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Tuatara: Volume 30, Issue 1, December 1988

Reptiles and the Biogeographic Interpretation of New Caledonia

page 39

Reptiles and the Biogeographic Interpretation of New Caledonia



The terrestrial reptilian fauna of New Caledonia consits almost entirely of lizards of the families Gekkonidae and Scincidae. Despite low familial diversity, species and generic diversity are high and both the geckos and skinks are primarily endemic. Patterns of high herpetofaunal similarity that typify the central and eastern Pacific are generally absent in the southwest Pacific. Despite phylogenetic ties to the faunas of Australia and New Zealand and relatively small distances between New Caledonia and components of the Outer Melanesian Arc, species level similarities between New Caledonia and other island groups is extremely low. Misinterpretation of the systematics and basic biology of both geckos and skinks has led to prevailing, erroneous views that these reptiles are of little use in biogeographic analysis. Implications of this invalid conclusion, as illustrated by a recent biogeographic analysis of the western Pacific, are exposed and criticized.

Key words: New Caledonia, Pacific biogeography, Gekkonidae, Scincidae, systematics, vagility, herpetofauna.


New Caledonia is a French territory located about 1500 km off the coast of Queensland. Along with the Loyalty Islands, it lies between the Coral Sea and the Vanuatu Trench. The islands have had a long geological history and occupy an area of over 19,00 km2 at the southern limits of the tropics.

Living representatives of two families of reptiles, the Gekkonidae and the Scincidae, are native to New Caledonia. A third family, the Typhlopidae, is represented by the introduced parthenogenetic Ramphotyphlops braminus (Bauer, 1987). In addition, an archaic mesosuchian crocodile (Buffetaut, 1983) is known from the Pleistocene karstic deposits of the Baie de Kanumera on the Isle of Pines, and meiolaniid turtles have been recorded from Nepoui on the New Caledonian mainland (1700 ± 70 ybp), from Tiga in the Loyalty group (Gaffney et al., 1984), and from Walpole Island to the southeast of New Caledonia. Unidentified varanid remains also come from the Nepoui site (Gaffney et al., 1984).

This herpetofauna has been considered improverished by some workers (e.g. Hedley, 1899; Buffetaut, 1983). Indeed, the vertebrate fauna of New Caledonia, with its lack of amphibians and non-volant mammals, has generally been regarded as rather uninteresting by zoologists (see Balgooy, 1969). Primary freshwater fish are lacking, with the exception of Nesogalaxias neocaledonicus, a member of a lineage of generally salt-tolerant fishes. The avifauna has also been sterotyped as unremarkable, with few endemic genera and only one endemic family (Diamond, 1984). Berlioz (1962), however, noted that only 26% of the avifauna was composed of passerines, in contrast to 50% for the world as a whole. Only relatively nonvagile invertebrate groups, such as land snails (which show 99% endemism on New Caledonia) (Tillier and Clarke, 1983) have generally been regarded as interesting from a broad zoological standpoint. This is in stark contrast to the flora of New Caledonia, which is characterized by high levels of endemism, especially in page 40 montane forests and on serpentine soils (Guillaumin, 1921, 1964; Dawson, 1981; Thorne, 1965; Baumann-Bodenheim, 1956; Schmid, 1981; Morat et al., 1984), and has been considered to have “good claim to be considered the most remarkable in the world” (Good, 1974).

The Herpetofauna of New Caledonia in Relation to that of other Regions of the Pacific

The number of reptile species in New Caledonia (38 terrestrial species) is low in absolute terms, but high relative to other areas of Oceania. Only New Guinea (total terrestrial herpetofauna 270 species), the Solomon Islands (87 species) and New Zealand (42 species) have more. Despite a general lack of interest among zoologists, a few workers (e.g. Bavay, 1869; Roux, 1913) have noted the high level of endemism among New Caledonian reptiles. The latter demonstrated the dissimilarity of the faunas of New Caledonia and neighbouring Vanuatu and suggested the Loyalty Islands as an area where elements of these two disparate faunas meet.

