The ultrastructure of the spermatozoa of the worm lizard Amphisbaena alba (Squamata, Amphisbaenidae) and the phylogenetic relationships of amphisbaenians

1999 ◽  
Vol 77 (8) ◽  
pp. 1254-1264 ◽  
Author(s):  
Ruscaia D Teixeira ◽  
Guarino R Colli ◽  
Sônia N Báo
Keyword(s):  
Transverse Section ◽  
Base Plate ◽  
Sister Group ◽  
Mature Spermatozoon ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Intrafamilial Variability ◽  
Anatomical Characters ◽  
Phylogenetic Hypotheses ◽  
Constraint Tree

We describe the ultrastructure of epididymal spermatozoa of Amphisbaena alba and make comparisons with spermatozoa of other squamates. The mature spermatozoon of A. alba is filiform and characterized by the following features: the acrosome is depressed in transverse section; the perforatorial base plate is absent; the perforatorial tip is pointed; the perforatorium is single; the epinuclear lucent zone is well developed; the midpiece is moderately long; the mitochondria are columnar, forming regular circlets interrupted by dense bodies in transverse section; the dense bodies are solid, arranged in regular rings and linear series; the nuclear shoulders are rounded; the nucleus is elongate; the endonuclear canal is absent; fibers 3 and 8 are enlarged; multilaminar membranes are absent; and the fibrous sheath is in the midpiece. A phylogenetic analysis of squamates using spermatozoon-ultrastructure characters resulted in 2415 equally parsimonious, largely unresolved trees. The use of a constraint tree derived from gross anatomical characters suggested that the Amphisbaenia is the sister-group of the Autarchoglossa. We conclude that to improve the resolution of phylogenetic hypotheses derived from spermatozoon-ultrastructure characters, the number of characters ought to be increased, and more investigations are necessary to ascertain the degree of intrafamilial variability.

The ultrastructure of the spermatozoon of the northern water snake, Nerodia sipedon (Colubridae, Serpentes), with phylogenetic considerations

1994 ◽  
Vol 72 (9) ◽  
pp. 1648-1652 ◽  
Author(s):  
B. G. M. Jamieson ◽  
L. Koehler
Keyword(s):  
Base Plate ◽  
Mature Spermatozoon ◽  
Boiga Irregularis ◽  
Nerodia Sipedon ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Water Snake ◽  
Northern Water Snake ◽  
Distal Centriole ◽  
Electron Lucent

The ultrastructure of the spermatozoon of Nerodia sipedon conforms closely to that of other described snake sperm: it is filiform; the acrosome vesicle is in the form of a hollow, concentrically zoned cone that basally overlies a subacrosomal cone which invests the tapered anterior end of the nucleus; the putative perforatorium is a slender rod extending anteriorly from the subacrosomal cone; the midpiece contains dense bodies and mitochondria; the axonemal fibrous sheath extends anteriorly into the midpiece (squamate autapomorphy); 9 peripheral dense fibres surround the distal centriole and the axoneme in the midpiece, of which fibres adjacent to 3 and 8 are enlarged; and the endpiece lacks peripheral fibres and the fibrous sheath. The midpiece is very long (a synapomorphy of the Serpentes) and is surrounded by a multilaminar membrane (an autapomorphy). In the squamates, only snakes, including N. sipedon, retain microtubules external to the plasma membrane of the mature spermatozoon. Helically arranged zigzag mitochondria are shared (probably homoplasically) with iguanid sperm. A poorly developed "stopperlike" putative perforatorial base plate in N. sipedon, unknown in other snakes, is questionably homologous with that of gekkonids. An electron-lucent space caps the nuclear point, as in the snakes Boiga irregularis and Stegonotus cucullatus and in some other squamate orders.

Ultrastructure of Spermatozoa of Elaphe schrenckii (Reptilia, Squamata)

2020 ◽  
Vol 27 (3) ◽  
pp. 149-155
Author(s):  
Shan-Shan Wang ◽  
Yu-Yan Lu ◽  
Chen-Hao Yao ◽  
Shuo Qi ◽  
Jian-Xin Cheng ◽  
...  
Keyword(s):  
Cross Section ◽  
Neck Region ◽  
Base Plate ◽  
Laminar Structure ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Transmission Electron ◽  
Principal Piece ◽  
Distal Centriole ◽  
The Stability

