, 359:125

Reproductive isolation and genetic differentiation in North American species of Triops (Crustacea: Branchiopoda: Notostraca)

  • Clay Sassaman
  • Marie A. Simovich
  • Michael Fugate

DOI: 10.1023/A:1003168416080

Cite this article as:
Sassaman, C., Simovich, M.A. & Fugate, M. Hydrobiologia (1997) 359: 125. doi:10.1023/A:1003168416080


Electrophoretic analysis of 31 populations, ranging from California to Kansas, indicates that the North American tadpole shrimp Triops longicaudatus (LeConte) is actually a mixture of at least two reproductively isolated species. In the central United States, the predominant species is T. longicaudatus, which is found typically in ephemeral prairie pools. In the southwestern United States, the predominant species is Triops newberryi (Packard), which characteristically inhabits large playa pools. The two species coexist occasionally and in sympatric situations they are reproductively isolated from each other. The two species are genetically distinct at a level greater than is typical of conspecific populations. These genetic differences are correlated with subtle morphological differences and profound differences in reproductive biology. Both species represent complexes of bisexual and unisexual populations. Bisexual populations of T. longicaudatus are usually composed of males and females in approximately equal frequencies; bisexual populations of T. newberryi are composed of males in low frequencies and self-compatible hermaphrodites. Unisexual populations of both species apparently consist entirely of self-compatible hermaphrodites.

allozymes androdioecy Triops longicaudatus Triops newberryi unisexuality 

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Clay Sassaman
    • 1
  • Marie A. Simovich
    • 2
  • Michael Fugate
    • 1
    • 3
  1. 1.Department of BiologyUniversity of CaliforniaRiversideUSA
  2. 2.Department of BiologyUniversity of San DiegoSan DiegoUSA
  3. 3.Joint Science DepartmentClaremont CollegesClaremontUSA

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