Ecomorphology and evolutionary novelty
My research is often at the interface between biomechanics and ecology or evolutionary biology, hence I have been interested in the basic issue of how organismal-level functional studies can help us answer ecological and evolutionary questions.
The performance of an organism is the crucial link between its phenotype and its ecological success. When does an organism's morphology affect its performance? Over the years, our quantitative mechanistic analyses of how function depends on biological form have shown that the relationship between morphology and performance can be nonlinear, context-dependent, and sometimes surprising. In some cases, small changes in morphology or simple changes in size can lead to novel functions, while in other cases changes in form can occur without performance consequences. Furthermore, the effect of a specific change in morphology can depend on the size, shape, stiffness, or habitat of an organism. Likewise, a particular change in posture or behavior can produce opposite effects when performed by bodies with different morphologies. These mechanistic studies not only reveal potential misconceptions that can arise from the descriptive statistical analyses often used in ecological and evolutionary research, but they also show how new functions, and novel consequences of changes in morphology can arise simply as the result of changes in size or habitat. Such organismal-level mechanistic research can be used in concert with other tools to gain insights about issues in ecology (e.g. foraging, competition, disturbance, keystone species, functional groups) and evolution (e.g. adaptation, interpretation of fossils, and origin of novelty).
Some examples of the evolution of novel functions we have studied include the evolution of aerodynamic performance in early insects, in dinosaur ancestors of birds, and in clades of gliding frogs, and the evolution of multicellularity in the protozoan ancestors of animals.
Selected references on this topic
- Koehl, M. A. R. (1996) When does morphology matter? Ann. Rev. Ecol. Syst. 27: 501-542. (overview)
- Horn, H. S., J. T. Bonner, W. Dohle, M. J. Katz, M. A. R. Koehl, H. Meinhardt, R. A. Raff, W.-E. Reif, S. C. Stearns, and R. Strathmann (1982) Adaptive aspects of development. pp. 215-235, In, J. T. Bonner [ed.], Evolution and Development. Dahlem Konferenzen, Berlin: Springer-Verlag.
- Kingsolver, J. G. and M. A. R. Koehl (1985) Aerodynamics, thermoregulation, and the evolution of insect wings: Differential scaling and evolutionary change. Evolution 39: 488- 504.
- Koehl, M. A. R. (1989) From individuals to populations. pp. 39-53 In, R. M. May, J. Roughgarden, and S. A. Levin [eds.], Perspectives in Ecological Theory. Princeton, NJ: Princeton University Press.
- Kingsolver, J. G. and M. A. R. Koehl (1989) Selective factors in the evolution of insect wings. Can. J. Zool. 67: 785-787.
- Emerson, S. B. and M. A. R. Koehl (1990) The interaction of behavior and morphology in the evolution of a novel locomotor type: "Flying frogs". Evolution 44: 1931-1946.
- Emerson, S. B., J. Travis, and M. A. R. Koehl (1990) Functional complexes and additivity in performance: A test case with flying frogs. Evolution 44: 2153-2157.
- Full, R. J. and M. A. R. Koehl (1993) Drag and lift on running insects. J. Exp. Biol. 176: 89-101.
- Kingsolver, J. G. and M. A. R. Koehl (1994) Selective factors in the evolution of insect wings. Ann. Rev. of Entomol. 39: 425-451.
- Koehl, M.A.R. (1999) Ecological biomechanics of benthic organisms: Life history, mechanical design and temporal patterns of mechanical stress. J. Exp. Biol. 202: 3469-3476.
- Martinez, M. M., R. J. Full, and M. A. R. Koehl (1998) Underwater punting by an intertidal crab: A novel gait revealed by the kinematics of pedestrian locomotion in air vs. water. J. Exp. Biol. 201: 2609-2623.
- Koehl, M.A.R. (2000) Consequences of size change. Pp. 67-86 In, Scaling in Biology J.H. Brown and G.B. West [eds.], Oxford Univ. Press, NY.
- Dickinson, M. H., C. T. Farley, R. J. Full, M. A. R. Koehl, R. Kram and S. Lehman (2000) How animals move: An integrative view. Science 288: 100-106.
- Koehl, M. A. R. (2003) Physical modelling in biomechanics. Phil Trans. Roy. Soc. Lond. B. 358: 1589-1596.
- Koehl, M. A. R. and B. D. Wolcott (2004) Can function at the organismal level explain ecological patterns? Ecology 85: 1808-1810.
- Koehl, M. A. R. (2010) How does morphology affect performance in variable environments? In: In search of the causes of evolution. From field observations to mechanisms. P.R. Grant and B. Grant [eds.] Princeton University Press, pp. 177-191.
- Koehl, M .A. R., D. Evangelista, and K. Yang (2011) Using physical models to study the gliding performance of extinct animals. Integr. Comp. Biol. doi:10.1093/icb/icr112.
- Roper, M., M. J. Dayel, R. E. Pepper, N. King, and M. A. R. Koehl, (2013) Cooperatively generated stresslet flows supply fresh fluid to multicellular choanoflagellate colonies. Physical Review Letters 110: 228104 DOI: 10.1103/PhysRevLett.110.228104.
- Evangelista, D., G. Cardona, E. Guenther-Gleason, T. Huynh, A. Kwong, D. Marks, N. Ray, A. Tisbe, K. Tse, and M. A. R. Koehl (2014) Aerodynamic characteristics of a feathered dinosaur measured using physical models. I. Effects of form on static stability and control effectiveness. PLOS One 9: e85203
Links to Specific Topics
- Fluid dynamics of hairy little legs
- Microscopic organisms swimming in turbulent flow/Larval Settlement
- Fluid dynamics of odor capture by olfactory antennae
- Selective factors in the evolution of multi-cellularity
- How do benthic organisms withstand and utilize moving water?
- Biomechanics of hydrostatic skeletons
- Biomechanics of morphogenesis