Using Phylogenetics to trace morphological evolution
Using Phylogenetics to trace morphological evolution.
Phylogenetics in the NY Times
The NY Times has a nice article on phylogenetic tree visualisation. Yes, really:
For years now the researchers have sequenced DNA from thousands of species from jungles, tundras and museum drawers. They have used supercomputers to crunch the genetic data and have gleaned clues to how today’s diversity of baobobs, dandelions, mosses and other plants evolved over the past 450 million years. The pace of their progress gives Dr. Sanderson hope that they will draw the entire evolutionary tree of plants within the next few years. “It’s within striking distance,” Dr. Sanderson said.
There’s just one problem. “We have no way to visualize such a tree at the moment,” he said. If they tried, they would end up with a blurry, inscrutable thicket. “It would be ironic,” Dr. Sanderson said. “We’d be saying, ‘We’ve built it, but we can’t show it to you.’
Systematic Biology T-Shirts
Everyone's favorite systematics journal Systematic Biology have produced a collection of T-Shirts that you can buy online (like the awesome one above). This is a fundraising project, and 100% of the profits will go to helping graduate students in the field of systematic biology (like me!).
There are others there that aren't official SB-products, but are still tempting...
Dinosaurs, Supertrees, and the Cretaceous Terrestrial Revolution
Today's PRS.B sees the publication of a supertree of 600 Dinosaur species. Awesome. ScienceDaily has more information here. Here's a picture of it (note: a full version is available here):
The abstract says:
The observed diversity of dinosaurs reached its highest peak during the mid- and Late Cretaceous, the 50Myr that preceded their extinction, and yet this explosion of dinosaur diversity may be explained largely by sampling bias. It has long been debated whether dinosaurs were part of the Cretaceous Terrestrial Revolution (KTR), from 125–80Myr ago, when flowering plants, herbivorous and social insects, squamates, birds and mammals all underwent a rapid expansion.
Although an apparent explosion of dinosaur diversity occurred in the mid-Cretaceous, coinciding with the emergence of new groups (e.g. neoceratopsians, ankylosaurid ankylosaurs, hadrosaurids and pachycephalosaurs), results from the first quantitative study of diversification applied to a new supertree of dinosaurs show that this apparent burst in dinosaurian diversity in the last 18 Myr of the Cretaceous is a sampling artefact. Indeed, major diversification shifts occurred largely in the first one-third of the group's history.
Despite the appearance of new clades of medium to large herbivores and carnivores later in dinosaur history, these new originations do not correspond to significant diversification shifts. Instead, the overall geometry of the Cretaceous part of the dinosaur tree does not depart from the null hypothesis of an equal rates model of lineage branching. Furthermore, we conclude that dinosaurs did not experience a progressive decline at the end of the Cretaceous, nor was their evolution driven directly by the KTR
A Look at Linguistic Evolution
In today's, Evolution: Education and Outreach, Anastasia Thanukos takes A Look at Linguistic Evolution:
Anyone who has ever tackled a Shakespeare play knows that English has changed substantially in the 400 years since Elizabeth I ruled England. In fact, Elizabethan English can seem like a completely different language from the one we speak today. Just try describing your mood with the Shakespearean terms allicholly and tetchy—you are more likely to get confused looks than sympathy for being unhappy and irritable. Four hundred years from now, English speakers will likely feel the same way about the language we speak today. Unless you are keeping up with the latest additions to the Oxford English Dictionary, you might already be behind the times: Do you know if you would be eligible to participate in a girlcott? Or whether you would want a job as a helmer? Or when it would be appropriate to wear a jandal?
The full-text is available at the EEO website here.
A Phylogenomic Study of Birds Reveals Their Evolutionary History
Today's Science sees the publication of a phylogenomic study of 196 bird species, which has some rather marked differences to the traditional phylogenies of bird species. Abstract says -
Deep avian evolutionary relationships have been difficult to resolve as a result of a putative explosive radiation. Our study examined ~32 kilobases of aligned nuclear DNA sequences from 19 independent loci for 169 species, representing all major extant groups, and recovered a robust phylogeny from a genome-wide signal supported by multiple analytical methods. We documented well-supported, previously unrecognized interordinal relationships (such as a sister relationship between passerines and parrots) and corroborated previously contentious groupings (such as flamingos and grebes). Our conclusions challenge current classifications and alter our understanding of trait evolution; for example, some diurnal birds evolved from nocturnal ancestors.
Abstract is here. Much news coverage will be forthcoming, I suspect, and I'll link to some of these as they come through.
Update: GrrlScientist has covers the paper excellently (although, not enough phylogenetic details for my liking :)
Stephen Shennan on Evolution in Archaeology
Stephen Shennan in the 2008 Annual Review of Anthropology (doi):
The term evolution in archaeology has accumulated an enormous range of meanings, with different implications, over many years. Traditionally, however, when not referring to the biological evolution of putatively ancestral species, it has occurred most commonly in the phrase cultural evolution (sometimes used interchangeably with social or sociocultural evo- lution), referring to the history of what are conceived as the key long-term trends in human history: from foraging to farming, or from farming to the origins of civilization and the state, accompanied by such developments as increased population, greater social complexity and inequality, and more complex technologies.
More recently, the term has increasingly come to refer to the idea that the processes producing cultural stability and change are analogous in important respects to those of biological evolution: On this view, just as biological evolution is characterized by changing frequencies of genes in populations through time as a result of such processes as natural selection, so cultural evolution refers to the changing distributions of cultural attributes in populations, likewise affected by processes such as natural selection but also by others that have no analog in genetic evolution. In fact, to understand changing patterns of human behavior and organization we need to take account of both the biological and the cultural dimensions.