Genetic variation and differentiation in the Japanese five-lined skink,Eumeces latiscutatus (Reptilia: Squamata)

The genetic variation in Eumeces latiscutatus from the main islands of Japan and the northern Ryukyus was investigated and compared with that of its close relatives (E. okadae and E. marginatus) using allozyme data. All three samples from the northern Tokara Island Group, currently identified as E. latiscutatus, were shown to belong to E. marginatus and not to E. latiscutatus. The non-monophyly of the northern Tokara samples and the great genetic differences within these samples may have resulted from colonization from more than one source population by northeastward overseas dispersal. The samples from the Izu Peninsula were genetically much closer to E. okadae than the other conspecific ones. This indicates that the samples from the Izu Peninsula and the other samples of E. latiscutatus should be treated as distinct species, and that E. latiscutatus from the Izu Peninsula and E. okadae from the Izu Island Group may be treated as conspecific. Samples from western Japan were genetically well differentiated from those of eastern Japan. Within the western group, the samples from the Osumi Island Group was genetically distinct from those from the other regions, by possessing unique alleles. Our phenograms also reveal a distant affinity between samples from the Danjo Island Group and the main islands of Japan. This may be the result of long geographic isolation of the Osumi and Danjo Island Groups from Kyushu. By contrast, samples from Sapporo and Aomori were poorly differentiated genetically in spite of the long separation of these two localities by the Tsugaru Strait. This suggests that overseas dispersal of E. latiscutatus occurred across this strait after its formation.     

Microsatellite loci from the five‐lined skink (Eumeces fasciatus)

The geographical range of the five‐lined skink is the most expansive of any eastern North American lizard, ranging from previously glaciated southern Canada southward to the Gulf of Mexico and from the Atlantic seaboard west to Texas and Minnesota. The most northerly populations occur in southern Ontario and are of conservation concern. We developed six polymorphic dinucleotide microsatellite loci to examine the genetic structure within and among Ontario's populations and to examine the intrapopulation levels of genetic diversity relative to more southern populations.     

Ontogeny of the extraembryonic membranes of the oviparous lizard, Eumeces fasciatus (Squamata: scincidae)

Oviposited eggs of Eumeces fasciatus contain embryos in the limb bud stage. Amniogenesis is complete and two yolk sac membranes, vascular trilaminar omphalopleure (choriovitelline membrane) and bilaminar omphalopleure, enclose the yolk vesicle. A small allantoic vesicle contacts the chorion. The choriovitelline membrane is the primary vascular system. Blood islands, sites of hematopoiesis, are associated with omphalomesenteric vessels of the choriovitelline membrane. The bilaminar omphalopleure, which contacts the eggshell over the abembryonic hemisphere of the egg, lies external to an isolated yolk mass and yolk cleft and is not vascularized. The definitive yolk sac (splanchnopleure) is formed when the extraembryonic coelom and allantoic vesicle intrude into the choriovitelline membrane. Omphalomesenteric vessels are retained with the yolk sac splanchnopleure and the associated hematopoietic sites are present throughout incubation. The chorioallantoic membrane reaches the equator of the egg, entirely supplanting the choriovitelline membrane, after 25% of incubation is completed. Further growth of the allantois is stalled until 65% of incubation is completed when rapid expansion of the allantoic vesicle, in conjunction with resorption of the isolated yolk mass, supplants the bilaminar omphalopleure. As a result, the chorioallantoic membrane completely envelopes the egg for the final 35% of incubation. This developmental event is coincident with published reports for the timing of increased growth and metabolism of embryos. As the isolated yolk mass regresses, intravitelline cells associated with the yolk cleft invade and resorb the yolk to form a large cavity. The wall of this cavity is a germinal epithelium that produces cells that fill the cavity. This structure appears to be a site of hematopoiesis previously undescribed in vertebrates.     

