Although biologists have made major strides in understanding the evolution and ecology of many ant species, sample-based data on the distribution of ant species and insects more generally remain illusive. Sample-based data (which record both presences and absences of species) are fundamental to modeling species distributions, and understanding patterns of diversity and diversification. We have developed a sample-based database for the ants of eastern North America based on quantitative samples of ant communities from over 400 separate study sites varying in their history, vegetation type, latitude, longitude and elevation among other factors.

In 2005, Rob Dunn, J. P. Lessard, Matt Fitzpatrick, Nate Sanders and Ed Laurent began the North American Ant Database with the goal of understanding patterns of diversity and distribution in North American ants. Below, we show examples from three types of questions that we are beginning to ask using the North American database. The figure below shows the location of the study sites entered into the database to date set against current (at left, 1990) and future (at right, 2100 for 2*current CO2) temperature models.

Species Distribution Models. Data from the sample-based database can be used to model not only the present distributions of species, but also to project future and even historical distributions of those species. At left we show distribution models for the Aphaenogaster rudis species group where the green area shows the current distribution of the Aphaenogaster rudis group and the red area the predicted distribution in 2106. These images represent part of the work Matt Fitzpatrick, Nate Sanders and I have undertaken to understand the future of ant species and communities in the eastern U.S. under different climate change scenarios. Aphaenogaster rudis is the most important seed dispersing ant species in eastern North America. This work is funded by a NICCR grant from the Department of Energy to Dunn and Sanders (http://www.niccr.duke.edu/awards/Dunn_NICCR07.pdf).

Drivers of Species Diversity. In addition to helping to understand distributions of particular species, data from the database can be used to model the drivers of diversity and composition of ant communities. The figure at left shows the relationship between temperature and diversity for a subset of the total dataset, the ants of Appalachia.

In all versions of our datasets, temperature appears to be strongly correlated with ant diversity. One of our current projects with the database is to try to understand more mechanistically why temperature and diversity are so strongly associated.

The Global Database

We have now broadened this database and associated research through a collaboration with more than twenty researchers from 6 continents and roughly a 13 countries (collaborators).The new database now includes data from more than 3000 sites. Unlike the North American database, the global database will, for the time being, focus only on the diversity of ants rather than on the distribution of particular species. Using the global database we will thus focus on questions related to the global patterns of ant diversity, rather than species composition or distribution.

More information...

To find out more about collaborating on this project, becoming involved as a student or postdoc or about the results of this project, contact Rob Dunn at Rob_Dunn "at" ncsu.edu.