The diversity and uniqueness of the New Caledonian herpetofauna can be appreciated by referring to a graphic representation of herpetofaunal similarity among island groups of the Pacific as a whole. The location of each group and the similarity of its terrestrial herpetofauna to that of its neighbours is illustrated in Figures 1-3. Similarity (at the species level) has been estimated using the formula: - % similarity = 2 (number of shared taxa)/sum of taxa of two areas x 100 page 41
Fig. 1Herpetofaunal similarity coefficients for island groups in the South-central and Southeast Pacific (degrees in south latitude and west longitude). Abbreviations for Figs. 1-3 as follows:

Fig. 1Herpetofaunal similarity coefficients for island groups in the South-central and Southeast Pacific (degrees in south latitude and west longitude). Abbreviations for Figs. 1-3 as follows:

  • AI - Austral Islands

  • CA - Caroline Islands

  • CI - Cook Islands

  • EI - Easter Island

  • FI - Fiji

  • GM - Gambier Archipelago

  • HI - Hawaiian Islands

  • KI - Kirbati

  • KP - Kapingamarangi Atoll

  • LH - Lord Howe Island

  • LI - Line Islands

  • LO - Loyalty Islands

  • MA - Marshall Islands

  • MI - Marquesas Islands

  • MR - Marianas islands (incl. Guam)

  • NA - Nauru

  • NC - New Caledonia

  • NF - Norfolk Island

  • NG - New Guinea

  • NI - Niue

  • NZ - New Zealand

  • OC - Ocean Island

  • PI - Pitcairn Island

  • PL - Palau

  • RB - Rennell and Bellona Islands

  • SA - Samoa

  • SC - Santa Cruz and Duff Islands

  • SI - Society Islands

  • SL - Solomon Islands

  • TA - Tuamotu Archipelago

  • TK - Tokelau Islands

  • TO - Tonga

  • TU - Tuvalu

  • VA - Vanuatu

  • WF - Wallis and Futuna Islands

Fig. 2Herpetofaunal similarity coefficients for island groups in the northwestern tropical Pacific (degrees in north latitude and east longtitude). For abbreviations see Fig. 1.

Fig. 2Herpetofaunal similarity coefficients for island groups in the northwestern tropical Pacific (degrees in north latitude and east longtitude). For abbreviations see Fig. 1.

page 42
Fig. 3Herpetofaunal similarity coefficients for island groups in the Southwest Pacific (degrees in south latitude and east longitude). For abbreviations see Fig. 1.

Fig. 3Herpetofaunal similarity coefficients for island groups in the Southwest Pacific (degrees in south latitude and east longitude). For abbreviations see Fig. 1.

Species lists (Bauer, 1986; W.C. Brown, MS) used as a basis for this analysis were prepared from museum data and an extensive literature review (see Bauer, 1986: 845-867). The similarity coefficient is heavily weighted by the absolute number of taxa occuring in the areas (thus Pitcairn Island, with only one species can have at most a 20% similarity with an island supporting nine species). In general, species diversity is low on the islands to the east of Fiji and decreases further to the east of Samoa. Likewise, areas to the north of Vanuatu and Samoa, and east of the Solomon Islands are also depauperate. Hawaii is anomalous with its relatively large lizard fauna, but this probably reflects the influence of Polynesian and European man (Stejneger, 1899; Hunsaker and Breese, 1967; Oliver and Shaw, 1953; McKeown, 1978). Small islands, no matter where they occur, are also poor in species diversity. These include Nauru, Ocean Island, the Line Islands (data only from Vostok and Caroline Atolls), Wallis and Futuna, Niue, Pitcairn Island and Easter Island. The last two islands also suffer from their extreme isolation. Despite this drawback, and the fact that it does not take into account the relatedness of congeners, the coefficient does give an overview of patterns of similarity between areas. Thus high percentages suggest a uniform fauna, both in size and composition, and very low percentages between islands of similar size suggest extreme faunal dissimilarity. Similarly, it may be extrapolated that islands page 43 that share much of their fauna with surrounding areas were probably populated largely through over-water dispersal, and those with low coefficients were populated earlier by means of dispersal or former land links (McCoy and Heck, [1987] have considered the precise implications of both mathematical and probabilistic measures of similarity for biogeographic interpretaion). The similarity coefficients of Australia, New Zealand and New Guinea have not been indicated.

