Biological Invasions

, Volume 10, Issue 8, pp 1229–1242

Red shiner invasion and hybridization with blacktail shiner in the upper Coosa River, USA

  • David M. Walters
  • Mike J. Blum
  • Brenda Rashleigh
  • Byron J. Freeman
  • Brady A. Porter
  • Noel M. Burkhead
Original Paper


Human disturbance increases the invasibility of lotic ecosystems and the likelihood of hybridization between invasive and native species. We investigated whether disturbance contributed to the invasion of red shiner (Cyprinella lutrensis) and their hybridization with native blacktail shiner (C. venusta stigmatura) in the Upper Coosa River System (UCRS). Historical records indicated that red shiners and hybrids rapidly dispersed in the UCRS via large, mainstem rivers since the mid to late 1990s. We measured the occurrence and abundance of parental species and hybrids near tributary-mainstem confluences and characterized populations at these incipient contact zones by examining variation across morphological traits and molecular markers. Red shiners represented only 1.2% of total catch in tributaries yet introgression was widespread with hybrids accounting for 34% of total catch. Occurrence of red shiners and hybrids was highly correlated with occurrence of blacktail shiners, indicating that streams with native populations are preferentially colonized early in the invasion and that hybridization is a key process in the establishment of red shiners and their genome in new habitats. Tributary invasion was driven by post-F1 hybrids with proportionately greater genomic contributions from blacktail shiner. Occurrence of red shiners and hybrids and the relative abundance of hybrids significantly increased with measures of human disturbance including turbidity, catchment agricultural land use, and low dissolved oxygen concentration. Red shiners are a significant threat to Southeast Cyprinella diversity, given that 41% of these species hybridize with red shiner, that five southeastern drainages are invaded, and that these drainages are increasingly disturbed by urbanization.


Land use Turbidity Hybrid swarm Introgression Southeastern fishes Disturbance 



Upper Coosa River System


Georgia Museum of Natural History


Polymerase chain reaction restriction fragment length polymorphism


Mitochondrial deoxyribonucleic acid


Base pair

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • David M. Walters
    • 1
  • Mike J. Blum
    • 1
    • 2
  • Brenda Rashleigh
    • 3
  • Byron J. Freeman
    • 4
  • Brady A. Porter
    • 5
  • Noel M. Burkhead
    • 6
  1. 1.U.S. Environmental Protection Agency, National Exposure Research LaboratoryCincinnatiUSA
  2. 2.Department of Ecology and Evolutionary BiologyTulane UniversityNew OrleansUSA
  3. 3.U.S. Environmental Protection Agency, National Exposure Research LaboratoryAthensUSA
  4. 4.Georgia Museum of Natural History and Odum School of EcologyUniversity of GeorgiaAthensUSA
  5. 5.Department of Biological SciencesDuquesne UniversityPittsburghUSA
  6. 6.U.S. Geological Survey, Florida Integrated Science CenterGainesvilleUSA

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