Gene conversion yields novel gene combinations in paralogs of GOT1 in the copepod Tigriopus californicus

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  • Willett, Christopher
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • Abstract Background Gene conversion of duplicated genes can slow the divergence of paralogous copies over time but can also result in other interesting evolutionary patterns. Islands of genetic divergence that persist in the face of gene conversion can point to gene regions undergoing selection for new functions. Novel combinations of genetic variation that differ greatly from the original sequence can result from the transfer of genetic variation between paralogous genes by rare gene conversion events. Genetically divergent populations of the copepod Tigriopus californicus provide an excellent model to look at the patterns of divergence among paralogs across multiple independent evolutionary lineages. Results In this study the evolution of a set of paralogous genes encoding putative aspartate transaminase proteins (called GOT1 here) are examined in populations of the copepod T. californicus. One pair of duplicated genes, GOT1p1 and GOT1p2, has regions of high divergence between the copies in the face of apparent on-going gene conversion. The GOT1p2 gene also has unique haplotypes in two populations that appear to have resulted from a transfer of genetic variation via inter-paralog gene conversion. A second pair of duplicated genes GOT1Sr and GOT1Sd also shows evidence of gene conversion, but this gene conversion does not appear to have maintained each as a functional copy in all populations. Conclusions The patterns of conservation and sequence divergence across this set of paralogous genes among populations of T. californicus suggest that some interesting evolutionary patterns are occurring at these loci. The results for the GOT1p1/GOT1p2 paralogs illustrate how gene conversion can factor in the creation of a mosaic pattern of regions of high divergence and low divergence. When coupled with rare gene conversion events of divergent regions, this pattern can result in the formation of novel proteins differing substantially from either original protein. The evolutionary patterns across these paralogs show how gene conversion can both constrain and facilitate diversification of genetic sequences.
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  • Article
Rights statement
  • In Copyright
Rights holder
  • Christopher S Willett et al.; licensee BioMed Central Ltd.
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Journal title
  • BMC Evolutionary Biology
Journal volume
  • 13
Journal issue
  • 1
Page start
  • 148
Language
  • English
Is the article or chapter peer-reviewed?
  • Yes
ISSN
  • 1471-2148
Bibliographic citation
  • BMC Evolutionary Biology. 2013 Jul 12;13(1):148
Publisher
  • BioMed Central Ltd
Access right
  • Open Access
Date uploaded
  • July 31, 2013

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file details 1471-2148-13-148.pdf 2019-05-06 Public Download
file details Genetic divergence among orthologs and paralogs of GOT1 in T. californicus. Numbers of fixed substitutions and sites are for comparisons of GOT1 homologs. 2019-05-06 Public Download
file details List of potential sites of gene conversion. Results are obtained from the program GENE_CONV. 2019-05-06 Public Download
file details Plot of conservation of GOT1 proteins from arthropods with divergent regions of T. californicus GOT1p1_GOT1p2 highlighted. 2019-05-06 Public Download
file details Most parsimonious tree for relationships among GOT paralogs. 2019-05-06 Public Download
file details 1471-2148-13-148.xml 2019-05-06 Public Download