Evolutionary Biology
grrlscientist | March 10, 2010tags: 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, researchblogging.org,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…
razib | March 1, 2010A few days ago I pointed to a paper which suggests the possible utility of looking at selection on standing genetic variation on quantitative traits to get a sense of the role of adaptation in the human genome. We humans like to think we're a complex species, so I see no a priori reason why our evolutionary history should be easily reducible to spare compact dynamics. Granted, we can start with the assumption that on the order of 50,000 years before the present there was a rapid demographic expansion of anatomically modern humans out of the continent of Africa. This story is simple, and is…
grrlscientist | February 8, 2010tags: 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, researchblogging.org, 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…
grrlscientist | February 5, 2010tags: evolutionary biology, paleontology, taphonomy, plumage color, feathers, color, melanin, eumelanin, phaeomelanin, dinosaurs, theropod, paravian, avialae, fossils, Anchiornis huxleyi, ornithology, birds, researchblogging.org,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.
Image: Michael DiGiorgio, Yale University [larger view]
Fig. 4. Reconstruction of the plumage color of…
grrlscientist | February 1, 2010tags: evolutionary biology, paleontology, fossils, fossilization, fossil forensics, Taphonomy, taxonomy, zoology, deep time, paleoceanography, amphioxus, Branchiostoma lanceolatum, lamprey, Lampetra fluviatilis, chordates, researchblogging.org,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.
Image: Mark…
grrlscientist | January 30, 2010tags: evolutionary biology, convergent evolution, paleontology, taxonomy, zoology, basal birds, theropods, dinosaurs, ornithology, birds, Alvarezsauroidea, Haplocheirus sollers, Maniraptora, Archaeopteryx, researchblogging.org,peer-reviewed research, peer-reviewed paper
A Newly Discovered Basal Alvarezsauroid Theropod from the Early Late Jurassic.
Artwork: Portia Sloan [larger view]
DOI: 10.1126/science.1182143
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…
grrlscientist | January 28, 2010tags: evolutionary biology, fossils, feathers, plumage color, color, dinosaurs, theropods, Sinosauropteryx, Sinornithosaurus, birds, Confuciusornis, melanosomes, phaeomelanosomes, eumelanosomes, keratinocytes, SEM, scanning electron microscopy, 10.1038/nature08740, researchblogging.org, 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]
DOI: 10.1038/nature08740
While looking at museum dioramas that feature dinosaurs, I often overhear people asking "How do they…
grrlscientist | January 26, 2010tags: evolutionary biology, behavioral ecology, biochemistry, biophysics, magnetoreception, photoreceptor, cryptochromes, geomagnetic fields, butterflies, Monarch Butterfly, Danaus plexippus, birds, migration, signal transduction, researchblogging.org,peer-reviewed research, peer-reviewed paper
Every autumn, millions of monarch butterflies, Danaus plexippus, each weighing less than one gram (one US penny weighs 2.5 grams), migrate nearly 4000 kilometers (3000 miles) between their summer breeding grounds in the United States and their wintering areas either in southern California or in the…
grrlscientist | January 22, 2010tags: evolution, evolutionary biology, evolutionary ecology, plumage color,carotenoid-based colour, carotenoids, lipid peroxidation, oxidative stress, sperm motility, sperm quality, sperm velocity, birds, ornithology, Great Tit, Parus major, researchblogging.org,peer-reviewed research, peer-reviewed paper
Great Tit, Parus major.
Image: Luc Viatour, Creative Commons/Wikipedia [larger view]
In some species of birds, males are more brightly colored than females. This phenomenon is due to female choice: females choose to mate with males that have the brightest plumage colors and most elaborate…
grrlscientist | January 15, 2010tags: evolutionary biology, behavioral ecology, life history, migration, long-distance migration,birds,ornithology,researchblogging.org,peer-reviewed research, peer-reviewed paper
White-rumped sandpiper, Calidris fuscicollis, chicks on Bylot Island, Nunavut, Canada.
Image: Laura McKinnon [larger view]
I recently told you about research that used new microtechnology to document the incredible journey of Arctic Terns, a small bird species that annually migrates from its wintering area in Antarctica to its breeding colonies in Arctic and sub-Arctic regions of Europe, Asia, and North America…
grrlscientist | January 13, 2010tags: evolutionary biology, behavioral ecology, migration, microtechnology, geolocator, natural history, biological hotspots, longest migration, seabirds, Arctic Tern, Sterna paradisaea, researchblogging.org,peer-reviewed research, peer-reviewed paper
Arctic Tern, Sterna paradisaea, Iceland.
Image: Arthur Morris, Birds as Art, 2007 [larger view].
