ulaulaman:

The forest from the past.
In the image there is the reconstruction of a 300-million-year old forest discovered by a team of archeologists in Mongolia, China.
The research was published on PNAS with a open access article, Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia by Jun Wang, Hermann W. Pfefferkornb, Yi Zhang, Zhuo Feng

Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m² of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.

In official press releasePfefferkornb says:

It’s marvelously preserved. We can stand there and find a branch with the leaves attached, and then we find the next branch and the next branch and the next branch. And then we find the stump from the same tree. That’s really exciting.

And about the likenesses with Pompei:

It’s like Pompeii: Pompeii gives us deep insight into Roman culture, but it doesn’t say anything about Roman history in and of itself. But on the other hand, it elucidates the time before and the time after. This finding is similar. It’s a time capsule and therefore it allows us now to interpret what happened before or after much better.

You can see the images of the findings on gizmodo.

(via scientificillustration)

scipsy:

15 Evolutionary Gems: A resource from Nature for those wishing to spread awareness of evidence for evolution by natural selection.

rhamphotheca:

GETTING A LEG UP ON WHALE AND DOLPHIN EVOLUTION

NEW ANALYSIS SHEDS LIGHT ON ORIGIN OF CETACEANS

via AMNH (2009)

When the ancestors of living cetaceans—whales, dolphins and porpoises—first dipped their toes into water, a series of evolutionary changes were sparked that ultimately nestled these swimming mammals into the larger hoofed animal group. But what happened first, a change from a plant-based diet to a carnivorous diet, or the loss of their ability to walk?

A new paper published this week in PLoS One resolves this debate using a massive data set of the morphology, behavior, and genetics of living and fossil relatives. Cetacean ancestors probably moved into water before changing their diet (and their teeth) to include carnivory; Indohyus, a 48-million year-old semi-aquatic herbivore, and hippos fall closest to cetaceans when the evolutionary relationships of the larger group are reconstructed.

“If you only had living taxa to figure out relationships within this group of animals, you would miss a large amount of diversity and part of the picture of what is going on,” says Michelle Spaulding, lead author of the study and a graduate student affiliated with the American Museum of Natural History. “Indohyus is interesting because this fossil combines an herbivore’s dentition with adaptations such as ear bones that are adapted for hearing under water and are traditionally associated with whales only.”

The origin of whales, dolphins, and porpoises—with their highly modified legs and lack of hair—has long been a quandary for mammalogists. About 60 years ago, researchers first suggested that cetaceans were related to plant-eating ungulates, specifically to even-toed, artiodactyl mammals like sheep, antelope and pigs. In other words, carnivorous killer whales and fish-eating dolphins were argued to fit close to the herbivorous hoofed animal group. More recent genetic research found that among artiodactyls, hippos are the cetaceans’ closest living relatives…

(read more: American Mus. of Nat. Hist.)   (image: Carl Buell)

(via scientificillustration)

Meet some new friends!

rhamphotheca:

Spider Eye Arrangement By Family

1. Family Lycosidae – the Wolf Spiders
2. Family Salticidae – the Jumping Spiders
3. Family Salticidae, genus Lyssomanes – the Magnolia Green Jumpers
4. Family Araneidae – the Orbweavers
5. Family Pisauridae, genus Dolomedes – the Fishing Spiders
6. Family Pisauridae, genus Pisaurina – the Nursery Web Spiders
7. Family Ctenidae – the Wandering Spiders
8. Family Oxyopidae – the Lynx Spiders
9. Family Philodromidae – the Running Crab Spiders
10. Family Dysderidae – the Woodlouse Hunters
11. Family Tetragnathidae, genus Tetragnatha – the Longjawed Orbweavers
12. Family Thomisidae, genus Xysticus – the Ground Crab Spiders
13. Family Agelenidae, genus Tegenaria – the Funnel Weavers
14. Family Agelenidae, genus Agelenopsis – the Grass Spiders (aka Funnel Weavers)
15. Family Selenopidae, genus Selenops – the Flatties (aka Crab Spiders)
16. Family Sparassidae, genus Heteropoda – the Huntsman (aka Giant Crab Spiders)
17. Family Sparassidae, genus Olios – Giant Crab Spiders (aka Huntsman)
18. Family Sicariidae, genus Loxosceles – the Brown Spiders (includes the Brown Recluse)
19. Family Uloboridae, genus Hyptiotes – the Triangle Weavers
20. Family Zoropsidae, species Zoropsis spinimana – the False Wolf Spider
21. Family Deinopidae, species Deinopis spinosa – the Net-casting Spider (aka Ogre-faced Spider); note that the four other eyes are not visible from the front.
22. Family Diguetidae, genus Diguetia – the Desertshrub Spiders
23. Family Antrodiaetidae, genus Antrodiaetus – the Folding-door Spiders (aka Turret Spiders); these are primitive spiders (mygalomorphs).
24. Family Segestriidae – the Tube Web Spiders
25. Family Scytotidae – the Spitting Spiders

(via: Spiders.us)

(via scientificillustration)

UW Madison Darwin Day 2012 promotional materials.

Owen’s archetypal vertebra. Apparently adapted from one in “Von den Ur-Theilen des Knochen- und Schalen- gerustes” by Carus (1828). From “Richard Owen and the concept of homology,” by Alec Panchen.

UW Madison Evolution Seminar Series, Spring 2012

Magdalena Vaio’s recent poster on the phylogenetic relationships and cytogenetic characteristics of the creeping Oxalis, sections Ripariae and Corniculatae. She has discovered that these species split into two main clades, one with a base chromosome number (x) of 6, and the other with 5 (fig. 2), apparently derived from the ancestral condition of 6 and of much larger size (fig. 1).

