Benkman, C. W. 2003. Divergent selection drives the adaptive radiation of crossbills. Evolution 57: 1176–1181.
A fascinating example of how adaptation associated with feeding behavior can eventually lead to speciation in birds.
Ehleringer, J. R. and R. K. Monson. 1993. Evolutionary and ecological aspects of photosynthetic pathway variation. Annual Review of Ecology and Systematics 24: 411–439.
Sage, R.F. 2003. The evolution of C4 photosynthesis. New Phytologist 161: 341-370.
These two papers thoroughly consider the evolution of different plant photosynthetic pathways and the ecological selection forces that favored their appearance and determine their habitat distributions.
Karasov, W.H. and C. Martinez del Rio. 2007. Physiological Ecology: How Animals Process Energy, Nutrients, and Toxins. Princeton University Press, Princeton, NJ.
This textbook provides clear coverage of the physiological factors associated with how animals obtain energy and nutrients from their environment within an ecological context.
Madigan, M. T. and J. M. Martinko. 2006. Brock Biology of Microorganisms. 15th ed. Pearson, Boston, MA.
Staley, J. T., R. P. Gunsalus, S. Lory and J. J. Perry. 2007. Microbial Life. 2nd ed. Sinauer Associates, Sunderland, MA.
These two textbooks are very useful references on the biology of bacteria and fungi, including the multitude of mechanisms they use to obtain energy.
Sage, R. F. and R. K. Monson, eds. 1999. C4 Plant Biology. Academic Press, San Diego, CA.
An excellent account of all aspects of C4 plants, including their evolution, physiology, ecology, and biogeography.