Journal articles: 'Lizard Sex'

1

Akani, Godfrey, Nwabueze Ebere, Valentin Pérez-Mellado, and Luca Luiselli. "Stomach flushing affects survival/emigration in wild lizards: a study case with rainbow lizards (Agama agama) in Nigeria." Amphibia-Reptilia 32, no. 2 (2011): 253–60. http://dx.doi.org/10.1163/017353711x565493.

Full text

Abstract:

AbstractStomach flushing is one of the proposed techniques to study lizard diets. Apparently, it is ranged, together with direct observation and faecal analysis, as a non-harmful method for dietary studies. Some works explored the usefullness of stomach flushing, but we lack information about its effect on lizard's survival probabilities. In this paper we studied the effect of stomach flushing in an urban population of the rainbow lizard (Agama agama) from Calabar (Nigeria). During a period of five months of 2010, 147 lizards were noosed, sexed and individually marked. One group of lizards was stomach flushed only once, whereas the rest of lizards were not flushed. The flushed sample of lizards showed a lower survival than non-flushed lizards of all sex and age classes. In this study, the pictured diet from stomach flushing was very similar to results obtained with a faecal analysis of the same lizard population. Thus, both methods seem to be reliable to study the diet of the rainbow lizard. However, our results indicate that stomach flushing increases the probability of mortality (or at least emigration rates) in all age and sex classes, precluding its extensive use as a method to study lizard's diets.

APA, Harvard, Vancouver, ISO, and other styles

2

Wieczorek, Magdalena, Robert Rektor, Bartłomiej Najbar, and Federico Morelli. "Tick parasitism is associated with home range area in the sand lizard, Lacerta agilis." Amphibia-Reptilia 41, no. 4 (May 26, 2020): 479–88. http://dx.doi.org/10.1163/15685381-bja10018.

Full text

Abstract:

Abstract The sand lizard (Lacerta agilis) is a common species in Europe that inhabits a wide range of habitats, including anthropogenic environments. It is a frequent carrier of common ticks (Ixodes ricinus), which poses a severe threat to the lizards’ health. We determined the living space used by lizards in a rapidly changing environment and ascertained the number of parasitic ticks found throughout the reptile’s active season. We conducted telemetry research on a dynamically developing housing estate located on the outskirts of the city of Zielona Góra (western Poland) in 2016-2017. We obtained data from 16 adult lizards, from which we collected 2529 ticks. Using generalized linear models (GLMs), we determined the relationships among the number of transmitted parasites, size of occupied areas (minimum convex polygon, MCP), the weight of lizards, and sex of lizards. Results indicated that the number of ticks was negatively correlated with lizard body mass, but positively correlated with home range. Sex was not significantly associated with the number of ticks. Additionally, the parasite load was lower during the lizard’s non-breeding season than during the breeding season and was lower for males than for females during the non-breeding season. Males have larger home ranges than females.

APA, Harvard, Vancouver, ISO, and other styles

3

Schall, J. J. "The sex ratio of Plasmodium gametocytes." Parasitology 98, no. 3 (June 1989): 343–50. http://dx.doi.org/10.1017/s0031182000061412.

Full text

Abstract:

SUMMARYSex ratio theory usually predicts an equilibrium sex ratio and equal proportions of males and females in a population, including the progenitors of the reproductive cells of protozoans. This proposal was tested with three species of malarial parasites of lizards, Plasmodium mexicanum of the western fence lizard, and P. agamae and P. giganteum of the African rainbow lizard, using single samples from naturally infected lizards, repeated samples from free-ranging lizards (P. mexicanum only), and repeated samples from laboratory maintained animals. Macrogametocytes were usually more abundant than microgametocytes, and were slightly larger, revealing a typically greater investment of resources by the progenitors of female reproductive cells. However, the proportion of microgametocytes varied among the three species and among infections within each species of Plasmodium. The sex ratio of gametocytes often remained constant within infections followed over time even if the absolute number of gametocytes was changing. However, the equilibrium sex ratio of gametocytes varied among those infections that had an unchanging microgametocyte proportion. Thus, although an equilibrium sex ratio apparently occurs for most infections, there appears to be no characteristic proportion of microgametocytes for any of the species. Potential explanations for this conflict with theory are presented.

