genetics
edyong | September 2, 2008
Love is all around us and love is in the air, and if I know my mainstream science reporters, today they will have you believe that love is in our genes too. A new report suggests that variation in a gene called AVPR1A has a small but evident influence on the strength of a relationship, the likelihood of tying the knot and the risk of divorce. It's news for humans, but it's well-known that the gene's rodent counterpart affects the bonds between pairs of voles. The story really starts with these small rodents and it's them that I now turn to.
Voles make unexpectedly good animals to study if…
razib | September 1, 2008Notes on Sewall Wright: the Adaptive Landscape:
My series of posts on the work of Sewall Wright is now approaching its (anti?)climax. The next post, on the shifting balance theory, should be the last. The present note deals with a closely related subject. Wright introduced the concept of the 'adaptive landscape' largely in order to illustrate the shifting balance theory. It does however have great interest in its own right, and there is a substantial literature on the concept of adaptive landscapes. [Note 1]
Wright's own treatment of the subject has attracted some controversy following the…
edyong | September 1, 2008Within a drop of blood, you can find all the information you need to reasonably guess where a person came from, without ever having to look at their face, name or passport. Small variations in our DNA are enough for the task. They can be used to pinpoint someone's place of origin to a remarkable degree of accuracy, often to within a few hundred kilometres.
The new discovery comes from a team of Swiss and American researchers led by John Novembre at UCLA, who wanted to understand how the human genome varies on a continental scale. To that end, they looked at the genomes of over 1.300 people…
razib | August 31, 2008My post The Genetic Map of Europe drew a lot of interest, but there's even a cooler paper on the same topic out, Genes mirror geography within Europe:
...Despite low average levels of genetic differentiation among Europeans, we find a close correspondence between genetic and geographic distances; indeed, a geographical map of Europe arises naturally as an efficient two-dimensional summary of genetic variation in Europeans. The results emphasize that when mapping the genetic basis of a disease phenotype, spurious associations can arise if genetic structure is not properly accounted for. In…
edyong | August 30, 2008
The complex cells that make up plants and animals only survive today because their ancestors formed partnerships with bacteria. In a previous post, I wrote about a microbe called Hatena, which provides us with a snapshot of what the early stages of this alliance might have looked like. Hatena swallows an alga which becomes an integrated part of its body.
Millions of years ago, the ancestors of complex cells did the same thing, taking in bacteria and merging with them to form a single creature. Today, these integrated bacteria are mitochondria, which provide us with energy, and…
razib | August 29, 2008War and the evolution of belligerence and bravery:
Tribal war occurs when a coalition of individuals use force to seize reproduction-enhancing resources, and it may have affected human evolution. Here, we develop a population-genetic model for the coevolution of costly male belligerence and bravery when war occurs between groups of individuals in a spatially subdivided population. Belligerence is assumed to increase an actor's group probability of trying to conquer another group. An actor's bravery is assumed to increase his group's ability to conquer an attacked group. We show that the…
razib | August 28, 2008Fortune favours the brave; but the brave are motivated by favours of another kind:
If courage makes it significantly more likely that small bands of tribes-men will win military confrontations with their neighbours, its overall advantages can easily outweigh its risks, a mathematical model has shown.
Some men who carry genetic variants that promote bravery might perish because of them, but the ones who survive may win more battles through their greater daring. The resulting opportunities for rape and pillage can create a net evolutionary benefit.
The study is published in The Proceedings of…
razib | August 27, 2008As I have said before biology is quite often the science of exceptions, of variation. Evolutionary biologists spend a great deal of time wondering about the origin of sex, but across vast swaths of the tree of life sex is simply not a consideration. W. D. Hamilton made his name with models of inclusive fitness, but complex social structures are constrained and fully elaborated to only a few branches of the tree of life. Like economics then what interests us in biology often has normative priors; we are a homocentric species. On a fundamental level we understand that we do not exist at the…
mikethemadbiologist | August 26, 2008In the midst of the kerfuffle about atheism, religion, and teaching evolution in high school, the NY Times article made me wonder if focusing part of the curriculum on molecular evolution would be a better way of teaching evolutionary biology* (and ScienceBlogling Sandra describes some good ways of doing so).
I pose this as a question--it could be a dreadful idea, but here are some things to consider:
Molecular biology is viewed as more 'scientific.' Like it or not (and I don't), molecular biology is viewed as more rigorous than organismal biology.
DNA sequence is pretty easy to understand…
gregladen | August 23, 2008Jamaican sprinters make people who are not really thinking about this jump, like pole vaulters, to the conclusion that there must be a gene for running fast that somehow evolved ... like Olympic Beach Volley Ball seemingly from sterile sand ... despite the numerous hurdles for such an event to happen. Such is the nature of amateur science.