Interspecific odour discrimination by a lizard (Eumeces laticeps)

When presented with odours on cotton swabs, adult borad-headed skinks (Eumeces laticeps) of both sexes flicked their tongues at much higher rates to conspecific odour stimuli than to those of their most closely related congeners, E. fasciatus and E. inexpectatus, during 60-s exposures to cloacal odours from lizards of the opposite sex. A successive discrimination design was used in which each lizard responded to five different odour treatments in a random sequence. In addition to the three lizard odours, water was used as a measure of baseline tongue protrusion rates and a cologne was used as a pungency control. There were no significant differences among the four non-conspecific odour treatments in numbers of tongue flicks elicited, but the skinks emitted significantly greater numbers of tongue flicks to conspecific cloacal odours than to any of the other stimuli. It is hypothesized that E. laticeps produces a pheromone which may function for species identification. Although it is tempting to speculate that the pheromone may serve as a pre-mating mechanism for maintaining reproductive isolation from syntopic congeners, insufficient information is avialable to draw firm conclusions regarding such a function.     

Ultrastructural studies of normal and alloxan-treated islet cells of the pancreas of the lizard, Eumeces fasciatus

Alpha and beta cells can be distinguished by differences in mitochondrial and secretion granule structure. Many mitochondria of alpha cells possess “tubular” or prismatic cristae oriented longitudinally and having triangular profiles in cross-section. The matrix is particulate, with the roughly spherical particles measuring about 100 A in diameter. Evidence is presented indicating that alpha and beta granules are sequestrated in association with Golgi elements. Fully-condensed beta granules, assumed to be insulin, appear homogeneously dense and crystalline. Recurrent profiles of crystalline beta granules suggest that they possess an octahedral configuration. Alpha cell granules also appear homogeneously dense but have round profiles. Many acinar cell nuclei in both normal and alloxan-treated pancreata display masses of moderately dense fibrils oriented roughly parallel to each other. These fibrils are about 200 A across and their terminal portions are rebranched and often appear to be continuous with the finely granular or filamentous component of the nucleoplasm. Not infrequently the fibrils show evidence of periodicity. Alloxan has a specific destructive effect on beta cells. An initial effect seems to be the disruption and coalescence of the bounding membranes of beta granules. Lysosome-like bodies are often seen in beta cell cytoplasm, which ultimately becomes degranulated and necrotic following prolonged administration of large doses of alloxan.     

Characterization of six microsatellite loci in the Bermuda skink (Eumeces longirostris)

Conservation strategies for the critically endangered Bermuda skink will require knowledge of genetic variation and population structure. We describe the isolation of six polymorphic microsatellites for this species suitable for use in population genetics studies or for monitoring success of potential breeding programmes. Tissue sampling for DNA extraction involved no blood loss or tail autonomy. Three of these loci cross‐amplify and are polymorphic in a related North American skink (Eumeces fasciatus) and should also be informative for this species.     

中国石龙子成熟精子的超微结构

利用透射电镜观察中国石龙子附睾成熟精子的超微结构。顶体囊前部扁平、由皮质和髓质组成 ,穿孔器中度倾斜、顶端尖 ,穿孔器基板塞子状 ,细胞核长形 ,核内小管缺 ,核前电子透亮区小 ,核肩圆 ,核陷窝锥形。颈段具片层结构 ,近端中心粒和远端中心粒的长轴呈直角 ,9束外周致密纤维与远端中心粒相应的 9束三联微管相联 ,向后与轴丝相应的 9束双联微管相联 ,中央纤维与 2个中央单微管相联。中段短 ,多层膜结构缺 ,含有线状嵴的柱状线粒体 ,不规则卵状致密体组成不连续的环状结构 ,纤维鞘伸入中段 ,具终环。线粒体与环状结构的模式为 :rs1 /mi1 ,rs2 /mi2 ,rs3/mi3,rs4 /mi4。主段前面部分具薄的细胞质颗粒区。纤维 3和 8至主段前端消失。轴丝呈“9 2”型。中国石龙子精子超微结构具有塞子状的穿孔器基板、致密体形成不连续的环状结构和纤维鞘始于ms2等特征与巨石龙子群和蜓蜥 -胎生群不同。没有发现石龙子科精子的独征     