APA, Harvard, Vancouver, ISO, and other styles

4

Mezzasalma, Marcello, Fabio M. Guarino, and Gaetano Odierna. "Lizards as Model Organisms of Sex Chromosome Evolution: What We Really Know from a Systematic Distribution of Available Data?" Genes 12, no. 9 (August 28, 2021): 1341. http://dx.doi.org/10.3390/genes12091341.

Full text

Abstract:

Lizards represent unique model organisms in the study of sex determination and sex chromosome evolution. Among tetrapods, they are characterized by an unparalleled diversity of sex determination systems, including temperature-dependent sex determination (TSD) and genetic sex determination (GSD) under either male or female heterogamety. Sex chromosome systems are also extremely variable in lizards. They include simple (XY and ZW) and multiple (X1X2Y and Z1Z2W) sex chromosome systems and encompass all the different hypothesized stages of diversification of heterogametic chromosomes, from homomorphic to heteromorphic and completely heterochromatic sex chromosomes. The co-occurrence of TSD, GSD and different sex chromosome systems also characterizes different lizard taxa, which represent ideal models to study the emergence and the evolutionary drivers of sex reversal and sex chromosome turnover. In this review, we present a synthesis of general genome and karyotype features of non-snakes squamates and discuss the main theories and evidences on the evolution and diversification of their different sex determination and sex chromosome systems. We here provide a systematic assessment of the available data on lizard sex chromosome systems and an overview of the main cytogenetic and molecular methods used for their identification, using a qualitative and quantitative approach.

APA, Harvard, Vancouver, ISO, and other styles

5

Rabiu, Safanu. "Dietary resource partitioning among age-sex classes of Agama agama (Squamata: Agamidae) assessed by fecal pellet analysis." Phyllomedusa: Journal of Herpetology 18, no. 1 (June 18, 2019): 63–75. http://dx.doi.org/10.11606/issn.2316-9079.v18i1p63-75.

Full text

Abstract:

Dietary resource partitioning among age-sex classes of Agama agama (Squamata: Agamidae) assessed by fecal pellet analysis. Dietary analysis is critical to understand the ecological roles of lizards, especially of species of Agama that are colonizing continents and islands from which they were previously absent. The foraging habits of four groups—viz., adult females, adult males, and young and juveniles (of both sexes)—of Agama agama in Nigeria were observed to assess the diet of the lizards and the contribution of the diet to separating age-sex classes. The claim that fying arthropods are less likely to be eaten by lizards was tested, and the hypothesis of dietary opportunism was explored. Sets (3–5 pellets) of 1453 fecal pellets collected during a 2-yr period were linked to individual lizards. Multivariate discriminant analysis of individual food items showed 61% lizards were correctly classifed to age-sex. However, items pooled into composite food groups, yielded fewer (43%) correctly classifed lizards. Cluster Analysis indicated that individual foods were less common (46.3%) to lizard classes than composite foods (76.1%). Thus, lizard age-sex classes are better differentiated when prey item is identifed at the lowest possible taxonomic level. Overall, arthropods are the largest, composite food for all lizard classes but, the relative amounts of different arthropod taxa varies signifcantly, and is highest for Diptera. Other foods include plants, seeds, and non-arthropod animal material. Differing coeffcients of variation accentuate dietary disparities within classes. Proportions of most individual and composite diet items differ signifcantly by month, season, and study site. Although consumed by lizards, no traces of white mold were found in the feces; this underscores the value of combining fecal analysis with surveillance of foraging habits of Agama agama.

APA, Harvard, Vancouver, ISO, and other styles

6

Kostmann, Alexander, Lukáš Kratochvíl, and Michail Rovatsos. "First Report of Sex Chromosomes in Plated Lizards (Squamata: Gerrhosauridae)." Sexual Development 14, no. 1-6 (2020): 60–65. http://dx.doi.org/10.1159/000513764.

