Ontogeny of Bradleya normani (Brady): Shape Analysis of Landmarks

Kaesler, Roger L.; Foster, David William

doi:10.1016/s0920-5446(08)70184-5

Cited by 6 publications

(6 citation statements)

References 17 publications

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“…So far, studies have focused either solely on the ostracod outline (e.g., [14, 18, 22, 31, 57]) or on specific features of the valve (e.g., [12, 14, 16, 18, 22, 31, 48, 57]). The geometric morphometric approach applied here enabled the detailed documentation of the patterns of allometric growth in two species of Cytheridella , the discrimination of closely related species, as well as the differentiation of regional morphotypes in one of them.…”

Section: Resultsmentioning

confidence: 99%

“…The marine species Tyrrhenocythere amnicola (Sars, 1887) evinces greatest morphological changes between A-6 and A-5 [28]. Bradleya normani (Brady, 1866), in turn, shows greatest change between instars A-4 to A-3 and A-3 to A-2 [48]. Our dataset comprises juveniles only down to A-4; it is, thus, possible that distinct shape changes, which might have occurred earlier during ontogeny, remained unnoticed.…”

Section: Discussionmentioning

confidence: 99%

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Shape Variation in Neotropical Cytheridella (Ostracoda) Using Semilandmarks-Based Geometric Morphometrics: A Methodological Approach and Possible Biogeographical Implications

et al. 2016

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Geometric morphometrics offer effective methods to obtain information about shape and shape variability. In ostracodology, landmark-based methods are, however, not well established. To test the applicability of geometric morphometric analyses for ostracods, we investigated shape variation among recent and fossil populations of the genus Cytheridella using a combination of landmarks and semilandmarks. The study focuses on the species' intraspecific morphological variability on a supra-regional scale, comparing living populations from Florida, Yucatán, Colombia and Brazil. We performed Generalized least-squares Procrustes Analysis on 508 adult and juvenile specimens (valves) including stages A-1 to A-4. The analyses show that the primary pattern in shape variation is ontogenetic allometry, supporting a clear separation of adults and juveniles. Shape changes are relatively small during ontogeny from A-4 to A-1. Greatest modification of valve shape occurs during the last molt phase. Insufficient differentiation of sexes is caused by females with less developed brood pouches. Disentangling size- and non-size-dependent shape changes reveals regional differences between populations of the species C. ilosvayi and supports its taxonomic distinction from a fossil relative (C. danielopoli). The distribution of regional morphotypes of C. ilosvayi in Florida, Mexico, and Brazil are congruent with fly ways of water birds.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Shape Variation in Neotropical Cytheridella (Ostracoda) Using Semilandmarks-Based Geometric Morphometrics: A Methodological Approach and Possible Biogeographical Implications

et al. 2016

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“…Morphometric techniques have experienced a significant progress in recent decades (Bookstein, 1982; Foster & Kaesler, 1988; Rohlf, 1990; Lestrel, 1997a). Some methods, which have been extensively applied to well ornamented ostracods (Kaesler & Foster, 1987; Abe et al , 1988; Reyment et al , 1988; Reyment & Bookstein, 1993; Reyment, 1995), require the identification of diagnostic homologous sites (called ‘landmarks’) on the organism (Bookstein, 1991). For smooth or poorly ornamented ostracods, as with most nonmarine ostracods, outline analysis is used instead (Kaesler & Waters, 1972; Kaesler & Maddocks, 1984; Schweitzer et al , 1986; Burke et al , 1987; Schweitzer & Lohmann, 1990).…”

Section: Methodsmentioning

confidence: 99%

Morphological disparity in populations with and without sexual reproduction: a case study in Eucypris virens (Crustacea: Ostracoda)