Figure 1 shows faunal similarities in the southeast Pacific. The relative homogeneity in the eastern Pacific is indicated by coefficients of 71 to 92% among all groups of Polynesian islands excluding Easter Island and Pitcairn. The species present are chiefly pan-Pacific geckos and skinks and, as with Hawaii, many may have arrived through the agencies of man (Garman, 1908; Ineich. 1982). This high degree of relatedness generally persists as far west as Samoa and the Tokelaus and then gives way to a more complex pattern of relationships.

Reasonably high similarities (39-67%) link the islands of Micronesia (Fig. 2). Palau, with a fauna of 28 species shows the influence of the Philippines (Brown, 1956) and this continues in attenuated form throughout the region. None of the northern islands shows a high similarity to the Tokelaus, although a similar coefficient characterized their relationship to the Marshall Islands to the north. The relatively isolated and small Kapingamarangi Atoll shares a surprisingly high coefficient (indicative of its relatively large fauna) when compared with the Caroline Islands as a whole. Kapingamarangi also possesses an endemic species of the gecko Perochirus.

In the western and west central south Pacific (Fig. 3), several interesting trends are seen. All of the adjacent island groups to the east of the South Fiji Basin (except Wallis and Futuna) share herpetofaunal similarities of about 40% with Fiji, Tonga, Samoa and the Tokelau Islands have largely similar faunas and also have similarities to the Cook Islands and eastern Polynesia in general. The components of the Outer Melanesian Arc - the Solomons, Santa Cruz and Duff Islands, Rennell and Bellona. Vanuatu and Fiji share a similar herepetofauna, although there is a general diminution of species number and diversity with distance from the Solomons. The Santa Cruz Islands, Rennell and Bellona, and Vanuatu all share about 30% of their herpetofaunas with the Solomons. The similarity coefficient for the Fiji-Solomons comparison (not shown) is 19%. Even this figure is fairly high given the large geographical distance separating the areas and the discrepancy in faunal size. There is an interesting relationship among the faunas of Vanuatu and Fiji in that the former has fewer species than the latter, despite its proximity to the supposed source (the Solomons) (Bauer, submitted). Further, Vanuatu lacks the ranid frog Platymantis present in the Solomons and in Fiji. A possible geological explanation for this anomaly is that, prior to the Miocene, Vanuatu lay north of Fiji and Tonga (Chase, 1971), more distant from the Solomons than either of the latter. On the whole the Outer Arc is typified by the presence of the boid Candoia and many species of the scincid Emoia, as well as a variety of generally widespread gekkonine geckos.

New Caledonia, on the other hand, is almost as distinct as New Zealand at the specific level. It shares only a 4% coefficient with the Solomons and 10% with Vanuatu, although the latter is only little more than 250 km distant. The Loyalty Islands, as Roux (1913) noted, are intermediate in character between New Caledonia and the Outer Arc. They share similarity coefficients of 41% with New Caledonia and 25% with Vanuatu. Lord Howe Island and Norfolk Island have identical faunas of two species, neither of which occurs elsewhere.