Full text

Abstract:

Squamate reptiles show high diversity in sex determination ranging from environmental sex determination to genotypic sex determination with varying degrees of differentiation of sex chromosomes. Unfortunately, we lack even basic information on sex determination mode in several lineages of squamates, which prevents full understanding of their diversity and evolution of sex determination. One of the reptilian lineages with missing information on sex determination is the family Gerrhosauridae, commonly known as the plated lizards. Several species of gerrhosaurids have been studied in the past by conventional cytogenetic methods, but sex-specific differences were not identified. In this study, we applied both conventional and molecular cytogenetic methods to metaphases from both sexes of the Peters’ keeled plated lizard (<i>Tracheloptychus petersi</i>). We identified accumulations of rDNA loci in a pair of microchromosomes in metaphases from males, but only in a single microchromosome in females. The restriction of the observed heterozygosity to females suggests a putative ZZ/ZW system of sex chromosomes, which represents the first report of sex chromosomes in a gerrhosaurid lizard. The lack of sex-specific signals in all other cytogenetic methods implies that the sex chromosomes of <i>T. petersi</i> are poorly differentiated in sequence content.

APA, Harvard, Vancouver, ISO, and other styles

7

Jacobson, Faelan, Grace Garrison, Jacob Penner, João Zecchini Gebin, Maria Eifler, and Douglas Eifler. "Escape behaviour in the leopard lizard (Gambelia wislizenii): effects of starting distance and sex." Amphibia-Reptilia 37, no. 3 (2016): 320–24. http://dx.doi.org/10.1163/15685381-00003054.

Full text

Abstract:

Predation risk influences decision making, escape behaviour, and resource use. Risk assessment and behavioural responses to predation can depend on demographic and environmental factors. We studied the escape behaviour of the long-nosed leopard lizard (Gambelia wislizenii) when approached by a human predator (= “simulated predator”), analysing flight initiation distance (FID) and flight distance (FD) relative to demographic and environmental variables. Starting distance (SD) of the simulated predator and orientation of prey lizards relative to the simulated predator influenced FID, but body size of the prey lizard did not. Sex interacted with SD to affect FID. Females lengthened their FIDs as SD increased, while male FID was unrelated to SD. Flight distance increased with increasing SD. Gambelia wislizenii’s ecological role as an ambush predator may explain their escape behaviour; reproductive status potentially affected the interaction between sex and SD.

APA, Harvard, Vancouver, ISO, and other styles

8

Gwiazdowicz, Dariusz J., Anna K. Gdula, Rafał Kurczewski, and Bogna Zawieja. "Factors influencing the level of infestation of Ixodes ricinus (Acari: Ixodidae) on Lacerta agilis and Zootoca vivipara (Squamata: Lacertidae)." Acarologia 60, no. 2 (April 30, 2020): 390–97. http://dx.doi.org/10.24349/acarologia/20204372.

Full text

Abstract:

The purpose of this study was to analyse selected factors determining the level of infestation of Ixodes ricinus ticks on Lacerta agilis and Zootoca vivipara lizards found in Central Europe. Both environmental factors (habitats within protected areas and areas transformed as a result of human activity) as well as morphological factors (age, sex and size of lizards, location of ticks on the lizard’s body) were assessed. We found that the age and size of a lizard played a significant role in the level of infestation, but this depended on the species and habitat. Females of both species differed significantly in their level of tick infestation; females of L. agilis had lower infection than Z. vivipara. In contrast, there was no difference in levels of infection between juveniles and males of the different species. We also found that the impact of body size changed in the different habitats: the number of ticks increased with body size in natural areas only. In addition, more frequently ticks were found in the front groin area (336 individuals) and forelimbs (202), less often on the neck (12) and never in the hind groin area. These differences might be because it is easier to infest a larger individual than a smaller one, and areas of the front of the lizard might be more accessible whilst foraging. This study provides additional information about tick infestation that may be relevant to the conservation of the species of lizards.

APA, Harvard, Vancouver, ISO, and other styles

9

Goymer, Patrick. "Warm and wild lizard sex changes." Nature Reviews Genetics 16, no. 8 (July 7, 2015): 440. http://dx.doi.org/10.1038/nrg3977.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Robert, Kylie A., and Michael B. Thompson. "Viviparous lizard selects sex of embryos." Nature 412, no. 6848 (August 2001): 698–99. http://dx.doi.org/10.1038/35089135.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Kacoliris, Federico, Alejandro Molinari, and Jorge Williams. "Selection of key features of vegetation and escape behavior in the Sand Dune Lizard (Liolaemus multimaculatus)." Animal Biology 60, no. 2 (2010): 157–67. http://dx.doi.org/10.1163/157075610x491707.

