e-mail: amyangert@gmail.com
Lab website: http://rydberg.biology.colostate.edu/angert/

Assistant Professor
B.A. (1998) Washington University in St. Louis
Ph.D. (2005) Michigan State University
Postdoctoral researcher (2005-2007) University of Arizona

Research Interests:

My lab group investigates mechanisms of adaptive divergence between populations and species and the consequences of divergence for patterns of distribution and abundance. We combine experimental manipulations in the field and in the lab and observations of natural populations with tools from quantitative genetics and physiological ecology. Much of our research focuses on the evolutionary ecology of geographic ranges within the genus Mimulus ("monkeyflowers") because of their ecological diversity, history of study, genomic resources, and ease of propagation.

Range limits
Every species occupies a limited geographic area, but the ecological and evolutionary factors that give rise to range limits remain poorly understood. We are working to determine how dispersal limitation, abiotic factors, and biotic interactions interact to create present-day range limits. When ecological limiting factors are identified, range boundaries still present an evolutionary conundrum. If populations are maladapted to environmental conditions beyond the range, then why don't they evolve by natural selection and expand their ranges through time? To address these questions, we combine a variety of approaches, including demographic modeling of central and marginal population dynamics, growth chamber studies to examine physiological responses to limiting environmental variables, experimental transplants to evolve populations beyond range boundaries, and population genomics to infer gene flow across species’ ranges. Finally, although ranges might be evolutionarily stable with respect to limiting ecological factors, their positions on the landscape are sometimes highly labile as climate changes. Many studies have documented poleward or altitudinal range shifts over the last century, but there is considerable variation among species in range shifts observed to date and tremendous uncertainty about species’ capacities to continue keeping pace with rapid climate change. We are involved in several projects that may help address some of this uncertainty, including “hindcasting” recent range shifts and developing distribution models that incorporate factors such as dispersal limitation, species interactions, and evolutionary change.

Range size and rarity
Although every species has a limited distribution, some species have much more limited ranges than others. We are extending our research on geographic range limits to investigate the evolutionary ecology of range size and rarity in Mimulus, a genus where species vary in range size by several orders of magnitude. We are using a comparative phylogenetic framework to address questions such as what mating system, life history, or physiological traits are associated with small range size? We are also using empirical approaches to address questions such as, do rare species have narrow environmental tolerances, and if so, what constrains the evolution of broader tolerance? Are widespread species highly plastic, specialized to a common environment, or composed of many locally adapted populations?

Ecological speciation and niche evolution
Recently diverged sister taxa often have non-overlapping (allopatric) or abutting (parapatric) geographic distributions. Questions about range limits are intimately related to the geography of speciation and the process of ecological divergence from a common ancestor. The evolution of ecological differences in different geographic regions can contribute to reproductive isolation by reducing opportunities for interbreeding. We are generally interested in studying how gene flow and plasticity may promote or hinder adaptation to novel environments, identifying mechanisms of divergent adaptation to contrasting habitats between populations and sister species, and in quantifying axes of niche divergence across Mimulus.

Species coexistence
In collaboration with Larry Venable, Travis Huxman, and Peter Chesson (University of Arizona), we are investigating how species differences in physiology and morphology promote coexistence among species of desert winter annuals. Our current projects focus on physiological and morphological traits that mediate responsiveness to rainfall and competitive interactions. Our studies combine coexistence theory, demographic observations, measurements of functional traits, and experimental manipulations of abiotic factors and species composition. We have found that species exhibit a strong trade-off between growth capacity and low-resource tolerance, and species position along this trade-off can predict the demographic responses to rainfall variation that maintain local biodiversity. We are also investigating the growth capacity/low-resource tolerance trade-off within species to determine whether the key functional traits that trade off across species are similarly constrained within species. By examining this key tradeoff within and between populations and at the phenotypic and genetic levels, we will determine how trade-offs scale from genetic variation within species to interspecific diversity and community structure.

Genetic variation and ecosystem function
Very recently, we have become interested in the link between genetic variation and ecosystem function. We are beginning new projects on the ecological genetics of blue grama grass (Bouteloua gracilis) on the shortgrass prairie and the sedge Carex aquatilis on the Arctic tundra to investigate how plasticity and genetic differentiation within these species affect ecosystem properties and responses to environmental perturbations.

Kimball S, JR Gremer, AL Angert, TE Huxman, and DL Venable.  2011.  “Fitness and physiology in a variable environment.” Oecologia, in press.

Paul JR, Sheth SN, and AL Angert. 2011.  “Quantifying the impact of gene flow on phenotype-environment mismatch: a demonstration with the scarlet monkeyflower (Mimulus cardinalis).”  American Naturalist 178: S62-S79.

Angert AL, SN Sheth and JR Paul.  2011.  “Incorporating population variation in thermal performance into predictions of geographic range shifts.” Integrative and Comparative Biology, Advance Access (doi: 10.1093/icb/icr048).

Angert AL, LG Crozier, LJ Rissler, SE Gilman, JJ Tewksbury, and AJ Chunco.  2011.  “Do species’ traits predict recent range shifts?” Ecology Letters 14: 677–689.

Gerst KL, AL Angert and DL Venable. 2011.  “The effect of geographic range position on demographic variability in annual plants.”  Journal of Ecology 99: 591-599.

Angert AL, JL Horst, TE Huxman, and DL Venable.  2010.“Phenotypic plasticity and precipitation response in Sonoran Desert winter annuals.”  American Journal of Botany 97: 405-411.

Kimball S, AL Angert, TE Huxman and DL Venable.  2010.  “Contemporary climate change favors cold-adapted species in the Sonoran Desert.”  Global Change Biology 16: 1555-1565.

Sexton JP, PJ MacIntyre, AL Angert and KJ Rice.  2009.  “Evolution and ecology of species range limits.”  Annual Review of Ecology, Evolution and Systematics 40: 415-436.

Angert AL.  2009.  “Colloquium Papers: The niche, limits to species’ distributions, and spatiotemporal variation in demography across the elevation ranges of two monkeyflowers.” Proceedings of the National Academy of Sciences 106: 19693-19698.

Angert AL, TE Huxman, P Chesson, and DL Venable.  2009.  “Functional trade-offs determine species coexistence via the storage effect.”  Proceedings of the National Academy of Sciences 106:11641-11645.

Angert AL, HD Bradshaw, and DW Schemske.  2008.  “Using experimental evolution to investigate geographic range limits in monkeyflowers.”  Evolution 62: 2660-2675.

Angert AL, TE Huxman, GA Barron-Gafford, KL Gerst, and DL Venable. 2007. “Linking growth strategies to long-term population dynamics in a guild of desert annuals.” Journal of Ecology 95: 321-331.

Angert AL. 2006. “Demography of central and marginal populations of monkeyflowers (Mimulus cardinalis and M. lewisii).” Ecology 87: 2014-2025.

Angert AL. 2006. “Growth and leaf physiology of monkeyflowers with different altitude ranges.” Oecologia 148: 183-194.

Angert AL and DW Schemske. 2005. “The evolution of species' distributions: Reciprocal transplants across the elevation ranges of Mimulus cardinalis and M. lewisii.” Evolution 59: 1671-1684.