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Sex ratio, reproductive mode and genetic diversity in Triops cancriformis

Zierold, Thorid; Montero-Pau, Javier; Hänfling, Bernd; Gómez, Africa


Thorid Zierold

Javier Montero-Pau

Bernd Hänfling


1. Aquatic invertebrates display a wide array of alternative reproductive modes from apomixis to hermaphroditism and cyclical parthenogenesis. These have important effects on genetic diversity and population structure. Populations of the 'living fossil'Triops cancriformis display a range of sex ratios, and various reproductive modes are thought to underlie this variation. Using sex ratio information and histological analyses European populations have been inferred to be gonochoric (with separate males and females), selfing hermaphroditic and androdioecious, a rare reproductive mode in which selfing hermaphrodites coexist with variable proportions of males. In addition, some populations have been described as meiotic parthenogens. 2. Here we use population genetic analysis using microsatellite loci in populations with a range of sex ratios including a gonochoric population, and marker segregation patterns in heterozygote individuals reared in isolation, to clarify the reproductive mode in this species. 3. Our data show that populations in general have very low levels of genetic diversity. Non-gonochoric populations show lower genetic diversity, more heterozygote deficiencies, higher inbreeding coefficients and stronger linkage disequilibria than the gonochoric population. The maintenance of some heterozygosity in populations is consistent with some male influence in T. cancriformis populations, as would be expected from an androdioecious reproductive system. Results of marker segregation in eggs produced in isolation from non-gonochoric populations indicate that meiosis occurs and are consistent with two reproductive modes: selfing hermaphroditism and a type of ameiotic parthenogenesis. 4. Overall, our data indicate that androdioecy and selfing hermaphroditism are the most likely reproductive modes of non-gonochoric European Triops populations. Triops populations are strongly structured, suggesting high genetic drift and low levels of gene flow.


Zierold, T., Montero-Pau, J., Hänfling, B., & Gómez, A. (2009). Sex ratio, reproductive mode and genetic diversity in Triops cancriformis. Freshwater biology, 54(7), 1392-1405.

Journal Article Type Article
Acceptance Date Jan 29, 2009
Publication Date Jul 1, 2009
Print ISSN 0046-5070
Electronic ISSN 1365-2427
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 54
Issue 7
Pages 1392-1405
Keywords Aquatic Science
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