UW Madison Evolution Seminar Series, Fall 2011

The anole ecomorphs, habitat specialists behaviorally and morphologically adapted to use different parts of the environment. The same set of ecomorphs (with several exceptions) have evolved independently on each island in the Greater Antilles. Figure from “Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles.”.

Lizard Genome Promises Great Advances in Understanding Evolution Posted by Jonathan Losos of National Geographic Committee for Research and Exploration August 31, 2011

The genome of Anolis carolinensis has just been published in the journal Nature, and most attention is focusing on how this genome, the first reptile to be sequenced (not including birds), differs from other vertebrate genomes, and what these differences may tell us about genome evolution. No doubt this is interesting, but the real value of this genome–in my unbiased opinion–resides in the questions we finally will be able to address about the evolutionary process, particularly in one model system of evolutionary study, Anolis lizards. Chris Schneider published a perceptive article, “Exploiting genomic resources in studies of speciation and adaptive radiation of lizards in the genus Anolis,” on this topic three years ago, and I will briefly expand on his points here (for more information on anole biodiversity and evolution, go to Anole Annals).

An anole genome will be useful for evolutionary studies in two ways. First, a long-standing question in evolutionary biology concerns the genetic basis of convergent evolution (i.e., when two or more evolutionary lineages independently evolve similar features). Do convergent phenotypes arise by convergent evolution of the same genetic changes, or do different lineages utilize different mutations to produce the same phenotype? In other words, does convergence at the phenotypic level result from convergent change at the genetic level, or can different genetic changes produce the same phenotypic response? In the last few years, molecular evolutionary biologists have produced a wealth of studies investigating whether convergent changes in coat color in rodents, eye and spine loss in fish, bristle loss in fruit flies and many other changes are the result of changes in the same gene, even some times by the very same genetic mutation. Underlying these questions are more fundamental questions about constraints and the predictability of evolution.

Anolis lizards are, of course, the poster child for evolutionary studies of convergent evolution. Indeed, convergence has run rampant in this clade.  Anoles are famous for the evolution of “ecomorphs,” sets of habitat specialist types that have evolved repeatedly on each island in the Greater Antilles to occupy different habitat niches. This convergence is usually studied in terms of limb length, tail length, and toepad dimensions: arboreal species have big toepads, twig species short legs, grass species long tails, and so on, with these traits independently evolving many times. But the ecomorphs are convergent in many other traits that have received less attention: head and pelvis dimensions, sexual dimorphism in both size and shape, territorial and foraging behavior, to name a few, and the more closely we look, the more convergent traits we find. And, further, anole convergence is not entirely an ecomorph phenomenon; some traits vary within an ecomorph class, but are convergent among species in different ecomorph classes, for example, thermal physiology and dewlap color.

In other words, there’s more convergence in Anolis than you can shake a stick at, and the availability of the anole genome sequence will provide the tools to investigate its underlying genetic basis. Anolis is already a textbook example of replicated adaptive radiation; getting at the genetics of this phenomenon will provide great insight on how adaptive radiation occurs and perhaps will help explain why anoles experience such identical adaptive radiations so readily, whereas most evolutionary lineages do not. In addition, given the well understood ecological and selective context for this convergence, genomic tools may make anoles are an ideal group in which to study the interplay between selection and developmental processes in evolutionary diversification. See Thom Sanger’s recent post on the developmental basis of limb convergence for one potential example.

The anole genome will be useful for evolutionary studies in a second way. In recent years, a number of researchers have used anoles to study the process of natural selection and how it produces adaptation. Such studies have been conducted by comparing populations of the same species that live in different environments, by following populations through time to see how they change, and by measuring the action of natural selection directly by following individuals and seeing how long they live. Some of these studies have even been experimental, altering selective conditions such as the presence of predators and seeing how natural selection changes and how, from one generation to the next, the population evolves.

The anole genome now gives us powerful tools to study natural selection and evolutionary change at the genetic level. For many evolutionists, the holy grail is to identify the actual genes under selection, and watch them change in response to selection. Though still not easy, this now is practical. In addition, the genome will provide a wealth of material for other related purposes, such as establishing maternity and paternity to quantify reproductive success–a key component of evolutionary fitness–and thus determine whether some individuals produce more descendants than others.

One could argue that in terms of breadth and depth of knowledge, Anolis is the best-studied species-rich adaptive radiation. Other radiations are well known in some respects, but for few do we know so much about so many aspects of the ecology, behavior, functional morphology, and physiology for so many species, not to mention having a good understanding of phylogenetic relationships and evolutionary processes. The genetic basis of trait variation has always been the one hole in our knowledge of anole evolutionary biology. The anole genome plugs this hole in a major way, and will make anoles an even more important evolutionary case study, allowing us to learn much not only about evolution in anoles, but the evolutionary process in general.

Bang Goes the Theory: Evolution Made Simple

fybiology:

skepttv:

David Attenborough On Eye Evolution

Creationists maintain that the eye is too complex to have evolved by natural selection, often calling on the “watchmaker” argument. Science can now with confidence demonstrate the opposite.

It is so not a secret that my dream job is to BE David Attenborough. 

-aspiring biologist, aka a.b. (because nerd has a cool nickname and I want one too)

(Source: youtube.com)

Oxalis phylogenies for the BSA meetings in mid July, St. Louis, MO.

Oxalis phylogenies for the BSA meetings in mid July, St. Louis, MO.