Search results for "LIZARD"
showing 10 items of 106 documents
Helminth communities of two lizard populations (Lacertidae) from Canary Islands (Spain): Host diet-parasite relationships
2005
Abstract A parasitological survey has been carried out to determine the relationships between host diet and parasite fauna. Diet, and infracommunities and component communities of two subspecies of lacertid lizards, Gallotia galloti galloti (Oudart, 1839) and G. g. palmae (Boettger et Müller, 1914) from Tenerife and La Palma islands (Canary Islands, Spain), have been analysed. High values of parasite infection parameters were found in both subspecies, which were only infected by nematodes of the family Pharyngodonidae. Plant matter was mainly consumed by both lizard subspecies and relevant amounts of mineral matter were also found in both hosts. Diet of these lacertid lizards was correlate…
Helminths of some lizards of the Iberian Peninsula: bioindicators of the ecology of their hosts.
2021
Parasitological studies carried out for more than three decades have been compared in twelve of the species of lizards that inhabit Iberian Peninsula. The species studied exhibit different ecological strategies in distinct aspects of their way of life. The working hypothesis is that these different ecological characteristics of these hosts will condition the quality and quantity of their helminth communities. Several parameters of host helminth faunas have been compared, such as prevalence, intensity and abundance of infection, and Brillouin diversity index in order to establish similarities and differences between the parasitic communities of the different hosts. Indeed, there are notable …
Food Habits of the Javelin Sand Boa Eryx jaculus (Linnaeus 1758; Serpentes, Erycidae) in Sicily, Italy
2021
The Javelin Sand Boa, Eryx jaculus, is reported to be a predator of mammals, lizards and their eggs, and occasionally of birds and invertebrates, but data on its diet are scarce and fragmentary. Here we describe some aspects of the feeding behavior of E. jaculus on the Mediterranean island of Sicily. A total of 132 individual snakes were examined. Prey remains were found in 43% of them, both in their feces (82.5%) and gut contents (17.5%). The number of snakes observed and their feeding rate decreased in August, probably as a result of the relatively higher temperatures. Feeding rate increases were observed in adult females in September, perhaps to enhance body reserves before hibernation. …
Zinc-positive boutons in the cerebral cortex of lizards show glutamate immunoreactivity
1991
Zinc-positive boutons, originating in the medial cortex of lizards, exhibit glutamate immunoreactivity. This finding supports the presumed homology between lizard zinc-positive boutons and the hippocampal mossy fibres of mammals, which are also glutamate-immunoreactive and zinc-positive. Zinc-positive boutons of lizards contain a chelatable pool of zinc located in the hippocampal mossy fibres of mammals. These synaptic systems also contain glutamate, which indicates a possible simultaneous action of zinc and glutamate during synaptic transmission.
Timm-staining intensity is correlated with the density of Timm-positive presynaptic structures in the cerebral cortex of lizards
1987
In cortical areas of the lizard, Podarcis hispanica, Timm staining reveals a distinct pattern of lamination. At the electron-microscope level, virtually all of the reaction product is located in the synaptic vesicles of Timm-positive boutons. Using linear-regression analysis, the area density of Timm-positive bouton profiles as well as the numerical and volume density of stained vesicles were found to be closely correlated with the light-microscopic densitometric values obtained for each Timm-positive cortical zone. We discuss the possibility of estimating stereological electron-microscopic data parameters from densitometric measurements at the light-microscope level.
Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion.
1998
The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/ substantia nigra and cen…
Hypoxia and hypothermia as rival agents of selection driving the evolution of viviparity in lizards
2017
[Aim]: The evolution of key innovations promotes adaptive radiations by opening access to new ecological opportunity. The acquisition of viviparity (live-bearing reproduction) has emerged as one such innovation explaining reptile proliferations into extreme climates. By evolving viviparity, females provide embryos with internally stable environments to complete development. The classical hypothesis suggests that natural selection for viviparity arises from low temperatures in cold climates, which promote prolonged egg retention in the mother's body. An alternative hypothesis proposes that declines in atmospheric oxygen at high elevations create natural selection for embryo retention to prov…
Daphnia females adjust sex allocation in response to current sex ratio and density
2018
Cyclical parthenogenesis presents an interesting challenge for the study of sex allocation, as individuals’ allocation decisions involve both the choice between sexual and asexual reproduction, and the choice between sons and daughters. Male production is therefore expected to depend on ecological and evolutionary drivers of overall investment in sex, and those influencing male reproductive value during sexual periods. We manipulated experimental populations, and made repeated observations of natural populations over their growing season, to disentangle effects of population density and the timing of sex from effects of adult sex ratio on sex allocation in cyclically parthenogenetic Daphnia…
Multiple paternity in clutches of Common lizard Lacerta vivipara: data from microsatellite markers
2004
The common lizard (Lacerta vivipara) is a small live-bearing lacertid that reproduces once a year. In order to document the poorly known mating system of this species, we present here an assessment of multiple paternity using microsatellite markers. Paternities were established within 122 clutches belonging to two wild populations from contrasted areas and to four seminatural enclosed populations. The proportion of multiply sired clutches was found to be very high (between 50.0% and 68.2%) and similar among populations, which suggests that the mating system of this species may be insensitive to environmental and population conditions.
The importance of integrative approaches in nematode taxonomy: the validity of Parapharyngodon and Thelandros as distinct genera
2018
AbstractDespite the advances of molecular tools, new nematode species are still described mainly based on morphological characters. Parapharyngodon and Thelandros are two genera of oxyurids with unclear related taxonomic histories. Here we use morphological characters (linear measurements and categorical variables) and genetic information (18S rRNA, 28S rRNA and COI partial gene sequences) to confirm the relationships between representatives of these two genera and to determine whether they can be discriminated morphologically. Genetic results confirm the existence of two main clades, mostly congruent with Parapharyngodon and Thelandros genera but with several discordances. Thelandros is po…