Mostrando recursos 81 - 100 de 1.744

  1. Palaeoclimatology of the eastern Canary Islands

    Petit-Maire, N.; Delibrias, G.; Meco, J.; Pomel, R.; Rosso, Jean-Claude

    [EN] Three levels with nests of Anthophora and molluscs shells (Subulinidae and Helicidae) in the dunes of Fuerteventura island are radiocarbon dated at 23 600+ or -550, 15 000+ or -200 and 9800+ or -140 BP.

  2. Two models of evolution in Canarian lizards based on the use of spatial resources

    López-Jurado, Luis Felipe; Mateo, José Antonio

    [EN] The morphological and genetic differences between populations of Canarian lizards on four islands were analysed in relation to two ecological systems: the laurisilva forest and the young volcanic ecosystems or 'malpaíses'. The two ecosystems induce two different evolutionary responses by lizard populations; morphological and genetic modifications are intense in the case of a very old ecosystem like laurisilva whereas in the young volcanic ecosystems, morphological modifications are much more pronounced although the temporary nature of the ecosystem is limiting from point of view of speciation.

  3. Study of dentition in lizards from Gran Ganaria Island (Canary Islands) and its ecological and evolutionary significance

    Mateo, José Antonio; López-Jurado, Luis Felipe

    [EN] The dentition of Gallotia stehlini from one extant and two subfossil populations dated as 4000 and 2000 years before present was studied. Body measurements were similar in the two subfossil populations, but much greater than the largest sizes observed today in G. stehlini. The morphology of the dental cusps in this G. stehlini differs greatly from that of other Lacertidae, including other congeneric Canarian species; this has been connected with a vegetarian diet.

  4. Pliocene chelonian fossil eggs from Gran Canaria, Canary islands

    Hirsch, Karl F.; López-Jurado, Luis Felipe

    [EN] Thirty years ago Macau-Vilar (1958) reported chelonian eggs from Gran Canaria. Analysis of the microstructure of these eggs corroborates this identification. Field studies show that these eggs, which were originally thought to be Miocene in age, are from Pliocene pyroclastic sediments about 3.5–4.5 my old.

  5. Estudios sobre la herpetofauna canaria I. El cariotipo de Gallotia simonyi stehlini y de G. atlantica en poblaciones de la isla de Gran Canaria.

    López-Jurado, Luis Felipe; Cano, Jesús;  Báez, M.

    [EN] A karyological analysis on lizards of the Canary Islands Gallotia simonyi stehlini and G. atlantica ssp., resulted in both cases in a formula of 2n = 40 (38 1 + 2 m; NF = 40); what, besides the results in Gallotia galloti, defines the genus Gallotia (Lacertidae) endemic of the Canary Islands as a monophyetic unit. Considering the ancestral characteristic demonstrated in several species of this genus by diferent authors such as some morphological aspects (the hemipenis) as well as ethological aspects (copulatory ritual), it pointed out the important coincidence of the karyotype of these species and its relictual...

  6. Primeros datos sobre la duración del periodo de incubación de los huevos de Tarentola mauritanica en Córdoba (sur de España).

    López-Jurado, Luis Felipe; Ruiz, Miguel; Gallego-Huidobro, J.

    [ES] El tiempo que tardan en eclosionar los huevos de Tarentola mauritanica en una localidad del sur de España contando a partir del momento de la puesta, ha resultado ser muy inferior al citado al respecto y hasta el presente para esta especie.

  7. Parallel gigantism and complex colonization patterns in the Cape Verde scincid lizards Mabuya and Macroscincus (Reptilia: Scincidae) revealed by mitochondrial DNA sequences

    Carranza, Salvador; Arnold, E. N.; Mateo, José Antonio; López-Jurado, Luis Felipe

    [EN] The scincid lizards of the Cape Verde islands comprise the extinct endemic giant Macroscincus coctei and at least five species of Mabuya, one of which, Mabuya vaillanti, also had populations with large body size. Phylogenetic analysis based on DNA sequences derived from the mitochondrial cytochrome b, cytochrome oxidase I and 12S rRNA genes (711, 498 and 378 base pairs (bp), respectively) corroborates morphological evidence that these species constitute a clade and that Macroscincus is unrelated to very large skinks in other areas. The relationships are ((M. vaillanti and Mabuya delalandii) (Mabuya spinalis and Macroscincus coctei (Mabuya fogoensis nicolauensis (Mabuya...

