2001 – Ph.D., Stanford University
Biodiversity is distributed unevenly on the planet. For example, at broad spatial scales, there tend to be more species near the equator than near the poles. At local spatial scales, such as within a 1-m2 plot of leaf litter, the number of species can vary from place to place within a forest. Research in the Sanders Lab seeks to document and explain such variation in diversity and addresses two fundamental questions:
- What factors govern broad-scale patterns in the distribution of biodiversity?
- Do trophic dynamics limit local community structure and mediate ecosystem processes?
Our approach combines large-scale surveys of biodiversity to take advantage of natural experiments (e.g., variation along climatic gradients or invasion by non-native species) and manipulative experiments at small spatial scales.
We routinely use elevational gradients to uncover the causes of broad-scale patterns of biodiversity because climate, area, stochastic factors, and history can vary systematically along numerous elevational gradients. In addition, it is possible to manipulate experimentally potential causal mechanisms along elevational gradients. Since 2004, we have worked in Great Smoky Mountains National Park on the causes and consequences of elevational gradients in ant diversity.
In addition, we use manipulative experiments, largely focused on foodwebs in old-field plant communities and in forests in the eastern US to determine the extent to which trophic dynamics limit community structure and how within-population diversity affects the structure and dynamics of communities and ecosystems.
Work in the Sanders Lab is not limited to the broad projects described here. Recent students have worked on tropical ant community dynamics in Costa Rica, modeling the effects of climatic change on plants in western Australia, long-term changes in forests and understory vegetation in Great Smoky Mountains National Park, the causes and consequences of biological invasions, and the effects of fire on ant and plant community structure.
- Crutsinger GM, Souza L, Sanders NJ (2008) Intraspecific diversity as a barrier to plant invasions. Ecology Letters 11: 16-23
- Sanders NJ, Gotelli NJ, Wittman SE, Ratchford JS, Ellison AM, Jules ES (2007) Assembly rules for ant communities across spatial scales and habitats. Journal of Biogeography 34: 1632-1641
- Sanders NJ, Lessard J-P, Dunn RR, Fitzpatrick MC (2007) Temperature, but not productivity or geometry, predicts elevational diversity gradients in ants across spatial grains. Global Ecology
- Sanders NJ, Crutsinger GM, Dunn RR, Majer JD, Delabie JHC (2007) An ant mosaic revisited: dominant ant species disassemble arboreal ant communities but co-occur randomly. Biotropica 39: 422-427
- Sanders NJ, Weltzin JF, Crutsinger GM, Fitzpatrick MC, Nuñez MA, Oswalt CM, Lane KE (2007) Multiple controls on a plant invasion: Insects mediate the interactive effects of propagule supply and resource availability. Ecology 88: 2383-2391
- Fitzpatrick MC, Weltzin JF, Sanders NJ, Dunn RR (2007) The biogeography of prediction error: Why doesn’t the introduced range of the fire ant predict its native range or vice versa? Global Ecology and Biogeography 15: 24-33
- Geraghty MJ, Dunn RR, Sanders NJ (2007) Bergmann’s rule in ants: are patterns along latitudinal and elevational gradients congruent? Myrmecological News 10: 51-58
- Crawford KM, Crutsinger GM, Sanders NJ (2007) Genotypic diversity mediates the distribution of an ecosystem engineer. Ecology 88: 2114-2120
- Crutsinger GM, Collins MD, Fordyce JA, Gompert Z, Nice CC, Sanders NJ (2006) Genotypic diversity predicts community structure and governs an ecosystem process. Science 313: 966-968