range margin

Willis, S.G., Hill, J.K., Thomas, C.D., Roy, D.B., Fox, R., Blakeley, D.S. & Huntley, B. (2009) Assisted colonization in a changing climate: a test-study using two U.K. butterflies. Conservation Letters, 2, 46-52.
Oliver, T.H., Hill, J.K., Thomas, C.D., Brereton, T.M. & Roy, D.B. (2009) Changes in habitat specificity of species at their climatic range boundaries. Ecology Letters, 12, 1091-1102.