Ultrastructural analysis of iridophore organellogenesis in a lizard, Sceloporus graciosus (Reptilia: Phrynosomatidae)

Transmission electron microscopy (TEM) data from the ultrastructure of lizard skin iridophores (reflective dermal chromatophores) are used to illustrate the organellogenesis of small rectangular reflecting platelets, which are the color-generating components of these cells. During the development of reflecting platelets, crystals are deposited within double-membraned vesicles from electron-dense material located within the vesicles. The crystals are initially small but expanded lengthwise eventually to fill the vesicle that contains them. The inner membrane then tightly surrounds the crystal whereas the outer membrane is much more loosely associated with the inner-membrane-bound crystal. These observations allow discussion of the possible origin of the precursor double-membraned vesicles from endoplasmic reticulum (ER) and Golgi-derived vesicles. A model is proposed that incorporates our findings and other published reports to explain the origin of the precursor double-membraned vesicles via three alternative pathways.     

Inter-familiar differences in sprint speed of hatchling Sceloporus occidentalis (Reptilia: Iguanidae)

Hatchling Sceloporus occidentalis from the same dam had more similar sprint speeds than did hatchlings from different dams. Families (e.g. siblings from the same dam) of hatchlings differ significantly in body size. However, family differences in sprint speed remain significant when the size differences are removed statistically. Genetic differences among the families of lizards may account for most of the family differences in speed, although environmental or maternal effects may also contribute to family differences in sprint speed.     

Characterization of gastrointestinal chitinase in the lizard Sceloporus undulatus garmani (Reptilia: Phrynosomatidae)

Most studies on chitinase activity in lizards have been concerned with Palaearctic (European) and Laurasian (Middle Eastern and Asian) taxa. Several genera of Old World lizards, Anguis, Uromastix, Chamaeleo and Lacerta, have been shown to possess chitinolytic activity. To date, only one New World lizard, Anolis carolinensis, has been reported to exhibit chitinolytic activity. In the present study, chitinase activity was characterized in a second New World taxon, Sceloporus undulatus garmani, a New World, phrynosomatid lizard. Chitinolytic activity was measured by incubating tissue extracts with a radioactive chitin substrate, acetyl-[H³]chitin and determining acid soluble radioactivity as an estimate for chitin hydrolysis. Chitinolytic activity was present in stomach, small intestine and pancreas extracts, with the stomach and pancreas having the highest specific activities. Chitinolytic activity was higher at pH 4.5 than at pH 7.5. The stomach chitinase is immunologically similar to the gastric chitinase previously described for rainbow trout. Western blot analysis showed anti-chitinase cross-reactivity in the extracts of the stomach, but no cross-reactivity in the pancreatic or intestinal extracts, suggesting different isoforms of chitinase. There was no detected lysozyme activity (less than 0.01 mg/ml lysozyme) present in the extracts of the stomach, small intestine and pancreas. The localization of chitinolytic activity in S. u. garmani is in agreement with earlier reptilian reports on the distribution of chitinase.     

Allozymes and fitness: Evolution of a problem

It was expected that studies of electrophoretic variability in natural populations would resolve longstanding controversies concerning the form of natural selection and its effect on genetic variance in fitness. Recent studies of fitness components for allozymes in E. coli and Drosophila, where genetic backgrounds have been rigidly controlled, and experiments designed to detect small selection coefficients, suggest that selection is much weaker than earlier investigations would indicate. However, perturbing the metabolic background associated with specific loci often allows functional differences to be amplified to an experimentally measurable level. Frequencies of null activity variants in natural populations indicate that the fitness consequences of reduced activity in heterozygoles are probably very small. These results are supported by recent theoretical considerations suggesting that the activity variation associated with electrophoretic variation will have little effect on overall flux in many pathways.     

