Rapid formation of reproductive isolation between two populations of side-blotched lizards, Uta stansburiana

Ammon Corl*, Lesley T. Lancaster, Barry Sinervo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Determining the factors that give rise to reproductive isolation is critical for understanding how species form. Observing reproductive isolation between closely related populations is especially interesting because it can show the factors initially involved in species formation. We studied two phenotypically different populations of Side-Blotched Lizards (Uta stansburiana), which diverged less than 22,500 years ago according to geologic evidence. The lava flow population has dark dorsal coloration for crypsis and is dimorphic for throat coloration used for signaling male mating type. The off-lava population has light dorsal coloration and is trimorphic for throat coloration. We tested whether there was reproductive isolation between these two populations in order to understand the factors that maintain the phenotypic differences between these populations. Our genetic crosses revealed evidence of reproductive incompatibilities because females from the dimorphic lava population produced fewer fertilized eggs and more unfertilized eggs when mated outside their population. In addition, male morphs varied in their reproductive compatibility because females from both populations produced fewer fertilized eggs and fewer clutches with orange-throated males from outside their population. The reproductive incompatibilities observed between the populations suggest that cryptic female choice of sperm may act as a post-mating, prezygotic barrier that contributes to the rapid formation of new species.

Original languageEnglish
Pages (from-to)593-602
Number of pages10
Issue number4
Publication statusPublished - 18 Dec 2012

Bibliographical note

Collecting permits from the California Department of Fish and Game were issued to B. Sinervo (permit 801060-01). Protocols for this study were approved by the University of California, Santa Cruz Institutional Animal Care and Use Committee (protocol SINE00.02-1). Thanks to all the UCSC undergraduate volunteers who helped with lizard husbandry and collecting egg data. Special thanks to E. Clancey for her help with the genetic crosses and to I. Zlatkovsky for help measuring the luminosity of the lizards. Thanks to G. Pogson, J. Thompson, and J. Wolf for comments on the manuscript. This research was supported by an NSF dissertation improvement grant to A. Corl and an NSF LTREB to B. Sinervo and A. McAdam.


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