Search results for "evolutionary"

Selecting ribosomal protein genes for invertebrate phylogenetic inferences: how many genes to resolve the Mollusca?

2010

Summary 1. Multi-gene analyses are currently the gold standard in phylogenetics, despite limited taxon sampling. To facilitate broad taxon representation on an economically tolerable level, we optimize the gene selection for future PCR-based sampling strategies. 2. Highly expressed ribosomal proteins (RP) were sampled chiefly for molluscs, the second largest metazoan phylum with largely unknown internal relationships. Thirty-two new sequences for Lepidochitona cinerea (Polyplacophora) were integrated into a data-matrix of 79 RP genes, comprising 16 mollusc species (five classes). The resulting maximum likelihood tree was used to evaluate each single-gene tree according to its topological fi…

Evolutionary dynamics of imatinib-treated leukemic cells by stochastic approach

2008

The evolutionary dynamics of a system of cancerous cells in a model of chronic myeloid leukemia (CML) is investigated by a statistical approach. Cancer progression is explored by applying a Monte Carlo method to simulate the stochastic behavior of cell reproduction and death in a population of blood cells which can experience genetic mutations. In CML front line therapy is represented by the tyrosine kinase inhibitor imatinib which strongly affects the reproduction of leukemic cells only. In this work, we analyze the effects of a targeted therapy on the evolutionary dynamics of normal, first-mutant and cancerous cell populations. Several scenarios of the evolutionary dynamics of imatinib-tr…

Independence between developmental stability and canalization in the skull of the house mouse.

2000

The relationship between the two components of developmental homeostasis, that is canalization and developmental stability (DS), is currently debated. To appraise this relationship, the levels and morphological patterns of interindividual variation and fluctuating asymmetry were assessed using a geometric morphometric approach applied to the skulls of laboratory samples of the house mouse. These three samples correspond to two random-bred strains of the two European subspecies of the house mouse and their F1 hybrids. The inter- and intraindividual variation levels were found to be smaller in the hybrid group compared to the parental ones, suggesting a common heterotic effect on skull canali…

Description of Dryocosmus destefanii new species (Hymenoptera: Cynipidae: Cynipini) from Quercus suber L. in Italy

2018

A new species, Dryocosmus destefanii Cerasa & Melika n. sp. associated with a Cerris section oak, Quercus suber L., is described from Italy. Description, diagnosis, host associations and biology for the new species and an illustrated identification key to the Western Palaearctic Dryocosmus species are given. The description is supported by morphological and molecular data.  

La costruzione del concetto di omologia e i vincoli materiali della forma

2016

Il concetto di omologia riveste un ruolo centrale nella biologia teoretica contemporanea perché attorno ad esso e per suo tramite trovano articolazione numerosi progetti di ricerca miranti a ripensare la centralità dell’organismo, i suoi percorsi evolutivi e il significato della sua interazione con la realtà ambientale. La rete di omologie che tesse l’organismo permette di strutturarne e canalizzarne le innovazioni morfologiche e funzionali. Appunto questa componente sistemica rende dunque l’omologia un concetto fondamentale per una considerazione dinamica della forma vivente, come quella cui mira un’estetica che non intenda limitarsi a indagare sull’atteggiamento estetico e sulle produzion…

Studying bipedal dinosaur trackways using geometric morphometrics

2019

Phenotypic plasticity in haptoral structures of Ligophorus cephali (Monogenea: Dactylogyridae) on the flathead mullet (Mugil cephalus): A Geometric M…

2015

Abstract Evaluating phenotypic plasticity in attachment organs of parasites can provide information on the capacity to colonise new hosts and illuminate evolutionary processes driving host specificity. We analysed the variability in shape and size of the dorsal and ventral anchors of Ligophorus cephali from Mugil cephalus by means of geometric morphometrics and multivariate statistics. We also assessed the morphological integration between anchors and between the roots and points in order to gain insight into their functional morphology. Dorsal and ventral anchors showed a similar gradient of overall shape variation, but the amount of localised changes was much higher in the former. Statist…

Developmental integration in a functional unit: deciphering processes from adult dental morphology

2014

The evolution of mammalian dentition is constrained by functional necessity and by the non-independence of morphological structures. Efficient chewing implies coherent tooth coordination from development to motion, involving covariation patterns (integration) within dental parts. Using geometric morphometrics, we investigate the modular organization of the highly derived vole dentition. Integration patterns between and within the upper and lower molar rows are analyzed to identify potential modules and their origins (functional and developmental). Results support an integrated adult dentition pattern for both developmental and functional aspects. The integration patterns between opposing mo…

Evaluation of criteria for species delimitation of bagworm moths (Lepidoptera: Psychidae)

2014

Accurate identification of species is fundamental for biological research and necessary for species conservation. DNA bar- coding is particularly useful when identification using morphological characteristics is laborious and/or unreliable. However, bar- codes for species are dependent on the availability of reference sequences from correctly identified specimens. The traditional use of morphology to delimit the species boundaries of Finnish bagworm moths (Lepidoptera: Psychidae: Naryciinae: Dahliciini) is contro- versial because there is overlap in their morphological characteristics. In addition, there are no suitable molecular markers. We veri- fied the delimitation of seven out of eight…

Six3 demarcates the anterior-most developing brain region in bilaterian animals

2010

Abstract Background The heads of annelids (earthworms, polychaetes, and others) and arthropods (insects, myriapods, spiders, and others) and the arthropod-related onychophorans (velvet worms) show similar brain architecture and for this reason have long been considered homologous. However, this view is challenged by the 'new phylogeny' placing arthropods and annelids into distinct superphyla, Ecdysozoa and Lophotrochozoa, together with many other phyla lacking elaborate heads or brains. To compare the organisation of annelid and arthropod heads and brains at the molecular level, we investigated head regionalisation genes in various groups. Regionalisation genes subdivide developing animals …