Search results for "Lizards"
showing 10 items of 67 documents
Host-parasite relationships of Zootoca vivipara (Sauria: Lacertidae) in the Pyrenees (North Spain)
2000
The helminths infesting the common lizard, Zootoca vivipara (Jacquin, 1787), were studied with special attention to the relations between the number of nematodes, Oswaldocruzia filiformis (Goeze, 1782), and the size, sex and age class of the host. The possible seasonality of the parasite intensity and the relationship with the feeding habits of the host were also tested. Helminth infracommunities of Z. vivipara were depauperate with lizards harbouring only two species, the trematode Plagiorchis molini (Lent et Freitas, 1940) and the nematode O. filiformis. A positive correlation between host size and the number of O. filiformis was found for female Z. vivipara. However, no correlation was d…
Using visual modelling to study the evolution of lizard coloration: sexual selection drives the evolution of sexual dichromatism in lacertids
2012
Sexual selection has been invoked as a major force in the evolution of secondary sexual traits, including sexually dimorphic colorations. For example, previous studies have shown that display complexity and elaborate ornamentation in lizards are associated with variables that reflect the intensity of intrasexual selection. However, these studies have relied on techniques of colour analysis based on human – rather than lizard – visual perception. Here, we use reflectance spectrophotometry and visual modelling to quantify sexual dichromatism considering the overall colour patterns of lacertids, a lizard clade in which visual signalling has traditionally been underrated. These objective method…
Ascending projections from the optic tectum in the lizard Podarcis hispanica.
1998
The ascending projections of the optic tectum, including their cells of origin, have been studied in the lizard Podarcis hispanica by means of a two-step experimental procedure. First, tracers were injected in the tectum to study the anterograde labeling in the forebrain. Second, the cells of origin of these projections have been identified by analyzing the retrograde labeling after tracer injections in the thalamus, hypothalamus, and pretectum. Three main tectal ascending pathways have been described: the dorsal tecto-thalamic tract (dtt), the medial tecto-thalamic tract (mtt), and the ventral tecto-thalamic tract (vtt). The dtt originates in radial cells of layers 5 and 7 and bipolar cell…
Social behavior, chemical communication, and adult neurogenesis: Studies of scent mark function in Podarcis wall lizards
2011
Lacertid lizards have been hailed as a model system for the study of reptilian chemical communication. However, results obtained with the genus Podarcis, a diverse group of wall lizards with complex systematics, challenge emerging paradigms and caution against hasty generalizations. Here we review the available evidence on the role of chemical stimuli in male-female and male-male interactions in Iberian Podarcis. Males of several species can discriminate between chemicals left on substrates by females of their own or a different species, suggesting that differences in female chemical cues may underlie species recognition in this group. Females, on the other hand, do not respond differential…
Study of adult neurogenesis in the Gallotia galloti lizard during different seasons.
2011
In a previous study we found a seasonal distribution of cell proliferation (the first stage of adult neurogenesis) in the telencephalic ventricular walls of the adult Gallotia galloti lizard. The aim of the present work was to determine the influence of seasonality on the subsequent migration of the resulting immature neurons. We used wild animals injected with bromodeoxyuridine and kept in captivity within 30 days. To confirm the neuronal identity of these cells, we used double immunohistochemical 5-bromo-2'-deoxyuridine (BrdU) and doublecortin (DCX, an early neuronal marker) labeling, as well as autoradiography after the administration of methyl-[³H]thymidine ([³H]T). We found that: (1) t…
Seasonal differences in ventricular proliferation of adult Gallotia galloti lizards.
2007
Lizards present neuronal production throughout the telencephalon in their adult state, both naturally and after experimentally induced brain lesions. As in birds, lizards present seasonal behavioural variations. In birds, such variations have been shown to alter neuronal production. In birds and mammals, lack of stimuli or exposure to stress interferes with adult neurogenetic capacity. The effect of this type of study has not been performed with lizards. In the present study we used bromodeoxyuridine to label dividing cells in the ventricular walls of Gallotia galloti lizards during all four seasons and we investigated the effect of captivity on such proliferation. We found that G. galloti …
Neuron regeneration reverses 3-acetylpyridine-induced cell loss in the cerebral cortex of adult lizards
1991
Systemic administration of the neurotoxin 3-acetylpyridine to adult lizards results in extensive loss of neurons in the medial cerebral cortex, other brain areas remaining largely unaffected. After the neurotoxic trauma, new cells are produced by mitotic division of cells in the ventricular wall. The new cells migrate along radial glial fibers and replace lost neurons in the medial cortex. Electron microscopic examination of cells labeled with [3H]thymidine confirms that the newly generated cells are neurons. Thus, neuron regeneration can occur in the cerebral cortex of adult lizards.
Gonadotropin Hormone Modulation of Testosterone, Immune Function, Performance, and Behavioral Trade‐Offs among Male Morphs of the Lizard Uta stansbur…
2008
Sexual selection predicts that trade-offs maintain trait variation in alternative reproductive strategies. Experiments often focus on testosterone (T), but the gonadotropins follicle-stimulating hormone and luteinizing hormone may provide a clearer understanding of the pleiotropic relationships among traits. We assess the activational role of gonadotropins on T and corticosterone regulation in traits expressed by polymorphic male side-blotched lizards Uta stansburiana. Gonadotropins are found to enhance and suppress multiple physiological, morphological, and behavioral traits independently, as well as indirectly via T, and we demonstrate selective trade-offs between reproduction and surviva…
PSA-NCAM immunocytochemistry in the cerebral cortex and other telencephalic areas of the lizard Podarcis hispanica: differential expression during me…
2002
The lizard medial cortex, a region homologous to the mammalian dentate gyrus, shows postnatal neurogenesis and the surprising ability to replace its neurons after being lesioned specifically with the neurotoxin 3-acetylpyridine. As the polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is expressed during neuronal migration and differentiation, we have studied its distribution in adult lizards and also during the lesion-regeneration process. In the medial cortex of control animals, many labeled fusiform somata, presumably corresponding to migratory neuroblasts, appeared in the inner plexiform layer. There were also scattered immunoreactive granule neurons in the cell layer.…
Intestinal helminth communities of Podarcis bocagei and Podarcis carbonelli (Sauria: Lacertidae) in NW Portugal
2006
Abstract A survey of gastrointestinal helminth communities of Podarcis bocagei and Podarcis carbonelli (Sauria: Lacertidae) from NW Portugal was conducted to determine the prevalence, intensity and diversity of intestinal parasites in these lizards. A few parasite species were found in both hosts, their prevalences, mean intensities and abundances of infection being low or very low. Low values of richness and abundance of parasite species were also found in the helminth infracommunities of individuals of both host species. These low values of parameters of infection and diversity are discussed and compared between both host species and among other Iberian lacertid lizards.