1st Place: D3093: Correlates of native bee extinction risk in fragmented habitats

As the human population continues to grow there is greater demand for urban development leading to habitat loss and fragmentation and an unparalleled loss in biodiversity. Habitat fragments support lower levels of taxonomic and functional diversity of native bees relative to larger preserves, yet the mechanisms for why remain unclear. The urban matrix may introduce barriers that reduce the recolonization of dispersal-limited bee species in habitat islands as indicated by small body size. Here, we utilize a dataset spanning 11 years to test a set of predictions concerning the persistence of native bee species in fragmented habitat islands and reserves in coastal sage scrub in southern California based on their dispersal ability and range size. We have 14 monitoring sites and initiated surveys of many of these sites in 2011 and have since resurveyed them every five years supplementing non-survey years with ongoing county-wide community science bee projects. The monitoring sites are 1-hectare plots in scrub habitat in two treatment categories: large natural reserves (n = 7) and small habitat fragments (n = 7) in an urban landscape. Analysis of data collected in 2012 provides significant evidence that range-restricted species are filtered out of habitat fragments, a pattern we expect to see in current and future sampling years. Understanding the traits (range size and dispersal) driving ecological filtering in habitat fragments in a biodiversity hotspot sheds light on which species are most vulnerable to extinction and will inform modes of action to conserve them.