A Population Without Females: Males of Baseodiscus delineatus (Nemertea: Heteronemertea) Reproduce Asexually by Fragmentation

Ikenaga, Jumpei; Hookabe, Natsumi; Kohtsuka, Hisanori; Yoshida, Manabu; Kajihara, Hiroshi

doi:10.2108/zs180203

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…On the other hand, fewer lineages are capable of regenerating a head. Within Nemertea, several species have independently gained this remarkable ability, one of the latest examples being Baseodiscus delineatus examined in Japan where male specimens reproduce by fissiparity in populations that appear to lack females (Ikenaga et al 2019;Zattara et al 2019). The best studied nemertean species in this respect is Lineus (= Ramphogordius) sanguineus that has already been studied for more than 200 years for its spontaneous fragmentation and regenerative capacities (e.g.…”

Section: Introductionmentioning

confidence: 99%

Occasional sexual reproduction significantly affects the population structure of the widespread, predominantly asexually reproducing marine worm Lineus sanguineus (Nemertea: Pilidiophora)

Sagorny

Döhren

2022

Mar Biol

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Asexual reproduction by fissiparity has only been described from very few of the approximately 1300 nemertean species that otherwise mainly reproduce sexually. The best studied fissiparous species, Lineus sanguineus (Rathke 1799), is a cosmopolitan heteronemertean species inhabiting intertidal habitats of temperate coasts. Although sexual reproduction has never been described, molecular data suggest that sexual reproduction substantially shapes the genetic structure of the investigated populations. In an attempt to clarify the extent of sexual reproduction, three gene fragments (COI, 16S, ITS) were sequenced for 108 specimens sampled in 8 European localities. The results of a phylogenetic analysis and haplotype network showed no clear distinction between different populations, thus indicating the presence of sexual reproduction. Furthermore, we provide circumstantial evidence for the presence of a comparably long-lived planktonic larval stage as present in the closest relatives of L. sanguineus. To further understand the impact of abiotic factors on sexual reproduction and fissiparity, the effect of different temperature and illumination regimes on reproductive behavior and fragmentation was studied in specimens from a population from Bergen, Norway that share the same haplotype. Experimental setups represented summer (long light period and elevated temperature) and winter (short light and decreased temperature) conditions. Under winter conditions, a higher number of animals remained sexually mature and at least one specimen shed eggs on one occasion. Thus, although short light and/or low temperatures are most likely the influential factors on sexual maturity, the factors that influence fissiparity are less clear. The results of this study further solidify the cosmopolitan status of L. sanguineus and clarify the population structuring of this species. In addition, the study provides first data on the dynamics of sexual and asexual reproduction modes on which future investigations will have to expand, especially regarding genetic and physiological aspects.

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Section: Introductionmentioning

confidence: 99%

Occasional sexual reproduction significantly affects the population structure of the widespread, predominantly asexually reproducing marine worm Lineus sanguineus (Nemertea: Pilidiophora)

Sagorny

Döhren

2022

Mar Biol

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“…Sexual reproduction in nemerteans may facilitate intraspecific and horizontal transfer of the microbiota. Furthermore, nemertean species are capable of asexual reproduction through fragmentation (Ikenaga et al, 2019;Zattara et al, 2019), which may also facilitate transfer of the microbiota directly to the new individuals, thereby offering an explanation for the observed patterns of phylosymbiosis in nemerteans. Lastly, as nemerteans primarily rely on predation, the acquisition of microbiota may vary depending on the specific prey species.…”

Section: Discussionmentioning

confidence: 99%

Microbiota associated with meiofaunal nemerteans reveals evidence of phylosymbiosis

