Reptiles from El Morado Natural Monument Region Metropolitana, Chile relative abundance, altitudinal distribution, and preference by different sizes of rocks Reptiles en el Monumento Natural el Morado region Metropolitana, Chile abundancia relativa, distribucion altitudinal y preferencia por rocas de distinto tamano
Mella, J.E.
Gayana 711: 16-26
2007
ISSN/ISBN: 0717-652X Document Number: 372734
This study caracterizes the reptilian fauna at El Morado Natural Monument in the Metropolitan Region of Chile. The relative abundance of lizards and snakes is described relative to altitude and the size of terrain boulders. Four species of lizards and two species of snakes were encountered; their observed relative abundances are: Liolaemus moradoensis (40,9%), L. nigroviridis (37,7%), L. valdesianus (17,1%), L. nitidus (2,7%), Tachymenis chilensis (1,2%), and Philodryas chamissonis (0,4%). The altitude range of the study area is 1,850 to 2,450 masl. L. nigroviridis was found throughout this altitudinal range. L. nitidus restricted to altitudes below 1,900 masl. L. moradoensis and L. valdesianus were observed no lower than 2,150 masl. (reaching L. valdesianus the 2,459 masl., increasing its previously known altitudinal range). With regard to boulder size preference, L. valdesianus demonstrated a preference for boulders with a long axis greater than 0.9 m in size. L. moradoensis preferred boulders 0.3 to 0.6 m in size. L. nigroviridis showed a preference for boulders 0.3-1.2 m in size below 2,150 masl, but above this altitude, where its distribution is syntopic with L. valdesianus, the distribution of L. nigroviridis was restricted to boulders in the 0.3-0.6 m size range. In terms of niche use (size of rocks as a niche axis): L. nigroviridis shows a niche superimposed to L. altissimus, who have a narrow niche, while L. valdesianus have a not superiimposed niche, to greater size of rocks. It is interesting the displacement of niche in L. nigroviridis, the only species Studied under different contexts of syntopy. Thermoregulatory factors and probably the reduction of Competitive pressure could explain the patterns found.