Current address: School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia.
EVIDENCE OF CONSTRAINED PHENOTYPIC EVOLUTION IN A CRYPTIC SPECIES COMPLEX OF AGAMID LIZARDS
Article first published online: 18 JAN 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 4, pages 976–992, April 2011
How to Cite
Smith, K. L., Harmon, L. J., Shoo, L. P. and Melville, J. (2011), EVIDENCE OF CONSTRAINED PHENOTYPIC EVOLUTION IN A CRYPTIC SPECIES COMPLEX OF AGAMID LIZARDS. Evolution, 65: 976–992. doi: 10.1111/j.1558-5646.2010.01211.x
- Issue published online: 4 APR 2011
- Article first published online: 18 JAN 2011
- Accepted manuscript online: 20 DEC 2010 04:58AM EST
- Received June 30, 2008, Accepted November 23, 2010
- morphological evolution;
- morphological stasis;
Lineages that exhibit little morphological change over time provide a unique opportunity to explore whether nonadaptive or adaptive processes explain the conservation of morphology over evolutionary time scales. We provide the most comprehensive evaluation to date of the evolutionary processes leading to morphological similarity among species in a cryptic species complex, incorporating two agamid lizard species (Diporiphora magna and D. bilineata). Phylogenetic analysis of mitochondrial (ND2) and nuclear (RAG-1) gene regions revealed the existence of eight deeply divergent clades. Analysis of morphological data confirmed the presence of cryptic species among these clades. Alternative evolutionary hypotheses for the morphological similarity of species were tested using a combination of phylogenetic, morphological, and ecological data. Likelihood model testing of morphological data suggested a history of constrained phenotypic evolution where lineages have a tendency to return to their medial state, whereas ecological data showed support for both Brownian motion and constrained evolution. Thus, there was an overriding signature of constrained evolution influencing morphological divergence between clades. Our study illustrates the utility of using a combination of phylogenetic, morphological, and ecological data to investigate evolutionary mechanisms maintaining cryptic species.