genetics
gregladen | March 24, 2008Significant cultural and physical differences ... the stuff of race and ethnicity ... are prominent when people move across continents or between them. Eventually, the ponderous events of history, which involve occasional foldings in the continuum of human variation, causing apparent patchiness, are offset by the frequent events of human activities, resulting in genetic and cultural admixtures. What colonialism, invasion, and migration do is undone.
A new study out in PLoS Genetics examines this phenomenon for Latin America, with a study of genetic admixture.
From the Author's Summary:…
gregladen | March 22, 2008A common presumption is that behavior is part of phenotype, and since phenotype arises from genotype (plus/minus Reaction Norm), that there can be a study of "behavioral genetics." This is certainly an overstatement (or oversimplification) for organisms with extensive and/or complex neural systems, such as humans and mice. Neural systems probably evolved (not initially, but eventually) to disassociate behavior with the kind of pre-determined micro-management of behavior that a simple gene-behavior link requires. However, in organisms with neural systems the size of the period at the end of…
razib | March 21, 2008New PLOS paper, Geographic Patterns of Genome Admixture in Latin American Mestizos. Nothing new, but pushing the ball forward....
A = autosomal
X = X chromosomal
Related: Genetics, the myth-buster? The case of Argentina.
mikethemadbiologist | March 20, 2008OK, last post about this bozo, and then I'm done (famous last words...). In the previous post, I dealt with Egnor's claim that the evolution of antibiotic resistance by selection of resistant genotypes is obvious, and not germane (namely, that it wasn't obvious at one point in time). What bothered me with not just Egnor's claim (which I'll get to a minute) and ScienceBlogling Mike's response is that evolutionary biology does have a significant role to play in combating the evolution and spread of antibiotic resistance.
First, what Egnor said:
The important medical research on antibiotic…
mikethemadbiologist | March 19, 2008In the previous post, I described how Egnor, like many creationists, refuses to answer serious rebuttals of his foolishness. But what's truly odd is how Egnor argues about natural selection.
Egnor repeatedly claims that 'Darwinism' is nothing except self-obvious: bacteria that are more likely to survive and reproduce because they are resistant to an antibiotic are more likely to survive and reproduce in the presence of that antibiotic.
It is obvious--today. If I were to give a talk which had as its central thesis the concept that natural selection has given rise to antibiotic resistant…
razib | March 16, 2008David has finally initiated his series on the major ideas of the great evolutionary biologist Sewall Wright. Check out his post on path analysis.
razib | March 16, 2008OK, the title is somewhat of an exaggeration, but not much. Out of Africa, Not Once But Twice:
Modern humans are known to have left Africa in a wave of migration around 50,000 years ago, but another, smaller group -- possibly a different subspecies -- left the continent 50,000 years earlier, suggests a new study.
While all humans today are related to the second "out of Africa" group, it's likely that some populations native to Israel, Jordan, Lebanon, Syria, Australia, New Zealand and Indonesia retain genetic vestiges of the earlier migrants, according to the paper's author, Michael…
grrlscientist | March 15, 2008tags: genetics, Bill Nye the Science Guy, education, streaming video
Those of you who do not know who Bill Nye the Science Guy! is will especially enjoy this video. In this streaming episode, Bill Nye the Science Guy explores the science behind genes (part 3). Basically, you can thank your parents for all those nice pairs of genes. Chromosomes are made up of sequences of genes, which are themselves made up of strands of DNA. The mutations in DNA during replication cause resulting changes within genes, which is the basis of evolution. [8:54].
gregladen | March 14, 2008You've all seen the PCR song:
I also recommend a look at this post on the Punk Professor's Blog
grrlscientist | March 14, 2008tags: genetics, Bill Nye the Science Guy, education, streaming video
Those of you who do not know who Bill Nye the Science Guy! is will especially enjoy this video. In this streaming episode, Bill Nye the Science Guy explores the science behind genes (part 2). Basically, you can thank your parents for all those nice pairs of genes. Chromosomes are made up of sequences of genes, which are themselves made up of strands of DNA. The mutations in DNA during replication cause resulting changes within genes, which is the basis of evolution. The third and last part appears tomorrow morning. [6:17].
razib | March 14, 2008A few days ago I mooted the possibility that balancing selection may be more common than we had assumed, and that much of the recent evolutionary action in our species' history might be characterized by non-fixed allele frequencies which exhibit the signatures of positive selection because of their shallow time depth. I was interested in the idea for an important reason. Below the fold are are a range of data for two loci implicated in skin color variation in human populations; SLC24A5 and SLC45A2.
SLC45A2
SLC24A5
Mozabite
0.4
0.87
Bedouin
0.23
0.97
Druze
0.51
1…
evolgen | March 13, 2008
It's not very funny, but it's about a topic that comes up around here often (groans...). That said, this is something you'd expect to see over at Genomicron, not evolgen. In fact, the guy looks a bit like a young TR Gregory.
For the full strip, go here.
grrlscientist | March 13, 2008tags: genetics, Bill Nye the Science Guy, education, streaming video
Those of you who do not know who Bill Nye the Science Guy! is will especially enjoy this video. In this streaming episode, Bill Nye the Science Guy explores the science behind genes (part 1). Basically, you can thank your parents for all those nice pairs of genes. Chromosomes are made up of sequences of genes, which are themselves made up of strands of DNA. The mutations in DNA during replication cause resulting changes within genes, which is the basis of evolution. [7:53].
razib | March 12, 2008Scientist calculates an equation for the common cold: "Ten percent of your life is spent fighting colds." Wow. That makes sense though. I've read that common cold viruses need at least the population density of agricultural societies to persist endemically. No wonder the recent work on natural selection among humans shows that immune related loci exhibit strong signatures of recent evolution.
razib | March 12, 2008Just noticed that Carlos Bustamante's chapter from Statistical Methods in Molecular Evolution, Population Genetics of Molecular Evolution, is online (PDF). Enjoy.
mikethemadbiologist | March 11, 2008Over at evolgen, ScienceBlogling RPM discusses a paper that describes a new barcoding technique for plants. It struck me while reading his post that barcoding has two very different meanings, even though both techniques are used in genomics--and often, at the same time.
One meaning of barcoding, and the one discussed by RPM, is the use of a gene to assign different groups of organisms a taxonomic DNA label (or barcode...). In other words, we're replacing Latin bionomials, like Escherichia coli or Homo sapiens, with a DNA sequence from a single gene (or a set of closely related sequences).…
razib | March 10, 2008Dan MacArthur has a post up, Climate genes: positive or balancing selection?, where he questions the interpretation of data from a recent paper, Adaptations to Climate in Candidate Genes for Common Metabolic Disorders:
The critical point I want to make is that while positive selection will usually tend to increase the frequency of an allele until it reaches 100% frequency, balancing selection can result in a situation where an allele reaches a stable frequency that is less than 100%. For a case of heterozygote advantage, the stable frequency will be the point at which the selective advantage…