Elaphe schrenckii (Serpentes, Colubridae), a kind of large nonvenomous snakes and great significance to maintain the stability of ecosystem in China. We provide detailed descriptions of the sperm microstructure and ultrastructure of E. schrenckii, experimented by light microscope and transmission electron microscope. The spermatozoon of E. schrenckii is filiform and consists of head and tail regions. The cross-section of acrosomal vesicle is always rounded and divided into medulla inside and cortex outside. The ultrastructure of acrosome complex observed the unilateral ridge, the single perforatorium, the perforatorium base plate, the epinuclear lucent zone, the subacrosomal space and the nuclear fossa at the end of nucleus connect the neck region. The neck region is short with the stratified laminar structure and observed the distal centriole and the proximal centriole are perpendicular and both consisted of nine triplets. Midpiece is long and observed the extracellular microtubules, the multilaminar membranec, the mitochondria with the dense bodies discontinuity distribting, the fibrous sheath, and the axoneme. The principal piece is after the annulus with no mitochondrias and the end piece with no mitochondrias neither the fibrous sheath. Our study contrasted the spermatozoa ultrastructure of 8 species belong to 5 families and 6 genera and added the sperm measurement compare, summarized that three Colubridae snakes are more similar than others momentarily but some specific characteristics in E. schrenckii and proved that the ultrastructure of sperm related to phylogeny in some ways.

Improved resolution of recalcitrant nodes in the animal phylogeny through the analysis of genome gene content and morphology

2021 ◽  
Author(s):  
Ksenia Juravel ◽  
Luis Porras ◽  
Sebastian Hoehna ◽  
Davide Pisani ◽  
Gert Wörheide
Keyword(s):  
Common Ancestor ◽  
Sister Group ◽  
The Other ◽  
Gene Content ◽  
Statistical Hypothesis ◽  
Phylogenetic Position ◽  
Last Common Ancestor ◽  
Statistical Hypothesis Testing ◽  
Animal Phylogeny ◽  
Phylogenetic Hypotheses

An accurate phylogeny of animals is needed to clarify their evolution, ecology, and impact on shaping the biosphere. Although multi-gene alignments of up to several hundred thousand amino acids are nowadays routinely used to test hypotheses of animal relationships, some nodes towards the root of the animal phylogeny are proving hard to resolve. While the relationships of the non-bilaterian lineages, primarily sponges (Porifera) and comb jellies (Ctenophora), have received much attention since more than a decade, controversies about the phylogenetic position of the worm-like bilaterian lineage Xenacoelomorpha and the monophyly of the "Superphylum" Deuterostomia have more recently emerged. Here we independently analyse novel genome gene content and morphological datasets to assess patterns of phylogenetic congruence with previous amino-acid derived phylogenetic hypotheses. Using statistical hypothesis testing, we show that both our datasets very strongly support sponges as the sister group of all the other animals, Xenoacoelomorpha as the sister group of the other Bilateria, and largely support monophyletic Deuterostomia. Based on these results, we conclude that the last common animal ancestor may have been a simple, filter-feeding organism without a nervous system and muscles, while the last common ancestor of Bilateria might have been a small, acoelomate-like worm without a through gut.

scholarly journals Towards a phylogeny of the Metazoa: evaluating alternative phylogenetic positions of Platyhelminthes, Nemertea, and Gnathostomulida, with a critical reappraisal of cladistic characters

2004 ◽  
Vol 73 (1-2) ◽  
pp. 3-163 ◽  
Author(s):  
Ronald A. Jenner
Keyword(s):  
Sister Group ◽  
Morphological Characters ◽  
Total Evidence ◽  
Morphological Data ◽  
Future Research ◽  
Sister Group Relationship ◽  
Cladistic Analyses ◽  
Phylogenetic Hypotheses ◽  
Data Matrices

