Navegando por Palavras-chave "Ecogeographical rules"

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    Macroecologia de populações continentais e insulares do complexo Bothrops jararaca (Serpentes, Viperidae)
    (Universidade Federal de São Paulo, 2015-07-15) Ferrarini, Jose Mario Gadiani [UNIFESP]; Sawaya, Ricardo Jannini [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Macroecology focuses on the relationship between organisms and their environments in broad spatial and temporal scales. One of its approaches is the analysis of geographical patterns in the morphological traits. Several ecogeographical rules have been proposed by relating morphometric characters with geographic distribution, such as Bergmman, Jordan and Foster?s rules. The Bergmann?s rule has proposed a positive relationship between body size and latitude. The Jordan?s rule, a negative relationship between the vertebrae number and temperature, and Foster?s rule posits that insular species have different body size. Although these ecogeographical rules have been demonstrated for different taxa, others are still poorly investigated, such as snakes. This study tested the application of these rules in species and populations of snakes from Bothrops jararaca complex (Viperidae). The following hypotheses were tested: (1) snakes inhabiting higher latitudes have smaller body size and lower number of ventral scales, reversing Bergmann and Jordan?s rules; (2) among climatic variables, temperature should be correlated with these morphological changes; (3) insular species and populations have different body size, according to Foster?s rule; and (4) changes in diet type may be the main reason for body size shifts in insular snakes. By performing spatial regression analysis, the following patterns were identified: snakes inhabiting higher latitudes had lower snout-vent length, fewer numbers of ventral scales and were stouter. Variance in stoutness was associated with precipitation of wettest month, while other characters were explained by the precipitation of driest month. As proposed, both length and number of ventral scales reversed Bergmann and Jordan?s rules. Nevertheless, stoutness corroborated the Bergmann?s rule, increasing with latitude. Seven from eight insular populations have evolved to dwarfism, corroborating the Foster?s rule. Moreover, it was detected that smaller body size populations only feed on ectothermic preys, corroborating the diet alteration hypothesis, proposed as the main mechanism responsible for body size shifts in insular species. Hence, this study contributed by detecting macroecological patterns of neotropical snakes and discussed the possible evolutionary process related to these patterns.