The Fossil amber fauna of the Simojovel formation and the Red Queen hypothesis

Amber from the Simojovel formation of Chiapas, Mexico contains fossil insect inclusions that are dated at Oligo-Miocene (23.7 mya). A study of this fauna, 97 arthropod genera identified, is placed in the context of the Red Queen hypothesis which holds that extinction rate should match speciation rate. The Red Queen hypothesis was based on vertebrate faunas. The Simojovel fauna contains 76% extant genera, as compared to Oligocene vertebrate faunas which typically contain few or no extant genera. Moreover the Oligocene Chiapas fauna is 50% circumtropical whereas modern Chiapas fauna is overwhelmingly (70-90%) New World, and dominantly Neotropical. This suggests that extinction rates are lower for Arthropods than vertebrates and can be related to the r-K selection paradigm. Consequently, insect faunal diversity in the Neotropics has resulted from accretion: speciation rates faster than extinction rates.