Search results for "morphometrics"
showing 10 items of 108 documents
Categorical versus geometric morphometric approaches to characterizing the evolution of morphological disparity in Osteostraci (Vertebrata, stem Gnat…
2020
Morphological variation (disparity) tends to be evaluated through two non-mutually exclusive approaches: (i) quantitatively, through geometric morphometrics, and (ii) in terms of discrete, ‘cladistic’, or categorical characters. Uncertainty over the comparability of these approaches diminishes the potential to obtain nomothetic insights into the evolution of morphological disparity, and the few benchmarking studies conducted so far show contrasting results. Here, we apply both approaches to characterising morphology in the stem-gnathostome vertebrate clade Osteostraci, in order to assess congruence between these alternative methods as well as to explore the evolutionary patterns of the grou…
Functional adaptations in the craniofacial morphology of Malagasy primates: shape variations associated with gummivory in the family Cheirogaleidae.
2005
Summary The infraorder Lemuriformes is characterized by a high level of homoplasy that clouds the evolutionary signal. The analysis of the morphological disparity of the Malagasy primates' crania and mandibles demonstrates the high determinism of functional specializations and developmental constraints, regardless of the phylogeny. In the present work, the weight of functional constraints linked to diet — a putative source of homoplasy — is analyzed first at the level of the infraorder Lemuriformes as a whole, and secondly at the level of a single family, the Cheirogaleidae, chosen because it contains taxa with two different diets (omnivory and gummivory). Malagasy primates are characterize…
Three-dimensional geometric morphometrics of thorax-pelvis covariation and its potential for predicting the thorax morphology: A case study on Kebara…
2020
The skeletal torso is a complex structure of outstanding importance in understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as researchers apply their own anatomical expertise to the process. Among different fossil reconstruction methods, 3D geometric morphometric techniques have been increasingly used in the last decades. Two-block partial least squares analysis has shown great potential for predicting missing elements by exploiting the covariation between two structures (blocks) in a reference sample: one block can be predicted from the other one based on the strength of covariation between blocks. The first aim of this study is to test w…
First finding of Ityogonimus lorum and I. ocreatus co-infection in the Iberian mole, Talpa occidentalis.
2018
Abstract The Ityogonimus lorum-I. ocreatus co-infection is reported for the first time in the Iberian mole Talpa occidentalis in Asturias (NW Spain). Both Ityogonimus species are stenoxenous helminths of insectivores of the genus Talpa and they have often been found parasitizing the Iberian mole and also the European mole T. europaea, but a mixed infection had not been previously reported. The present study also highlights the main differential morphometric characteristics between I. lorum and I. ocreatus such as the body length, the ventral sucker diameter, the ratio between suckers and the distance between suckers.
Comparative morphometrics of sharpsnout seabream (Diplodus puntazzo Cetti, 1777), reared in different conditions
1999
The same genetic stock of sharpsnout seabream (Diplodus puntazzo), cultured in different conditions (lot A, monoculture tank; lot B, monoculture offshore cage; lot C, polyculture tank), was analysed using geometric morphometrics in order to detect changes in shape. Rearing in the offshore cage (lot B) had a significant effect on shape variation when compared to rearing in the two enclosed tanks (A and C). Fish from the tanks show a higher frequency (43.7% in lot A and 37.5% in lot C) of the so-called ‘goitred’ and ‘dorsal flat’ forms, their deformations shown by displacements in the corresponding landmarks of the infraopercular and dorsal areas. In contrast, the so-called ‘belly’ fish were …
Phenotypes of intermediate forms of Fasciola hepatica and F. gigantica in buffaloes from Central Punjab, Pakistan.
2013
AbstractFascioliasis is an important food-borne parasitic disease caused by the two trematode species, Fasciola hepatica and Fasciola gigantica. The phenotypic features of fasciolid adults and eggs infecting buffaloes inhabiting the Central Punjab area, Pakistan, have been studied to characterize fasciolid populations involved. Morphometric analyses were made with a computer image analysis system (CIAS) applied on the basis of standardized measurements. Since it is the first study of this kind undertaken in Pakistan, the results are compared to pure fasciolid populations: (a) F. hepatica from the European Mediterranean area; and (b) F. gigantica from Burkina Faso; i.e. geographical areas wh…
Mandible morphology, dental microwear, and diet of the extinct giant rats Canariomys (Rodentia: Murinae) of the Canary Islands (Spain)
2010
An ecomorphological approach of mandible shape through Fourier analyses combined with a paleodietary analysis of dental microwear patterns is used to reconstruct the diet of the extinct endemic Canariomys bravoi Crusafont, Pairo & Petter, 1964 and Canariomys tamarani Lopez-Martinez & Lopez-Jurado, 1987. These two large rodents, respectively, lived on Tenerife and Gran Canaria, the central islands of the Canarian Archipelago. Mandible shape and dental microwear respectively inform us on the volume of vegetal matter and on the presence of grass in the diet. Both Canariomys, which are of similar size, possess relatively similar mandible outlines and microwear patterns. For each species, a diet…
Evolutionary morphology in shape and size of haptoral anchors in 14 Ligophorus spp. (Monogenea: Dactylogyridae).
2017
The search for phylogenetic signal in morphological traits using geometric morphometrics represents a powerful approach to estimate the relative weights of convergence and shared evolutionary history in shaping organismal form. We assessed phylogenetic signal in the form of ventral and dorsal haptoral anchors of 14 species of Ligophorus occurring on grey mullets (Osteichthyes: Mugilidae) from the Mediterranean, the Black Sea and the Sea of Azov. The phylogenetic relationships among these species were mapped onto the morphospaces of shape and size of dorsal and ventral anchors and two different tests were applied to establish whether the spatial positions in the morphospace were dictated by …
Morphometric diversity of the mussel Brachidontes pharaonis in different coastal environments
2010
In the debate on how and why biodiversity evolves spatially and temporally and in an attempt to assess the further effects of anthropogenic activities, the ability of marine invertebrate to express a large spectrum of phenotypical plasticity can have a central role. The ability of a single genotype to produce more than one alternative form of morphology and/or physiological state should be larger in species living in highly changing waters like shallow habitats. Invertebrates, there, usually experience ample changes of temperature and food availability on annual, seasonal, diurnal and hourly bases which are the two main drivers leading the life histories of these organisms. In such circumst…
Species identification of the psammophilous tenebrionid beetles Phaleria acuminata Juster, 1852 and Phaleria bimaculata (Linnaeus, 1767) from central…
2013
Dominating global arid environments, from desert to coastal dunes, most Tenebrionidae are highly specific in their habitat preferences and display limited dispersal potential, thus exhibiting a remarkable degree of regional genetic and morphological differentiation. The tenebrionid genus Phaleria is speciose and widely distributed, with P. acuminata and P. bimaculata having a wide Mediterranean distribution, with numerous morphological differentiations at population level, often described as different taxa of doubtful taxonomical significance. In order to investigate the variability of the central Mediterranean populations of P. bimaculata and P. acuminata and to compare the results obtaine…