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Stricker, Stephen A.; Folsom, Michael W.

doi:10.1023/a:1003186611254

Cited by 39 publications

(6 citation statements)

References 35 publications

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“…In summary, our study rea rms previous interpretations of the evolution of substructures in nemertean sperm cells (Stricker and Folsom 1998;Döhren et al 2010;Chernyshev et al 2020;Yurchenko et al 2021). It also highlights the potential of sperm ultrastructure as a valuable source of characters for phylogenetic analyses.…”

Section: Discussionsupporting

confidence: 92%

“…According to this and other studies (Stricker and Folsom 1998;Döhren et al 2010), but in contrast to Döhren and Bartolomaeus (2006) nemertean spermatozoa consist of a sperm head and a single agellum. Although the sperm head may sometimes appear to be slightly subdivided, a separate midpiece containing the mitochondria and enwrapping the proximal section of the cilium is not present.…”

Section: Termssupporting

confidence: 54%

“…Sperm cells of all pilidiophoran species studied thus far possess at least three mitochondria, the majority of them ve mitochondria (Table 2). Outside the Pilidiophora a single mitochondrion is found, except for the hoplonemertean Malacobdella grossa, Nectonemertes mirabilis Verill, 1892 and an undetermined Callinera species (Afzelius 1971;Stricker and Folsom 1998;Yurchenko et al 2021). Due to their phylogenetic position, it is likely that an increased number of mitochondria evolved independently in both, so that a single mitochondrion represents the primary condition in Nemertea (Döhren et al 2010;Yurchenko et al 2021).…”

Section: Pilidiophoramentioning

confidence: 99%

“…Due to their phylogenetic position, it is likely that an increased number of mitochondria evolved independently in both, so that a single mitochondrion represents the primary condition in Nemertea (Döhren et al 2010;Yurchenko et al 2021). In several nonpilidiophoran nemertean species spermiogenesis was studied in, several mitochondria fuse to form a single one (Stricker and Folsom, 1998; Yurchenko and Chernychev 2022). These observations allow inferring that several mitochondria evolve by a truncated process of mitochondrial fusion (Döhren et al 2010;Yurchenko et al 2021).…”

Section: Pilidiophoramentioning

confidence: 99%

“…Hoplonemertea comprises Polystilifera and Monostilifera as sister groups. Stricker and Folsom (1998) provided rst data on the sperm ultrastructure of a polystiliferan, the pelagic Nectonemertes mirabilis. Their sperm cells possess several mitochondria and a cilium equipped with a rootlet.…”

Section: Hoplonemerteamentioning

confidence: 99%

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Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Bartolomaeus,

Bronkars,

Adam

et al. 2023

Preprint

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Sperm ultrastructure is frequently employed as a source for phylogenetic inference due to the ease of accessing spermatozoa. Despite being unicellular, sperm cells exhibit a relatively high number of diverse characters and character states. Spermatozoa are subject to strong sexual selection as they are finely tuned for maximizing male reproductive success. Given this strong functional constraint, one might anticipate the emergence of convergent characters in line with similar modes of reproduction. As a result, it might be expected that sperm cells do not possess substantial phylogenetic signal, with functional constraints overshadowing any evolutionary heritage. To test this assumption, we conducted a study on sperm ultrastructure in 12 nemertean species, representing closely related groups and major nemertean lineages. We analyzed these data for their phylogenetic signal within the context of the most recent nemertean phylogenies. Our findings demonstrate that, at all systematic levels, functional constraints imposed by sexual selection or the mode of reproduction do not supersede the influence of historical constraints on sperm ultrastructure.

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Section: Discussionsupporting

confidence: 92%

Section: Termssupporting

confidence: 54%

Section: Pilidiophoramentioning

confidence: 99%

Section: Pilidiophoramentioning

confidence: 99%

Section: Hoplonemerteamentioning

confidence: 99%

See 3 more Smart Citations

Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Bartolomaeus,

Bronkars,

Adam

et al. 2023

Preprint

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Multiple triggers of oocyte maturation in nemertean worms: The roles of calcium and serotonin

Stricker

Smythe

2000

J. Exp. Zool.

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Comparative sperm ultrastructure in Nemertea

Döhren

Beckers

Vogeler

et al. 2010

Journal of Morphology

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Although the monophyly of Nemertea is strongly supported by unique morphological characters and results of molecular phylogenetic studies, their ingroup relationships are largely unresolved. To contribute solving this problem we studied sperm ultrastructure of 12 nemertean species that belong to different subtaxa representing the commonly recognized major monophyletic groups. The study yielded a set of 26 characters with an unexpected variation among species of the same genus (Tubulanus and Procephalothrix species), whereas other species varied in metric values or only one character state (Ramphogordius). In some species, the sperm nucleus has grooves (Zygonemertes virescens, Amphiporus imparispinosus) that may be twisted and give a spiral shape to the sperm head (Paranemertes peregrina, Emplectonema gracile). To make the characters from sperm ultrastructure accessible for further phylogenetic analyses, they were coded in a character matrix. Published data for eight species turned out to be sufficiently detailed to be included. Comparative evaluation of available information on the sperm ultrastructure suggests that subtaxa of Heteronemertea and Hoplonemertea are supported as monophyletic by sperm morphology. However, the data do not provide information on the existing contradictions regarding the internal relationships of "Palaeonemertea." Nevertheless, our study provides evidence that sperm ultrastructure yields numerous potentially informative characters that will be included in upcoming phylogenetic analyses.

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Untitled

Cited by 39 publications

References 35 publications

Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Ultrastructure and phylogenetic significance of spermatozoa in Nemertea

Multiple triggers of oocyte maturation in nemertean worms: The roles of calcium and serotonin

Comparative sperm ultrastructure in Nemertea

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