Brachionus calyciflorus is a Species Complex: Mating Behavior and Genetic Differentiation Among Four Geographically Isolated Strains

Gilbert, John J.; Walsh, Elizabeth J.

doi:10.1007/s10750-005-4205-3

Cited by 94 publications

(44 citation statements)

References 27 publications

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“…Such divergence could have happened during speciation and would result in sexual isolation between diverged lineages (Gilbert, 2003b). It is true that some of the clones of B. calyciflorus represent separate lineages and may even belong to different members of a cryptic species complex (Gilbert & Walsh, 2005). Even provided there was divergence of the mixis signal, one would, however, expect sexual isolation in both directions: sexuals should be unable to induce asexuals and vice versa.…”

Section: Discussionmentioning

confidence: 99%

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Obligate asex in a rotifer and the role of sexual signals

Stelzer¹

2007

J of Evolutionary Biology

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Transitions to asexuality have occurred in many animals and plants, yet the biological mechanisms causing such transitions have often remained unclear. Cyclical parthenogens, such as cladocerans, rotifers or aphids often give rise to obligate asexual lineages. In many rotifers, chemical signals that accumulate during population crowding trigger the induction of sexual stages. In this study, I tested two hypotheses on the origin of obligate parthenogenesis in the rotifer Brachionus calyciflorus: (i) that obligate parthenogens have lost the responsiveness to the sexual signal; and (ii) that obligate parthenogens have lost the ability to produce the sexual signal. Pairwise cross‐induction assays among three obligate parthenogenetic strains and two cyclically parthenogenetic (sexual) strains were used to test these hypotheses. I found that obligate parthenogens can induce sexual reproduction in sexual strains, but not vice versa. This demonstrates that obligate parthenogens do still produce the sexual signal, but have lost responsiveness to that signal.

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Section: Discussionmentioning

confidence: 99%

“…NY in Fussmann et al. , 2003; TX, FL and GA in Gilbert & Walsh, 2005). Three of the strains were obligate parthenogens (FL, GA and NY), i.e.…”

Section: Methodsmentioning

confidence: 99%

Obligate asex in a rotifer and the role of sexual signals

Stelzer¹

2007

J of Evolutionary Biology

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“…The geographic origin of these two strains has been described in detail in an earlier study [31]. The rotifers were cultured in COMBO medium [32] with the unicellular algae Chlamydomonas reinhardii as food source (Strain: SAG11-32b, Sammlung fuer Algenkulturen, Goettingen, Germany).…”

Section: Methodsmentioning

confidence: 99%

Loss of Sexual Reproduction and Dwarfing in a Small Metazoan

et al. 2010

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BackgroundAsexuality has major theoretical advantages over sexual reproduction, yet newly formed asexual lineages rarely endure. The success, or failure, of such lineages is affected by their mechanism of origin, because it determines their initial genetic makeup and variability. Most previously described mechanisms imply that asexual lineages are randomly frozen subsamples of a sexual population.Methodology/Principal FindingsWe found that transitions to obligate parthenogenesis (OP) in the rotifer Brachionus calyciflorus, a small freshwater invertebrate which normally reproduces by cyclical parthenogenesis, were controlled by a simple Mendelian inheritance. Pedigree analysis suggested that obligate parthenogens were homozygous for a recessive allele, which caused inability to respond to the chemical signals that normally induce sexual reproduction in this species. Alternative mechanisms, such as ploidy changes, could be ruled out on the basis of flow cytometric measurements and genetic marker analysis. Interestingly, obligate parthenogens were also dwarfs (approximately 50% smaller than cyclical parthenogens), indicating pleiotropy or linkage with genes that strongly affect body size. We found no adverse effects of OP on survival or fecundity.Conclusions/SignificanceThis mechanism of inheritance implies that genes causing OP may evolve within sexual populations and remain undetected in the heterozygous state long before they get frequent enough to actually cause a transition to asexual reproduction. In this process, genetic variation at other loci might become linked to OP genes, leading to non-random associations between asexuality and other phenotypic traits.

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“…DNA was extracted using Aidlab DNA extraction kit (Aidlab Biotechnologies, Beijing), and 18S and Cox1 fragments amplified (Table 1) and sequenced to corroborate the accuracy of the morphological identification [16,18,22]. Degenerate primers were designed to match the generally conserved regions of mtDNA genes and used to amplify and sequence short fragments of 12s , Cox1 , Cox3 , Cytb , Nad1 and Nad4-5 genes.…”

Section: Methodsmentioning

confidence: 99%

“…Mitogenome sequence of one of the most abundant and most studied monogonont rotifers, Brachionus calyciflorus , is currently not available. It is a cryptic species complex, occurring in freshwater ecosystems, that represents an excellent system for inferring the evolutionary processes of phylogeographic structure due to its patchy nature of habitats, lack of hybridization and cyclical parthenogenesis [18,19]. In order to further explore the phenomenon of fragmented mitogenomes in monogonont rotifers, we have sequenced and analysed the mitogenome of Brachionus calyciflorus .…”

Section: Introductionmentioning

confidence: 99%

Monogonont Rotifer, Brachionus calyciflorus, Possesses Exceptionally Large, Fragmented Mitogenome

Nie

et al. 2016

PLoS ONE

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In contrast to the highly conserved mitogenomic structure and organisation in most animals (including rotifers), the two previously sequenced monogonont rotifer mitogenomes were fragmented into two chromosomes similar in size, each of which possessed one major non-coding region (mNCR) of about 4–5 Kbp. To further explore this phenomenon, we have sequenced and analysed the mitogenome of one of the most studied monogonont rotifers, Brachionus calyciflorus. It is also composed of two circular chromosomes, but the chromosome-I is extremely large (27 535 bp; 3 mNCRs), whereas the chromosome-II is relatively small (9 833 bp; 1 mNCR). With the total size of 37 368 bp, it is one of the largest metazoan mitogenomes ever reported. In comparison to other monogononts, gene distribution between the two chromosomes and gene order are different and the number of mNCRs is doubled. Atp8 was not found (common in rotifers), and Cytb was present in two copies (the first report in rotifers). A high number (99) of SNPs indicates fast evolution of the Cytb-1 copy. The four mNCRs (5.3–5.5 Kb) were relatively similar. Publication of this sequence shall contribute to the understanding of the evolutionary history of the unique mitogenomic organisation in this group of rotifers.

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Brachionus calyciflorus is a Species Complex: Mating Behavior and Genetic Differentiation Among Four Geographically Isolated Strains

Cited by 94 publications

References 27 publications

Obligate asex in a rotifer and the role of sexual signals

Obligate asex in a rotifer and the role of sexual signals

Loss of Sexual Reproduction and Dwarfing in a Small Metazoan

Monogonont Rotifer, Brachionus calyciflorus, Possesses Exceptionally Large, Fragmented Mitogenome

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