As much as I'd like to make a contribution to this discussion right now, I'm engaged in other activities that preclude a knee-jerk reaction. So for now, I offer this repost of an earlier piece on running and genetics. As a wet blanket. Enjoy the wet…
razib | August 22, 2008My previous post, Weird lands of the tails, had some concepts implicit which I didn't elucidate in detail. For example, I assumed that the speed is a quantitative trait, and the many genes which control its variation have pleiotropic effects. That is, gene 1 has effect on phenotypes 1 through n. Gene 2 has effect on phenotype 1 through n. Speed may be just one of those phenotypes. More formally what I'm thinking about is a genetic variance-covariance matrix, or G matrix. If you keep the G matrix in mind I think it's kind of ludicrous to expect that speed was actually what was being selected…
clock | August 22, 2008Friendly blogger Pamela Roland, the author of Tomorrow's Table: Organic Farming, Genetics, and the Future of Food which I am reading right now (and which was recently reviewed in PLoS Biology), has just had a paper published in PLoS Genetics:
Identification and Functional Analysis of Light-Responsive Unique Genes and Gene Family Members in Rice
Rice, a model monocot, is the first crop plant to have its entire genome sequenced. Although genome-wide transcriptome analysis tools and genome-wide, gene-indexed mutant collections have been generated for rice, the functions of only a handful of rice…
razib | August 22, 2008Yesterday's post on the speed of Jamaican sprinters, and Genetic Future's skepticism of a one-gene answer for their dominance. The discussion brought up some adaptive talk; I'm not against adaptation, and I think it's entirely plausible that populations differ enough in the distribution of phenotypes that there are different genetic potentialities...but, I have some issues with the intersection of the two in this particular case. Here's my logic....
Sprinters at the Olympic level are the best of the best. They're not just good, they're not just superior, they are the pushing the limits of…
razib | August 20, 2008I haven't been watching the Olympics, but my news feeds are broad enough that I get a general sense of who is winning, and who is not. Over at Genetic Future Dan MacArthur has a post up, The gene for Jamaican sprinting success? No, not really:
And Bolt is not the only Jamaican to impress in short distance events in Beijing: the country's women's sprint team took all three medals in their 100 metre dash.
Naturally, these performances have provoked widespread speculation about the basis of Jamaica's sprinting success, and the short-distance prowess of other populations of West African ancestry…
razib | August 17, 2008p-ter points me to a new paper in Trends in Ecology, Pleiotropy in the melanocortin system, coloration and behavioural syndromes:
In vertebrates, melanin-based coloration is often associated with variation in physiological and behavioural traits. We propose that this association stems from pleiotropic effects of the genes regulating the synthesis of brown to black eumelanin. The most important regulators are the melanocortin 1 receptor and its ligands, the melanocortin agonists and the agouti-signalling protein antagonist. On the basis of the physiological and behavioural functions of the…
razib | August 15, 2008MHC-correlated odour preferences in humans and the use of oral contraceptives:
Previous studies in animals and humans show that genes in the major histocompatibility complex (MHC) influence individual odours and that females often prefer odour of MHC-dissimilar males, perhaps to increase offspring heterozygosity or reduce inbreeding. Women using oral hormonal contraceptives have been reported to have the opposite preference, raising the possibility that oral contraceptives alter female preference towards MHC similarity, with possible fertility costs. Here we test directly whether…
edyong | August 15, 2008Hey folks, I've got a feature article in this week's New Scientist, which is my second for the magazine. The article describes the story of FOXP2, the "language gene" that's not really a language gene.
The story started a few years ago, when a group of scientists led by Simon Fisher found that a single genetic mutation was responsible for an inherited language disorder in a British family called KE. The gene in question - FOXP2 - was quickly touted as a "gene for language" by an overenthusiastic and sensationalist media.
Since then, researchers have probed the true nature of FOXP2 using…
razib | August 15, 2008Brain Size and the Diversification of Body Size in Birds:
Large brains are associated with increased cognitive skills, enabling animals to use new environments and resources more successfully. Such behavioral flexibility is theoretically expected to have macroevolutionary consequences. First, populations of big-brained individuals should more easily become established in new locations, increasing opportunities for allopatric speciation and decreasing chances that the species as a whole becomes extinct. Second, the ability to use new resources should place new selection pressures on…
razib | August 13, 2008
The figure above comes from the an article in The New York Times, The Genetic Map of Europe, which draws from a new paper, Correlation between Genetic and Geographic Structure in Europe. The authors sampled 2,500 Europeans across 300,000 points of genetic variation, then extracted out the components of that variation, and plotted the individual data points along the two largest independent dimensions. You note that various samples tend to cluster geographically with each other; i.e., Finns tend to cluster with other Finns, Italians with Italians. This makes sense since Europe hasn't been a…
gregladen | August 13, 2008From Sex, Genes and Evolution, a story of publishing in PLoS Open Access Journal:
My lab has taken its initial journey on the PLoS ONE train.
Yesterday, our paper entitled "An Expanded Inventory of Conserved Meiotic Genes Provides Evidence for Sex in Trichomonas vaginalis" was published in PLoS ONE. It's a updated and detailed report on the ongoing work in my lab to generate and curate an "inventory" of genes involved in meiosis that are present across major eukaryotic lineages. This paper focuses on the protist, Trichomonas vaginalis, an organism not known to have a sexual phase in its life…