浙江丽水中国石龙子的食性、两性异形和雌性繁殖

丽水分布的中国石龙子（Ｅｕｍｅｃｅｓ ｃｈｉｎｅｎｓｉｓ）摄入的食物均为无脊椎动物,分别属于环节、软体和节肢动物,涉及３０余科,成体和幼体的食物生态位宽度分别为７．２６和６．６９,成体的幼体的食物生态们重叠度为０．５９。性成熟雄性个体大于雌体。成雄和幼体的头长和头宽随体长ＳＶＬ的增长速率大于成雌,成雄头长随ＳＶＬ的增长速度显著大于幼体,成雌和幼体的头长随ＳＶＬ的增长速率无显著差异。成雄头部大于成雌     

Karyotype of the lizard Eumeces taeniolatus]

Using bone marrow cell preparations, the karyotype of Eumeces taeniolatus Blyth was examined. The diploid chromosome set of E. taeniolatus is found equal to 28 (24 meta- and 4 submetacentrics), NF=56. Sex chromosomes do not differ morphologically.     

Mitochondrial phylogeography of the Dalmatian wall lizard, Podarcis melisellensis (Lacertidae)

A 903 bp section of the mitochondrial cytochrome b gene was sequenced from 73 specimens of Podarcis melisellensis collected at 52 localities distributed over the major part of the species’ range. In addition, parts of the 12S (about 470 bp) and 16S rRNA (about 500 bp) genes were analysed for 11 representative samples leading to a congruent phylogeny. Our study includes representatives of all 20 subspecies recognized today. The phylogenetic analysis of the sequence data revealed three main clades: mainland with nearby islands, Vis archipelago, and Lastovo archipelago. The degree of mitochondrial DNA divergence among these clades suggests a separation of the respective population groups during the earliest Pleistocene. The phylogenetic pattern observed within the species is in sharp contrast to the actual taxonomic division into subspecies. A correlation between genetic diversity of P. melisellensis populations and paleogeography of the regions they inhabit is discussed.     

Energetic and locomotor costs of tail loss in the Chinese skink, Eumeces chinensis

Caudal autotomy is a defense mechanism used by numerous lizards to evade predators, but this entails costs. We collected 294 adult Chinese skinks (Eumeces chinensis) from a population in Lishui (eastern China) to evaluate energetic and locomotor costs of tail loss. Of the 294 skinks, 214 (c. 73%) had previously experienced caudal autotomy. Neither the proportion of individuals with regenerated tails nor the frequency distribution of locations of the tail break differed between sexes. We successively removed four tail segments from each of the 20 experimental skinks (adult males) initially having intact tails. Lipid content in each removed tail segment was measured, and locomotor performance (sprint speed, the maximal length traveled without stopping and the number of stops in the racetrack) was measured for each skink before and after each tail-removing treatment. Another independent sample of 20 adult males with intact tails was measured for locomotor performance to serve as controls for successive measurements taken for the experimental lizards. Caudal lipids were disproportionately stored along the length of the tail, with most lipids being aggregated in its proximal portion. Tail loss significantly affected sprint speed, but not the maximal length of, or the number of stops during the sprint. However, the adverse influence of tail loss on sprint speed was not significant until more than 51% of the tail (in length) was lost. Our data show that partial tail loss due to predatory encounters or other factors may not severely affect energy stores or locomotor performance in E. chinensis. As tail breaks occurred more frequently in the proximal portion of the tail in skinks collected from the field, we conclude that caudal autotomy occurring in nature often incurs substantial energetic and locomotor costs in E. chinensis.     