Leasi,

Eckert,

Norenburg

et al. 2023

Preprint

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Phylosymbiosis, the association between the phylogenetic relatedness of hosts and the composition of their microbial communities, is a widespread phenomenon in diverse animal taxa. However, the generality of the existence of such a pattern has been questioned, and there seems evidence against its occurrence in small-sized aquatic animals, for which the microbiota composition is mostly shaped by local environmental factors. This study aims to investigate the microbial communities associated with poorly known marine interstitial nemerteans to uncover their microbiota diversity and assess the occurrence of phylosymbiosis. Through a comprehensive approach, specimens from various Central American sites were analyzed using morphology-based taxonomy and molecular techniques targeting the host 18S rRNA gene whereas their microbial association was analyzed by targeting the prokaryotic 16S rRNA gene. Phylogenetic and statistical analyses were conducted to examine the potential effects of host nemertean taxa and sampling locations on the host-associated microbial communities. The results provide compelling evidence of phylosymbiosis in meiofaunal nemerteans, emphasizing the significant impact of host genetic relatedness on microbiome diversity also in small-sized animals. Additional research is needed to fully unravel potential symbiotic relationships as well as the complex mechanisms that govern the relationships between hosts and their microbiota across various organisms and ecological settings. The remarkable diversity of meiofaunal animals, spanning various animal phyla with different lifestyles and inhabiting diverse ecosystems, combined with the advancements in multi-omics approaches, offers a promising avenue for comprehensive understanding of the evolutionary and ecological interactions between hosts and their microbiota throughout the animal tree of life.

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“…Ament-Velásquez et al 2016). However, asexual reproduction by fragmentation in the valenciniid Baseodiscusdelineatus (Delle Chiaje, 1825) (Ikenaga et al 2019) and B.hemprichii (Ehrenberg, 1831) (Kajihara and Hookabe 2019), as well as head-regenerative ability in the lineid Cerebratuluslineolatus Coe, 1905 (Zattara et al 2019), Lineuspictifrons Coe, 1904 (Coe 1932), and L.rubescens Coe, 1904 (Coe 1930), have been documented. Asexual reproductive capacity may have evolved in more lineages than previously thought among heteronemerteans, possibly including Y.pratensis .…”

Section: Discussionmentioning

confidence: 99%

Morphological and molecular study on Yininemertes pratensis (Nemertea, Pilidiophora, Heteronemertea) from the Han River Estuary, South Korea, and its phylogenetic position within the family Lineidae

Park

Lee

Sun

et al. 2019

Self Cite

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Outbreaks of ribbon worms observed in 2013, 2015, and 2017–2019 in the Han River Estuary, South Korea, have caused damage to local glass-eel fisheries. The Han River ribbon worms have been identified as Yininemertespratensis (Sun & Lu, 1998) based on not only morphological characteristics compared with the holotype and paratype specimens, but also DNA sequence comparison with topotypes freshly collected near the Yangtze River mouth, China. Using sequences of six gene markers (18S rRNA, 28S rRNA, histone H3, histone H4, 16S rRNA, and COI), the phylogenetic position of Y.pratensis was inferred among other heteronemerteans based on their sequences obtained from public databases. This analysis firmly placed Y.pratensis as a close relative to Apatronemertesalbimaculosa Wilfert & Gibson, 1974, which has been reported from aquarium tanks containing tropical freshwater plants in various parts of the world as well as a wild environment in Panama.

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A Population Without Females: Males of Baseodiscus delineatus (Nemertea: Heteronemertea) Reproduce Asexually by Fragmentation

Cited by 5 publications

References 30 publications

Occasional sexual reproduction significantly affects the population structure of the widespread, predominantly asexually reproducing marine worm Lineus sanguineus (Nemertea: Pilidiophora)

Occasional sexual reproduction significantly affects the population structure of the widespread, predominantly asexually reproducing marine worm Lineus sanguineus (Nemertea: Pilidiophora)

Microbiota associated with meiofaunal nemerteans reveals evidence of phylosymbiosis

Morphological and molecular study on Yininemertes pratensis (Nemertea, Pilidiophora, Heteronemertea) from the Han River Estuary, South Korea, and its phylogenetic position within the family Lineidae

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