A positive fever response in Agama agama and Sceloporus orcutti (Reptilia: Agamidae and iguanidae)

Summary Three species of lizards (Agama agama, Mabuya perrotetii, and Sceloporus orcutti) were tested for a possible increase in mean selected body temperature (MSBT) in response to intraperitoneal injection of alcohol-killed Aeromonas sobria, a gram-negative bacterium known to be pathogenic to reptiles. A paired experimental design was utilized in which each animal was given an injection of sterile saline and 1 · 10¹⁰ A. sobria. Body temperatures were monitored via indwelling cloacal thermocouples at 4-min intervals for one 12-h light period under saline injection and for two consecutive 12-h light periods under bacteria injection. Agama agama demonstrated a significant increase in MSBT on both day 1 and day 2 of bacteria injection with increases of 2.7 and 2.3°C, respectively. The latency period on day 1 averaged 6.4 h. Sceloporus orcutti demonstrated a significant decrease in MSBT on day 1 of bacteria injection and a significant increase in MSBT of 1.0°C on day 2 of bacteria injection. No fever was evident in S. orcutti until the beginning of day 2. Mabuya perrotetii did not exhibit a significant change in MSBT on either day 1 or day 2 of bacteria injection. Agama agama (family Agamidae) is the first Old World reptile to exhibit a fever response to bacteria injection, and with these results fever has now been demonstrated in the lizard families Agamidae, Iguanidae, and Teiidae.Abbreviations MSBT mean selected body temperature - T _b body temperature     

Phylogenetic relationships of Australian skinks of the Mabuya group (Reptilia: Scincidae) inferred from mitochondrial DNA sequences

Portions of two mitochondrial genes (12S and 16S ribosomal RNAs) were sequenced to analyze the phylogenetic relationships of the Mabuya group from the Australian region (Corucia, Egernia and Tiliqua). Results indicated the monophyly of these genera and their divergence from Asian and African members of this group. This suggests that the diversity of the Mabuya group in the Australian region has increased through an endemic radiation, not through multiple colonizations from outside. Among the genera from this region, Corucia and Tiliqua were closest to each other. This result contradicts with those of the previous hypotheses on the basis of morphological and immunological data that, respectively, suggested closest affinities between Corucia and Egernia, and Egernia and Tiliqua. We suppose that the morphological characters exclusively joining Corucia and Egernia are actually in plesiomorphic state.     

The ultrastructure of spermatid development during spermiogenesis within the rosebelly lizard,Sceloporus variabilis (Reptilia,Squamata, Phrynosomatidae)

Several recent studies have mapped out the characters of spermiogenesis within several species of squamates. Many of these data have shown both conserved and possibly apomorphic morphological traits that could be important in future phylogenetic analysis within Reptilia. There, however, has not been a recent study that compares spermiogenesis and its similarities or differences between two species of reptile that reside in the same genus. Thus, the present analysis details the changes to spermiogenesis in Sceloporus variabilis and then compares spermatid morphologies to that of Sceloporus bicanthalis. Many of the morphological changes that the spermatids undergo in these two species are similar or conserved, which is similar to what has been reported in other squamates. There are six main character differences that can be observed during the development of the spermatids between these two sceloporid lizards. They include the presence (S. variabilis) or absence (S. bicanthalis) of a mitochondrial/endoplasmic reticulum complex near the Golgi apparatus during acrosome development, a shallow (S. variabilis) or deep (S. bicanthalis) nuclear indentation that accommodates the acrosomal vesicle, filamentous (S. variabilis) or granular (S. bicanthalis) chromatin condensation, no spiraling (S. variabilis) or spiraling (S. bicanthalis) of chromatin during condensation, absence (S. variabilis) or presence (S. bicanthalis) of the longitudinal manchette microtubules, and the lack of (S. variabilis) or presence (S. bicanthalis) of nuclear lacunae. This is the first study that compares spermiogenic ultrastructural characters between species within the same genus. The significance of the six character differences between two distantly related species within Sceloporus is still unknown, but these data do suggest that spermiogenesis might be a good model to study the hypothesis that spermatid ontogeny is species specific. J. Morphol. 275:258–268, 2014. © 2013 Wiley Periodicals, Inc.     