Full text

Abstract:

AbstractVegetation structure and cover are two of the main factors which determine microhabitat preferences in lizards. The Sand Dune Lizard (Liolaemus multimaculatus) is a vulnerable and endemic species of the pampean coastal habitats from Argentina. We hypothesized that: a) Sand Dune Lizard prefer to perch in microhabitats that offer a good balance between visibility and refuge, and; b) lizards prefer microhabitats in which plant types allow them to resort to sand burying behavior. We recorded data of microhabitat (bunch-grasses sizes and plant types) used by lizards (males, females and juveniles) in a population at the Mar Chiquita Provincial Nature Reserve. We applied the use-availability design to assess preferences. We evaluated differences between sex and relation between sizes of lizards. Lizards preferred bunch-grasses of intermediate size. Habitats conformed only by herbaceous species were the most preferred by lizards. We did not find differences between males and females, neither relations between size of lizards and the tested variables. Adult lizards of both sexes use bunch-grasses more frequently than juvenile individuals. The preferences for herbaceous species could be related to the sand-bury behavior that lizards use to escape from predators. More studies are necessary in order to assess the processes related with habitat preferences

APA, Harvard, Vancouver, ISO, and other styles

12

Radder, Rajkumar S., Alexander E. Quinn, Arthur Georges, Stephen D. Sarre, and Richard Shine. "Genetic evidence for co-occurrence of chromosomal and thermal sex-determining systems in a lizard." Biology Letters 4, no. 2 (December 18, 2007): 176–78. http://dx.doi.org/10.1098/rsbl.2007.0583.

Full text

Abstract:

An individual's sex depends upon its genes (genotypic sex determination or GSD) in birds and mammals, but reptiles are more complex: some species have GSD whereas in others, nest temperatures determine offspring sex (temperature-dependent sex determination). Previous studies suggested that montane scincid lizards ( Bassiana duperreyi , Scincidae) possess both of these systems simultaneously: offspring sex is determined by heteromorphic sex chromosomes (XX–XY system) in most natural nests, but sex ratio shifts suggest that temperatures override chromosomal sex in cool nests to generate phenotypically male offspring even from XX eggs. We now provide direct evidence that incubation temperatures can sex-reverse genotypically female offspring, using a DNA sex marker. Application of exogenous hormone to eggs also can sex-reverse offspring (oestradiol application produces XY as well as XX females). In conjunction with recent work on a distantly related lizard taxon, our study challenges the notion of a fundamental dichotomy between genetic and thermally determined sex determination, and hence the validity of current classification schemes for sex-determining systems in reptiles.

APA, Harvard, Vancouver, ISO, and other styles

13

Luiselli, Luca, Leonardo Vignoli, and Dario Capizzi. "Flight initiation distance in relation to substratum type, sex, reproductive status and tail condition in two lacertids with contrasting habits." Amphibia-Reptilia 28, no. 3 (2007): 403–7. http://dx.doi.org/10.1163/156853807781374827.

Full text

Abstract:

AbstractFlight initiation distance in relation to substratum type, sex, reproductive status and tail condition was studied in two lacertid lizards with contrasting habits: the ground-dwelling common lizard Zootoca vivipara and the rupicolous Horvath's rock lizard Iberolacerta horvathi. These species were studied in sympatric populations in a mountain area in North-Eastern Italy, Tarvisio Forest. Mean escape distance was significantly higher in I. horvathi than in Z. vivipara. In both species there were significant differences between sexes, with males escaping at longer distances than females but there were no significant differences between adults and subadults. In both species there were no differences in escape distance of females in different reproductive states. In Z. vivipara specimens with broken tails escaped at a shorter distance than individuals with intact tails. Substratum type had a significant effect on escape distance in both species.

APA, Harvard, Vancouver, ISO, and other styles

14

Carazo, Pau, Daniel W. A. Noble, Dani Chandrasoma, and Martin J. Whiting. "Sex and boldness explain individual differences in spatial learning in a lizard." Proceedings of the Royal Society B: Biological Sciences 281, no. 1782 (May 7, 2014): 20133275. http://dx.doi.org/10.1098/rspb.2013.3275.

