evolution
razib | October 31, 2009Intergenerational Wealth Transmission and the Dynamics of Inequality in Small-Scale Societies:
Small-scale human societies range from foraging bands with a strong egalitarian ethos to more economically stratified agrarian and pastoral societies. We explain this variation in inequality using a dynamic model in which a population's long-run steady-state level of inequality depends on the extent to which its most important forms of wealth are transmitted within families across generations. We estimate the degree of intergenerational transmission of three different types of wealth (material,…
pharyngula | October 31, 2009How can I resist an opportunity to see Ruse gibbering on the stage? I'm curious to see whether he annoys or enlightens. It could go either way.
He's not going to talk about evo-devo! OK, I'm already annoyed.
Criticizes the infamous New Scientist cover, "Darwin Was Wrong"; received email from Paul Nelson (boo) claiming the edifice of darwinism is crumbling; Rudy Raff has written that evolution requires development to remain relevant. Are today's evolutionists genuinely Darwinian or not?
Plans to pick on something that was self-consciously in Darwin's thinking. Darwin became an evolutionist in…
pharyngula | October 31, 2009Shubin had a tough act to follow, coming after Kingsley's great talk. I'm sure it will be good, though — last night I got a tour of his lab, saw the original Tiktaalik specimens and some new ones, and some of his work in progress (which I won't tell you about until it's published), so I'm confident I'm going to have a happy hour.
Darwin pulled together diverse lines of evidence to document his ideas. The different lines all reinforce each other making the argument even stronger, and what we're seeing now is new syntheses, which is the theme of this talk: how do we use different lines of…
pharyngula | October 31, 2009This talk should put me back in my comfort zone—developmental biology, evolution, and fish, with the stickleback story, one of the really cool model systems that have emerged to study those subjects.
What is the molecular basis of evolutionary change in nature? How many genetic changes are required to produce new traits? Which genes are used? What types of mutations? Few or many changes required?
The dream experiment would be to cross a whale and a bat and figure out what their genetic differences are. That's impossible, so they searched for other organisms with a suite of differences that…
pharyngula | October 31, 2009Darwin had problems with the fossil record that he explained as a result of imperfections. Modern paleo has corrected some of that with the discovery of many intermediates. Jablonski is going to talk about the fossil record as a laboratory for testing evolutionary hypotheses. Marine bivalves are model systems with both modern forms and good fossil preservation for developing analysis techniques.
The fossil record gives access to raw rates of development, unique events, and long intervals, spatial dynamics, and morphological transitions in form.
Extinction in the fossil record is a problem.…
jrosenhouse | October 30, 2009I had intended to leave this subject behind, at least for a while, but Josh Rosenau has a lengthy post up that I think merits a reply. See also this post and the ensuing comments.
On several occasions at this blog (here and here for example) I have endorsed the efforts of the NCSE and other science advocacy groups to reach out to religious groups. I think it is great that NCSE has a permanent employee devoted to such outreach. Religious supporters of evolution have been essential in every major victory, both legal and political, our side can claim. If we can open people's eyes to the…
pharyngula | October 30, 2009A phylogeny is a statement about the evolutionary history of organisms. Cladograms give branching order only, but phylograms include branch lengths as well. They inform us about diversification of lineages, patterns and rates of trait evolution, and the ages of taxa and timing of radiations.
The tree is a model for the history of life at the macroevolutionary level. Darwin fully embraced the idea.Trees now being built with DNA sequence data, using improved phylogenetic algorithms and increased computational power. We now have many well-supported phylogenies backed up by multiple lines of…
pharyngula | October 30, 2009Lander began by saying he wasn't an evolutionist — an interestingly narrow definition of the term. He's a fan of the research, but considers himself a biomedical geneticist, as if that was something different.
Having entire genomes of many species available for quantitative analysis is going to lead to a qualitative change in the science we can do.
He gave a pocket summary of the human genome project. Mouse genome followed, then rat and dog, and now have sequence (to varying degrees of completeness) of 44 species, out of 4600 mammals. Within Homo, there's the hapmap project and the 1000…
pharyngula | October 30, 2009Earlier today, Jerry mentioned to me that he noticed my earlier blog posts on the meeting, and thought I wasn't being critical enough. So I think that means I'm supposed to let my inner beast out for this one. (Nah, actually, it's because I'm in note-taking transcription mode while listening to these talks. I have to digest them for a bit before I can do any synthesis.)
What is the biogeography of speciation? Can one species split into two while splitting into two? Allopatric speciation: no gene exchange; Parapatric: limited exchange; Sympatric: free gene exchange. Allopatric is sort of the…
laelaps | October 30, 2009
Whenever I sit down to write an entry for this blog I remind myself that I might not always speak the same language as the people I am trying to reach. A statement that might be technically accurate, such as "Mammuthus primigenius was a Late Pleistocene proboscidean with a Holarctic distribution", will likely cause nonspecialist readers to go cross-eyed and vow never to visit this blog again. Instead I have to remember what it was like when I began to teach myself about paleontology and evolution. What do those words mean? And how can I quickly and accurately define them without sacrificing…
pharyngula | October 30, 2009How do we distinguish bacterial species? Cohan shows us some nice diagrams of phenotypic and molecular clusters, and they show groups separated by gaps — therefore, species. Unfortunately the species defined thereby are big and contain considerable diversity within them. Darwin defined species as divergent forms between which one finds morphological gaps. Mayr: cohesive set of organisms whose divergence is constrained by genetic exchange. Speciation requires a breakdown of that exchange.
