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THE VERTEBRATE coagulation system is a complicated cascade of enzymes, yet it evolved by the gradual addition of enzymes. It is thought that this complex system evolved by the repeated duplication and divergence of two ancestral genes. We are most familiar with the prothrombin activators as essential clotting cascade elements, yet some snakes have weaponized these enzymes.
THERE IS A new article published online at PNAS reporting the results of a 36-year experiment on the Italian wall lizard Podarcis sicula. A population of lizards was already living on a small islet called Pod Kopiste, and the authors moved five females and five males to the nearby islet Pod Mrcaru. This was originally an experiment in “competitive exclusion”, as the islet was already inhabited by the Dalmatian wall lizard, Podarcis melisellensis, which was apparently outcompeted and is now extinct on that islet.
I RECENTLY REVIEWED some of the advantages and disadvantages of sexual and asexual reproduction. Sexual reproduction is thought to be chiefly useful in the elimination of negative mutations, while these build up in asexually reproducing lineages. Without some type of genetic recombination it is thought that asexual reproduction will lead eventually to extinction.
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