Deferred agonistic behavior in a long-lived scincid lizard Eumeces laticeps

Summary A laboratory experiment with the broad-headed skink (Eumeces laticeps) involving staged agonistic encounters demonstrates that larger males have an advantage over smaller ones in agonistic bouts. Field data on head wounds produced by intraspecific fighting during the breeding season show a much higher frequency of new wounds among males over 100 mm in snout-vent-length than in smaller males. The significant difference in new-wound frequency strongly suggests avoidance of fights by the small males, which is corroborated by laboratory and field observations. Access by males to reproductively active females depends on the ability to defeat other males in aggressive contests virtually always involving head biting if the males are of nearly equal size. Because the probability of winning agonistic encounters increases with size, young males avoid fights with older males. Aggressive contests with larger males and reproductive attempts other than courtship in the absence of larger males are deferred.Aggressive behavior in E. laticeps may be employed in direct defense of females, but might also be expressed in defense of specific sites and/or territories. In the laboratory, males in their home cages were significantly more likely to win encounters with males of similar size than were males fighting in the home cages of opponents. This suggests that encounter site could be important in determining encounter outcome and that field study of possible site defense or territoriality is needed.     

Fine‐scale genetic structuring in a group‐living lizard,the gidgee skink (Egernia stokesii)

By constraining gene flow, group living and natal philopatry can result in fine‐scale genetic structure. Although the genetic structure of some group‐living lizards has been characterised, studies are few compared with those for group‐living bird and mammal species. The Egerniinae group of lizards exhibits a high diversity of social structures, making it a useful group for comparative studies of genetic structure across a broader range of social taxa. A well‐studied member of Egerniinae is Egernia stokesii, a lizard that forms long‐term pair bonds and stable social groups and exhibits natal philopatry and limited dispersal. Evidence exists for consistent E. stokesii social structure across seven close but disconnected rocky outcrops within a 40 × 10 km area. We used summary statistics, analysis of molecular variance, Bayesian clustering, and discriminant analysis of principal components to assess if E. stokesii exhibit a consistent pattern of fine‐scale genetic structure across the same seven outcrops. Due to E. stokesii social structure and constrained dispersal, we predicted significant genetic structuring – based on microsatellite markers – among outcrops. We found significant fine‐scale genetic structuring and evidence for two genetic clusters. We discuss features of E. stokesii biology and ecology that may explain our findings. Some rocky outcrops, and some social groups, contained lizards from both genetic clusters. An examination of the composition of mixed cluster social groups did not detect any notable patterns. Therefore, further work is necessary to identify how the observed patterns may have arisen. Future investigations in E. stokesii and other group‐living lizard species are likely to contribute greatly to our understanding of the genetic consequences of group living.     

Multilocus phylogeography of the Patagonian lizard complex Liolaemus kriegi (Iguania: Liolaemini)

This study presents a detailed phylogeographical analysis of one of the most conspicuous groups of lizards in northwestern Patagonia, the Liolaemus kriegi complex. This region is geographically very complex as a result of Andean orogeny and subsequent volcanism coupled with a long history of glaciations and climatic changes. For 247 individuals we sequenced one mitochondrial gene (cytochrome b) and for a subset we sequenced another mitochondrial gene [12S ribosomal RNA (12S)] and two nuclear fragments [kinesin family member 24 (KIF24) and BA3 ribosomal RNA (BA3)]. We obtained gene trees and mitochondrial and nuclear haploytpe networks, and estimated genetic distances between the main lineages and basic molecular diversity indices. We also performed spatial analysis of molecular variance (SAMOVA) and Bayesian Skyline Plot (BSP) analyses, and concordant patterns from different lines of evidence permitted delimitation of seven lineages: two described species, Liolaemus buergeri and Liolaemus tregenzai; four candidate species, Liolaemus sp. A, Liolaemus sp. B, Liolaemus sp. C, and Liolaemus sp. D; and one lineage that includes all individuals from the geographical range of Liolaemus ceii and L. kriegi, referred to as L. kriegi + L. ceii. We discuss the evolutionary processes that may contribute to the origin of these lineages and their taxonomic and conservation implications. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 256–269.     

