homozygosity (XP-EHH).
One of…
esiegel | January 28, 2008Okay, so I got a question from my friend Tamara, who's a high school teacher in my hometown of New York City. It concerns a recent article she read on the front page of the New York Times about something funny that us scientists are calling Boltzmann Brains.
I've read this article three times since it was featured on the front page of the science section in the NYT and I'm still confused about the Boltzmann brain problem, it's (non?)validity, the reason it made it's way onto the front page and whether Emerson's philosophy about imagined worlds came from this...
There's a lot of interesting…
laelaps | October 29, 2007A little more than a week ago, scientist James Watson made a complete idiot of himself with some despicable and racist comments about the intelligence of white people and black people, and Greg Laden justifiably kicked his arse over the ill-founded statements. I was certainly surprised, then, to visit the official Rutgers University newspaper (The Daily Targum) website and see an opinion article by a freshman named Brad Pironciak who apparently has no idea what natural selection is, his piece being an idiotic espousal of Social Darwinism (although he didn't use the phrase that pays, "survival…