Variação geográfica em lagartos (Reptilia: Squamata) presentes em seis localidades da Amazônia Meridional

Abstract

Studies of geographic variation address the genetic, morphological, or behavioral differences that populations of the same species may have throughout their range. Such studies are important to identify distribution patterns that help to understand the evolutionary processes of the region in focus. Recent studies of Amazonian herpetosauna indicate a faunal differentiation, at the species level, in an east-west direction when considering the southern Amazon. In this work we tried to verify if the same could be observed at the population level, or if other geographic patterns could be found at this level, when comparing several species of lizards. We studied the meristic characters of 17 species from six localities in the southern Amazon, with a total of 910 specimens. For each species, six localities were compared, using a discriminant function analysis (DFA), from which a first indication of possible population differences was obtained. Non-variable characters were excluded from the analysis, and for all symmetric characters the sum of the two sides was considered. Seven species were excluded from the AFD, because they had few individuals per population. For all species analyzed except Mabuya nigropunctata, the correlation plot of factors 1 and 2 indicated the presence of two or more population clusters. The groupings, however, varied in the various species, indicating no pattern, except for the population of Caxiuanã, isolated totally or partially from the others in all cases (Anolis fuscoauratus, Plica umbra, Uranoscodon superciliosus, Coleodactylus amazonicus, Gonatodes bumeralis, Cercosaura ocellata, Leposoma percarinatus, Ameioa ameioa, Kentropyx calcarata). Santarém stands out from the others in five of the nine species. These data seem to indicate the existence of historical factors that have somehow contributed to the isolation of Caxiuanã from the other populations, all to the west. Regarding the other areas, the absence of a pattern of variation leads us to believe that the differences found are the result of random factors, or ecological factors specific to each species. These data, however, are still preliminary and should be tested from further analyses taking into account the characteristics indicated as important in defining the groups found