Earliest migratory cephalic NC cells are potent to differentiate into dental ectomesenchyme of the two lungfish dentitions: tetrapodomorph ancestral condition of unconstrained capability of mesencephalic NC cells to form oral teeth

2021 ◽  
Vol 108 (5) ◽  
Author(s):  
Martin Kundrát
Keyword(s):  
Ancestral Condition

The cytotaxonomy of three species in the jenningsi-group of the subgenus Simulium (Diptera: Simuliidae) in New York State

1984 ◽  
Vol 62 (3) ◽  
pp. 347-354 ◽  
Author(s):  
A. Elizabeth Gordon
Keyword(s):  
New York ◽  
Sex Determination ◽  
Sibling Species ◽  
New York State ◽  
York State ◽  
Ancestral Condition ◽  
Finger Lakes ◽  
Finger Lakes Region

The chromosomal constitutions of three species in the jenningsi-group in the Adirondacks and the Finger Lakes Region in New York State are detailed. No sibling species were found in Simulium jenningsi, S. fibrinflatum, or S. luggeri in these areas. The species were found to differ by 6 fixed inversions and by 19 floating inversions. 4 of which are related to sex determination in S. jenningsi. The major chromosomal differences between the venustutm-group and the jenningsi-group are detailed. The ancestral condition for each arm was determined using ex-group and L′ analyses. A phylogenetic sequence for these three species from the ancestral condition is proposed.

A Comparative Study of Trichomes in Angophora Cav. And Eucalyptus L'hérit. - A Question of Homology

1984 ◽  
Vol 32 (5) ◽  
pp. 561 ◽  
Author(s):  
PY Ladiges
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Comparative Study ◽  
Light Microscopy ◽  
Evolutionary Trends ◽  
Oil Glands ◽  
Ancestral Condition ◽  
Scanning Electron

The trichomes of Angophora and Eucalyptus are illustrated from scanning electron microscopy and light microscopy, and evolutionary trends are discussed. Bristle glands of Angophora and Eucalyptus subgen. Blakella and Corymbia are emergent oil glands of varying lengths. Emergent oil glands occur in all other Eucalyptus subgenera but they are most conspicuous in Blakella, Corymbia and Angophora, in which they are characterized by four cap cells each ornamented with micropapillae. Hairs in Angophora are unique, being multicellular; they are also uniseriate and scattered on the epidermis. In contrast, hairs in Eucalyptus are simple extensions, short or long, of the cells on the sides of or the cap cells of the emergent oil glands, and they are not homologous with those of Angophora. Eucalyptus setosa (subgen. Blakella) and E. brockwayi (subgen. Symphyomyrtus) are two exceptions, having unicellular hairs on the epidermis, not associated with oil glands. It is suggested that this is an ancestral condition (or secondary reversal to it).

The enigmatic diapsid Acerosodontosaurus piveteaui (Reptilia: Neodiapsida) from the Upper Permian of Madagascar and the paraphyly of “younginiform” reptiles

2009 ◽  
Vol 46 (9) ◽  
pp. 651-661 ◽  
Author(s):  
Constanze Bickelmann ◽  
Johannes Müller ◽  
Robert R. Reisz
Keyword(s):  
Phylogenetic Analysis ◽  
Data Matrix ◽  
Upper Permian ◽  
Phylogenetic Position ◽  
Ancestral Condition ◽  
Phylogenetic Data ◽  
First Time ◽  
Evolutionary Lineages

A restudy of the Upper Permian diapsid Acerosodontosaurus piveteaui from Madagascar indicates that the bone formerly identified as the quadratojugal is a fragment of a rib. This in turn implies that, in contrast to previous studies, the lower temporal arcade must be considered incomplete and derived relative to the ancestral condition. Since the phylogenetic position of Acerosodontosaurus is poorly understood, the taxon was entered into a modified phylogenetic data matrix of diapsid reptiles, and the purported monophyly of “Younginiformes” was tested for the first time by including all potential members of the clade as separate taxa, as well as other taxa from the same deposits. The results of the phylogenetic analysis do not support the monophyly of “younginiform” reptiles. Instead, most taxa cluster unresolved at the base of Neodiapsida, a finding that has important implications for the understanding of early diapsid evolution because it suggests that early neodiapsids represent several distinct evolutionary lineages. Acerosodontosaurus and Hovasaurus do form a clade, a finding consistent with the stratigraphic age and biogeography of these taxa.

