genetics
clock | May 26, 2007Back in the late 1990s, when people first started using various differential screens, etc. looking for elusive "genes for sleep", I wrote in my written prelims (and reprinted it on my blog several years later):
Now the sleep researchers are jumping on the bandwagon of molecular techniques. They are screening for differences in gene expression between sleeping and awake humans (or rats or mice), searching quite openly for the "genes for sleep". Every time they "fish out" a gene, it turns out to be Protein kinase A, a dopamine receptor, or something similar with a general function in the brain…
pharyngula | May 25, 2007We've often heard this claim from creationists: "there is no way for genetics to cause an increase in complexity without a designer!". A recent example has been Michael Egnor's obtuse caterwauling about it. We, including myself, usually respond in the same way: of course it can. And then we list examples of observations that support the obviously true conclusion that you can get increases in genetic information over time: we talk about gene duplication, gene families, pseudogenes, etc., all well-documented manifestations of natural processes that increase the genetic content of the organism.…
clock | May 18, 2007
As we mentioned just the other day, studying animal behavior is tough as "animals do whatever they darned please". Thus, making sure that everything is controlled for in an experimental setup is of paramount importance. Furthermore, for the studies to be replicable in other labs, it is always a good idea for experimental setups to be standardized. Even that is often not enough. I do not have access to Science but you may all recall a paper from several years ago in which two labs tried to simultaneously perform exactly the same experiment in mice, using all the standard equipment,…
razib | May 18, 2007Blackbirds Evolving Uptown:
More than a century ago, some European Blackbirds gave up the commuting life. The traditional routine was to nest in northern forests but head for southern Europe or northern Africa at the first sign of winter. Then some populations discovered that winter in the city isn't half-bad: The microclimate is warm with plenty of tasty leftovers. So strong is the appeal of city life, according to a research team in Germany, that it is has not only changed the blackbirds' behavior, but their genetics, too.
worldsfair | May 15, 2007"The concept of a gene is a fundamental part of the fields of genetics, molecular biology, evolution and all the rest of biology. Gene concepts can be divided into two main categories: abstract and physical. Abstract genes are the kind we refer to when we talk about genes "for" a certain trait, including many genetic diseases. Most geneticists and many evolutionary biologists use an abstract gene concept."
(Click here to go to post)
worldsfair | May 15, 2007"I talk a lot about genes, so let's just step way back and give a useful definition of a gene. I admit right up front, though, that there are two limitations: I'm going to give a very simplified explanation that fits with a molecular genetics focus (pure geneticists define genes very differently), and I'm going to talk only about eukaryotic/metazoan genes. I tell you right now that if I asked a half dozen different biologists to help me out with this, they'd rip into it and add a thousand qualifiers, and it would never get done. So let's plunge in and see what a simple version of a gene is…
evolgen | May 14, 2007
The Canadian research organization Genome BC has unveiled a science education website, Genomics Education. One of the features of the website is Floyd the Fruit Fly, who, we can only presume, is some sort of cartoon drosophilid. Or maybe he's a tephritid, but I highly doubt it. When you hear "fruit fly" and "genetics", you think Drosophila, even if they really aren't fruit flies.
In the accompanying illustration, we see Floyd with smelly feet. Apparently, Floyd thinks that his foot stank is due to mitosis. He then learns, via a disembodied voice backed up by a soundtrack from an early Ron…
razib | May 12, 2007The New York Times has a piece which goes over the issue of genetic testing and abortion. Most of the coverage is given over to people who support abortion rights but are not particularly happy about the consequences of the rhetoric of "choice." I'm not old enough to remember, but does this airing of "concerns" remind anyone of some of the sounds made when "test tube" babies were a big social issue? I suspect that most "progressives" given space in this article would concede the importance of points the disability rights activist person makes. That being said, I also suspect that they won'…
clock | May 12, 2007Shackleford ponies are often in the media around here. Some love them, some hate them, some want to preserve them, some to exterminate them, and it is not easy to get all the surplus horses adopted each year. Perhaps the new findings of their Spanish origin (DNA will tell the tale of wild horses) will tilt the scales towards their preservation, especially on the island of Corolla.
Thanks to Bill for the heads-up.
evolgen | May 10, 2007Rick at My Biotech Life is organizing all the genetics feeds into a single Feedburner feed. The DNA Network is a collection of feeds from sites that blog on genetics. You can subscribe to the DNA Network Feed to get the web's best genetics content delivered to your newsreader. If you would like to join the network, leave a comment on Rick's blog.