Baltanás

Alcorlo

Danielopol

2002

Biological Journal of the Linnean Society

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Morphological disparity in carapace outline was investigated in sexual and asexual populations of a widely spread nonmarine ostracod, Eucypris virens (Jurine, 1820) (Crustacea, Ostracoda). Only shape similarities have been considered; size effect was removed by standardizing all outlines. Multivariate analysis of morphometric descriptors (Elliptic Fourier coefficients) show that efficient discriminant functions can be obtained to differentiate between sexual and asexual populations, left and right valves, as well as among local populations (86.7% correct classifications in average). Principal component analysis revealed main patterns in shape variability among average population shapes. Sexual dimorphism is shown in body size but not in carapace outline. Although two morphotypes, unrelated to geographical locality, have been recognized, shape variation was largely continuous among all populations. Disparity at the within-population level was similar for both right and left valves. Morphological disparity was lower in syngamic populations than in parthenogenetic populations. The results are discussed with regard to theories relating genetic and morphological diversity and to evidence on evolutionary ecology of reproductive modes in nonmarine ostracods. Advantages and further applications of morphometric analysis to taxonomic groups with rich fossil record, such as ostracods, is emphasized.

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“…They were used for morphological characterization of taxa (Baltanás & Danielopol, ), as well as for description of shape variations, especially those resulting from different environmental factors (Ramos et al, ). Numerous studies on ostracods applied landmark methods with diverse carapace ornaments and pores as landmarks (Elewa, ; Hunt, ; Kaesler & Foster, ; Reyment, ; Reyment & Bookstein, ; Reyment, Bookstein, McKenzie, & Majoran, ). Another, more frequently used, method in geometric morphometrics in ostracodology is the outline approach, utilizing Fourier Analysis or Linhart's B‐spline algorithms (Baltanás & Geiger, ; Van der Meeren, Verschuren, Ito, & Martens, ; Yin, Geiger, & Martens, ).…”

Section: Introductionmentioning

confidence: 99%

A complete survey of normal pores on a smooth shell ostracod (Crustacea): Landmark‐based versus outline geometric morphometrics

Karanovic

Lavtižar

Djurakić

2017

Journal of Morphology

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Pores and sensilla on ostracod shell have often been used in studies of ontogeny, taxonomy, and phylogeny of the group. However, an analysis of sexual dimorphism and variation between valves in the number and distribution of pores is lacking. Also, such studies have never been done on a widely distributed, morphologically variable, and weakly ornamented freshwater ostracod. Here, we survey pores in one such species, Physocypria kraepelini. We choose 27 homologous pores as landmarks for 2D-geometric morphometric analysis, with the aim to assess intersexual and between valves variation in size and shape relative to the Fourier outline analysis. This species has only simple (Type A) pores with and without a lip, and each pore carries an undivided sensory seta. Our results show that the total number of pores varies (from 270 to 296), but this is not associated with a specific valve. Males carry fewer pores than females, however no sex specific pores are found. Small intrapopulation divergence of the Cyt b molecular marker (1%) indicates that morphological variability is not species related. We found that P. kraepelini exhibits directional asymmetry of size and shape, sexual size dimorphism (SSD) but lacks sexual shape dimorphism (SShD). Two geometric morphometrics methods were congruent in the estimation of SSD, SShD, and directional asymmetry of shape but differ in the statistical evaluation of directional asymmetry of size. Contrary to other animal groups, our study suggests that ostracods have more pronounced directional asymmetry of shape compared to directional asymmetry of size.

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Ontogeny of Bradleya normani (Brady): Shape Analysis of Landmarks

Cited by 6 publications

References 17 publications

Shape Variation in Neotropical Cytheridella (Ostracoda) Using Semilandmarks-Based Geometric Morphometrics: A Methodological Approach and Possible Biogeographical Implications

Shape Variation in Neotropical Cytheridella (Ostracoda) Using Semilandmarks-Based Geometric Morphometrics: A Methodological Approach and Possible Biogeographical Implications

Morphological disparity in populations with and without sexual reproduction: a case study in Eucypris virens (Crustacea: Ostracoda)

A complete survey of normal pores on a smooth shell ostracod (Crustacea): Landmark‐based versus outline geometric morphometrics

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