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

Sassaman, Clay; Simovich, Marie A.; Fugate, Michael

doi:10.1007/978-94-017-3177-5_14

Cited by 32 publications

(43 citation statements)

References 36 publications

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“…Species determination followed the keys by Longhurst (1955) and Rogers (2001) and the characters given by Sassaman et al (1997) and . One sample from Bolivia could not be determined morphologically because it had not reached maturity.…”

Section: Determination Of Specimensmentioning

confidence: 99%

“…For this purpose, a reduced version of the 'Notostraca taxon set' was generated that comprises all outgroup sequences of Anostraca and Spinicaudata as listed above, and a representative subset of notostracan sequences (mainly reduced by excluding some closely related conspecific sequences. The divergence time between Triops longicaudatus and T. newberryi was not dated because they likely form a case of introgression, as inferred from comparison of results from allozymes in Sassaman et al, 1997, with results from mitochondrial markers, e.g. in Vanschoenwinkel et al, 2012).…”

Section: Divergence Time Estimationmentioning

confidence: 99%

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Molecular phylogeny of the Notostraca

Korn

Rabet

Ghate³

et al. 2013

Molecular Phylogenetics and Evolution

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a b s t r a c tWe used a combined analysis of one nuclear (28S rDNA) and three mitochondrial markers (COI, 12S rDNA, 16S rDNA) to infer the molecular phylogeny of the Notostraca, represented by samples from the six continents that are inhabited by this group of branchiopod crustaceans. Our results confirm the monophyly of both extant notostracan genera Triops and Lepidurus with good support in model based and maximum parsimony analyses. We used branchiopod fossils as a calibration to infer divergence times among notostracan lineages and accounted for rate heterogeneity among lineages by applying relaxed-clock models. Our divergence date estimates indicate an initial diversification into the genera Triops and Lepidurus in the Mesozoic, most likely at a minimum age of 152.3-233.5 Ma, i.e., in the Triassic or Jurassic. Implications for the interpretation of fossils and the evolution of notostracan morphology are discussed. We further use the divergence date estimates to formulate a biogeographic hypothesis that explains distributions of extant lineages predominantly by overland dispersal routes. We identified an additional hitherto unrecognised highly diverged lineage within Lepidurus apus lubbocki and three additional previously unknown major lineages within Triops. Within T. granarius we found deep differentiation, with representatives distributed among three major phylogenetic lineages. One of these major lineages comprises T. cancriformis, the T. mauritanicus species group and two hitherto unrecognised T. granarius lineages. Samples that were morphologically identified as T. granarius diverged from the most basal nodes within this major lineage, and divergence dates suggested an approximate age of 23.7-49.6 Ma for T. cancriformis, indicating the need for a taxonomic revision of Triassic and Permian fossils that are currently attributed to the extant T. cancriformis. We thus elevate T. cancriformis minor to full species status as Triops minor Trusheim, 1938 and include in this species the additional Upper Triassic samples that were attributed to T. cancriformis. We further elevate T. cancriformis permiensis to full species status as Triops permiensis Gand et al., 1997.

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Section: Determination Of Specimensmentioning

confidence: 99%

Section: Divergence Time Estimationmentioning

confidence: 99%

Molecular phylogeny of the Notostraca

Korn

Rabet

Ghate³

et al. 2013

Molecular Phylogenetics and Evolution

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“…If selffertilization, rather than automixis, indeed occurs in Holopedium or other cladocerans, it could simply reflect the recovery of a trait that was common in ancestral branchiopod lineages. Certainly, self-fertilization is prevalent in both notostracans (Sassaman et al 1997) and conchostracans (Sassaman 1995). In particular, breeding systems appear to be very labile among members of the conchostracan order Spinicaudata.…”

Section: Discussionmentioning

confidence: 99%

“…The latter breeding system is unknown in cladocerans but is common in two allied groups of branchiopod crustaceans, the notostracans and conchostracans (Sassaman 1995;Sassaman et al 1997;Weeks et al 2000). Because of this fact, a firm diagnosis of reproductive system for female-only populations requires either formal breeding studies or the survey of genotypic diversity in natural populations.…”

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confidence: 99%

Life at low temperatures: A novel breeding‐system adjustment in a polar cladoceran

Rowe

Adamowicz

2007

Limnology & Oceanography

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The typical breeding system of cladocerans, cyclic parthenogenesis, is poorly suited to polar settings because it requires one or more rounds of parthenogenesis before the production of males and sexual eggs. Past work has shown that many arctic cladocerans have secondarily made the transition to obligate, apomictic parthenogenesis. Arctic populations of Holopedium gibberum lack males, suggesting their possible adoption of this breeding system. However, this study shows that these lineages instead possess genotypic characteristics expected under either selffertilization or automictic parthenogenesis, the first record of such a breeding system in the Cladocera. As populations of Holopedium from southerly areas reproduce by cyclic parthenogenesis, this breeding system transition appears to represent an adaptive response to living at low temperatures.

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“…In spite of their "unusual morphological conservatism" (Fisher 1990), Notostraca and also Conchostraca show an extensive variation in their reproductive biology with an array of highly diversified reproductive modes that adds many problems to their taxonomy. In particular, reproductive strategies of even a single taxon may range from gonochorism (sex ratio varying in different populations from equality to a female or a male bias) to self fertilizing hermaphroditism and parthenogenesis; further, Triops newberryi (Packard) (Notostraca) and Eulimnadia texana Packard (Conchostraca) (Sassaman 1991(Sassaman , 1995Sassaman et al 1997;Weeks et al 2000) are known as androdioecious animal systems (populations embody males in low frequencies and self-compatible hermaphrodites).…”

Section: Notostraca and Conchostraca Are Crustaceanmentioning

confidence: 99%

Chromosomes in sexual populations of Notostracan and Con-chostracan taxa (Crustacea, Branchiopoda)

Marescalchi¹,

Cesari²,

Eder

et al. 2005

Caryologia

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-Branchiopods reproductive mechanisms range from gonochorism to unisexuality, passing through androdioecy. In order to contribute to still lacking or controversial basic knowledges, we analyzed the karyotype of the main Italian taxa: the Notostracan living fossils Triops cancriformis (parthenogenetic) and Lepidurus apus lubbocki (bisexual), and the Conchostracan Eoleptestheria ticinensis (bisexual). Also one male obtained from a supposedly hermaphroditic Austrian population of T. cancriformis was checked. In T. cancriformis a diploid number of 12 chromosomes is observed in both females and male; this is in line with previous results on other Italian populations, but contrasts with observations on European samples. The richness of normal meiotic pictures indicates that the male specimen is able to produce sperms. L. apus lubbocki shows a diploid number of 10 chromosomes; in male specimens the mispairings during meiosis I could explain the haploid number of 6 chromosomes obtained from diakinetic plates in Palestinian samples of the same subspecies found in literature. Irregular meiotic divisions also highlight the ultrastructurally observed abortive spermatogenesis. Finally, in the presently analyzed population of E. ticinensis, the adult females show 10 chromosomes as diploid number, while males present 10 or 11 elements; in the nauplii, chromosome numbers range from 8 to 12, differing among unrelated individuals, between nauplii produced by the same female and even within the same nauplius. B elements are taken into account.

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

Cited by 32 publications

References 36 publications

Molecular phylogeny of the Notostraca

Molecular phylogeny of the Notostraca

Life at low temperatures: A novel breeding‐system adjustment in a polar cladoceran

Chromosomes in sexual populations of Notostracan and Con-chostracan taxa (Crustacea, Branchiopoda)

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