Full text

Abstract:

Understanding individual differences in cognitive performance is a major challenge to animal behaviour and cognition studies. We used the Eastern water skink ( Eulamprus quoyii ) to examine associations between exploration, boldness and individual variability in spatial learning, a dimension of lizard cognition with important bearing on fitness. We show that males perform better than females in a biologically relevant spatial learning task. This is the first evidence for sex differences in learning in a reptile, and we argue that it is probably owing to sex-specific selective pressures that may be widespread in lizards. Across the sexes, we found a clear association between boldness after a simulated predatory attack and the probability of learning the spatial task. In contrast to previous studies, we found a nonlinear association between boldness and learning: both ‘bold’ and ‘shy’ behavioural types were more successful learners than intermediate males. Our results do not fit with recent predictions suggesting that individual differences in learning may be linked with behavioural types via high–low-risk/reward trade-offs. We suggest the possibility that differences in spatial cognitive performance may arise in lizards as a consequence of the distinct environmental variability and complexity experienced by individuals as a result of their sex and social tactics.

APA, Harvard, Vancouver, ISO, and other styles

15

Gardner, M. G., S. S. Godfrey, A. L. Fenner, S. C. Donnellan, and C. M. Bull. "Fine-scale spatial structuring as an inbreeding avoidance mechanism in the social skink Egernia stokesii." Australian Journal of Zoology 60, no. 4 (2012): 272. http://dx.doi.org/10.1071/zo12089.

Full text

Abstract:

Egernia stokesii is a monogamous and group-living species of Australian scincid lizard. We used genotype data from 10 microsatellite loci to examine evidence for sex-biased dispersal and kin-based discrimination as mechanisms for inbreeding avoidance of E. stokesii within seven rocky outcrops in the southern Flinders Ranges of South Australia. We also examined the relatedness of individuals observed using the same crevice within groups. We found no evidence for sex-biased dispersal at these sites, but found that adult lizards of the opposite sex observed using the same crevice were less related to each other than expected by chance. Our results suggest a behavioural mechanism for minimising inbreeding in large related aggregations of this species.

APA, Harvard, Vancouver, ISO, and other styles

16

Leu, Stephan T., Grant Jackson, John F. Roddick, and C. Michael Bull. "Lizard movement tracks: variation in path re-use behaviour is consistent with a scent-marking function." PeerJ 4 (March 22, 2016): e1844. http://dx.doi.org/10.7717/peerj.1844.

Full text

Abstract:

Individual movement influences the spatial and social structuring of a population. Animals regularly use the same paths to move efficiently to familiar places, or to patrol and mark home ranges. We found that Australian sleepy lizards (Tiliqua rugosa), a monogamous species with stable pair-bonds, repeatedly used the same paths within their home ranges and investigated whether path re-use functions as a scent-marking behaviour, or whether it is influenced by site familiarity. Lizards can leave scent trails on the substrate when moving through the environment and have a well-developed vomeronasal system to detect and respond to those scents. Path re-use would allow sleepy lizards to concentrate scent marks along these well-used trails, advertising their presence. Hypotheses of mate attraction and mating competition predict that sleepy lizard males, which experience greater intra-sexual competition, mark more strongly. Consistent with those hypotheses, males re-used their paths more than females, and lizards that showed pairing behaviour with individuals of the opposite sex re-used paths more than unpaired lizards, particularly among females. Hinterland marking is most economic when home ranges are large and mobility is low, as is the case in the sleepy lizard. Consistent with this strategy, re-used paths were predominantly located in the inner 50% home range areas. Together, our detailed movement analyses suggest that path re-use is a scent marking behaviour in the sleepy lizard. We also investigated but found less support for alternative explanations of path re-use behaviour, such as site familiarity and spatial knowledge. Lizards established the same number of paths, and used them as often, whether they had occupied their home ranges for one or for more years. We discuss our findings in relation to maintenance of the monogamous mating system of this species, and the spatial and social structuring of the population.

APA, Harvard, Vancouver, ISO, and other styles

17

Hofmann, Sylvia. "Who is sitting next to me? Relatedness between next neighbours in common lizards." Amphibia-Reptilia 29, no. 1 (2008): 19–24. http://dx.doi.org/10.1163/156853808783431497.

