Archive for the 'Journal Club' category
tags: evolution, evolutionary biology, UV light, flight, dinosaur, dromaeosaur, theropods, Microraptor gui, paleontology, fossils, birds, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper, journal club
Figure 1. The holotype of Microraptor gui, IVPP V 13352 under normal light. This shows the preserved feathers (white arrow) and the 'halo' around the specimen where they appear to be absent (black arrows). Scale bar at 5 cm. [larger view]
It has long been known that when exposed to ultraviolent light, fossilized bones and shells -- and even tissues -- will fluoresce, thus rendering undetectable details visible. But this technique has been used mostly to visualize fossilized invertebrates, and inexplicably, has rarely been used to investigate hidden structures in most vertebrate fossils. But a team of paleontologists recently studied the Microraptor gui holotype using UV light.
tags: evolution, evolutionary biology, behavioral ecology, animal behavior, molecular ecology, parental care, mating systems, monogamy, sexual selection, frogs, poison dart frogs, Dendrobatidae, Ranitomeya, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper, journal club
Genetic tests have revealed the secret sex life of a tiny poison dart frog species that lives in the Peruvian rain forests: remarkably, it turns out that these frogs are monogamous. But the reason this species is monogamous is surprising: it's all about the size of the pools that their tadpoles mature in. This is the best evidence yet that just a single cause can affect evolution of a major life history trait, such as a species' mating system.
tags: evolution, evolutionary biology, gynandromorph, bilateral gynandromorph bird, half-sider, mixed-sex chimaera, sex determination, molecular biology, genetics, developmental biology, endocrinology, birds, chicken, Gallus gallus, ornithology, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper, journal club
Almost exactly one year ago, hundreds of American birders
were thrilled by sightings and photographs of this remarkable
Northern Cardinal, or Redbird, Cardinalis cardinalis,
photographed in Warrenton, VA.
Image: DW Maiden, 2 March 2009.
I'll never forget the first time I saw a bilateral gynandromorph. I was a bird-crazy teenager reading my way through a stack of avicultural publications when I spied the strangest bird I'd ever seen on the cover of one magazine: an eclectus parrot that was very precisely divided down the middle: one side was rich scarlet and the other was brilliant emerald. Because eclectus parrots are sexually dimorphic -- females are red and males are green -- this remarkable bird was easily identifiable as being composed of both sexes, one on each side.
Even though this was the first time I'd ever seen a gynandromorph, these mysterious birds do pop up from time to time. For example, bird watchers occasionally run across them in the wild (see above photograph) and poultry farmers sometimes find them in their flocks: it is estimated that roughly one in 10,000 domestic chickens -- another sexually dimorphic species -- is a gynandromorph.
tags: evolution, evolutionary biology, ancient DNA, aDNA, molecular biology, molecular ecology, archaeology, paleontology, fossil eggshell, extinct birds, giant moa, Dinornis robustus, elephant birds, Aepyornis maximus, Mullerornis, Thunderbirds, Genyornis, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper, journal club
Elephant bird, Aepyornis maximus, egg
compared to a human hand with a hummingbird egg balanced on a fingertip.
To conduct my avian research, I've isolated and sequenced DNA from a variety of specimens, such as blood, muscle, skin and a variety of internal organs, dry toepads from long-dead birds in museum collections, feathers, the delicate membranes that line the inside of eggs, and even occasionally from bone. But I was surprised to learn that avian DNA can also be extracted directly from fossilized eggshells -- eggshells that completely lack eggshell membranes.
tags: evolutionary biology, molecular biology, Thoroughbred race horses, horses, aerobic capacity, muscle development, myostatin, MSTN, myostatin-suppressing C variant, myostatin-suppressing T variant, Horse Genome Project, Equinome, bpr3.org/?p=52, peer-reviewed research, peer-reviewed paper
Emerging from the mist is Rachel Alexandra, a champion American Thoroughbred who excels at winning both long and short distance races.
