Evan’s research focuses on evolution and biodiversity of the poison frogs, with an emphasis on how diversification of color patterns can lead to population divergence and speciation. His doctoral research focused on ecological speciation in Ranitomeya imitator,a species that has undergone a "mimetic radiation", that is, where different populations have diverged in appearance to resemble different model species. Currently he is studying the influence of color pattern divergences on speciation more broadly.

Twomey, E., Vestergaard, J. S., Venegas, P. J. & K. Summers - Mimetic divergence and the speciation continuum in the mimic poison frog Ranitomeya imitator. The American Naturalist, in press.

Twomey, E., Mayer, M. & K. Summers, 2015 - Intraspecific call variation in the mimic poison frog Ranitomeya imitator. Herpetologica 71: 252–259.

Twomey, E.,  Vestergaard, J. S. & K. Summers, 2014 - Reproductive isolation related to mimetic divergence in the poison frogRanitomeya imitator. Nature Communications 5: 1–8.

Twomey, E., Delia, J. & S. Castroviejo-Fisher, 2014 - A review of Northern Peruvian glassfrogs (Centrolenidae), with the description of four new remarkable species. Zootaxa 3851: 1–87.

Twomey, E., Yeager, J., Brown, J. L., Morales, V., Cummings, M. & K. Summers, 2013 - Phenotypic and genetic divergence among poison frog populations during a mimetic radiation. PLoS ONE 8: e55443

Brown, J.L., Twomey, E., Amezquita, A., Barbosa de Souza, M., Caldwell, J.P., Lötters, S., von May, R., Melo Sampaio, P.R., Mejia-Vargas, D.,Perez-Peña, P., Pepper, M., Poelman, E.H., Sanchez-Rodriguez, M. & K. Summers, 2011 - A taxonomic revision of the Neotropical poison frog genus Ranitomeya (Amphibia: Dendrobatidae). Zootaxa 3083: 1–120.

Twomey, E & J.L. Brown, 2009 - Another new species of Ranitomeya (Anura: Dendrobatidae) from Amazonian Colombia. Zootaxa 2302: 48–60.

Brown, J.L. & E. Twomey, 2009 - Complicated histories: three new species of poison frogs of the genus Ameerega (Anura: Dendrobatidae) from north-central Peru. Zootaxa 2049: 1–38.

Twomey, E. & J.L. Brown, 2008 - Spotted poison frogs: rediscovery of a lost species and a new genus. Herpetologica 64: 121–137.

Twomey, E., Morales, V. & K. Summers, 2008 - Evaluating condition-specific and asymmetric competition in a species distribution context. Oikos 117: 1175–1184.