The low similarity of the New Caledonian herpetofauna to that of the Outer Arc, or in comparison with inter-Outer Arc elements, clearly suggests distinctness page 44 at the species level. Examination of the taxa involved (Bauer, 1986) shows that the same applies at the generic level. Endemism is extremely high in New Caledonia, and virtually nil in most of Oceania. Since island size does not limit the species composition of New Caledonia, it appears that the long independent history of the island has accounted for the faunal composition. There is little evidence of “recent” immigration via dispersal, except in the case of the small pan-Pacific gecko and skink species. Leiolopisma atropunctatus is the only New Caledonian species that seems to have reached Vanuatu, and it is likely that this dispersal occurred via the Loyalty Islands in the Quaternary. That some New Caledonian forms (e.g. Bavayia and Phoboscincus) occur in the Loyalty Islands indicates that dispersal can take place, but either most New Caledonian forms have low vagility or the water gap prior to the rotation of Vanuatu and the emergence of the Loyalty Islands was too great a barrier to dispersal for this to occur.

A Genus is a Genus, A Gecko is a Gecko, and other Fallacies

Although the geckos and skinks of New Caledonia are primarily endemic, there is a general consensus that these animals are not particularly useful in terms of assessing biogeographical hypotheses. This assessment appears to stem from two misconceptions. The first is a problem that pervades biogeography and many other branches of biology and that stems from inadequate systematic analysis of the groups involved. While the geckos of New Caledonia have usually been placed in their own genera, the skinks have not, and it is the genus which is usually taken as the unit of analysis in biogeography. Indeed, because of the system of binomial nomenclature, the genus assumes more reality in the minds of many biologists than it has in nature. It is thus incumbent upon systematists to apply generic names in the most informative manner possible, maintaining as far as is possible phylogenetic information in the nomenclature (Greer, 1979). It must be remembered that for the physiologist or behaviorist working on representative animals in a familial taxon, with no direct access to systematic literature, any two genera will probably be taken as being as disparate as any other two, a phenomenon that can, and does, lead to incorrect generalizations and false predictions. While this situation should not apply to biogeographers, (see Nelson and Platnick, 1981), sadly it often does.

In the case of the New Caledonian and New Zealand skinks, the application of the generic name Lygosoma until the middle of this century (Greer, 1977) obscured true relationships and suggested that much of the world was populated by a single genus which must have spread rapidly and recently. The high number of Lygosoma species in the Old World tropics reinforced or helped form Darlington's (1948, 1957) views of this area as the cradle of most reptilian groups. In New Zealand, additional problems resulted from the use of the generic name Sphenomorphus for certain scincids. As currently recognized (Greer, 1974), this genus occurs in New Guinea, the Solomon Islands, Australia and parts of southeast Asia. Again, the association of New Zealand forms with these species suggested affinities similar to those of Outer Arc birds and downplayed the uniqueness of the fauna.

Currently, the skinks of New Zealand are placed into two genera, Leiolopisma and Cyclodina, and, until recently, those of New Caledonia were placed into five, Leiolopisma, Anotis (a nomenclatoral and systematic tangle in itself), Cryptoblepharus, Eugongylus (recognized by Greer (1974) to be a paraphyletic) and Phoboscincus (regarded by Bohme (1976) as a derived Eugongylus). Leiolopisma accounts for most of these species. This genus is distributed in Australia, New Caledonia, New Zealand, Fiji and the Mascarene Islands (Leiolopisma lichengera of page 45 Lord Howe Island and Norfolk Island has recently been transferred to the genus Cyclodina). It is definitely paraphyletic (Greer, 1980; Zug, 1985). If one were ignorant of the systematic problems with the genus, its distribution might suggest an early Gondwanan origin for the group and subsequent vicariant splitting of lineages. However, current thought is that the group has achieved its present distribution at least in part by means of dispersal. This, in turn, leads us back to the problem of Lygosoma. However, Sadlier (1987) has divided the New Caledonian skinks into presumably monophyletic groupings which, by virtue of the binomial, erases nomenclatural evidence of broader relationships but increases the apparent level of endemicity in New Caledonia by creating taxa with generic names different from those found elsewhere in the southwest Pacific. Similarly, the reinstatement of Cyclodina by Hardy (1977) for certain New Zealand skinks formerly assigned to Leiolopisma successfully increased the apparent wealth of the herpetofauna, but still left Leiolopisma paraphyletic.