Image: Rob Carr, 2009, Associated Press [larger view]
If you've worked at or been around a racetrack very much, as I have, you'll quickly realize that everyone there has their own pet idea for picking winners. Horse breeders rely on pedigree analysis and studying the horse's conformation to predict whether a particular racehorse is better suited for running short or longer distances. But this is an art that requires both practice and experience and it can waste valuable time, money and sometimes, horses. Which makes one wonder whether modern science can be applied to the challenge of identifying specific genes that make a particular horse better suited to running sprints or distances?
tags: evolutionary biology, paleontology, taphonomy, plumage color, feathers, color, melanin, eumelanin, phaeomelanin, dinosaurs, theropod, paravian, avialae, fossils, Anchiornis huxleyi, ornithology, birds, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper
New research reveals that recently-described 155-million-year-old
Anchiornis huxleyi, a woodpecker-like dinosaur the size of
a modern-day domesticated chicken, had black-and-white spangled wings and a rusty red crown.
Fig. 4. Reconstruction of the plumage color of the Jurassic troodontid Anchiornis huxleyi. The tail is unknown specimen BMNHC PH828, and reconstructed based on the complete specimen previously described. Color plate by Michael A. Digiorgio.
Ever since dinosaurs were discovered, scientists, artists and children everywhere have speculated about what they really looked like. Fossilized bones, skin impressions and recently, feathers, provide a general mental image of these animals' appearances, but these materials also leave important questions unanswered, basic questions such as what color were dinosaurs?
tags: evolutionary biology, paleontology, fossils, fossilization, fossil forensics, Taphonomy, taxonomy, zoology, deep time, paleoceanography, amphioxus, Branchiostoma lanceolatum, lamprey, Lampetra fluviatilis, chordates, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper
Three rotting Amphioxus heads.
A sequence of images showing how the characteristic features of the body of amphioxus, a close living relative of vertebrates, change during decay. Colours are caused by interference between the experimental equipment and the light illuminating the specimens.
How do you know what something looks like when you've never seen it before? This is the question that paleontologists deal with every day: describing the appearance of ancient animals based on incomplete information gathered from small fossilized fragments of those animals. As if that is not difficult enough, they also use this incomplete information about physical appearances to build family trees that describe the evolution of these animals.
tags: evolutionary biology, convergent evolution, paleontology, taxonomy, zoology, basal birds, theropods, dinosaurs, ornithology, birds, Alvarezsauroidea, Haplocheirus sollers, Maniraptora, Archaeopteryx, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper
A Newly Discovered Basal Alvarezsauroid Theropod from the Early Late Jurassic.
Artwork: Portia Sloan [larger view]
A long-standing scientific debate focuses on the origins of birds: did they evolve from reptiles or dinosaurs? Currently, most scientists think that birds are modern dinosaurs, but because small hollow bones like those of birds and small dinosaurs don't fossilize well, the early fossil record for birds is sparse. However, a new dinosaur species unearthed in China's Gobi Desert strengthens the dinosaur-bird hypothesis and may also provide valuable clues as to how flight evolved.
tags: evolutionary biology, fossils, feathers, plumage color, color, dinosaurs, theropods, Sinosauropteryx, Sinornithosaurus, birds, Confuciusornis, melanosomes, phaeomelanosomes, eumelanosomes, keratinocytes, SEM, scanning electron microscopy, 10.1038/nature08740, bpr3.org/?p=52, peer-reviewed research, peer-reviewed paper
Reconstruction of two Sinosauropteryx, sporting their orange and white striped tails.
Artwork by Chuang Zhao and Lida Xing [larger view]
While looking at museum dioramas that feature dinosaurs, I often overhear people asking "How do they know what color dinosaurs were?" The truth is that artists and scientists didn't know -- until now. A new paper was just published in Nature that carefully examines fossilized plumage and comes to an interesting conclusion: scientists can identify at least some of the original colors in ancient feathers.