Browsing by Author "FUENTES, E"

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    CAN WE EXTRAPOLATE THE CALIFORNIA MODEL OF GRASSLAND-SHRUBLAND ECOTONE
    (1993) MARTINEZ, E; FUENTES, E
    In California, a number of studies on the interaction between shrubs (Baccharis pilularis) and herbaceous species in annual grasslands have led to the proposal of a conceptual functional model for the dynamics of ecotones between species patches. In our study in Chile we used a similar shrub (Baccharis linearis) and annual grassland species to test the robustness of the hypothesis that ecotones between similar landscape elements under similar climate constraints also have similar dynamics. The herbaceous and shrubby ecotone vegetation was described using cover measurements along the same transects in aerial photographs of 1955, 1962, and 1980, and in the field in 1987. The herbaceous species were then determined and quantified by their mass on both sides of the ecotone. Colonization capacity of B. linearis was estimated by describing its establishment on perturbed sites and estimating its seed dispersion. Field and laboratory experiments evaluated the effect of herbaceous species on shrubs at seedling stages.
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    ENVIRONMENTAL DETERMINANTS OF SIZE IN SOLITARY POPULATIONS OF WEST-INDIAN ANOLIS LIZARDS
    (1977) ROUGHGARDEN, JD; FUENTES, E
    The relationship between jaw size in Anolis lizards and properties of the local insect fauna was examined in solitary populations on islands in the Grenadines and within the island of Dominica. Average lizard size in adult males is strongly correlated with local insect abundance. Adult females show a weaker correlation. There was no discernible relation between average lizard size and average insect size in the environment. The spatial scale of geographical variation in lizard size was quantified with the variance spectrum and the variance transfer function. Large gradients in average lizard size occur over less than 100 m, and the spatial pattern of lizard size strongly tracks patches of insect abundance occupying 60 m in length. The data are relevant to explaining discrepancies in the parallel evolution of a characteristic body size in solitary populations of Anolis. The data show that some, and imply strongly that all but 1, of the discrepancies in parallel evolution are explained by the presence of an unusually high local productivity.