Full text

Abstract:

Abstract Several lizard species have been shown to exhibit kin recognition, including green iguanas (Iguana iguana), three Australian Scincid species (Egernia stokesii, E. striolata and Tiliqua rugosa) and common lizards (Lacerta vivipara). Thus, observations of close neighboured individuals of the common lizard that consist of differently or same-aged individuals at a given site may generate speculation about the relatedness structure of such combinations and putative “social” patterns of this species. A total of 682 lizards were sampled from a population in a nature reserve near Leipzig, Germany. Relatedness statistics were calculated using five microsatellite DNA loci. The relatedness of individuals that were sighted or captured together was compared by grouping them on sex and age. The results showed that pairs of adults and juveniles were significantly more related than all other combinations, with adults showing the lowest mean values of relatedness, followed by a similar low level of relatedness between subadults. Most “pairs” were found in juveniles. Pairs of subadults and juveniles as well as of adults and juveniles consisted mainly of females. In subadults and adults, males were non-related. Little evidence was found to indicate that relatedness is relevant to the spatial distance between individuals. The relatedness patterns of associated individuals may arise from male sex-biased dispersal rather than from active kin preferences based on kin discrimination.

APA, Harvard, Vancouver, ISO, and other styles

18

Tang, Xiao-Long, Feng Yue, De-Jiu Zhang, Xue-Feng Yan, Ying Xin, Cui Wang, and Qiang Chen. "The effect of operational sex ratio on sex allocation and neonate phenotype in a viviparous lizard Eremias multiocellata." Amphibia-Reptilia 33, no. 3-4 (2012): 485–93. http://dx.doi.org/10.1163/15685381-00002851.

Full text

Abstract:

Maternal investment in the production of male versus female neonates was approximately equal in most animal species. However, sex allocation theory predicts that under certain conditions, selection may favor the females’ ability to adjust the sex ratio of their offspring, which females tend to use more for an investment of the rare sex. The mechanism of operational sex ratio (OSR) influence on sex allocation is still unclear, and recent studies conducted on lizards have reached conflicting conclusions. Here, we selected a viviparous lizard Eremias multiocellata to test whether pregnant females could adjust the sex ratio of their offspring in response to OSRs. Our results showed that mothers did not adjust the sex ratios or phenotypes of neonates in the laboratory and field-based experiments, except tail length. However, the OSRs subsequently affected growth in both mass and SVL of the offspring in laboratory experiments; whereas only the mass was affected in the semi-nature field experiments. Our results, thus, contradict the predictions of sex allocation theory and challenge the idea that female investment in the scarcity sex might serve as a mechanism which is used for adjusting the population sex ratio.

APA, Harvard, Vancouver, ISO, and other styles

19

Teixeira, A. A. M., R. J. Silva, S. V. Brito, D. A. Teles, J. A. Araujo-Filho, L. D. Franzini, D. O. Santana, W. O. Almeida, and D. O. Mesquita. "Helminths infecting Dryadosaura nordestina (Squamata: Gymnophthalmidae) from Atlantic Forest, northeastern Brazil." Helminthologia 55, no. 4 (December 1, 2018): 286–91. http://dx.doi.org/10.2478/helm-2018-0026.

Full text

Abstract:

Abstract We analyzed the patterns of infection by helminths in populations of the Gymnophthalmidae lizard Dryadosaura nordestina from three Atlantic Forest fragments in Northeast Brazil. Prevalence and mean intensity of infection by location showed the following results: ARIE Mata de Goiamunduba (60.8 % and 10.4 ± 8), RPPN Engenho Gargaú (83.3 % and 20.8 ± 19.7) and Benjamim Maranhão Botanical Garden (70.4 % and 7.78 ± 5.8). We provide the first records of helminth infection for the lizard D. nordestina, in which three species of nematodes, Aplectana sp., Cosmocerca sp. and Physaloptera lutzi and one trematode Haplometroides odhneri were recovered. Trematodes of the genus Haplometroides were previously known as parasites only in snake and amphisbaenian hosts in South America. Now, our study provides the first record of a species belonging to this genus parasitizing lizards. In conclusion, our study shows that D. nordestina have a depleted helminth fauna (three species at maximum), similar to other studies with lizards of this family in Brazil and that its parasite abundance is related to host snout-vent length, but not to the sex.

APA, Harvard, Vancouver, ISO, and other styles

20

Billy, Allen J. "Developmental deformities in the parthenogenetic lizard Cnemidophorus uniparens (Teiidae) and the "anomalous male" phenomenon." Canadian Journal of Zoology 64, no. 11 (November 1, 1986): 2418–24. http://dx.doi.org/10.1139/z86-361.