The second factor leading to a de-emphasis of the uniqueness of the New Caledonian (and New Zealand) herpetofauna, and to the misinterpretation of historical biogeography, is the persistent myth that geckos, and to a lesser extent, skinks, are animals adapted to disperal. A glance through island species lists shows that skinks and geckos are the only reptiles present on many remote islands, and that on islands where other groups also occur, geckos and skinks are the most speciose. Thus, as a legacy of the school of dispersalism, these animals have been generally considered highly vagile.

The vagility associated with geckos, in particular, has traditionally been predicted on the view that geckos and their eggs are particularly well suited to transoceanic travel and that they are likely to be transported (as evidenced by their commensalism with humans and subsequent accidental transport). Indeed, it has been demonstrated that geckos eggs are relatively more resistant to sea-water exposure than are the eggs of other reptiles, including skinks (Brown and Alcala, 1957; Dunson, 1982; Dunson and Bramham, 1981; Gardner, 1985) and eggs have been recovered from driftwood (Kew, 1983). This “transportability” and gekkonid commensalism with man is probably responsible for the huge ranges of such forms as Lepidodactylus lugubris (a species also possessing another quality condusive to dispersability - parthenogensis (Cuellar, 1977)) and Hemidactylus frenatus, these being found today on almost every island in the tropical Pacific. In fact, the range of the latter species is known to have increased as a result of the transport of men and equipment in the Pacific Theatre of World War II. Stejneger (1899), Oliver and Shaw (1953), Hunsaker and Breese (1967) and McKeown (1980) all agreed that most if not all of the Hawaiian herpetofauna could be accounted for by human activities. Ineich (1982) considered Lepidodactylus lugubris, Crytoblepharis boutonii poecilopleurus and Emoia cyanura as the only species likely to have inhabited the Society and neighboring islands in pre-Polynesian times.

These features of dispersability do not, however, extend to all geckos (Pasteur, 1964). In fact, they probably apply to only a small number of species. Species of the gekkonidae subfamily Diplodactylinae, in particular, have low vagility. The calcareous egg-shell that permits gekkonine eggs to withstand exposure to sea water is absent in the Diplodactylinae, which have a leathery shell, typical of most squamates (Werner, 1972). Furthermore, no diplodactylines (with the possible exception of Hoplodactylus chrysosireticus) are commensal with man, although Phyllurus platurus may be associated with homes constructed in areas of suitable rocky habitat.

McCann's (1953) analysis of gekkonid dispersal is flawed in its application of the qualities of vagility to the New Zealand species of carphodactylines. He further suggested page 46 unlikely means of dispersal such as the transport of geckos or their eggs on twigs being used by birds for nest building. Support for McCann's claims of the dispersal abilities of geckos came from the widespread distributions of several polyphyletic (as then constituted) gekkonid genera incuding Gymnodactylus, Gonatodes (including Cnemaspis), and Phyllodactylus and thus ran into the nomenclatoral problem mentioned earlier.

A glance at the ranges of the carphodactyline species (see Bauer, 1986; Cogger, 1986; Robb, 1986) shows that, with the exceptions of Bavayia on the Loyalty Islands and Hoplodactylus on the Three Kings and Poor Knights Islands, no species occur on islands that were not connected to the closest mainland during periods of Pleistocene glaciations.

