evolutionary biology | This Scientific Life

Are Zombie Vultures In Our Future?

Jul 01 2010 Published by grrlscientist under Biology, Conservation, Endangered Species, Environment, Epidemiology, Evolution, Journal Club, Medicine & Health, Ornithology, Zoology

tags: vultures, Gyps species, conservation biology, endangered species, veterinary medicine, toxicology, physiology, evolutionary biology, pharmaceutical chemistry, epidemiology, mathematical modeling, bpr3.org/?p=52,peer-reviewed research, journal club

Only thirty years ago, tens of millions of White-rumped Vultures, Gyps bengalensis,
were flying the skies of Asia. They are now classified as Critically Endangered.
Image: Marek Jobda / rarebirdsyearbook.com [larger view]

A zombie is another name for The Walking Dead -- those who are lifeless, apathetic, or totally lacking in independent judgment. But in an ecological sense, a zombie species no longer fulfills its ecological function because it is becoming extinct. This is a topic that I hope to explore further in another blog entry, but for now, today's zombie theme and vultures' delightful dining habits (they eat zombies) and my zombie icon have inspired me to focus on them.

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Is That A T. rex Up Your Nose? New Species of Nose-dwelling Leech Discovered

Apr 19 2010 Published by grrlscientist under Biology, Invertebrates, Journal Club, Medicine & Health, Zoology

tags: evolutionary biology, evolutionary biogeography, molecular biology, medicine, ectoparasite, orificial hirudiniasis, mucosal leech infestation, hirudinoids, leech, Tyrannobdella rex, public health, zoology, PLoS ONE, anatomy, phylogenetic analysis, taxonomy, bpr3.org/?p=52,peer-reviewed research, journal club

Figure 1. Mucosally invasive hirudinoid leeches. Known from a wide variety of anatomical sites including eyes (A) as in this case involving Dinobdella ferox (B), mucosal leech species, as in a case involving Myxobdella annandalei (C), more frequently feed from the nasopharyngeal surfaces of mammals (D). [larger (and more delightfully repulsive) picture.]
DOI: 10.1371/journal.pone.0010057.

Most people are repulsed by leeches -- those spineless blood sucking animals that are not only ugly, but can, in extreme cases, pose a threat to the host's life. But most people are blissfully unaware that some species of leeches specialize in attacking mammalian mucous membranes -- those hairless, smooth and moist tissues that line the mouth, intestines, eyes and urinary and reproductive tracts (Figure 1).

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What do Great Tits Reveal about the Genetics of Personality?

Apr 08 2010 Published by grrlscientist under Biology, Brain & Behavior, Evolution, Genetics, Journal Club, Mental Health, Molecular Biology, Ornithology

tags: evolutionary biology, behavioral ecology, molecular ecology, personality, novelty seeking, exploratory behavior, dopamine receptor, dopamine receptor D4 gene, DRD4 gene polymorphism, ornithology, birds, Great Tit, Parus major, bpr3.org/?p=52,peer-reviewed research, peer-reviewed paper

Bold or cautious? Individuals with a particular gene variant are very curious --
but only in some populations.
Image: Henk Dikkers.

Research suggests that personality variations are heritable in humans and other animal species, and there are many hypotheses as to why differences in personality exist and are maintained. One approach for investigating the heritability of personality lies in identifying which genes underlie specific personality traits so scientists can then determine how the frequencies of specific variants of personality-related genes change in both space and time as well as in relation to changing environmental influences.

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UV, You See? Black Light Reveals Secrets in Fossils

Mar 30 2010 Published by grrlscientist under Biology, Evolution, Fossils, Journal Club, Paleontology, Zoology

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]
DOI: 10.1371/journal.pone.0009223

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.

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Made for Each Other: Evolution of Monogamy in Poison Frogs

Mar 29 2010 Published by grrlscientist under Amphibians, Biology, Brain & Behavior, Endangered Species, Evolution, Journal Club, Molecular Biology

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

Peruvian mimic poison frog, Ranitomeya imitator.
Image: Jason Brown [larger view]

To know the breeding system is to know the genetic architecture of a species.
To know the evolution of a breeding system is to know how evolution works ..
~ Lewis & Crowe, Evolution (1955)

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.

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Gender-Bending Chickens: Mixed, Not Scrambled

Mar 12 2010 Published by grrlscientist under Avicultural Society of America, Biology, Brain & Behavior, Essays republished in print media, Evolution, Genetics, Journal Club, Molecular Biology, Ornithology, Sexuality

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

Half-sider.
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.

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Ancient DNA from Fossil Eggshells May Provide Clues to Eggstinction of Giant Birds

Mar 10 2010 Published by grrlscientist under Biology, Evolution, Fossils, Genetics, Journal Club, Molecular Biology, Ornithology, Paleontology, Zoology

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.

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Racehorse Research Identifies Speed Gene

Feb 08 2010 Published by grrlscientist under Biology, Brain & Behavior, Genetics, Horses, Journal Club, Molecular Biology

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?

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Fossil Feather Colors Really ARE Written In Stone

Feb 05 2010 Published by grrlscientist under Biology, Evolution, Fossils, Journal Club, Ornithology, Paleontology, Streaming videos

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.

Image: Michael DiGiorgio, Yale University [larger view]

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?

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Fetid Fish Revise Understanding of Fossil Formation

Feb 01 2010 Published by grrlscientist under Evolution, Fossils, Journal Club, Paleontology, Streaming videos, Zoology

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.

Image: Mark Purnell, Rob Sansom, Sarah Gabbott, University of Leicester.
[larger view]
DOI: 10.1038/nature08745

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.

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