The "Polyphyletic" Origin of the Genus Ablepharus (Reptilia, Scincidae): a Case of Parallel Evolution

It is generally admitted that the some 38 species referred to Ablepharus Lichtenstein, 1823 (Sauria, Scincidae) belong to the same evolutionary level. S mith (1935), followed by P arker (1936), D e W itte (1936), M itchell and S torr (in. litt.) pointed out the "polyphyletic" origin of the "ablepharine" skinks, and G reer (1967) presented arguments on the basis of the skull morphology. The study of nearly all the skinks assigned to the genus Ablepharus is in agreement with the above statements. A tentative new generic arrangement is presented, based on the assumption of several parallel evolutionary series, starting from closely related although different lines, showing convergent morphological features under the action of a similar way of life (burrowing and cryptic). The "ablepharine" skinks assemblage includes different evolutionary levels, which have to be referred to distinct genera. Only bivittatus, pannonicus, deserti and kitaibelii are assigned to Ablepharus Lichtenstein; boutonii belongs to Cryptoblepharus Wiegmann. The African "ablepharine" skinks, together with several other species having a transparent window in the lower lid, are included in Panaspis Cope. The Australian species commonly ascribed to the genus Ablepharus , should be considered as belonging to following generic taxa:
1. Morethia Gray, 1844, including the species lineo-ocellata, butleri, taeniopleura ;
2. Pseudemoia Fuhn, 1967, monotypic ( spenceri );
3. Cryptoblepharus Wiegmann, 1834, monotypic ( boutonii ), but the species is polytypic.
4. Notoscincus n. g., with the species ornatus and wotjulum ;
5. Menetia Gray, 1844, monotypic ( greyi );
6. Species incertae sedis, burnetti (polytypic);
7. Proablepharus n. g., including tenuis (polytypic);
8. Species incertae sedis, with the species davisi and kinghorni ;
9. Lerista Bell, 1833, including elegans, distinguenda, lineata, muelleri, timida and all the species assigned to Rhodona and Nodorha (G reer , 1967).     

Phylogenetic relationships of a new species of pseudoxyrhophiine snake (Reptilia: Lamprophiidae: Thamnosophis) suggest a biogeographical link between western and northern Madagascar

We describe a new species of the pseudoxyrhophiine snake genus Thamnosophis from a dry forest of the karstic massif Tsingy de Bemaraha in central western Madagascar. Thamnosophis mavotenda sp. n. is characterised by 19 dorsal scale rows, 188 ventrals, 110 subcaudals, and by colouration (e.g. yellow head sides). Morphological and molecular phylogenetic data indicate that the species is most closely related to the recently described Thamnosophis martae from the far north of the island which inhabits dry karstic forest and subhumid lowland rainforest. This species pair represents a well-supported example of a sister-group relationship in snakes between northern Madagascar and the Tsingy de Bemaraha plateau, and corroborates preliminary observations in other reptile species. We discuss this finding in the light of recent hypotheses on the biogeographic zonation of Madagascar.     

Phylogenetic Relationships and Evolution of the Androecia in Ruteae (Rutaceae)

Ruta, which belongs to tribe Ruteae, is the type genus of the subfamily Rutoideae and the family Rutaceae. Molecular systematic studies have shown that the genera in Ruteae are closer related to Aurantioideae than to most other genera of Rutoideae, some of the genera traditionally placed in Ruteae have been shown to be nested within the Aurantioideae clade, but the diagnostic characters for determining new patterns in the relationship are poor. In this study, we investigated the floral development of Boenninghausenia in Ruteae (sensu stricto), Haplophyllum in the basal position of Aurantioideae and Murraya in traditional Aurantioideae using scanning electron microscopy. The androecium of Boenninghausenia is obdiplostemony. As androecia in other genera within Ruteae (s.s.) are also obdiplostemonous, reconstruction of the ancestral state indicates that obdiplostemony is an ancestral character in this clade. Because the androecia of Haplophyllum and Murraya are also obdiplostemonous, obdiplostemony is also an ancestral character in Aurantioideae clade. The ancestral state reconstruction indicates this character can serve as a synapomorphy of the Ruteae-Aurantioideae clade. The results of our work also shed light on the evolution of the androecium in Rutaceae, as the obdiplostemony of this group is clearly derived from haplostemony in the ancestral genera in Rutaceae and has develop into polyandry by increasing antepetalous stamens.     