Mallet has developed a version of Darwin's species definition that includes molecular characters. Under…
pharyngula | October 30, 2009Oops, missed the first part of this talk due to the distractions of Lunch. Walked in as he was talking about tree vs. ladder thinking (people have a hard time conceptualizing trees) and history as a chronicle — barebones description of events — or a narrative — events linked by causal explanations.
It took a century for biologists to use systematics to make testable hypotheses about evolution. Darwin himself talked at length about all kinds of evidence for evolution, but strangely neglected fossils and dinosaurs altogether. Sereno blames this on rivalry with Richard Owen, who was the big…
pharyngula | October 30, 2009How do different varieties become species? Darwin credited selection. What are the details of this process? Speciation is a booming topic in the science literature, with 25,000 titles last year. Need to define a species to begin. Uses Mayr's biological species concept, which focuses on the importance of reproductive isolating factors.
Darwin on speciation: recommends Stauffer's compilation of Darwin's notes as much more thorough and specific than the Origin. Darwin explained speciation as a consequence of selection, divergence, and extinction. Mayr thought Darwin considered geographic…
pharyngula | October 30, 2009How do we explain the diversity of species in the world? The core process is speciation, a splitting of a lineage into two divergent lines that at the end, cannot interbreed. What do we know about speciation in Darwin's finches?
They evolved from a common ancestor in 2-3 million years into 14 different species, filling different ecological niches in the Galapagos, largely free of human interference. Showed us photos of four different species with very different beaks.
Developed predictions of population density from things like available biomass, and worked out relationship of expected…
pharyngula | October 30, 2009I have wireless access in the lecture hall today, so I'm going to try liveblogging these talks. This may get choppy! What it will lack in editing will be compensated for by more timely and regular updates. I hope. At least I'll be able to dump something to the site every 40-60 minutes.
He summarizes the idea that there is a wealth of genetic diversity in populations to allow for effective selection. Lack of mutations should not limit a straightforward selection response. This raises a paradox, however: organisms have phylogenetic niche conservatism. Many species are evolutionarily…
edyong | October 30, 2009Tiger snakes are a group of extremely venomous serpents found all over the southern half of Australia, and on many of its islands. Some were cut off from the mainland by rising sea levels more than 9,000 years ago, while others were inadvertently introduced by travelling humans and have been around for less than 30 years.
When the snakes first arrive on an island, they find prey that are generally larger than they're used to on the mainland. That puts them under strong evolutionary pressure to have larger heads, in order to swallow larger meals. But by feeding snakes from different…
pharyngula | October 29, 2009It was a fine evening here in Chicago, with all these superstars of evolutionary biology in attendance. It was also an information-dense evening — I tried to keep up on my little laptop, but I know I missed a lot. Fortunately, I'm not alone: Rob Mitchum and Jeremy Manier were also covering the event, and have a play-by-play available. I'll just dump what I've got here tonight. I do have wi-fi passwords so I can get things up a little more promptly tomorrow and Saturday.
Richard Lewontin opened up with a few deprecatory comments about the religiosity of our surroundings (the talks were given…
jrosenhouse | October 29, 2009What with all the general business and the ample supply of recent blog fodder, I seem to have gotten away from my Blogging Dawkins project. That state of affairs ends now.
In Chapter Two Dawkins laid out the case that artificial selection can and has caused enormous changes in the physical features of organisms in a relatively short amount of time. In terms of the broader case for evolution, this can be viewed as a plausibility argument. If random variations sifted through selection can craft both chihuahuas and Great Danes from a common wolf-like ancestor in a relatively short amount of…
razib | October 29, 2009Carl Zimmer points me an article about a former anthropologist who has some weird ideas about the origin of man:
Since his resignation from the university in 1990, however, Horn has changed his tune. Once a staunch Darwinist and tenured CSU anthropology professor, Horn has devoted the last 19 years of his life to the study of alternative theories of human origin.
After receiving a doctorate in anthropology from Yale University and while teaching at CSU, Horn focused his energies on the study of the evolution of non-human primates, his wife Lynette Horn said.
He now advocates the theory that…
edyong | October 29, 2009The Northern short-tailed shrew is a small, energetic mammal that lives in central and eastern North America. The Mexican beaded lizard is a much larger reptile found in Mexico and Guatemala. These species are separated by a lot of a land and several million years of evolution, yet they share astonishing similarities. Not only are they both venomous, but the toxic proteins in their saliva have evolved in very similar ways from a common ancestor, converging on parallel lethal structures independently of one other.
This discovery, from Yael Aminetzach at Harvard University, shows that…