MBE Advance Access published online on July 29, 2008
Molecular Biology and Evolution, doi:10.1093/molbev/msn164
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Research Article |
Intron presence-absence polymorphisms in Daphnia
1 Department of Biology, Indiana University, 1001 E. Third Street, Bloomington, Indiana, 47405, USA
2 Current address: Department of Biological Sciences, University at Buffalo, Buffalo, New York, 14260, USA
3 Current address: Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Box 951606, Los Angeles, California, 90095, USA
* Author for correspondence. Email: alr2{at}buffalo.edu, phone: 716-645-2363 ext. 181
Received for publication February 21, 2008. Revision received July 11, 2008. Accepted for publication July 16, 2008.
Here, we report two novel intron gains segregating in populations of Daphnia pulex endemic to Oregon. These novel introns do not have an obvious source and are not present in any D. pulex populations outside Oregon, other species of Daphnia that we examined, or any other organism for which sequence data are available. Furthermore, the novel introns are both found in the same gene, a Rab GTPase (rab4), and they appear to differ in their insertion site by one base pair, providing some support to the proto-splice site hypothesis. The rarity of intron gain polymorphisms is questioned as we discovered two events in an initial survey of only six nuclear loci in 36 Daphnia individuals. Neutrality tests failed to ascertain a clear selective effect for either intron insertion, and a significant difference in recombination rate was not observed in alleles that contain the novel intron insertion vs. alleles lacking it. We conclude that one novel intron insertion segregating at high frequencies in Daphnia populations in Oregon is unlikely to be adaptive and may result from the reduced efficacy of selection in isolated populations of small effective size.
Key Words: Daphnia • intron insertion • intron gain • intron polymorphism
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  F. Catania, X. Gao, and D. G. Scofield Endogenous Mechanisms for the Origins of Spliceosomal Introns J. Hered., September 1, 2009; 100(5): 591 - 596. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. R. Omilian and M. Lynch Patterns of Intraspecific DNA Variation in the Daphnia Nuclear Genome Genetics, May 1, 2009; 182(1): 325 - 336. [Abstract] [Full Text] [PDF]
|
|