Full text

Abstract:

Parthenogenetic species of lizard occasionally produce male progeny characterized by developmental defects and low viability. Production of anomalous males is an unresolved problem in sexual differentiation as parthenogenetic female lizards are expected to produce female offspring. The "anomalous male" phenomenon was examined by sexing nonviable embryos produced by the parthenogenetic whiptail lizard Cnemidophorus uniparens. Twenty-six deformed embryos were obtained; all were female except for three which did not possess gonads. Male embryos were not detected. Developmental deformities found in Cnemidophorus embryos included anophthalmia, micropthalmia, encephalocoele, hypoplasia of the lower jaw, head foreshortening, gastroschisis, and malformations of the vertebral column. Several embryos possessed a combination of defects. Four hypotheses are presented to account for production of anomalous males by reptilian parthenoforms. Three hypotheses involve production of sex-reversed males (genetic females). A fourth hypothesis asserts that anomalous males are derived from hybridization events between a female from a unisexual species and a male from a bisexual species. Of the four hypotheses, the hybridization hypothesis has the greatest utility in explaining production of anomalous males by parthenogenetic lizards.

APA, Harvard, Vancouver, ISO, and other styles

21

Bezerra, C. H., R. W. Ávila, D. C. Passos, D. Zanchi-Silva, and C. A. B. Galdino. "Levels of helminth infection in the flat lizard Tropidurus semitaeniatus from north-eastern Brazil." Journal of Helminthology 90, no. 6 (September 16, 2015): 779–83. http://dx.doi.org/10.1017/s0022149x15000826.

Full text

Abstract:

AbstractParasites represent a great, unknown component of animal biodiversity. Recent efforts have begun to uncover patterns of infection by helminth parasites in several Neotropical lizards. The present study reports, for the first time, levels of helminth infection in a population of the flat lizard Tropidurus semitaeniatus. One hundred and thirty-nine lizards were examined and evidence of five intestinal helminth species was found, comprising four species of nematodes, one species of cestode and an unidentified encysted larval nematode. The most frequently occurring species was the intestinal nematode Parapharyngodon alvarengai, which did not exhibit differences in prevalence and intensity of infection relative to host sex or age/body size. Furthermore, helminth species richness was not related to host body size.

APA, Harvard, Vancouver, ISO, and other styles

22

Shamiminoori, Leili, Aaron L. Fenner, and C. Michael Bull. "Weight watching in burrows: variation in body condition in pygmy bluetongue lizards." Australian Journal of Zoology 62, no. 4 (2014): 284. http://dx.doi.org/10.1071/zo13072.

Full text

Abstract:

The pygmy bluetongue lizard, Tiliqua adelaidensis, is an endangered scincid lizard that occurs in remnants of natural grasslands in the mid-north of South Australia. We assessed the factors affecting body condition of male and female lizards, using body size residuals as an index, over five sampling years. We included sex, phenotypic (patterned or plain morphs), temporal (sampling year and activity period within year), and climatic factors in our analyses. The results indicated that sampling year and activity period within the year were the two most important factors influencing variation in body condition of both male and female lizards over the period of the study. There were similar trends when we considered males and females separately. However, when prepartum and postpartum females were analysed separately, sampling year did not affect their body condition. None of the analyses showed any significant effect of phenotype on body condition. Winter–spring rainfall was positively correlated with body condition of females in the prepartum period, but showed no significant effect on mean body condition of any other grouping of adult lizards, nor a consistent direction of correlation among the different subsets of adult lizards that we considered. The substantial annual variations in the body condition of lizards, although of uncertain cause, provide important information for conservation managers who monitor persisting populations of this endangered species.

APA, Harvard, Vancouver, ISO, and other styles

23

Nielsen, Stuart V., Irán Andira Guzmán-Méndez, Tony Gamble, Madison Blumer, Brendan J. Pinto, Lukáš Kratochvíl, and Michail Rovatsos. "Escaping the evolutionary trap? Sex chromosome turnover in basilisks and related lizards (Corytophanidae: Squamata)." Biology Letters 15, no. 10 (October 2019): 20190498. http://dx.doi.org/10.1098/rsbl.2019.0498.

