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  • Karyotypes and evolution of the spinosus group of Lizards in the Genus Sceloporus

    Publicado: New York American Museum of Natural History

    Autor(es): Cole, Charles J.

    Ubicación: Centro de Documentación INVEMAR

    Palabras clave: CYTOGENETICA, GENETICA, EVOLUCION, CYTOGENETICS, GENETICS, EVOLUTION, LIZARDS - SOUTHEASTERN STATES, LAGARTOS - SURESTE DE ESTADOS UNIDOS, LAGARTOS - MEXICO, REPTILES - MEXICO

"Karyotypes of all the species in the spinosus group of lizards of the genus Sceloporus were analyzed by means of the colchicine, hypotonic citrate, air-dried technique, employing both bone marrow and testicular tissues. The following cytogenetic phenomena were found within this species group: interspecific and intraspecific variation in chromosome number and morphology; polymorphism in local populations; cytologically recognizable sex chromosomes; and natural chromosomal aberrations. There are four general karyotypes in the species group, though some exhibit relatively minor variations. Diploid chromosome numbers range from a high of 40 (with nearly all chromosomes telocentric) to a low of 22 (with all or nearly all chromosomes metacentric or submetacentric). The cytogenetic data, together with ecological, behavioral, and biogeographic data, indicate that speciation within the group has produced several phylads. Karyotypic evolution primarily involved chromosomal centric fusion (whole-arm translocation). The proposed phylogeny of the group is strongly compatible with the evidence that desert-dwelling species were derived from ancestors occurring in tropical to subtropical forests"