This paper critically assesses all morphological cladistic analyses of the Metazoa that were published during the last one and a half decades. Molecular and total evidence analyses are also critically reviewed. This study focuses on evaluating alternative phylogenetic positions of the ‘acoelomate’ worms: Platyhelminthes, Nemertea, and Gnathostomulida. This paper consists of two parts. In Part I, all recently proposed sister group hypotheses and the supporting synapomorphies for these phyla are evaluated. Discrepancies in the treatment of corresponding characters in different cladistic analyses are identified, and where possible, resolved. In Part II, the overall phylogenetic significance across the Metazoa of all characters relevant for placing the ‘acoelomate’ worms is examined. The coding and scoring of these characters for other phyla are evaluated, and uncertainties in our understanding are pointed out in order to guide future research. The characters discussed in this paper are broadly categorized as follows: epidermis and cuticle, reproduction and sexual condition, development, larval forms, coeloms and mesoderm source, nervous system and sensory organs, nephridia, musculature, digestive system, and miscellaneous characters. Competing phylogenetic hypotheses are compared in terms of several criteria: 1) taxon sampling and the fulfillment of domain of definition for each character; 2) character sampling; 3) character coding; 4) character scoring and quality of primary homology; 5) quality of the proposed diagnostic synapomorphies as secondary homologies. On the basis of this study I conclude that a sister group for the Platyhelminthes has not yet been unambiguously established. A clade minimally composed of Neotrochozoa (Mollusca, Sipuncula, Echiura, Annelida) emerges as the most likely sister group of the Nemertea on the basis of morphological and total evidence analyses. Finally, morphological data currrently favor a sister group relationship of Gnathostomulida and Syndermata (probably plus Micrognathozoa). In contrast, molecular or total evidence analyses have not identified a reliable sister group of Gnathostomulida.Further progress in our understanding of metazoan phylogeny crucially depends on the improvement of the quality of currently adopted cladistic data matrices. A thorough reassessment of many of the more than 70 morphological characters discussed here is necessary. Despite the recent compilation of comprehensive data matrices, the power to test competing hypotheses of higher-level metazoan relationships is critically compromised due to uncritical data selection and poor character study in even the most recently published cladistic analyses.

Phylogenetic relationships of the subfamily Pyrgulinae (Gastropoda: Caenogastropoda: Hydrobiidae) with emphasis on the genus Dianella Gude, 1913

Zootaxa ◽  
2005 ◽  
Vol 891 (1) ◽  
pp. 1 ◽  
Author(s):  
Magdalena Szarowska ◽  
Andrzej Falniowski ◽  
FRANK Riedel ◽  
Thomas Wilke
Keyword(s):  
Type Species ◽  
Sister Group ◽  
Molecular Data ◽  
Character Evolution ◽  
Phylogenetic Position ◽  
Sister Group Relationship ◽  
Data Sets ◽  
Sequencing Data ◽  
The Family ◽  
Anatomical Characters

The phylogenetic position of the subfamily Pyrgulinae within the superfamily Rissooidea has been discussed very controversially. Different data sets not only led to different evolutionary scenarios but also to different systematic classifications of the taxon. The present study uses detailed anatomical data for two pyrgulinid taxa, the type species of the subfamily, Pyrgula annulata (Linnaeus, 1767), and the type species of the little known genus Dianella, D. thiesseana (Kobelt, 1878), as well as DNA sequencing data of three gene fragments from representatives of eight rissooidean families to A) infer the phylogenetic position of Pyrgulinae with emphasis on its relationships within the family Hydrobiidae, B) to study the degree of concordance between anatomyand DNAbased phylogenies and C) to trace the evolution of anatomical characters along a multi-gene molecular phylogeny to find the anatomical characters that might be informative for future cladistic analyses. Both anatomical and molecular data sets indicate either a very close or even sister-group relationship of Pyrgulinae and Hydrobiinae. However, there are major conflicts between the two data sets on and above the family level. Notably, Hydrobiidae is not monophyletic in the anatomical analysis. The reconstruction of anatomical character evolution indicates that many of the characters on which the European hydrobioid taxonomy is primarily based upon are problematic. The inability to clearly separate some hydrobiids from other distinct families based on those characters might explain why until only a few years ago, "Hydrobiidae" was a collecting box for numerous rissooidean taxa (mostly species with shells small and lacking any characteristic features). The present study not only stresses the need for comprehensive molecular studies of rissooidean taxa, it also demonstrates that much of the problems surrounding anatomical analyses in rissooidean taxa are due to the lack of comprehensive data for many representatives. In order to aid future comparativeanatomical studies and a better understanding of character evolution in the species-rich family Hydrobiidae, detailed anatomical descriptions for P. annulata and D. thiesseana are provided.Key words: Pyrgulinae, Pyrgula, Dianella, Hydrobiidae, phylogeny, DNA, anatomy, Greece

scholarly journals Phylogeny and biogeography of midwife toads (Alytes, Discoglossidae): a rebuttal

1997 ◽  
Vol 66 (4) ◽  
pp. 263-268
Author(s):  
J.W. Arntzen ◽  
M. García-París
Keyword(s):  
Sister Group ◽  
Evolutionary Rates ◽  
Sister Taxon ◽  
Phylogenetic Hypotheses ◽  
Time Of Divergence ◽  
Subsequent Splitting

Three competing phylogenetic hypotheses for the genus Alytes (midwife toads) are evaluated. Based on quantitative coding of protein characters the most parsimonious solution shows a sister taxon relationship for Alytes dickhilleni and A. muletensis. The alternatives in which A. obstetricans has its sister group in either A. dickhilleni or A. muletensis lack support. Using calibrations derived from protein evolutionary rates, the vicariant events giving rise to A. obstetricans and the lineage leading to the A. muletensis and A. dickhilleni clade and the subsequent splitting between A. muletensis and A. dickhilleni cannot be placed much earlier than the Miocene-Pliocene boundary. Biogeographical scenarios invoking an earlier time of divergence should be rejected.

