Multivariate Discrimination by Shape in Relation to Size

Humphries, Julian M.; Bookstein, Fred L.; Chernoff, Barry; Smith, Gerald R.; Elder, R. L.; Poss, Stuart G.

doi:10.1093/sysbio/30.3.291

Cited by 264 publications

(184 citation statements)

References 29 publications

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“…Prior to analysis, all body distance measurements were log 10 -transformed to remove positive correlations between the magnitudes and variances of measurements. Variation in these characters was then summarized using a modified principal components analysis (PCA) known as shearing (Humphries et al 1981;Bookstein et al 1985;Rohlf and Bookstein 1987). The first component from traditional PCA of morphometric data typically summarizes variation due to size and is generally interpreted as such.…”

Section: Statistical Analysesmentioning

confidence: 99%

Phenotypic Consequences of Genetic Variation in a Gynogenetic Complex of Phoxinus Eos-Neogaeus Clonal Fish (Pisces: Cyprinidae) Inhabiting a Heterogeneous Environment

et al. 2004

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We examined the genetic composition, habitat use, and morphological variation of a Phoxinus eos-neogaeus unisexual hybrid complex and its sexually reproducing progenitor species inhabiting beaver-modified drainages of Voyageurs National Park, Minnesota. In addition to the single diploid P. eos-neogaeus gynogenetic clone, triploid and diploid-triploid mosaic biotypes were present at our study sites. Both P. eos and P. neogaeus, and all three hybrid biotypes were ubiquitous throughout one intensively surveyed drainage, but abundances and relative frequencies of the parental species and hybrids varied considerably within and among successional environments. Data from a large number of additional sites indicated that the proportion of polyploid hybrids within an environment was negatively related to hybrid relative frequency, implying that the genomic constitution of hybrids is an important determinant of clonal fitness among successional environments. Statistical comparisons of variation along size-free multivariate body shape axes indicated that despite its genetic uniformity, the P. eos-neogaeus clone is no less variable than its sexual progenitors, suggesting that a single genotype may actually respond to environmental variation with as much phenotypic variation as a genetically variable sexual population. The incorporation and expression of a third genome in triploid and diploid-triploid mosaic biotypes derived from the gynogenetic clone significantly expanded phenotypic variation of the clone. This additional variation results in greater similarities in habitat use and morphological overlap with the parental species, primarily P. eos, the predominant sperm donor for gynogenetic hybrid females in this complex. Polyploid augmentation of a diploid gynogenetic clone appears to be typical in the P. eos-neogaeus complex, and the additional genetic and phenotypic variation that it generates has potentially significant ecological and evolutionary consequences for the success and persistence of a single genotype in highly variable environments.

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Section: Statistical Analysesmentioning

confidence: 99%

Phenotypic Consequences of Genetic Variation in a Gynogenetic Complex of Phoxinus Eos-Neogaeus Clonal Fish (Pisces: Cyprinidae) Inhabiting a Heterogeneous Environment

et al. 2004

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“…For the principal components analysis, principal components were calculated from a covariance matrix because the first principal component scores can be used to obtain bivariate allometric equations (Jolicoeur, 1963). Although size and shape are often confounded in the first two principal components in a multigroup analysis (Humphries et al, 1981), the present data did not show clear correlation between the first two principal components for each site. Therefore, individuals were compared based on second and third principal component scores without further adjustment for body size.…”

Section: Methodsmentioning

confidence: 58%

Genetic subdivision and morphological variation in a freshwater snail species complex formerly referred to as Viviparus georgianus (Lea)

Katoh

Foltz

1994

Biological Journal of the Linnean Society

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Genetic and morphological variation was studied in a brooding (ovoviviparous) and morphologically variable freshwater snail [ Viviparus georgianus (Lea)] species complex in southern Georgia and Florida. Eleven populations were clustered into three genetically isolated, allopatric groups characterized by 7 to 14 diagnostic loci out of the 38 loci examined. These allopatric groups were identified as V. georgianus (in eastern and southern Florida), V. limi (in the Ochlockonee River) and V. goodrichi (in the Florida panhandle). Nei's standard genetic distances between the species were large (0.23-0.52) compared to intraspecific distances (O.OCr0.06). Hierarchical F-statistics for differentiation among sites within drainage systems (FsD) for V. goodrichi and V. georgianus were large (0.519 and 0.387, respectively). The F,., values (differentiation among drainage systems within the total area sampled) were negative or close to zero, so most of the intraspecific genetic differentiation was due to differences among populations within drianage systems, rather than to differences among systems. Canonical discriminant analysis of nine shell morphological measurements separated all three species with little overlap. Principal components analysis of the shell morphology revealed intraspecific variation among sites possibly due to environmental effects. This study demonstrates the marked genetic and morphological variation among and within drainage systems in freshwater prosobranchs.

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“…Truss measurements are a powerful tool for the analysis of shape, and generally are designed to cover all, or most, of the animal's body (Strauss & Bookstein, 1982). Ideally, the truss lengths measured between these landmark points should be curved vectors, as generally they lie on curved surfaces (Humphries et al, 1981). However, in this study, all the distances measured were assumed to represent straight lines lying on a flat plane.…”

Section: Measurement Proceduresmentioning

confidence: 99%

Using truss networks to estimate the biomass of Oreochromis niloticus, and to investigate shape Characteristics

Hockaday

Beddow

Stone

et al. 2000

Journal of Fish Biology

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Truss and length measurements were made on 463 tilapia Oreochromis niloticus of known mass. These measurements were then used to build mathematical models to estimate tilapia biomass. Two different approaches were used to build the models. The first was to take some simple mathematical models, and to optimize them using least squares regression. The second approach was to build models using artificial neural network software. Models were built for two different but overlapping size ranges and both approaches were successful in creating models that estimated the total biomass to within 1%. The truss measurements were also used to assess the principal shape components of different sized tilapia. 2000 The Fisheries Society of the British Isles

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Multivariate Discrimination by Shape in Relation to Size

Cited by 264 publications

References 29 publications

Phenotypic Consequences of Genetic Variation in a Gynogenetic Complex of Phoxinus Eos-Neogaeus Clonal Fish (Pisces: Cyprinidae) Inhabiting a Heterogeneous Environment

Phenotypic Consequences of Genetic Variation in a Gynogenetic Complex of Phoxinus Eos-Neogaeus Clonal Fish (Pisces: Cyprinidae) Inhabiting a Heterogeneous Environment

Genetic subdivision and morphological variation in a freshwater snail species complex formerly referred to as Viviparus georgianus (Lea)

Using truss networks to estimate the biomass of Oreochromis niloticus, and to investigate shape Characteristics

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