Hurlbert Lab

Macroecology and Biodiversity

"Ecological patterns, about which we construct theories, are only interesting if they are repeated. They may be repeated in space or in time, and they may be repeated from species to species. A pattern which has all of these kinds of repetition is of special interest because of its generality..."

--Robert MacArthur, 1968


Macroecology charts

While the ideal gas laws are useless for describing the trajectory of any particular molecule they represent an extremely useful characterization of the behavior of molecules in general. Analogously, macroecology focuses on identifying general properties of populations, species, communities and ecosystems across the globe despite, or in some cases because of, the idiosyncratic differences among them. In particular, we are interested in ways to analyze large datasets that inform us about the ecological and evolutionary processes that structure assemblages. Examples of recent macroecological research in the lab include:

Avian Richness and Community Structure

Avian field research

Birds are the group for which the most globally comprehensive data on distribution and diversity exist. In North America in particular, we have data on thousands of communities that in many cases span decades. Empirically, we find a strong positive relationship between measures of net primary productivity (or measures of climate that might reflect this) and species richness. One major aim of the lab is to more fully understand this macroecological relationship by conducting targeted field work collecting data on bird communities, but also on resource availability, habitat structure, and foraging behavior of key species over broad geographic gradients. In addition, we aim to incorporate data from other continental monitoring programs that include information on demography, population trends, and the phenology of migration and breeding. This research thus includes components of field work, sorting of arthropod (aka bird food) specimens, remote sensing, and modeling.

Phenological Mismatch Between Birds and Bugs

Magnolia Warbler

We are part of the collaborative Pheno Mismatch project. Together with Morgan Tingley at the University of Connecticut and Leslie Ries at Georgetown, our lab uses long term continental scale monitoring datasets of birds, butterflies, moths, and other insects to evaluate how climate change may be affecting the timing of spring leaf out, insect emergence, and bird migration. Our lab has developed a new citizen science project called Caterpillars Count! which is being carried out at environmental education centers throughout the country to better understand the phenology of foliage arthropods that birds rely on for raising young.

Eco-Evolutionary Models of Diversification

Temperature diversification Richness and and the distribution of thermal niches over time

Observed patterns of distribution, diversity and turnover are the result of, to paraphrase G.E. Hutchinson, an evolutionary play unfolding within an ecological theater. We are interested in divining the processes and rules by which contemporary patterns have unfolded. One way of making such inferences is using in silico experiments in which we identify patterns in macroecological and phylogenetic structure of assemblages that seem to be diagnostic of particular processes involved in the diversification and dispersal of life across the globe. These simulation models can help us evaluate the myriad of biodiversity theories that have been put forward to explain pervasive patterns like the latitudinal gradient.

Animation illustrates the development of a richness gradient over time (top panel), and the distribution of species' thermal niches over time at four distinct locations (colors) across the spatial gradient (bottom panel). Click to enlarge.

Copyright © 2020 (Allen Hurlbert).