Journal Abstracts on Legless Lizards
Compiled by Melissa Kaplan
Morphogenesis of the rudimentary hind-limb of the glass snake (Ophisaurus apodus Pallas). J Embryol Exp Morphol 1974 Oct;32(2):431-43. Rahmani TM. No abstract available.
Comparative volumetric analysis of the main subdivisions of the brain in saurian reptiles. J Hirnforsch 1976;17(6):513-37. Platel R.
The volumetric measure of the main subdivisions of the brain has been carried out on 32 species of Lizards and 3 species of Snakes. The analysis of the allometrical relations between the volume (the weight) of these subdivisions and the body weight shows firstly that the evolutionary or/and adaptative processes are only located at the mesencephalic and metencephalic levels. A more elaborate study leads meanwhile to the conclusion that anothers brain structures - pallium, basal areas, dorsal thalamus - are also implicated, according to the possibility to group the various species into taxomic units (such as family) or in another way; thus it has been possible to corroborate with quantitative datas the NORTHCUTT'S definition (1972) of the Type I (Lacertomorpha) and Type II (Dracomorpha) lizards; the Dracomorpha show "dynamical" structures - pallium and dorsal thalamus - and remind, in some degree the mammal organization. Each structure in each species can be expressed by the way of a relation index; like the encephalization index, the referrence is given by the 6 Lacertidae of the sample.
The analysis of these indices is carried according to the legless condition, tree-dwelling life, vision performance and the various possibilities to group the species (taxonomic units such as family or another else); the comparison of the various indices corroborates the pecularities of the Lacertomorpha on the one hand and of the Dracomorpha on the other hand. The isoponderal percentages are calculated taking into account the allometrical relations and thus are better than the relative volumes commonly used. They lead to results previously expressed by the various relation indices.
The comparison between Lizards and Snakes leads to the following conclusions: Snakes are less different among themselves than the Lizards, but the species of modern type (Caenophidia) are more telencephalized; they show a proper brain organization; meanwhile the legless condition is expressed, like in the so-called lizards, by a reduced cerebellar volume.
[Comparative volumetric analysis of the principal subdivisions of the telencephalon in saurian reptiles][Article in French]. J Hirnforsch 1980;21(3):271-91. Platel R.
The volumetric measure of the main subdivisions of the telencephalon has been carried on 24 species of Lizards and 2 species of Snakes. The studied structures are termed as follows: main and accessory olfactory bulbs, medial cortex (M 1 and M 2), dorsal cortex (D 1, D 2 and D 3), lateral cortex (L), Septum, Tuberculum olfactorium, dorsal and ventral striatum, amygdala and nucleus sphaericus. The analysis of the datas makes use of the SNEL L's formula which relates the volume of the various telencephalic subdivisions (V) to the somatic weight (S): V = k x S alpha. Each alpha value is compared to the value of the coefficient of allometry (A) of the whole brain. The evolutive (phylogenetic) growth of a structure is said fast (or slow) when its corresponding alpha value is higher (or lower) than the encephalic A value. At the cortical level such analysis shows the progressive nature of the dorsal cortex. A partition of the sample into Lacertomorpha (14 species) and Dracomorpha (10 species) (in agreement with the NORTHCUTT'S definition of his Type I and Type II Lizards) corroborates this cortical detail, more distinctly with the second group as well (especially for the D 2 portion). Moreover the high number of progressive structures among the Dracomorpha leads to consider this group as phylogenetically the most advanced in the Order of Lizards. The somatic indices are calculated according the allometric characteristics of the Reference Lizards.
The judicious choice of some species allows to show how the development of a biological function may be expressed by the values of the indices of the related structures. For examples: dorsal cortex, dorsal striatum and mode of locomotion; olfactory bulbs, lateral cortex, part M 1 of the medial cortex and olfactory system; D 3 subdivision of the dorsal cortex and visual performances. The duality between Lacertomorpha and Dracomorpha is therefore corroborated by significant differences found for the various indices of a great number of telencephalic subdivisions. It leads moreover to find, grosso modo, two functional types of Lizards: moving-on-the-ground and wellsmelling (mainly Lacertomorpha) on the one hand, arboreal and with a fine vision (mainly Dracomorpha) on the other hand. The isoponderal percentages take an useful illustration of these results; it allows to establish the telencephalic pattern of a standard Lizard in which the pallium keeps the larger part (42%); in the pallium itself, the M 1 subdivision of the medial cortex has the most important percentage, a little more than the D 2 part of the dorsal cortex. A comparative study carried on 2 Snakes gives for Boa constrictor the lowest values of the indices, for almost all the structures. In return Natrix natrix stays, for a great number of structures, close to the level of the legless Lizards; this last result confirms distinctly the two levels of telencephalization already found in Snakes (PLATEL, 1976 a).
Temperature responses of standard, aerobic metabolism by the California legless lizard, Anniella pulchra. Comp Biochem Physiol A 1984;77(1):97-101 Fusari MH.
Standard metabolic rates, measured for the lizard Anniella pulchra at 6 and 13 degrees C were statistically identical, showing notable thermal-independence at low temperature. Metabolic rates, measured at 25 and 30 degrees C, were significantly less than the rates predicted by standard equations. Thermal-independence and reduced aerobic metabolism at temperatures above the preferred range may result in water and energy savings in the fossorial habitat. Body-mass adjusted comparisons with other lizards suggest that reduced metabolism may be a correlative adaptation in small, fossorial lizards.
A new coccidian parasite (Apicomplexa: Eimeriidae) from the legless lizard Diplometopon zarudnyi (Amphisbaenia: Trogonophidae) in Saudi Arabia. J Egypt Soc Parasitol 1998 Apr;28(1):257-61. al Yousif MS, al-Shawa YR. Department of Zoology, College of Science, Kind Saud University, Riyadh, Saudi Arabia.
Large numbers of coccidian oocysts belonging to the genus Isospora were obtained from the intestinal contents of ten legless lizards Diplometopon zarudnyi collected from eastern region, Saudi Arabia. The oocysts are spherical to subspherical, 33.3 x 30.9 (28.6-35.2 x 26.8-32.7) microns with a bilayered wall 1.4 (1.3-1.6) microns thick. Micropyle, polar granule and oocyst residuum are absent. The sporocysts are ellipsoid, 20.1 x 13.8 (17.5-22.3 x 12.2-15.4) microns. A sporocyst residuum, stieda and substieda bodies are present. Sporozoites are banana shaped, blunt at one end and tapered at the other and containing spherical anterior and posterior refractile bodies of the same size. Since this Isospora sp. does not resemble, any other species of Isospora previously described from lizards of the genus Diplometopon, it has been named Isospora diplometoponi n.sp. after the host generic name.
Parallel evolution of the melanic form of the California legless lizard, Anniella pulchra, inferred from mitochondrial DNA sequence variation. Evolution Int J Org Evolution 54:1041-6 2000 Jun. Pearse DE, Pogson GH
The phylogenetic relationships among populations of the fossorial California legless lizard, Anniella pulchra, were examined by sequencing a 990-bp region of the mitochondrial cytochrome b gene. The mitochondrial DNA gene tree was then compared with the geographic distributions of two currently recognized subspecies: A. p. nigra, a melanic form restricted to two disjunct coastal populations, and A. p. pulchra, a more widely distributed, silvery form. We tested the null hypothesis that all A. p. nigra form a clade that is monophyletic with respect to A. p. pulchra. Our results strongly reject the monophyletic origin of the melanic forms and suggest that the two populations of the nominal subspecies A. p. nigra may have arisen independently from different ancestral populations in a parallel evolutionary response to selection in cool, coastal habitats.
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