  8. Long-distance colonization and radiation in gekkonid lizards, Tarentola (Reptilia: Gekkonidae), revealed by mitochondrial DNA sequences

    Carranza, Salvador; Arnold, E. N.; Mateo, José Antonio; López-Jurado, Luis Felipe

    [EN] Morphological systematics makes it clear that many non-volant animal groups have undergone extensive transmarine dispersal with subsequent radiation in new, often island, areas. However, details of such events are often lacking. Here we use partial DNA sequences derived from the mitochondrial cytochrome b and 12S rRNA genes (up to 684 and 320 bp, respectively) to trace migration and speciation in Tarentola geckos, a primarily North African clade which has invaded many of the warmer islands in the North Atlantic Ocean. There were four main invasions of archipelagos presumably by rafting.

  9. Intraspecific variability in nucleolar organiser position in Lacerta (Timon) lepida

    Mateo, José Antonio; López-Jurado, Luis Felipe; Cano, Jesús; Guillaume, Claude P.

    [EN] Discusses several studies on herpetology. Intraspecific variability in nucleolar organiser position in Lacerta (Timon) lepida; Habitat characteristics of the spectacled salamander Salamandrina terdigitata in southern Latium in Central Italy; Body temperatures of the monitor lizard Varanus tristis during the breeding season.

  10. Proteic and morphological variations in ocellated lizards (Lacertidae): A complex of species across the Strait of Gibraltar

    Mateo, José Antonio; López-Jurado, Luis Felipe; Guillaume, Claude P.

    [ES] We have studied protein and morphological variation patterns in lizards belonging to several European and African populations of the ocellated lizard complex, a group of species distributed in the western Mediterranean region. European ocellated lizard (Lacerta lepida ssp. lepida, iberica, nevadensis) are highly variable in body shape, folidosis, colour and dentition characteristics along the large latitudinal range of their distribution area, but relatively homogeneous for electrophoretic characteristics.

  11. Endemism, gigantism and extinction in island lizards: The genus Gallotia on the Canary Islands

    Barahona, Fabiola; Evans, S.; Mateo, José Antonio; García-Márquez, Marcos; López-Jurado, Luis Felipe

    [EN] In the Canary Islands five extant and two extinct giant lacertid lizards belonging to the endemic genus Gallotia are known. A comparative study of the living and subfossil specimens from the Western Canary Islands demonstrates that the extinct giant species Gallotia goliath and Gallotia maxima are synonymous with the living Gallotia simonyi. Characters formerly used in the diagnosis of the extinct species and subspecies fall within the range of intraspecific variation (ontogenetic and individual) of the living species.

  12. The shrews of the eastern canary islands: A new species (mammalia: Soricidae)

    Hutterer, Rainer; López-Jurado, Luis Felipe; Vogel, Peter

    [EN] The karyotype, morphology and biology of Crocidura from Fuerteventura (Canary Islands) are described. The species has a diploid chromosome number of 2n = 36, thus differing from all other species of the genus.

  13. The Canary Islands current during isotopic stage 5, as implied by the fauna of a marine terrace at Fuerteventura, 28°N

    Meco, J.; Petit Maire, Nicole; Reyss, Jean-Louis

    [EN] In Fuerteventura Canary Island, a past sea level with equatorial fauna is observed between -2m and +3m relative to the upper limit of the current intertidal zone. Two samples collected at +0.50m are U/Th dated at 106±7 ka and 112±ka.

  14. Paleotemperature of the last interglacial period based on ?18O of Strombus bubonius from the western Mediterranean Sea

    Cornu, S.; Patzold, J.; Bard, E.; Meco, J.; Cuerdabarcelo, J.