A phylogeny of Plesiosauria (Sauropterygia) and its bearing on the systematic status of Leptocleidus Andrews, 1922

Zootaxa ◽  
2008 ◽  
Vol 1863 (1) ◽  
pp. 1 ◽  
Author(s):  
PATRICK S. DRUCKENMILLER ◽  
ANTHONY P. RUSSELL
Keyword(s):  
Late Jurassic ◽  
Cladistic Analysis ◽  
Sister Group ◽  
Phylogenetic Position ◽  
Sister Group Relationship ◽  
New Taxon ◽  
Short Neck ◽  
Operational Taxonomic Units ◽  
Phylogenetic Hypotheses ◽  
The Uk

Leptocleidus Andrews, 1922 is a poorly known plesiosaur genus from Lower Cretaceous successions of the UK, South Africa, and Australia. Historically, there has been little consensus regarding its phylogenetic position within Plesiosauria, largely because of its seemingly aberrant combination of a relatively small skull and short neck. As a result, a diverse array of potential sister groups have been posited for Leptocleidus, including long-necked Cretaceous elasmosaurids, Early Jurassic “rhomaleosaurs”, and Middle to Late Jurassic pliosaurids. A cladistic analysis including Leptocleidus, and a new, apparently morphologically similar specimen from Alberta, TMP 94.122.01, was undertaken to assess their phylogenetic position within Plesiosauria. A character-taxon matrix was assembled afresh, consisting of 33 operational taxonomic units sampled broadly among plesiosaurs. 185 cranial and postcranial characters used in plesiosaur phylogenetics were critically reanalyzed, of which 152 were employed in the parsimony analysis. The results indicate a basal dichotomous split into the traditionally recognized pliosauroid and plesiosauroid clades. Nested within Pliosauroidea, a monophyletic Leptocleididae was recovered, consisting of L. superstes Andrews, 1922 and L. capensis (Andrews, 1911a). In contrast to earlier suggestions, Leptocleidus neither clusters with Rhomaleosaurus, which was found to be paraphyletic, nor with large-skulled pliosaurid taxa, such as Simolestes. Rather, a sister group relationship between Cretaceous Polycotylidae and Leptocleididae was recovered, which is here named Leptocleidoidea. Although TMP 94.122.01 is superficially similar to Leptocleidus, several discrete characters of the skull nest this new taxon within Polycotylidae. Compared to other phylogenetic hypotheses of plesiosaurs, these results are more congruent with respect to the stratigraphic distribution of leptocleidoids. A classification for Plesiosauria is presented.

Ultrastructure of the spermatozoon of the tuatara ( Sphenodon punctatus ) and its relevance to the relationships of the Sphenodontida

1992 ◽  
Vol 335 (1274) ◽  
pp. 193-205 ◽  
Keyword(s):  
Posterior Extremity ◽  
Sister Group ◽  
Sister Group Relationship ◽  
Electron Microscopic ◽  
Fibrous Sheath ◽  
Sphenodon Punctatus ◽  
Principal Piece ◽  
Distal Centriole ◽  
Material Form ◽  
Complex Length