Phylogenetic Analysis and Karyotype Evolution in the Genus Clivia(Amaryllidaceae)

Phylogenetic relationships of five taxa of Clivia, one probablenew species plus four recognized species, and three outgroupspecies were studied using sequences of the nuclear ribosomal5S non-transcribed spacer and the internal transcribed spacer(ITS) of 45S rDNA. Analysis of the data sets separately generatedsome well-supported groupings and congruent phylogenies. Cliviaminiata and C. gardenii are closely related. ‘Robust Gardenii’,the putative new species, is a sister clade of this group. Clivianobilis is distantly related to these three taxa and C. caulescensoccupies an intermediate position between the two groups. Chromosomelocations and distribution patterns of the 5S nuclear ribosomalgene in the species of Clivia were investigated using fluorescenceinsitu hybridization (FISH). In all species, only one pair of5S rDNA signals was observed. These were located on the shortarm of chromosome 8, at the position of the interstitial C-bands.The phylogenies obtained from the DNA sequences together withthe chromosome data accumulated here and previously publishedinformation on the location of the 45S rDNA sites have beenused to postulate evolutionary trends in Clivia chromosomes.Copyright 2001 Annals of Botany Company Clivia, chromosome evolution, 45S and 5S rDNA, ITS, FISH, molecular phylogeny     

Indomethacin influences arginine vasotocin-induced parturition and oviposition in lizards (Sceloporus jarrovi and Sceloporus undulatus )

The effect of the prostaglandin blocker indomethacin on arginine vasotocin-induced birth was examined. Gravid female, oviparous (Sceloporus undulatus ) and viviparous (Sceloporus jarrovi ) lizards were pretreated with saline or indomethacin, a potent blocker of PG synthesis. Pretreatment was followed by an intraperitoneal injection of AVT. Pretreatment with indomethacin significantly delayed the onset of AVT-induced oviposition in S. undulatus , whereas it had no effect on latency to birth in S. jarrovi . Female S. jarrovi treated with indomethacin, however, gave birth to only part of the total litter, whereas control females gave birth to complete litters. In viviparous females, an interaction of embryonic age with pretreatment was evident; females having more developed embryos decreased birth latency significantly and increased the percentage of parturition when compared with females that had embryos at earlier stages of development. Our data suggest that although exogenous AVT can stimulate oviposition or parturition, these events occur more rapidly and completely when prostaglandin synthesis is not inhibited.     

Phylogenetic relationships, taxonomy, character evolution and biogeography of the lacertid lizards of the genus Takydromus (Reptilia: Squamata): a molecular perspective

Historical relationships were inferred for the oriental lizards of the genus Takydromus Daudin 1802 (Lacertidae) on the basis of DNA sequences. Of the 17 species currently recognized for the genus, 13 species represented by 42 specimens from 29 localities were examined. Maximum-likelihood and maximum-parsimony analyses of data for 829 aligned sites from parts of the mitochondrial 12S and 16S rRNA genes yielded relationships that, while showing no substantial discrepancy with each other, were strikingly different from a currently prevailing phylogenetic hypothesis from a parsimony analysis of morphological characters. Based on the results of these molecular analyses, supplemented by results of the morphological analysis that offered robust evidence for positions of two additional species ( T. khasiensis and T. sylvaticus ), the following interrelationships were hypothesized as the most preferred phylogeny: ( kuehnei ( sexlineatus khasiensis ))( tachydromoides (( smaragdinus ( sauteri ( dorsalis sylvaticus ))) ( amurensis ((( formosanus wolteri ) hsuehshanensis )( toyamai ( septentrionalis stejnegeri )))))). These interrelationships indicate: (1) invalidity of Platyplacopus Boulenger 1917 , which was recently resurrected as a subgenus of Takydromus on the basis of the morphological analysis; (2) homoplasy in states of some morphological characters, such as green dorsal coloration, that were considered as synapomorphs of certain nodes in the morphological analysis; and (3) involvement of the genus in a series of vicariances in both the continental and insular parts of eastern Eurasia. Due to the paucity of available samples, phylogenetic status of T. intermedius and T. haughtonianus remain to be examined in future studies.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 76 , 493–509.     