    [EN] The objective of the present study is to quantify sea surface temperature (SST) by measuring ?18O in shells of Strombus bubonius. First we present data obtained from modern shells collected at different locations in the Gulf of Guinea where Strombus bubonius is now geographically restricted (islands of Corisso, Bioko and Pagalu). Next we give the results of our investigations of fossils found in two classical Mediterranean sites: Monastir in Tunisia and Palma Nova, a Pleistocene deposit on the island of Majorca. Both sites have been assigned an age corresponding to the last interglacial period (LIP) by stratigraphic correlation with...

  15. Quaternary palaeoclimates in the eastern Canary islands

    Damnati, B.; Petit Maire, Nicole; Fontugne, M.; Meco, J.; Williamson, D.

    [EN] In the eastern Canary islands, aeolian formations interbedded with palaeosols have been studies. The sequences cover the last 40 ka, as evidenced by one 14C accelerator analysis and several classical radiocarbon dates. As in the Sahara, at least two wet episodes characterize isotopic stage 3. A short pedogenesis corresponds to the first deglaciation step at 15 ka.

  16. Morphology and palaeoenvironment of brood cells of Quaternary ground-nesting solitary bees (Hymenoptera, Apidae) from Fuerteventura, Canary Islands, Spain

    Edwards, Nicholas; Meco, J.

    [EN] On Fuerteventura, the abundance of in situ brood cells of ground-nesting solitary bees in Pleistocene and early Holocene loessic palaeosols and calcretes, and the presence of several taxa of land snails, living species of which occur today in the Mediterranean region and northwest Africa, indicates a semiarid climate, probably with hot, dry summers.

  17. The Barranco de Tirajana basin, Gran Canaria (Spain). A major erosive landform caused by large landslides

    Lomoschitz, Alejandro; Meco, J.; Corominas, Jordi

    [EN] The Barranco de Tirajana (BdT), located on the island of Gran Canaria (Spain), has some specific features that differentiate it from the ravines of other volcanic islands in the Atlantic Ocean. The origin of this unusually wide upper basin (35 km2) has been under discussion over the last century although its erosional origin is nowadays widely accepted. The purpose of this paper is to describe the landslide deposits that appear at the bottom of the basin and to assess their role in the geomorphological evolution of the basin.

  18. The maximum warmings of the Pleistocene world climate recorded in the Canary Islands

    Meco, J.; Guillou, Hervé; Carracedo, J.C.; Lomoschitz, Alejandro; González-Ramos, Antonio Juan; Rodr??guez-Yánez, José-Juan

    [EN] Evidence of the warmest Pleistocene climatic changes is preserved in the eastern Canary Islands. Although the existence of raised fossiliferous marine deposits in northern Gran Canaria has been known since the 19th century, their chronology and significance with regard to past sea levels and temperatures have remained uncertain. Here, we show three marine transgressions recorded by raised marine deposits. The highest (85 m above sea level (masl)) and oldest marine deposit is interbedded in basaltic lava flows and has been dated using both palaeomagnetic and radiometric methods.

  19. Paleoclimats de L´ile de Fuerteventura ( Archipel Canarien)

    Petit Maire, Nicole; Delibrias, G.; Meco, J.; Pomel, Simon; Rosso, Jean-Claude

    [EN] Fuerteventura, the most arid island in the Canary archipelago, due to its location about 100km off the Saharan coast of Morocco, holds important Quaternary deposits indicating recent climatic change. Three levels with Hymenoptera nests and terrestrial mollusk shells were observed in the fixation of the dunes by vegetation: they are radiocarbon dated at 23.600 ± 550 BP, 15.000 ± 200 BP and 9.800 ± 140 BP.

  20. Le courant des Canaries pendant le stade isotopique 5, d´aprés la composition faunistique d´un haut niveau marin à Fuerteventura (28ºN)

    Meco, J.; Petit Maire, Nicole; Reyss, Jean-Louis

    [EN] In Fuerteventura Canary Island, a past sea level with equatorial fauna is observed between -2m and +3m relative to the upper limit of the current intertidal zone. Two samples collected at +0.50m are U/Th dated at 106±7 ka and 112±ka. It brings evidence for year-round sea surface temperatures warmer than 23ºC during isotopic stage 5, possibly 5c.

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