The general view of geckos as highly vagile organisms has become entrenched in the biogeographical literature, and geckos are frequently dismissed as having no utility as biogeographical indicators (e.g. Paulin, 1961). Authors have invariably highlighted the herpetofaunal poverty of New Caledonia and New Zealand by stressing that only geckos and skinks among squamates occur there (Thorne, 1965; Carlquist, 1965, 1974; Diamond, 1984). Undoubtedly, the acceptance of the vagility of the carphodactylines, even in the face of evidence of their ability to disperse, has influenced the writing of those who have continued to accept a Mid Tertiary radiation of the group into Tasmantis despite geological evidence to the contrary (see Bauer, 1986). Thus, our biogeographic explorations depend not only upon a clear understanding of historical geological phenomena, but also a willingness to take the time to perform adequate systematic studies of the groups that occupy the regions in which we are interested. Furthermore, the biological attributes of the taxa of the region of study should be evaluated in this systematic context and not merely be indirectly superimposed from the more generalized conception gleaned from “characterizing” the higher taxa to which they belong. Is a platypus any less of a mammal because it lays eggs?

The Uniqueness of New Caledonia: A Response to Diamond (1984)

Diamond (1984) chose New Caledonia as an example to illustrate his views on speciation in Pacific vertebrates. He regarded many Pacific island biotas as mosaics. In contrast to the fauna of New Guinea, which he regarded as rich and diverse. Diamond stated “from the vertebrate fauna one could not guess that New Caledonia had existed prior to the Pleistocene”. Diamond's goal was to build a case for his hypothesis (Diamond, 1977) that the pattern of diversity of Pacific island faunas is largely a function of the ability of vertebrates to speciate into a radiation in some areas but not in others. This ability, Diamond argued, is related to the minimum size at which islands take on continental characteristics with respect to their faunas.

Diamond's work (1977, 1984) is based primarily on data from birds, and for this group of vertebrates his hypothesis is well supported by patterns of distribution and diversity. However, there is little evidence to suggest that this hypothesis is applicable to all other vertebrates. In particular, Diamond's (1984) support for his theory gleaned from New Caledonian reptiles is based on misconceptions rooted in the fallacies discussed above. Reinterpretation of Diamond's arguments in light of this may or may not seriously weaken this hypothesis as a whole, but they do serve to point out the inherent differences between the study of the biogeography of birds and that of reptiles. They also illustrate the biological uniqueness of the New Caledonian region that has been neglected because of a page 47 traditional emphasis on highly vagile organisms (i.e. birds and some insects) as biogeographical indicators in the southwest Pacific.

Diamond characterized the reptile fauna of New Caledonia as rather depauperate, with only half of the genera endemic, no endemic families and no especially ancient lineages. These statements are either false or do not reflect the intimated poverty of the fauna. In the first case Diamond (1984) accepted nomenclature which does not reflect phylogeny; in the current view of the New Caledonian fauna (Sadlier, 1987) there are, in fact, a large number of endemic genera (while Sadlier's revision was not available to Diamond, the work of Greer [1974] was, and would have provided a suitable basis for analysis). Furthermore, the non-endemic gekkonine genera are represented by single species of wide-ranging forms. The discussion of endemic families belies Diamond's avian bias and is largely irrelevant to the distinctness of the New Caledonian faunas. Reptile families are few in number (20 are represented in Oceania compared with approximately 100 avian families) and are in no biological sense comparable in definition or extent to avian groups of the same nomenclatural rank. The only endemic lizard “family” in Oceania is the Pygopodidae, which is in fact a subgroup to the family Gekko-nidae (Kluge, 1987). In terms of the antiquity of the fauna, Diamond seems not even to have accepted Kluge's (1967a, 1967b) scenario for the group; this implied at least a Mioclene presence of geckos in New Caledonia. More recent work (Bauer, 1986) has indicated that a Paleocene or late Mesozoic presence is more likely.

