Sean Mullen

Assistant Professor, Boston University


NSF Dimensions: Collaborative Research: Connecting the proximate mechanisms responsible for organismal diversity to the ultimate causes of latitudinal gradients in species richness.

The latitudinal gradient in species diversity is one of the most striking biogeographic patterns in nature, with species richness peaking in equatorial regions for nearly all groups. Despite considerable effort to understand the origin and maintenance of latitudinal gradients in species diversity, a multitude of potentially interacting, non-mutually exclusive hypotheses exist, and no single over-riding explanation has emerged. However, multiple hypotheses link the latitudinal diversity gradient to a presumed gradient in the strength of biotic interactions between temperate and tropical environments. While biotic interactions are believed to play a major role in the origin and maintenance of diversity and may drive increased rates of adaptation and speciation in tropical regions, this hypothesis remains virtually untested.. To bridge this gap, a comprehensive analysis of the evolutionary mechanisms underlying adaptive phenotypic variation in color, vision, and smell across a rapidly diversifying lineage of butterflies will be performed together with field-studies.

Understanding the ecological and evolutionary processes that shape temporal and spatial patterns of biodiversity is a central goal of biology, and an increasingly important facet of the endangered species management, particularly in a time of rapid global climate change. This proposal links biodiversity researchers across the US and Latin America, and will lead to sustained international collaboration, to broadened access to STEM fields for both women and minorities through targeted recruitment, to substantial employment opportunities across institutions and countries, and, finally, to an enhanced public understanding of the science and of the current and developing threats to global biodiversity.

Collaborators:  Marcus Kronforst (U. Chicago),  Adriana Briscoe (UC Irvine),  Keith Willmott (FLMNH), & Ryan Hill (UPacific)