genetics
clock | September 15, 2006A Community Genetics Forum 2006: Finding the Genome is a 3-day conference here in the Triangle. I will try to go to the third day events on Saturday, 10am - 3pm.
It is a very medically oriented meeting, so I doubt they will mention the importance of comparative genomics in the study of evolution, but it will be fun anyway.
On the other hand, it is probably good for my emotional well-being that there is likely to be no mention of Francis' awful book...
pharyngula | September 14, 2006A few carnivals have popped up:
Carnival of Education #84
Skeptics' Circle #43
I & the Bird #32
Carnival of the Liberals #21
Also, Mendel's Garden #6 is looking for submissions — it will be hosted at The Voltage Gate tomorrow!
razib | September 13, 2006I just noticed that David C. Queller's review of the history of the evolutionary biology of sex ratios is open access. Here's the conclusion:
Most important, this seemingly arcane topic has played very prominent roles in the development of game theory, in the debate over group selection, in supporting kin selection and parent-offspring conflict, and in the field of within-organism conflict. Many biological advances will require high tech instrumentation and deeper probing into molecular mechanisms of model organisms. But there remains room for a good theory, for adroit choice of non-…
razib | September 12, 2006Scent of father checks daughter's maturity. Basically the authors found in a survey that if biological fathers are around, girls mature more slowly. This sounds like the Harpending-Draper model of father absence, though with a somewhat more biological edge. The researchers suggest that the late maturity reduces the risk of inbreeding. Frankly, I'm skeptical that that is it, many animals do have pheromonally sensitivities which seem to adopt a "near enough" & "not too far" strategy for genetic diversity & compatibility, but humans seem a bit better at kin recognition than say...…
pharyngula | September 12, 2006I'm a little surprised at the convergence of interest in this news report of a conserved mechanism of organizing the nervous system—I've gotten a half-dozen requests to explain what it all means. Is there a rising consciousness about evo-devo issues? What's caused the sudden focus on this one paper?
It doesn't really matter, I suppose. It's an interesting observation about how both arthropods and vertebrates seem to partition regions along the dorso-ventral axis of the nervous system using exactly the same set of molecules, a remarkable degree of similarity that supports the idea of a common…
clock | September 12, 2006Remember this post from a couple of weeks ago? It was quite popular on tagging sites like Digg, Reddit and Stumbleupon. It was about endogenous retroviruses and their role in the evolution of placenta (which made the evolution of other mammalian traits possible).
Now, there is a new study in sheep, on this same topic, and it looks very good at first glance:
Researchers Discover That Sheep Need Retroviruses For Reproduction:
A team of scientists from Texas A&M University and The University of Glasgow Veterinary School in Scotland has discovered that naturally occurring endogenous…
razib | September 8, 2006As of this moment RPM has not commented on a new paper in Science, Gene Transposition as a Cause of Hybrid Sterility in Drosophila. Here is an accessible summary. The basic idea is found in the abstract:
...Genomic and molecular analyses show that JYAlpha transposed to the third chromosome during the evolutionary history of the D. simulans lineage. Because of this transposition, a fraction of hybrids completely lack JYAlpha and are sterile, representing reproductive isolation without sequence evolution.
JYAlpha is implicated in sperm motility. In D. melanogaster is located on the 4th…
pharyngula | September 8, 2006Perusable blogaliciousness for your Friday morning:
Carnival of Education
Friday Ark #103
Mendel's Garden #5
The Hairy Museum of Natural History has put out a call for submissions to the Tangled Bank, with an early deadline. If you want a shot at maybe seeing your link with a custom illustration, send it in by Sunday evening. He'll try to accept stuff up through Tuesday, but make life easy on the guy, OK?
pharyngula | September 7, 2006I was reading a review paper that was frustrating because I wanted to know more—it's on the evolution of complex brains, and briefly summarizes some of the current confusion about what, exactly, is involved in building a brain with complex problem solving ability. It's not as simple as "size matters"—we have to jigger the formulae a fair bit to take into account brain:body size ratios, for instance, to get humans to come out on top, and maybe bulk is an inaccurate proxy for more significant matters, such as the number of synapses and nerve conduction velocities.
