Hemidactylus frenatus

Hemidactylus frenatus View in CoL .

– Hemidactylus frenatus is an extremely adept over-water disperser, human facilitated ( Bauer, 1994) or otherwise. Many authors have documented this species’ relatively recent arrival all over the world. Its colonizing abilities are illustrated well within the Seribuat Archipelago, being that it occurs on at least 41 of the 62 islands. Some of these islands are little more than barren rocks (i.e., P. Tokong Bahara) whereas others are large and environmentally diverse (i.e., P. Tioman). Two other adept colonizing geckos, Gehyra mutilata and Lepidodactylus lugubris , also occur within the Seribuat Archipelago. The latter shows some interesting distribution patterns with respect to H. frenatus which suggests that on some small islands, competition between these two species may be intense. In the Lima group, eight small islands are inhabited by one or the other of these two species ( Table 2 View Table 2 ) and they basically alternate in occurrence in a north to south directional trend (P. Sanggol – L. lugubris ; P. Lima Kecil and P. Lima Besar – H. frenatus ; P. Tokong Raket – L. lugubris ; P. Tokong Condong and P. Tokong Belalai – H. frenatus ; and P. Tokong Chupak – L. lugubris ) suggesting that whichever species colonizes the island first will eventually exclude the other species. On P. Sepoi, this apparent phenomenon is even more striking. Here, H. frenatus occupies every conceivable niche (terrestrial and arboreal) within the island’s interior and occurs in an extremely high density. Lepidodactylus lugubris , however, occurs only on the periphery of the island amongst the larger boulders in the splash zone within the intertidal areas. On P. Layak, H. frenatus is also found in the intertidal areas and L. lugubris has not been found on that island. Similar observations have been made on islands in the South Pacific (Petren & Case, 1996). Yet on P. Mawar, a relatively large island ( Table 1 View Table ) with a high degree of environmental diversity, H. frenatus and L. lugubris can be found syntopically beneath the bark of dead trees in the mangrove forest.