A phylogenetic perspective on absence and presence of a sex-limited polymorphism

2008 ◽  
Vol 58 (2) ◽  
pp. 257-273 ◽  
Author(s):  
Michelle. Mattern ◽  
Hans Van Gossum
Keyword(s):  
Mating System ◽  
North American ◽  
Phylogenetic Trees ◽  
Evolutionary Perspective ◽  
Ancestral Condition ◽  
End Point ◽  
Subsequent Loss ◽  
Phylogenetic Perspective

AbstractSex-limited polymorphism is widely distributed among animal taxa, but has only rarely been studied from a macro-evolutionary perspective. We investigate the evolution of female-limited polymorphism by mapping presence or absence of multiple discrete morphs on published phylogenetic trees for North American representatives of two damselfly genera. The results indicate that female polymorphy represents the ancestral condition based on the species included with subsequent loss and monomorphy representing the evolutionary end-point in most cases. According to one phylogeny, character optimization suggests that expression of the polymorphism may be lost (to a state of monomorphy) and gained again (back to polymorphy). Earlier work indicated that changes from polymorphy to monomorphy might be coupled with evolution of the mating system from polyandry to monandry. The results presented here, however, do not convincingly support such view.

The ontogeny of trilobite segmentation: a comparative approach

Paleobiology ◽  
2006 ◽  
Vol 32 (4) ◽  
pp. 602-627 ◽  
Author(s):  
Nigel C. Hughes ◽  
Alessandro Minelli ◽  
Giuseppe Fusco
Keyword(s):  
Direct Development ◽  
Comparative Approach ◽  
Phase Boundaries ◽  
Free Living ◽  
Ancestral Condition ◽  
Morphological Transitions ◽  
Posterior Trunk ◽  
Close Relatives ◽  
Number Of Segments ◽  
Trunk Segments

Ontogenetic stages of trilobites have traditionally been recognized on the basis of the development of exoskeletal segmentation. The established protaspid, meraspid, and holaspid phases relate specifically to the development of articulated joints between exoskeletal elements. Transitions between these phases were marked by the first and last appearances of new trunk segment articulations. Here we propose an additional and complementary ontogenetic scheme based on the generation of new trunk segments. It includes an anamorphic phase during which new trunk segments appeared, and an epimorphic phase during which the number of segments in the trunk remained constant. In some trilobites an ontogenetic boundary can also be recognized at the first appearance of morphologically distinct posterior trunk segments. Comparison of the phase boundaries of these different aspects of segment ontogeny highlights rich variation in the segmentation process among Trilobita. Cases in which the onset of the holaspid phase preceded onset of the epimorphic phase are here termed protarthrous, synchronous onset of both phases is termed synarthromeric, and onset of the epimorphic phase before onset of the holaspid phase is termed protomeric. Although these conditions varied among close relatives and perhaps even intraspecifically in some cases, particular conditions may have been prevalent within some clades.Trilobites displayed hemianamorphic development that was accomplished over an extended series of juvenile and mature free-living instars. Although developmental schedules varied markedly among species, morphological transitions during trilobite development were generally regular, limited in scope, and extended over a large number of instars when compared with those of many living arthropods. Hemianamorphic, direct development with modest change between instars is also seen among basal members of the Crustacea, basal myriapods, pycnogonids, and in some fossil chelicerates. This mode may represent the ancestral condition of euarthropod development.

Larval morphology and analysis of primary chaetotaxy in the genus  Suphis Aubé, 1836 (Coleoptera: Noteridae)

Zootaxa ◽  
2019 ◽  
Vol 4619 (1) ◽  
pp. 121-138 ◽  
Author(s):  
JUAN I. URCOLA ◽  
YVES ALARIE ◽  
CESAR J. BENETTI ◽  
GEORGINA RODRIGUEZ ◽  
MARIANO C. MICHAT
Keyword(s):  
Abdominal Segment ◽  
Distal Portion ◽  
The Other ◽  
Larval Morphology ◽  
Larval Instars ◽  
Ancestral Condition ◽  
Ground Plan ◽  
Other Hand ◽  
Segment Viii ◽  
First Time

