D3213: Composition of Pheidole Westwood, 1839 on an island system over deep time

Biodiversity is fundamentally a product of three factors: speciation, extinction, and immigration. While speciation and immigration are potentially visible by studying living species alone, extinction is much harder to assess given the limitations of the fossil record. Dominican amber is dated to the Miocene approximately 16 million years ago, and preserves a rich insect fauna. This amber was formed on the island of Hispaniola, which has been consistently isolated from any mainland, offering a unique opportunity to assess extinction in an insular biogeographic setting. This study investigates the morphological structure of members of the ant genus Pheidole, across two distinct time slices on Hispaniola – contemporary species living on the island today and fossil taxa preserved in amber. We employed linear morphometric sampling of 17 morphological traits typically used in ant systematics and with demonstrated ecological significance. To assess patterns of extinction, we constructed a comparative morphospace across time using a dimension reduction technique (principal component analysis). This work aims to help reveal what morphotypes are potentially most vulnerable to loss over time, which may shed light on modern trends in insect extinction.