In arguing for relatively recent dispersal and subsequent radiation to account for certain facets of the New Caledonian biota Diamond (1984) posed the question “where are the frogs, lizards, birds and mammals of Gondowanan origin?” I shall address each group mentioned. Frogs are absent as far as is known, but if present would most likely be leiopelmatids. It is quite possible that frogs, if they had been present in New Caledonia, would not have survived the Eocene ultramafic over-thrusts, because these imposed dramatic changes on aquatic environments and vegetation. The kagu, Rhynchocetos jubatus, represents a monotypic family that may have pre-Oligocene ties to the rail-like birds of New Zealand. Mammals had not arrived in the eastern reaches of Gondwanaland prior to the opening of the Tasman Sea (Raven and Axelrod, 1974). The lizards are there! Geckos of Mesozoic origin outnumber the “modern” pan-tropical forms in all natural habitats (Bauer, 1986; Bauer and DeVaney, in press). Some skinks too may be of Gondwanan origin, but this is less likely (Greer, 1974). Although Diamond (1984) recognized the fact that there are many lizard species in New Caledonia, he regarded them as relatively recent arrivals that had not undergone significant divergence from their ancestral stock.

Diamond (1984) thus used an incorrect evaluation of the age and diversity of the New Caledonian vertebrate fauna to support his (1977) view that successful radiations in continental (i.e. non archipelagic) situations are area-limited. Diamond (1984) claimed that New Caledonia, with “11 endemic Lygosoma” and 10 species of geckos in three endemic genera, is continental for lizards but not for birds. He further suggested that New Caledonia is the smallest area in which lizards can radiate and that the radiation there was not a major one. This claim is difficult to refute because few small islands in the tropics are “continental” in his sense. Indeed, all of the islands to the south and east of New Caledonia are basically archipelagic, while those to the north and west are either larger than New Caledonia or are also archipelagic.

Although Diamond's (1984) hypothesis that the ability to radiate is area-limited cannot be falsified by data from reptiles, it would appear that any island with page 48 sufficiently diverse habitats, appropriate climate and a long enough period of existence could support a lizard radiation. Most islands of the central and eastern Pacific have faunas composed largely or entirely of successful, wide-ranging “weedy” species of lizards, which are extreme generalists, and little likely to radiate in any environment. Unfortunately there are no examples of continental Pacific islands smaller than New Caledonia that are old enough to have received Gondwanan faunas, so the question of area is a limiting factor to lizard radiations is moot. Island size may play some role in determining the diversity of vertebrate faunas in the tropical Pacific. However, it seems likely that the key factors are island age and history, which determine what organisms will be present as raw materials for future evolution. Organismal vagility is also a major component in establishing the potentiality of island faunas. Most lizards have low vagility and can radiate only on old islands where they are already present (e.g. New Caledonia). Lizards with high vagility can colonize new islands but typically have the biology of “weedy” invaders (e.g. Lepidodactylus lugubris) and are not likely to speciate in their new island homes. Lizards of intermediate vagility, which have successfully colonized islands of intermediate age, have done so only in archipelagic situations and so do not shed light on the question at hand.

Regardless of whether New Caledonia represents the minimal continental area for lizards, its herpetofauna is both old and diverse. Diamond's (1984) vision of New Caledonia as an uninteresting island cannot be maintained in light of the probable Mesozoic origin of its resident geckos. It seems appropriate that the evolutionary history of the groups present be interpreted in the context of paleo-geography before we accept ad hoc hypotheses of recent speciation in this geologically ancient area.


I would like to thank Drs K. Padian, A.P. Russell, D.B. Wake and M.H. Wake for their comments on various versions of the manuscript. J. Larson patiently typed several versions of the manuscript. This paper began as a portion of a chapter of a Ph.D. dissertation submitted to the Department of Zoology at the University of California, Berkely. I am indebted to the many people who contributed, both materially and intellectually to the development of my dissertation and I thank them for their roles in the formation of my own ideas expressed in this paper.


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1 Present address: Department of Biological Sciences, The University of Calgary, 2500 University Drive, N.W., Calgary, Alberta, Canada T2N 1N4.