We are broadly interested in evolution, with a focus on understanding the evolutionary and ecological mechanisms involved in speciation. We employ an integrative approach, combining field and lab work to ask research questions about the speciation process, from early to late stages. For more details about Dr. Rice's lab and her research, please click here for her lab research page.
Briefly, we are pursuing two main avenues of research:
Hybridization and its consequences
Hybridization--when individuals from different species mate and produce offspring--has a wide variety of potential outcomes, which can both positively and negatively affect biodiversity. It can even promote adaptation to new environments through the transfer of genetic variation between species ('adaptive introgression'). To better understand the conditions affecting the likelihood of these different outcomes, we are interested in the ecological and evolutionary factors influencing the probability of hybridization, as well as the genetic and fitness consequences of hybridization. We use a combination of ecological field research, ecological niche modeling, and population genetics/genomics to investigate hybridization and its consequences in our model system, hybridizing black-capped and Carolina chickadees (Poecile atricapillus and P. carolinensis, respectively).
Photo Caption: To study hybridization in black-capped and Carolina chickadees, we have established artificial nesting snags in several nearby forests. We can monitor the breeding success of individuals, collect blood samples, and measure a variety of traits. Photo credit: Christa Neu / Lehigh University
Character displacement as an initiator of speciation
When closely related species co-occur, they may compete for resources or interfere in each others' reproduction. If this competition or reproductive interference results in reduced fitness, then selection is expected to favor individuals of each species with traits that reduce the likelihood of these interactions. Over time, such selection leads to divergence between the species in such traits, a process called 'character displacement.' Character displacement will only happen where the species co-occur, however. Recently, it has been hypothesized that reproductive isolation can result between populations of one species that have and have not undergone character displacement. Our results support this hypothesis in spadefoot toads, and show that conspecific populations that have and have not undergone character displacement exhibit genetic divergence and reduced gene flow. Ongoing analyses will evaluate the genomic extent of divergence between populations in these two selective environments.
Photo Caption: Spadefoot toads (Spea multiplicata) have undergone ecological and reproductive character displacement where they co-occur with a congener, S. bombifrons. As a result, S. multiplicata populations in sympatry and in allopatry with S. bombifrons have evolved reproductive isolation and exhibit reduced gene flow.My ResearchGate profile
McQuillan, M. A. and Rice, A. M. 2015. Differential effects of climate and species interactions on range limits at a hybrid zone: Potential direct and indirect impacts of climate change. Ecology and Evolution, Early View. doi: 10.1002/ece3.1774.
Kawakami, T., Backström, N., Burri, R., Husby, A., Olason, P., Rice, A. M., Ålund, M., Qvarnström, A., Ellegren, H. 2014. Estimation of linkage disequilibrium and interspecific gene flow in Ficedula flycatchers by a newly developed 50k single-nucleotide polymorphism array. Molecular Ecology Resources 14: 1248-1260.
Pfennig, K. S. and Rice, A. M. 2014. Reinforcement generates reproductive isolation between neighbouring conspecific populations of spadefoot toads. Proceedings of the Royal Society B 281: 20140949. (featured on cover)
Rice, A. M. 2013. The genetics of speciation: Considering early-acting isolation, hybrid evolution, and epigenetic mechanisms. Current Zoology 59: 654-657. (invited editorial)
Rice, A. M., Vallin, N., Kulma, K., Arntsen, H., Husby, A., Tobler, M., and Qvarnström, A. 2013. Optimizing the trade-off between offspring number and quality in unpredictable environments: Testing the role of differential androgen transfer to collared flycatcher eggs. Hormones and Behavior 63: 813-822.
Ålund, M., Immler, S., Rice, A. M., Qvarnström, A. 2013. Low fertility of wild hybrid male flycatchers despite recent divergence. Biology Letters 9: 20130169.
Vallin, N., Rice, A. M., Arntsen, H., Kulma, K., Qvarnström, A. 2012. Combined effects of interspecific competition and hybridization impede local coexistence of Ficedula flycatchers. Evolutionary Ecology 26: 927-942.
Vallin, N., Rice, A. M., Bailey, R. I., Husby, A., Qvarnström, A. 2012. Positive feedback between ecological and reproductive character displacement in a young avian hybrid zone. Evolution 66: 1167-1169.
Rice, A. M. and Pfennig, D. W. 2010. Does character displacement initiate speciation? Evidence of reduced gene flow between populations experiencing divergent selection. Journal of Evolutionary Biology 23: 854-865.
Rice, A. M., Leichty, A. R., and Pfennig, D. W. 2009. Parallel evolution and ecological selection: Replicated character displacement in spadefoot toads. Proceedings of the Royal Society of London, Series B 276: 4189-4196.
Rice, A. M., Pearse, D. E., Becker, T., Newman, R. A., Lebonville, C., Harper, G. R., and Pfennig, K. S. 2008. Development and characterization of nine polymorphic microsatellite markers for Mexican spadefoot toads (Spea multiplicata) with cross amplification in Plains spadefoot toads (S. bombifrons). Molecular Ecology Resources 8: 1386-1389.
Rice, A. M. and Pfennig, D. W. 2008. An analysis of range expansion in two species undergoing character displacement: Why might invaders generally “win” during character displacement? Journal of Evolutionary Biology 21: 696-704.
Pfennig, D. W. and Rice, A. M. 2007. An experimental test of character displacement’s role in promoting postmating isolation between conspecific populations in contrasting competitive environments. Evolution 61: 2433-2443.
Conner, J. K., Rice, A. M., Stewart, C., Morgan, M. T. 2003. Patterns and mechanisms of selection on a family-diagnostic trait: evidence from experimental manipulation and lifetime fitness gradients. Evolution 57: 480-486.