RELATIVE CONTRIBUTION OF DISPERSAL AND NATURAL SELECTION TO THE MAINTENANCE OF A HYBRID ZONE IN LITTORINA
Version of Record online: 9 MAY 2007
Volume 58, Issue 12, pages 2734–2746, December 2004
How to Cite
Cruz, R., Vilas, C., Mosquera, J. and García, C. (2004), RELATIVE CONTRIBUTION OF DISPERSAL AND NATURAL SELECTION TO THE MAINTENANCE OF A HYBRID ZONE IN LITTORINA. Evolution, 58: 2734–2746. doi: 10.1111/j.0014-3820.2004.tb01625.x
- Issue online: 9 MAY 2007
- Version of Record online: 9 MAY 2007
- Received November 5, 2003. Accepted September 21, 2004.
- habitat preference;
- parapatric speciation;
- reproductive isolation
Abstract Habitat preference behavior may play an important role in nonallopatric speciation. However, most examples of habitat preference contributing to differentiation within natural populations correspond to parasites or herbivores living in the discrete environments constituted by their animal or plant hosts. In the present study we investigated migration guided by habitat preference in the intertidal snail Littorina saxatilis in a hybrid zone associated with an ecotone across the shore, which is therefore a continuously varying environment. First, we found evidence for this behavior in one of the two locations studied. Second, we made reciprocal transplants to suppress the phenotypic gradient observed across the hybrid zone and measured the relative contributions of selection and migration to its regeneration. Selection played an important role at the two locations studied, but migration was only important at one, where it accounted for between a third and a half of the regenerated gradient. This overall minor effect of migration was relevant for theoretical models dealing with nonallopatric speciation, because it suggested that variation for habitat preference did not have an important role in the initiation of the differentiation process. The preference behavior observed in the hybrid zone would have evolved secondarily, as a consequence of habitat-dependent fitness differences between phenotypes.