Canon 400mm f/5.6L lens (handheld) with the EOS-1D Mark III. ISO 200. Evaluative metering +1/3 stop: 1/1000 sec. at f/5.6 in Manual mode. Manual Flash with Better Beamer at 1:1.
For decades, it was widely suspected that a small seabird, the…
grrlscientist | January 7, 2010tags: evolutionary biology, immunology, immune response, antibodies, parasite, avian pox virus, Poxvirus avium, nest fly, Philornis downsi, birds, ornithology, Darwin's Finches, Medium Ground Finch, Geospiza fortis, Ecuador, Galapagos Islands, researchblogging.org,peer-reviewed research, peer-reviewed paper
A male Medium Ground Finch, Geospiza fortis, sits on a tree branch in Ecuador's Galapagos Islands.
Image: Jen Koop.
People often view the Hawaiian islands as a tropical paradise, the ideal vacation site, but you wouldn't agree with this assessment if you happen to be a bird. According…
gregladen | December 16, 2009It turns out I write academia erotica!
I can tell you that the three dimensional visual imagery in the post to which Stephanie refers was a replacement for the actual visual imagery I had in mind when I wrote it. But I couldn't use that because ...
... because it was too narrowly defined, topically, focusing on protein function in the intracellular environment. But I can tell you how that image would look.
In the ultra tiny world of proteins, inside cells, there is little difference between form and function. Form is function. Its like putting a hammer and a pile of nails in your…
razib | November 10, 2009In the comments below I referred to the "Price Equation." Here is what William D. Hamilton had to say about George Price's formalism in Narrow Roads of Gene Land:
A manuscript did eventually come from him but what I found set out was not any sort of new derivation or correction of my 'kin selection' but rather a strange new formalism that was applicable to every kind of natural selection. Central to Price's approach was a covariance formula the like of which I had never seen...Price had not like the rest of us looked up the work of the pioneers when he first became interested in selection;…
gregladen | October 26, 2009Do Individual Females Differ Intrinsically in Their Propensity to Engage in Extra-Pair Copulations?
A repost
Now, this is truly important applied science, in PLoS.
While many studies have investigated the occurrence of extra-pair paternity in wild populations of birds, we still know surprisingly little about whether individual females differ intrinsically in their principal readiness to copulate, and to what extent this readiness is affected by male attractiveness.
Oh, it’s about birds … well, it’s still interesting.
For decades, and even to this day, much of the discussion of behavioral…
gregladen | October 14, 2009Research on giant sea scorpions (eurypterids) - the largest bugs that ever lived - has shed new light on why eurypterids became so large and eventually died out.
In the 1930s, Romer argued that eurypterids became larger and larger over time because they were in a kind of arms race with giant fish called placoderms. Presumably the larger would be the predator of the smaller, so the smaller grows. Others have suggested that a greater abundance of oxygen in an ancient atmosphere (and thus sea) just made things big. New research seems to indicate that both ideas are still valid.
There are…
gregladen | September 2, 2009Today's falsehood is the idea that individual animals act for the benefit of their own species.
Let me give you an example. When I was a kid, I watched a nature show about cougars. The show 'documented' a single female cougar going about doing cougar-things and being generally cougar-like. At one point she had cute little baby cougar kittens.
Then a flood came. The stream near her chosen lair swelled its banks and threatened to drown the kittens. So, she carried one of the kittens up the hill to a new lair. She went back to get the second kitten, and the flood waters were even higher…
gregladen | August 24, 2009Another look at falsehoods about evolution.
We previously addressed the falsehood "Evolution has stopped for humans" and concluded that background change in allele frequency independent of natural selection does not just stop for any viable, continuing population. So, no, saying that "evolution has stopped for humans" is tantamount to saying that "gravity has stopped for my coffee cup" (which is sitting here on my desk minding its own business).
But this question is a falsehood at another level. In reality, there are two additional questions that are actually being asked when this…
gregladen | August 21, 2009In my initial list of Falsehoods, I included these two closely related items:
Evolution has stopped for humans; and
Serious scientists often entertain the question: "Has evolution stopped for humans?"
I'll make the distinction between them clear eventually. For now, let's focus on the first: Has evolution stopped for humans or not?
The reason we bring up these falsehoods to begin with is because examining them exposes assumptions or requires the investigation of knowledge that is worth talking about. In this case, the deeper question is this: What is evolution exactly? So, this is a…
gregladen | August 17, 2009Biology is harder to learn than quantum physics. Why? Because most people think they totally get biology, but everyone knows nobody gets quantum physics. Therefore, any effort to explore quantum physics will result in new learning, but people rarely learn new biology. The bottom line is that our brains are full of biology, which would be good if most of it did not consist of falsehoods.
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The things that people know already often need to be removed from the brain prior to teaching new stuff. This may seem a little offensive to some, but really, it is easier to just admit it. I'm not…