Category Archives: News

Stop the Press! – Homaeothermic Marine Reptiles 

All,

Old news, new research, enjoy!

Review:

Ryosuke Motani: Warm-Blooded "Sea Dragons"?
Science 11 June 2010: 1361-1362
http://www.sciencemag.org/cgi/content/full/328/5984/1361

Article:

Aurélien Bernard, Christophe Lécuyer, Peggy Vincent, Romain Amiot,
Nathalie Bardet,Eric Buffetaut, Gilles Cuny, François Fourel,
François Martineau, Jean-Michel Mazin, Abel Prieur: Regulation of
Body Temperature by Some Mesozoic Marine Reptiles
http://www.sciencemag.org/cgi/content/full/328/5984/1379

Abstract: "What the body temperature and thermoregulation processes
of extinct vertebrates were are central questions for understanding
their ecology and evolution. The thermophysiologic status of the great
marine reptiles is still unknown, even though some studies have suggested
that thermoregulation may have contributed to their exceptional
evolutionary success as apex predators of Mesozoic aquatic ecosystems.
We tested the thermal status of ichthyosaurs, plesiosaurs, and mosasaurs
by comparing the oxygen isotope compositions of their tooth phosphate to
those of coexisting fish. Data distribution reveals that these large
marine reptiles were able to maintain a constant and high body
temperature in oceanic environments ranging from tropical to cold
temperate. Their estimated body temperatures, in the range from 35° ± 2°C
to 39° ± 2°C, suggest high metabolic rates required for predation and 
fast swimming over large distances offshore."

--Mikko

Human Ancestor’s Ancient Home Debated

For New debates about Ardipithecus:

http://www.livescience.com/history/ardi-human-ancestor-hominid-debate-100527.html

Comment on the Paleoenvironment of Ardipithecus:
http://www.sciencemag.org/cgi/reprint/328/5982/1105-d.pdf

Response to Comment on the Paleoenvironment of Ardipithecus ramidus:
http://www.sciencemag.org/cgi/reprint/328/5982/1105-e.pdf

Comment on the Paleobiology and Classification of Ardipithecus ramidus:
http://www.sciencemag.org/cgi/reprint/328/5982/1105-b.pdf

Response to Comment on the Paleobiology and Classification of Ardipithecus ramidus:
http://www.sciencemag.org/cgi/reprint/328/5982/1105-c.pdf

Neandertal genome sequenced!

Science 7 May 2010:
Vol. 328. no. 5979, pp. 710 – 722

A Draft Sequence of the Neandertal Genome

Richard E. Green et al.

Neandertals, the closest evolutionary relatives of present-day humans, lived in large parts of Europe and western Asia before disappearing 30,000 years ago. We present a draft sequence of the Neandertal genome composed of more than 4 billion nucleotides from three individuals. Comparisons of the Neandertal genome to the genomes of five present-day humans from different parts of the world identify a number of genomic regions that may have been affected by positive selection in ancestral modern humans, including genes involved in metabolism and in cognitive and skeletal development. We show that Neandertals shared more genetic variants with present-day humans in Eurasia than with present-day humans in sub-Saharan Africa, suggesting that gene flow from Neandertals into the ancestors of non-Africans occurred before the divergence of Eurasian groups from each other.

http://www.sciencemag.org/cgi/content/full/328/5979/710

____________________________________

Laura K. Säilä, PhD

Woolly mammoth antifreeze!

All over the internet today! – Laura

Substitutions in woolly mammoth hemoglobin confer biochemical properties adaptive for cold tolerance

We have genetically retrieved, resurrected and performed detailed structure-function analyses on authentic woolly mammoth hemoglobin to reveal for the first time both the evolutionary origins and the structural underpinnings of a key adaptive physiochemical trait in an extinct species. Hemoglobin binds and carries O2; however, its ability to offload O2 to respiring cells is hampered at low temperatures, as heme deoxygenation is inherently endothermic (that is, hemoglobin-O2 affinity increases as temperature decreases). We identify amino acid substitutions with large phenotypic effect on the chimeric b/d-globin subunit of mammoth hemoglobin that provide a unique solution to this problem and thereby minimize energetically costly heat loss. This biochemical specialization may have been involved in the exploitation of high-latitude environments by this African-derived elephantid lineage during the Pleistocene period. This powerful new approach to directly analyze the genetic and structural basis of physiological adaptations in an extinct species adds an important new dimension to the study of natural selection.

http://www.nature.com/ng/journal/vaop/ncurrent/abs/ng.574.html#/