Monday, July 7, 2014

Role of predators overrated

One would expect that on all islands, baby deer safely grow up into adulthood without much trouble, far away from warm-blooded carnassial danger. On islands, with their typically unbalanced faunas, large and medium-sized terrestrial carnivores are entirely missing. This creates a safe, perhaps even arcadian environment. Not so. We found for a fossil population of endemic deer (Candiacervus, Crete, Late Pleistocene) an unexpectedly high juvenile mortality, similar to that reported for extant mainland ruminants. Age profiles show that deer surviving past the fawn stage were relatively long-lived for ruminants, indicating that high juvenile mortality was not an expression of their living a "fast" life. The Sicilian dwarf elephant (Palaeoloxodon falconeri) was shown to have lived a "fast" life, which means a short life, lots of offspring of which many don't make it (Raia et al. 2003). This is not the case for Candiacervus. Juvenile mortality for Candiacervus was caused by diseases, accidents (Crete is mountaineous), starvation and so on, just as on the mainland or perhaps even more so. What does this message tell us? We think that precisely this high juvenile mortality acts as a great selective tool, permitting rapid adaptation to the new environment, and in the case of Candiacervus, radiation and speciation. Without this selective filtering, such processes likely could not take place so fast: 6 or 8 species in at most 125 thousand years. Read the article at

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