There's also a growing amount…
razib | September 7, 2006A few weeks ago I explored the issue of smart individuals generally not being particularly fecund. I thought some readers might find this table from Cavalli-Sforza and Bodmer's Genetics of Human Populations interesting:
Sperm Donors
% Females Participating (p)
IQ
Mean of selected males
Minimum of selected males
% of males selected
1
5
10
20
50
100
115
105
38
100
100.2
100.4
100.8
100.9
103.8
130
122
6
100.1
100.4
100.8
101.5
103.8
107.5
145
140
.36
100.1
100.6
101.1
102.2
105.6
111.2
160
156
0.008
100.1
100.8
10.5
103.0
107.5
115.0
175
171
0.0001
100.2…
razib | September 4, 2006From The Genetics of Human Populations:
Considering only recessive genes for which the hetrozygotes are at present distinguishable [present is 1971]...only about 30 percent of the human population would be eligible for reproduction. These genes are, however, only a small minority of the recessive deleterious genes in existence...The probability that an individual would be free of such deleterious recessives would be e-4 or only 1/55. It might be even much less than this figure, which is computed on the assumption that all recessive deleterious genes have full penetrance, as the expected…
evolgen | September 4, 2006
Welcome to the fifth edition of Mendel's Garden -- the blog carnival devoted to all things genetical. In this edition, we have 17 articles from 14 blogs on biomedical research, evolutionary genetics, and molecular and cell biology. The entire collection can be found below the fold.
Biomedical Genetics
Ruth Schaffer at Eating Fabulous reviews how genetically engineered tomatoes may help fight human disease. Ruth also writes for The Biotech Weblog, where she has written a post on genetic markers that can be used to predict premature birth.
Hsien Hsien Lei, who blogs at Genetics and Health…
razib | September 2, 2006As I've been posting about effective population and inbreeding, I thought this re-post would be appropriate.
Begin repost
Reading a bit about inbreeding and population bottlenecks I came upon the extreme example of the northern elephant seal. In the late 19th century its population was reduced to about 20 individuals (undiscovered and isolated on a Mexican island). Today, there are around ~100,000 northern elephant seals. Compared to the southern elephant seal the northern hemisphere species exhibits far less genetic variation (surprise!). A relatively recent paper concluded that the…
razib | September 2, 2006In a few posts below I mentioned long term effective population. The effective population is basically the breeding population as opposed to the census size. Depending on the species this can vary quite a bit. One important point to consider (and this is obviously relevant to inbreeding and genetic diversity) is that the breeding generation alive must be placed in its historical context, how many ancestors does this population have?
For non-overlapping generations long term effective population size is the harmonic mean of the effective population sizes of each generation. It is defined by…
evolgen | September 1, 2006I'm slowly turning into a cyclist. I currently own three bikes, but that number may change when I buy the fixed gear I've been longing for. I bought a mountain bike a couple of years ago for commuting to and from campus. It's a little over a mile from my front door to my building, but I lost the patience required to walk that distance and driving was out of the question. I was now riding a bike regularly for the first time since the eighth grade. Last summer I picked up a used Cannondale CAD3 road bike from a guy who had only ridden it indoors on a trainer. The bike was in near mint condition…
razib | September 1, 2006Inbreeding is bad. At least that is the take home message of my various posts. But biology doesn't have one final answer, it is a serious of approximations which capture part of a given system. My posts on racial hybridization point to this issue. Today in the West we live in an anti-racist age, so the intuitive benefits of hybridization known from agriculture are often tacitly promoted in the discourse, but the reality is more complex. 100 years ago eugenicists set out to prove the inverse because the norms of society demanded it (e.g., Charles Davenport's studies of Jaimaican Mullatoes…
evolgen | September 1, 2006Reminder: Today is the last day to submit a post for the upcoming edition of Mendel's Garden. Either email me (evolgen [at] yahoo [dot] com) or use the Blog Carnival submission page.
clock | August 31, 2006Now, this is the gene that was meant to be named "hairy" instead of this one:
Hirsute-s You, Sir! Could Super Furry Animals Provide Clues For Baldness?:
The team found that cells given the genetic command to become hair follicles will send out signals to neighbouring cells to prevent them from doing likewise, so producing a specific hair pattern.
They also demonstrated that by hyperactivating the 'hair protein' in embryonic mice, young with considerably more fur than normal were produced.