Induction of sexual receptivity in the female broad-headed skink, Eumeces laticeps, by estradiol-17 beta

Sexual receptivity in the female scincid lizard Eumeces laticeps occurs naturally only during the spring breeding season, which is also when maximal follicular development occurs. The presumption that high estrogen levels are coincidentally present and the need for a reliable method of inducing sexual receptivity for behavioral studies prompted tests of the hypothesis that estrogen induces sexual behavior. A series of experiments established that estradiol-17 beta induces sexual behavior. A series of experiments established that estradiol-17 beta induces sexual receptivity within 4 days when injected every other day at 2.0 micrograms in 20 microliters peanut oil in intact or ovariectomized females. In behavioral tests conducted during August, all control females (intact or ovariectomized injected with vehicle only) rejected courtship whereas all females receiving estrogen copulated. Estrogen injections also induced a statistically significant change from rejection to receptivity within individuals. Initial attempts to implant estradiol-17 beta in Silastic tubes killed all females so treated.     

Cladogenesis and phylogeography of the lizard Phrynocephalus vlangalii (Agamidae) on the Tibetan plateau

Phrynocephalus vlangalii is restricted to dry sand or Gobi desert highlands between major mountain ranges in the Qinghai (Tibetan) Plateau. Mitochondrial DNA (mtDNA) sequence (partial ND2, tRNA(Trp) and partial tRNA(Ala)) was obtained from 293 Phrynocephalus sampled from 34 sites across the plateau. Partitioned Bayesian and maximum parsimony phylogenetic analyses revealed that P. vlangalii and two other proposed species (P. erythrus and P. putjatia) together form a monophyletic mtDNA clade which, in contrast with previous studies, does not include P. theobaldi and P. zetangensis. The main P. vlangalli clade comprises seven well-supported lineages that correspond to distinct geographical areas with little or no overlap, and share a most recent common ancestor at 5.06 +/- 0.68 million years ago (mya). This is much older than intraspecific lineages in other Tibetan animal groups. Analyses of molecular variance indicated that most of the observed genetic variation occurred among populations/regions implying long-term interruption of maternal gene flow. A combined approach based on tests of population expansion, estimation of node dates, and significance tests on clade areas indicated that phylogeographical structuring has been primarily shaped by three main periods of plateau uplift during the Pliocene and Pleistocene, specifically 3.4 mya, 2.5 mya and 1.7 mya. These periods corresponded to the appearance of several mountain ranges that formed physical barriers between lineages. Populations from the Qaidam Basin are shown to have undergone major demographic and range expansions in the early Pleistocene, consistent with colonization of areas previously covered by the huge Qaidam palaeolake, which desiccated at this time. The study represents one of the most detailed phylogeographical analyses of the Qinghai Plateau to date and shows how geological events have shaped current patterns of diversity.     

Influence of food type on specific dynamic action of the Chinese skink Eumeces chinensis

We used the Chinese skink (Eumeces chinensis) as an experimental model to study influence of food type on specific dynamic action (SDA) of feeding. Thirty-three adult males collected from a natural population were divided equally into three (one control and two experimental) groups. We starved all skinks at 30 degrees C for 3 days and then provided the experimental skinks with a single meal consisting of either mealworms or meat [the flesh of the bullfrog (Rana catesbeiana)]. Food ingested by skinks of the two experimental groups differed in lipid content and lean dry mass but not in total dry mass and energy. Defecation following feeding occurred slightly earlier in skinks ingesting mealworms (mean=41.7 h) than in those ingesting meat (mean=47.7 h), but the difference was not significant. Analyses of variance (ANOVAs) with repeated measures showed that temporal variation in oxygen consumption over 72 h after feeding was evident in the experimental skinks but not in the control ones. Oxygen consumption was higher in the experimental skinks than in the control ones during the time interval between 4.5 and 36 h after feeding. The peak metabolic rate was greater but occurred later in skinks ingesting meat than in those ingesting mealworms. The estimated amounts of oxygen consumed by mealworm-fed, meat-fed and unfed skinks at 30 degrees C over 72 h after feeding were 356.5, 393.8 and 295.2 mL, respectively. Our results provide a support for the previous prediction that SDA is affected by types of food ingested by animals as skinks ingesting mealworms and meat differed in the time to reach a peak metabolic rate, the level of the peak metabolic rate and the magnitude of the SDA effect.