Patterns of intraspecific variation through ontogeny: a case study of the Cretaceous nautilid Eutrephoceras dekayi and modern Nautilus pompilius

Palaeontology ◽  
2020 ◽  
Vol 63 (5) ◽  
pp. 807-820
Author(s):  
Amane Tajika ◽  
Neil H. Landman ◽  
Naoki Morimoto ◽  
Kenji Ikuno ◽  
Tom Linn
Keyword(s):  
Intraspecific Variation ◽  
Nautilus Pompilius

scholarly journals Does intraspecific variation in the energy value of a prey species to its predators matter in studies of ecological energetics? A case study using insectivorous vertebrates

Ecoscience ◽  
1996 ◽  
Vol 3 (3) ◽  
pp. 247-251 ◽  
Author(s):  
Stephen J. Brooks ◽  
Michael C. Calver ◽  
Christopher R. Dickman ◽  
Catherine E. Meathrel ◽  
J. Stuart Bradley
Keyword(s):  
Intraspecific Variation ◽  
Prey Species ◽  
Energy Value ◽  
Ecological Energetics

Intraspecific variation in cephalopod conchs changes during ontogeny: perspectives from three-dimensional morphometry of Nautilus pompilius

Paleobiology ◽  
2018 ◽  
Vol 44 (1) ◽  
pp. 118-130 ◽  
Author(s):  
Amane Tajika ◽  
Naoki Morimoto ◽  
Ryoji Wani ◽  
Christian Klug
Keyword(s):  
Intraspecific Variation ◽  
Three Dimensional ◽  
Time Averaging ◽  
Common Pattern ◽  
Data Set ◽  
Nautilus Pompilius ◽  
The Past ◽  
Geographic Populations ◽  
Measurement Biases ◽  
Excessive Number

AbstractIntraspecific variation of organisms is of great importance to correctly carry out taxonomic work, which is a prerequisite for key disciplines in paleontology such as community paleoecology, biostratigraphy, and biogeography. However, intraspecific variation is rarely studied in ectocochleate cephalopods (ammonoids and nautiloids), for which an excessive number of taxa was established during the past centuries. Because intraspecific variation of fossilized organisms suffers from various biases (time averaging and taphonomy), an extant example is needed for actualistic comparison. We applied 3D morphometry to 93 specimens of Nautilus pompilius from three different geographic populations. This data set was used to examine the intraspecific variation throughout ontogeny in detail. Although there are slight differences between the populations as well as some measurement biases, a common pattern of intraspecific variation appears to be present. High variation in morphometric variables appears early in ontogeny and then decreases gradually in the following ontogenetic stages. Subsequently, the variation shows an increase again before maturity until a sharp increase or decrease occurs toward the end of ontogeny. Comparison with intraspecific variation of ammonoids and belemnites illustrated that some groups have ontogenetic patterns of intraspecific variation that are similar to that of N. pompilius. This implies that the abovementioned ontogenetic pattern of intraspecific variation might be common in some major cephalopod clades.

scholarly journals Intraspecific variation of phragmocone chamber volumes throughout ontogeny in the modern nautilidNautilusand the Jurassic ammoniteNormannites

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1306 ◽  
Author(s):  
Amane Tajika ◽  
Naoki Morimoto ◽  
Ryoji Wani ◽  
Carole Naglik ◽  
Christian Klug
Keyword(s):  
Computed Tomography ◽  
Sexual Dimorphism ◽  
Intraspecific Variation ◽  
Middle Jurassic ◽  
Growth Trajectories ◽  
Similar Morphology ◽  
Nautilus Pompilius ◽  
Computed Tomographic ◽  
History Of

Nautilusremains of great interest to palaeontologists after a long history of actualistic comparisons and speculations on aspects of the palaeoecology of fossil cephalopods, which are otherwise impossible to assess. Although a large amount of work has been dedicated toNautilusecology, conch geometry and volumes of shell parts and chambers have been studied less frequently. In addition, although the focus on volumetric analyses for ammonites has been increasing recently with the development of computed tomographic technology, the intraspecific variation of volumetric parameters has never been examined. To investigate the intraspecific variation of the phragmocone chamber volumes throughout ontogeny, 30 specimens of RecentNautilus pompiliusand two Middle Jurassic ammonites (Normannites mitis) were reconstructed using computed tomography and grinding tomography, respectively. Both of the ontogenetic growth trajectories from the twoNormannitesdemonstrate logistic increase. However, a considerable difference inNormanniteshas been observed between their entire phragmocone volumes (cumulative chamber volumes), in spite of their similar morphology and size. Ontogenetic growth trajectories fromNautilusalso show a high variation. Sexual dimorphism appears to contribute significantly to this variation. Finally, covariation between chamber widths and volumes was examined. The results illustrate the strategic difference in chamber construction betweenNautilusandNormannites. The former genus persists to construct a certain conch shape, whereas the conch of the latter genus can change its shape flexibly under some constraints.

scholarly journals How many ontogenetic points are needed to accurately describe the ontogeny of a cephalopod conch? A case study of the modern nautilid Nautilus pompilius

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8849
Author(s):  
Amane Tajika ◽  
Christian Klug
Keyword(s):  
Morphological Analysis ◽  
Growth Trajectories ◽  
Nautilus Pompilius ◽  
Ontogenetic Trajectories ◽  
Tomographic Data ◽  
Growth Changes ◽  
Growth Change ◽  
External Stimuli ◽  
Ideal Group

Recent advancements in tomographic techniques allow for detailed morphological analysis of various organisms, which has proved difficult in the past. However, the time and cost required for the post-processing of highly resolved tomographic data are considerable. Cephalopods are an ideal group to study ontogeny using tomography as the entire life history is preserved within a conch. Although an increasing number of studies apply tomography to cephalopod conchs, the number of conch measurements needed to adequately characterize ontogeny remains unknown. Therefore, the effect of different ontogenetic sampling densities on the accuracy of the resultant growth trajectories needs to be investigated. Here, we reconstruct ontogenetic trajectories of a single conch of Nautilus pompilius using different numbers of ontogenetic points to assess the resulting accuracies. To this end, conch parameters were measured every 10°, 30°, 45°, 90°, and 180°. Results reveal that the overall patterns of reconstructed growth trajectories are nearly identical. Relatively large errors appear to occur where growth changes occur, such as the points of hatching and the onset of morphogenetic countdown before the attainment of maturity. In addition, a previously undocumented growth change before hatching was detected when measurements were taken every 10°, 30°, and 45°, though this growth change was obscured when fewer measurements were used (90° and 180°). The lower number of measurements also masks the subtle fluctuating patterns of conch parameters in middle ontogeny. We conclude that the measurements of a conch every 30° and 45° permit a reasonably precise description of conch ontogeny in nautilids. Since ammonoids were likely more responsive to external stimuli than to nautilids, a much denser sampling may be required for ammonoids.

scholarly journals Intraspecific variation in the postcranial skeleton morphology in African clariids: a case study of extreme phenotypic plasticity

2004 ◽  
Vol 140 (3) ◽  
pp. 437-446 ◽  
Author(s):  
NATALIE DE SCHEPPER ◽  
DOMINIQUE ADRIAENS ◽  
GUY G. TEUGELS ◽  
STIJN DEVAERE ◽  
WALTER VERRAES
Keyword(s):  
Phenotypic Plasticity ◽  
Intraspecific Variation ◽  
Postcranial Skeleton
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