Global diversity of lizards in freshwater (Reptilia: Lacertilia)

No lizards are strictly aquatic, but at least 73 species in 11 different families can be considered to regularly utilize freshwater habitats. There are no aquatic lizards in the Nearctic or Palearctic regions, whereas the Neotropics, Southeast Asia, and the Indo-Australian Archipelago support the greatest diversity of freshwater forms, particularly in the families Gymnophthalmidae, Scincidae and Varanidae. A number of larger aquatic lizards are harvested for food and for the reptile skin trade and several are CITES listed. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Phylogenetic relationships in the Sceloporus variabilis (Squamata: Phrynosomatidae) complex based on three molecular markers,continuous characters and geometric morphometric data

The monophyly of the Sceloporus variabilis group is well established with five species and two species complexes, but phylogenetic relationships within species complexes are still uncertain. We studied 278 specimens in 20 terminals to sample all taxa in the “variabilis group,” including three subspecies in the “variabilis complex,” and two outgroups (Sceloporus grammicus and Sceloporus megalepidurus). We assembled an extensive morphological data set with discrete and continuous characters (distances and scale counts), including geometric morphometric data (landmark coordinates of three shapes), and a three‐marker molecular data set as well (ND4, 12S and RAG1). We conducted parsimony and Bayesian phylogenetic inferences on these data, including several partitioning and weighting schemes. We suggest elevating three subspecies to full species status. Therefore, we recommend recognition of nine species in the “variabilis group.” First, S. variabilis is sister to Sceloporus teapensis. In turn, Sceloporus cozumelae is sister to Sceloporus olloporus. These four species are a monophyletic group, which is sister to Sceloporus smithi. Finally, Sceloporus marmoratus is sister of the clade of five species. The other species in the “variabilis group” (Sceloporus chrysostictus, Sceloporus couchii and Sceloporus parvus) are a paraphyletic grade at the base of the tree. Our analyses reject the existence of the “variabilis complex.” We conducted a parsimony‐based ancestral reconstruction on body size (snout–vent length), femoral pores and dorsal scales and related morphological changes to geographic distribution of the species. Our phylogenetic hypothesis will allow best designs of comparative studies with species in the “variabilis group,” one of the earliest divergent lineages in the genus.     

Placentation in the Mexican lizard Sceloporus mucronatus (Squamata: Phrynosomatidae)

We used light microscopy to study placental structure of the lizard Sceloporus mucronatus throughout 6 months of embryonic development. Three stages of placental development could be assigned to embryos based on the arrangement of the extraembryonic membranes. A highly vascular choriovitelline placenta was present in the embryonic hemisphere and a nonvascular bilaminar omphalopleure covered most of the abembryonic hemisphere of the egg during embryonic Stages 10-28. A chorioallantoic placenta replaced the choriovitelline placenta by embryonic Stage 29 and an omphaloplacenta covered the abembryonic hemisphere at this stage. The combination of these two placental types occurred in Stage 29-36 embryos. The final stage of placentation, embryonic Stages 37-40, was characterized by an omphalallantoic placenta in the abembryonic hemisphere and a chorioallantoic placenta in the embryonic hemisphere of the egg. The choriovitelline and chorioallantoic placentae are well vascularized, with closely apposed maternal and embryonic blood vessels. These structures are the most likely sites of respiratory exchange. In contrast, the omphaloplacenta and omphalallantoic placentae contain cuboidal or columnar epithelia and these structures may function in histotrophic exchange. Placentation of S. mucronatus is similar to that of predominantly lecithotrophic species in other squamate lineages suggesting that the evolution of this placental morphology is a response to similar factors and is independent of phylogeny.     

Speciational history of North American Haemorhous finches (Aves: Fringillidae) inferred from multilocus data

We investigated species relationships and timing of speciation in North American Haemorhous finches by using a mitochondrial phylogeographic approach combined with a multilocus species tree reconstruction. Haemorhous purpureus and H. cassinii were strongly supported as sister taxa, and H. mexicanus was sister to H. purpureus + H. cassinii. Our divergence times indicated that diversification within Haemorhous occurred progressively from the Late Miocene into the Pleistocene. Our inferred pattern of speciation demonstrates the complexity of the origins of North American birds, and provides additional evidence that a single cause for speciation in closely related North American birds, such as Late Pleistocene glacial–interglacial cycles, is unlikely.