Spermatozoa of the New Zealand tuatara , Sphenodon punctatus punctatus (Gray), are described from light and electron microscopic observations and compared with spermatozoa of other living ‘reptiles’ (Chelonia, Crocodilia, Squamata), birds and mammals. Mature Sphenodon spermatozoa consist of an acrosomal complex (length 4 µm), elongate, helical nucleus (54-56 µm), a relatively short midpiece (7-8 µm), elongate principal piece (74-78 µm) and short end piece (2-4 µm). The acrosomal vesicle and underlying subacrosomal material form a double, curved, conical sheath around the nucleus anteriorly. Two parallel, loosely helical, endonuclear canals each containing perforatorial material, extend posteriorly from the apex of the nucleus to at least 2.5 µm below the base of the acrosomal complex. Rings of several spherical mitochondria are stacked around the elongate distal centriole to form the midpiece. Each mitochondrion has concentric cristae surrounding a dense central body. Proximal and distal centrioles, although differing markedly in length, are similar in having triplets with an open C tubule. Nine peripheral fibres are intimately associated with the triplets of the distal centriole. A well developed annulus defines the posterior extremity of the midpiece. The principal piece consists of a 9 + 2 axoneme (accompanied anteriorly by nine peripheral fibres) surrounded by a highly electron-dense fibrous sheath and the plasma membrane. Absence of a penis in Sphenodon has not resulted in recognizable modifications of the spermatozoon. Sphenodon shares many spermatozoal features here interpreted as plesiomorphies with crocodiles and turtles, particularly the latter group, but exhibits none of the advanced character states (apomorphies) diagnostic of the Squamata. These data not only underscore the primitive status of living tuatara (recently questioned in the literature) but also militate against a close, sister-group relationship between the Sphenodontida and Squamata.

Field, anatomical and development studies on southern Australian species of Ulva (Ulvaceae, Chlorophyta)

1988 ◽  
Vol 1 (4) ◽  
pp. 411 ◽  
Author(s):  
JA Phillips
Keyword(s):  
Cell Shape ◽  
Transverse Section ◽  
Distinct Species ◽  
Basal Region ◽  
Ulva Rigida ◽  
The West ◽  
Australian Species ◽  
Ulva Australis ◽  
The Status ◽  
Anatomical Characters

Populations of Ulva growing in southern Australia were examined to ascertain the taxonomic value of the range of morphological and anatomical characteristics. Cell shape and chlorplast position, as seen in transverse section of the basal region of the thallus, proved to be non-viable characters which separate the species from each other. In culture, the morphology of mature plant is constant and characteristic for each species and thus confirms the validity of the species as defined by anatomical differences. Five species of Ulva (Ulva fasciata Delile, Ulva lactuca L., Ulva laetevirens Areschoug, Ulva rigida C. Agardh, Ulva stenophylla Setchell et Gardner) occur in southern Australia. Ulva rigida C. Agardh and Ulva rigida sensu Bliding, through morphological similarities, are distinct species and the latter is referred to as U. laetevirens. The two species show marked differences in diagnostic anatomical characters and in the pattern of development in culture. Two taxa, Ulva australis Areschoug and Ulva spathulata Papenfuss, are included within U. rigida. Records of Ulva latissma L. in this geographical region probably refer to the broadly expanded morphological forms of U. rigida and U. laetevirens. The status of Phycoseris ulva Sonder, described from the West Australian specimens, is unresolved.

The phylogeny of cockroach families: a cladistic appraisal of morpho-anatomical data

1996 ◽  
Vol 74 (3) ◽  
pp. 508-527 ◽  
Author(s):  
Philippe Grandcolas
Keyword(s):  
Sister Group ◽  
Reproductive Behaviour ◽  
Consensus Tree ◽  
Strict Consensus Tree ◽  
Anatomical Data ◽  
The Family ◽  
Life Habits ◽  
Anatomical Characters ◽  
Test Current

Seventy-two morpho-anatomical characters were examined in 221 genera belonging to the families Blattidae, Polyphagidae, Blattellidae, and Blaberidae. They were cladistically analyzed and polarized using two mantids and two termites. As no autapomorphies of the family Blattellidae were found, the constituent subfamilies were used as terminal taxa together with other families. Three trees were found (CI = 0.81 and RI = 0.88, without autapomorphies) that differed only by the position of Nyctiborinae relative to Blattellinae and Ectobiinae. The strict consensus tree was [Blattidae [Polyphagidae [Anaplectinae [[Pseudophyllodromiidae, Blaberidae] [Nyctiborinae, Blattellinae, Ectobiinae]]]]]. The main discrepancies with McKittrick's tree were the monophyly of Polyphagidae (instead of paraphyly) and that the Blaberidae is the sister-group of Pseudophyllodromiinae (instead of the sister-group of Blattellinae, Ectobiinae, and Nyctiborinae). These results made it necessary to elevate the Anaplectinae and Pseudophyllodromiinae to familial status, and to give a new sense to the family Blattellidae, which includes only the subfamilies Blattellinae, Ectobiinae, and Nyctiborinae. This phylogeny was used to test current evolutionary hypotheses concerning sociality and reproductive behaviour; many traits were assumed to be ancestral to all cockroaches (protozoan symbionts and familial life habits) or preadaptive (progressing from advanced oviparity in Blattellidae to ovoviviparity in Blaberidae) that must actually be considered homoplasic.

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