Meeting Abstract
Latitudinal gradients of biodiversity are a central focus of macroecological research in both terrestrial and marine systems. Functional diversity is an important facet of biodiversity linking species with the ecosystems that they influence and evolve within, but the relationship of this extra-taxonomic component of biodiversity to latitude and its environmental correlates is poorly understood. Here we compare spatial patterns of functional diversity in marine bivalves to those of a primarily terrestrial taxon, birds. Birds and bivalves are both taxonomically and functionally diverse and together have already been used to identify marine-terrestrial parallels in range size evolution. We used global data on bird and bivalve species-level ecological attributes to place them in multidimensional functional frameworks, and used species occurrence data to estimate changes in functional diversity with latitude, using motif analysis to explore gain and loss of functional groups (FGs) with latitude and habitat types. We found that both tropical bivalve and tropical bird faunas show high functional richness (FR) but low evenness (FE); species richness across tropical functional groups for both taxa follows a “hollow curve”. The few FGs that persist toward the poles are more uniformly speciose, such that FR declines and FE rises with latitude. Ultimately, our analyses reveal large-scale parallels in marine and terrestrial systems, and suggest that the disparate FR and FE of the tropics in these systems is a consequence of unsaturated tropical faunas containing rare FGs.