Via Neil Saunders I learned about Google's Image Labeler, in which you team up with another person to come up with labels for random pictures. I presume these labels will be used for smart searching in the future. Beware, this is an amazing time sink.
razib | May 10, 2007Science Daily has a summary of new fly research in behavioral genetics which puts the spotlight on deep time evolutionary dynamics. Here's the important bit:
The researchers found that when the fruit fly larvae were competing for food, those that did best had a version of the foraging gene that was rarest in a particular population. For example, rovers did better when there were lots of sitters, and sitters did better when there were more rovers.
In short the researchers here are pointing to negative frequency dependent selection, where traits/alleles exhibit a fitness as an inverse…
razib | May 7, 2007I have stated before that additive genetic variance is the relevant component of variance when modeling the response to selection in relation to a quantitative trait. In other words:
Response = (additive genetic variance)/(total phenotypic variance) X Selection
Consider height, which is about 80% heritable in the narrow sense in modern developed nations. What do I mean 80% heritable in the narrow sense? I mean that 4/5 of the variation in height, which is distributed in a normal fashion, is controlled by additive variation in the genotype. In other words, if I substitute allele 2 for…
razib | May 7, 2007I'm reading Derek Roff's chapter in Evolutionary Genetics: Concepts and Case Studies about quantitative genetics and the G Matrix. He revisits some of the territory covered in Evolutionary Quantitative Genetics, but his tone is strikingly pessimistic on both theoretical and empirical grounds. I'm still chewing over some issues, so for now I recommend two posts on the G Matrix elsewhere. Also, this review covers a lot of G Matrix ground....
pharyngula | May 6, 2007The latest Gene Genie #6 is rich in genetical goodness, but the rap video about Mendel? That's pure wickedness. I almost regret that my genetics lectures are over for this term, so I can't inflict it on my students.
grrlscientist | May 4, 2007tags: evolution, birds, orioles, Icterus, research
"Oriole."
Image appears here with the kind permission of the photographer, Pamela Wells.
[Larger image].
I often think about differences in morphological and behavioral traits in closely-related species and wonder whether the speed and character of changes in these traits reveal anything about the evolutionary relationships between taxa. For example, in birds, both visual and auditory cues, such as plumage and song patterns, are essential for identifying members of their own species. However, these phenomena have rarely been…
evolgen | May 3, 2007Here's some interesting science:
A commonly used medicinal leach may have been misidentified as the wrong species.
Here is a description of the Human Variome Project, which seems more focused on mapping disease genes than doing cool population genetics. That's too bad.
Science has an article on the benefits of undergraduate research. The most important one: to get into grad school.
You can use molecular markers to determine that a lonesome tortoise has no reason to feel alone.
The central nervous system is homologous across all animals.
What is the greatest innovation? I've tackled this…
razib | May 2, 2007I've talked about "the breeder's equation," R = h2S, before.
R = response
S = selection differential
h2 = narrow sense heritability
For example, if you have a population where the mean phenotypic value is 100, and you select a subpopulation with a mean value of 125 to breed the next generation, and the heritability is 0.50, then:
R = 0.50 * (125 - 100) = 12.5
In other words, the response to selection in this case where the differential is 25 units in the parental generation would be 12.5 units in the offspring with respect to the original population. This is because the "narrow sense…
evolgen | April 29, 2007A few articles have come out recently dealing with sex chromosomes in a variety of taxa. Here are some links to those articles, in list form:
Given all we know about vertebrate sex chromosomes, it's surprising that we don't know how sex determination works in many fish, including the pufferfish Takifugu rubripes. That's especially surprising given that the fugu genome was sequenced. That is, we didn't know much until researchers mapped a sex determining locus and reported it in this paper. You see, fish use a wide range of mechanisms for sex determination, including environmental cues and…
evolgen | April 27, 2007The most recent issue of the Journal of Heredity contains a bunch of articles from a symposium on the "Genetics of Speciation" organized by Loren Rieseberg. Included in the collection is an article by Allen Orr and two of his students on speciation in Drosophila, which discusses mapping speciation genes, the role of meiotic drive in speciation, and Dobzhansky Muller incompatibilities via gene translocation (the latter two are the topics of recent papers from Orr's group -- here and here). Also in the special issue is an article from Mohamed Noor's lab on mapping inversion breakpoints between…