STRONG SELECTION AGAINST HYBRIDS MAINTAINS A NARROW CONTACT ZONE BETWEEN MORPHOLOGICALLY CRYPTIC LINEAGES IN A RAINFOREST LIZARD
Article first published online: 13 JAN 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 5, pages 1474–1489, May 2012
How to Cite
Singhal, S. and Moritz, C. (2012), STRONG SELECTION AGAINST HYBRIDS MAINTAINS A NARROW CONTACT ZONE BETWEEN MORPHOLOGICALLY CRYPTIC LINEAGES IN A RAINFOREST LIZARD. Evolution, 66: 1474–1489. doi: 10.1111/j.1558-5646.2011.01539.x
- Issue published online: 20 APR 2012
- Article first published online: 13 JAN 2012
- Accepted manuscript online: 22 DEC 2011 05:12AM EST
- Received September 12, 2011, Accepted December 1, 2011, Data Archived: Dryad doi:10.5061/dryad.4gh6hf5g
- hybrid zones;
- Lampropholis coggeri;
Phenotypically cryptic lineages comprise an important yet understudied part of biodiversity; in particular, we have much to learn about how these lineages are formed and maintained. To better understand the evolutionary significance of such lineages, we studied a hybrid zone between two morphologically cryptic phylogeographic lineages in the rainforest lizard, Lampropholis coggeri. Analyzing a multilocus genetic dataset through cline inference, individual-based methods and population measures of disequilibrium and using simulations to explore our genetic results in context of theoretical expectations, we inferred the processes maintaining this hybrid zone. We find that these lineages meet in a hybrid zone that is narrow (≈400 m) relative to inferred dispersal rate. Further, the hybrid zone exhibits substantial genetic disequilibrium and sharply coincident and largely concordant clines. Based on our knowledge about the region’s biogeography, the species’ natural history, and our simulation results, we suggest that strong selection against hybrids structures this system. As all clines show a relatively narrow range of introgression, we posit that this hybrid zone might not yet be in equilibrium. Nonetheless, our results clearly show that phylogeographic lineages can evolve substantial reproductive isolation without concomitant morphological diversification, suggesting that such lineages can constitute a significant component of evolutionary diversity.