NICHE, MORPHOLOGY AND LOCOMOTION IN LACERTID LIZARDS 
PHYLOGENETIC RELATIONSHIPS OF THE 
LACERTIDAE 
The successively distant outgroups of the Lacertidae appear to be the 
1. the Tetioidea, consisting of theTeiidae and the Gymnophthalmidae; 
2. the Scincoidea consisting of the Scincidae, Cordylidae, 
Gerrhosauridae and probably the Xantusiidae; 3. the Anguimorpha 
(Estes, De Queiroz & Gauthier, 1988; Gauthier, pers. comm.). 
Phylogenetic hypotheses within the family based on morphology 
have been discussed elsewhere (Arnold, 1989a) and some of these 
relationships have been modified and extended on the basis of 
investigations using mitochondrial DNA sequence (Harris, Arnold 
& Thomas, submitted a). The phylogenies of particular groups of 
lacertids have also been explored (Arnold, 1989b, 1991, 1997; 
Harris, Arnold & Thomas, in press, submitted b—d). 
DNA evidence suggests that the most basal branch within the 
family may comprise the sister genera Gallotia and Psammodromus. 
There may then be a dichotomy into two large clades (Fig. 1), one 
consisting of relatively primitive mainly west Palaearctic taxa the 
other of forms that possess a combination of a complex supporting 
structure in the hemipenis, the armature, and a usually derived ulnar 
nerve condition (Arnold, 1989a). This Armatured clade contains 
Omanosaura and all the Afrotropical lacertids and some morpho- 
logically derived genera found in the arid parts of the Saharo-Eurasian 
region (Fig. 2). While relationships within the Armatured clade are 
reasonably well resolved, largely on the basis of morphology, those 
in the primitive west Palaearctic assemblage are less clear. This 
group can be referred to as Lacerta and its allies, and consists of a 
paraphyletic Lacerta from which is derived Algyroides and Podarcis. 
The east Asian Takydromus may be sister taxon to Lacerta and its 
allies but the evidence for this is not strong and for present its 
relationships to this group and the Armatured clade are best regarded 
as unresolved. A number of assemblages within Lacerta and its 
allies can be tentatively recognised (Fig. 1). 
1. Lacerta agilis group: L. agilis, L. bilineata, L. media, L. 
pamphylica, L. schreiberi L. strigata, L. trilineata, L. viridis 
2. L. lepida group:L. lepida, L. pater, L. princeps and L. 
tangitana.This assemblage has often been associated with the L. 
agilis group on the basis of morphology (Boulenger, 1920;Arnold, 
1973, 1989a) and, although immunological data do not suggest 
such a relationship, DNA sequence does give some admittedly 
weak support. 
3. Lacerta vivipara. 
. Podarcis and its relatives Lacerta andreanszkyi and the sister 
species, L. dugesii and L. perspicillata. 
. L. saxicola group, consisting of Lacerta saxicola and generally 
similar ‘archaeolacertas’ in the Caucasus area including L. 
chlorogaster, L.derjugini and L. praticola. L. brandtii may be 
related to this assemblage. 
6. Northwestern ‘archaeolacertas’. Lacerta bonnali and the similar 
L. aranica and. aurelioi, L. horvathi, L. monticola, L. mosorensis. 
7. Algyroides 
8. Southern ‘archavolacertas’: L. bedriagae, L. cappadocica, L. 
danfordi group (Lacerta anatolica, L. danfordi, L. oertzent), L. 
bedriagae, L. graeca, L. kulzeri, L. laevis and L. oxycephala. 
Unlike the other groupings, there is no evidence that these species 
consititute a clade. 
9. L. parva and L. fraasii. Although morphology suggests these 
forms may be related to Psammodromus and Gallotia (Arnold, 
1989a), mDNA sequence provides no support for this arrange- 
ment, suggesting instead a relationship to L. danfordi. 
a 
Nn 
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STRUCTURAL NICHES OF LACERTID 
LIZARDS 
Overview of lacertid structural niche space 
The spatial niches that lacertid lizards occupy differ in both 
microclimate and their structural properties (Arnold 1973, 1987). 
The main structural variables include the nature, continuity and 
angle of the surfaces on which the lizards are active. Essentially the 
range of structural niches occupied forms a continuum. Many 
species occur on open ground that is flat or gently sloping. The 
substratum may be gravel or small stones, earth or sand or some 
mixture of these. Sandy substrata may be firm, soft, or even the 
mobile slip faces of dunes. In some situations the ground may be 
entirely bare but there is frequently cover of varying density and 
patchiness, consisting of grass or other herbaceous vegetation, 
bushlets or bushes. Lizards may take refuge among such plants when 
disturbed and, when cover is more continuous, some forms may 
spend much time in the interstices of vegetation near the ground. The 
interstices among pebbles or small rocks constituting scree may be 
occupied in a similar way. Some lacertids regularly climb high 
among vegetation including the twiggy matrixes of bushes and tree 
canopies, or flimsy plant matter such as herbs or high grass, over the 
top of which some forms may run. In contrast, many species climb 
in a different kind of situation characterised by continuous sloping 
or vertical surfaces, for instance rock faces, large boulders and tree 
boles and branches. 
Some lacertid species specialise in a relatively narrow and homo- 
geneous section of the habitat continuum occupied by the family as 
a whole. Others may spend time in more than one part, for instance, 
Podarcis muralis occurs on occasion on bare ground and among low 
vegetation but also climbs in hedges, on boulders and rock faces and 
even tree boles. Similarly, Psammodromus algirus is cursorial on the 
ground but also climbs in dense often spiny vegetation. 
Structural habitats occupied by groups within the 
Lacertidae 
Few quantitative data exist on differences in structural niche between 
lacertid taxa, but less formal information is available for many 
forms. This is briefly summarised here. Citations often refer to 
summaries rather than scattered primary sources. Information on 
many west Palaearctic taxa can be found in Bohme, 1981, 1984, 
1986; Arnold, 1987 and Arnold & Burton, 1978). The notes on 
lacertid habitats by R.H.R. Taylor cited below were made in north- 
ern Somalia in the 1930s and are deposited in the archives of the 
Reptile Amphibian Section, Natural History Museum, London. 
Taxa are discussed in the approximate order in which they appear 
on the estimates of phylogeny in Figs. | and 2. 
Primitive Palearctic forms 
Psammodromus (SW Europe, NW Africa) 
P. algirus often occurs on the ground in dry vegetated places but, as 
noted, also climbs extensively in bushes etc. The three species that 
constitute the Psammodromus hispanicus clade are strictly ground 
dwelling usually in places with patches of low dense vegetation in 
which they take refuge. 
Gallotia (Canary islands) 
All species occur extensively on the ground but also climb effec- 
tively. 