The three larval instars of Suphis cimicoides Aubé, 1837 are described and illustrated, including morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment and urogomphus. A preliminary ground plan of primary chaetotaxy for noterid larvae is presented for the first time, based on the species described herein and examination of larvae of the genera Hydrocanthus Say, 1823 and Suphisellus Crotch, 1873. This ground plan is compared with previous systems proposed for other adephagan families. Larvae of Noteridae can be distinguished from those of other families of Hydradephaga by the following combination of characters: (1) antennomere 3 with a rugged area on distal portion; (2) abdominal segment VIII with a U-shaped wavy membranous area ventrally; (3) absence of pore FRd; and (4) presence of seta AB16. Several sensilla present in noterid larvae (notably setae TR2 and TA1 and pores PAl, PAm, COd, TRb and FEb) are absent in larvae of Meruidae. On the contrary, parietal seta PA5 is present in Meruidae but absent in Noteridae. The presence of pore COc in Noteridae may indicate that this family has retained the ancestral condition found only in Carabidae. On the other hand, the absence of setae FE7, FE8, FE9 and FE10 in Noteridae is similar to the condition found in Carabidae, Gyrinidae and Meruidae. 

Karyotypes of side-necked turtles (Testudines: Pleurodira)

1980 ◽  
Vol 58 (5) ◽  
pp. 828-841 ◽  
Author(s):  
James J. Bull ◽  
John M. Legler
Keyword(s):  
Sex Chromosome ◽  
Ancestral Condition ◽  
Chromosome Heteromorphism

Karyotypes are presented for 13 of the 14 genera of side-necked turtles (suborder Pleurodira, families Pelomedusidae and Chelidae). Pelomedusids have low diploid numbers and few microchromosomes (2n = 26–36); the five largest chromosomes are homologous in the three genera. Chelids have high diploid numbers and many microchromosomes (2n = 50–64) and are similar in this respect to cryptodires (2n = 50–66). The pelomedusid karyotype is regarded as derived, probably from an ancestral condition like that seen in chelids. Gross karyotypic differences are slight or nil within genera and among closely related pleurodiran genera. Triploidy probably occurs in Platemys platycephala (family Chelidae) which has 96 chromosomes. No sex chromosome heteromorphism was observed.

scholarly journals Can an ancestral condition for milk oligosaccharides be determined? Evidence from the Tasmanian echidna (Tachyglossus aculeatus setosus)

Glycobiology ◽  
2014 ◽  
Vol 24 (9) ◽  
pp. 826-839 ◽  
Author(s):  
Olav T Oftedal ◽  
Stewart C Nicol ◽  
Noel W Davies ◽  
Nobuhiro Sekii ◽  
Epi Taufik ◽  
...  
Keyword(s):  
Milk Oligosaccharides ◽  
Ancestral Condition ◽  
Tachyglossus Aculeatus

scholarly journals Testing models of dental development in the earliest bony vertebrates, Andreolepis and Lophosteus

2012 ◽  
Vol 8 (5) ◽  
pp. 833-837 ◽  
Author(s):  
John A. Cunningham ◽  
Martin Rücklin ◽  
Henning Blom ◽  
Hector Botella ◽  
Philip C. J. Donoghue
Keyword(s):  
Synchrotron Radiation ◽  
Skeletal Development ◽  
Dental Development ◽  
Ancestral Condition ◽  
X Ray ◽  
Phylogenetic Classification ◽  
Mineralized Tissues ◽  
Development And Evolution ◽  
Successional Development

Theories on the development and evolution of teeth have long been biased by the fallacy that chondrichthyans reflect the ancestral condition for jawed vertebrates. However, correctly resolving the nature of the primitive vertebrate dentition is challenged by a dearth of evidence on dental development in primitive osteichthyans. Jaw elements from the Silurian–Devonian stem-osteichthyans Lophosteus and Andreolepis have been described to bear a dentition arranged in longitudinal rows and vertical files, reminiscent of a pattern of successional development. We tested this inference, using synchrotron radiation X-ray tomographic microscopy (SRXTM) to reveal the pattern of skeletal development preserved in the sclerochronology of the mineralized tissues. The tooth-like tubercles represent focal elaborations of dentine within otherwise continuous sheets of the dermal skeleton, present in at least three stacked generations. Thus, the tubercles are not discrete modular teeth and their arrangement into rows and files is a feature of the dermal ornamentation that does not reflect a polarity of development or linear succession. These fossil remains have no bearing on the nature of the dentition in osteichthyans and, indeed, our results raise questions concerning the homologies of these bones and the phylogenetic classification of Andreolepis and Lophosteus .

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