Frugivory and seed dispersal by the lizard Gallotia galloti (Lacertidae in a xeric habitat of the Canary Islands

The relationship between an endemic lizard (Gallotia galloti) and plants with fleshy fruits was examined in a xeric habitat on the island of Tenerife, Canary Islands. An analysis of 441 droppings collected in May 1991, showed that fruits are an important item in the diet of this amnivorous lizard; 92% and 56% of droppings contained fruits from two different areas. Fruits of seven plant species were found in the droppings: Ruhia fruticosa, Neochamalea pulverulenta, Withania aristata, Lyrium untricatum, Atriplex semibaccata, Opuntia dillenii and Scilla et haemorrhoidalis. The number of fruit species consumed at each area by G. galloti was related to their availability. Seed viability did not differ between control seeds and seeds from the droppings, except for N. pulverulenta and L. intricatum, where viability was higher in control seeds. The gut passage of seeds significantly reduced the germination of R. fruticosa and N. pulverulenta, increased that of W. aristata while no differences were found for the rest. Gallotia galloti preferred rocky and grassy sites with less open fround and more shrubcover (>50 cm in height). This should produce a non-random seed shadow in the habitats, potentially affecting the distribution of species with fleshy fruits. Omnivorous lizards on islands can actas important seed disperses over short distances for plant species with fleshy fruits, actively influencing both their relative abundance and vegetation structure in serie habitats.Peer reviewe