Full text

Abstract:

Most pleurodont lizard families (anoles, iguanas and their relatives), with the exception of the basilisks and casquehead lizards (family Corytophanidae), share homologous XX/XY sex chromosomes, syntenic with chicken chromosome 15. Here, we used a suite of methods (i.e. RADseq, RNAseq and qPCR) to identify corytophanid sex chromosomes for the first time. We reveal that all examined corytophanid species have partially degenerated XX/XY sex chromosomes, syntenic with chicken chromosome 17. Transcriptomic analyses showed that the expression of X-linked genes in the corytophanid, Basiliscus vittatus, is not balanced between the sexes, which is rather exceptional under male heterogamety, and unlike the dosage-balanced sex chromosomes in other well-studied XX/XY systems, including the green anole, Anolis carolinensis . Corytophanid sex chromosomes may represent a rare example of a turnover away from stable, differentiated sex chromosomes. However, because of poor phylogenetic resolution among pleurodont families, we cannot reject the alternative hypothesis that corytophanid sex chromosomes evolved independently from an unknown ancestral system.

APA, Harvard, Vancouver, ISO, and other styles

24

Moreno-Rueda, Gregorio, Senda Reguera, Francisco J. Zamora-Camacho, and Mar Comas. "Inter-Individual Differences in Ornamental Colouration in a Mediterranean Lizard in Relation to Altitude, Season, Sex, Age, and Body Traits." Diversity 13, no. 4 (April 6, 2021): 158. http://dx.doi.org/10.3390/d13040158.

Full text

Abstract:

Animals frequently show complex colour patterns involved in social communication, which attracts great interest in evolutionary and behavioural ecology. Most researchers interpret that each colour in animals with multiple patches may either signal a different bearer’s trait or redundantly convey the same information. Colour signals, moreover, may vary geographically and according to bearer qualities. In this study, we analyse different sources of colour variation in the eastern clade of the lizard Psammodromus algirus. Sexual dichromatism markedly differs between clades; both possess lateral blue eyespots, but whereas males in the western populations display strikingly colourful orange-red throats during the breeding season, eastern lizards only show some commissure pigmentation and light yellow throats. We analyse how different colour traits (commissure and throat colouration, and the number of blue eyespots) vary according to body size, head size (an indicator of fighting ability), and sex along an elevational gradient. Our findings show that blue eyespots function independently from colour patches in the commissure and throat, which were interrelated. Males had more eyespots and orange commissures (which were yellow or colourless in females). Throat colour saturation and the presence of coloured commissures increased in older lizards. The number of eyespots, presence of a coloured commissure, and throat colour saturation positively related to head size. However, while the number of eyespots was maximal at lowlands, throat colour saturation increased with altitude. Overall, our results suggest that this lizard harbours several colour signals, which altitudinally differ in their importance, but generally provide redundant information. The relevance of each signal may depend on the context. For example, all signals indicate head size, but commissure colouration may work well at a short distance and when the lizard opens the mouth, while both throat and eyespots might work better at long distance. Meanwhile, throat colouration and eyespots probably work better in different light conditions, which might explain the altitudinal variation in the relative importance of each colour component.

APA, Harvard, Vancouver, ISO, and other styles

25

Roca, V., F. Jorge, Ç. Ilgaz, Y. Kumlutaş, S. H. Durmuş, and M. A. Carretero. "The intestinal helminth community of the spiny-tailed lizard Darevskia rudis (Squamata, Lacertidae) from northern Turkey." Journal of Helminthology 90, no. 2 (January 16, 2015): 144–51. http://dx.doi.org/10.1017/s0022149x14000911.

Full text

Abstract:

AbstractPopulations of the lizard Darevskia rudis (Bedriaga, 1886) from northern Anatolia were examined for intestinal parasites in adult specimens. One cestode, Nematotaenia tarentolae López-Neyra, 1944 and four nematode species, Spauligodon saxicolae Sharpilo, 1962, Skrjabinelazia hoffmanni Li, 1934, Oswaldocruzia filiformis (Goeze, 1782) and Strongyloides darevskyi Sharpilo, 1976, were found. Three of these nematodes, S. saxicolae, S. hoffmanni and S. darevskyi are suggested to be part of a module in the network of Darevskia spp. and their parasites. Only one, S. darevskyi, was identified as a Darevskia spp. specialist. The very low infection and diversity parameters are indicative of the depauperate helminth communities found in this lacertid lizard, falling among the lowest within the Palaearctic saurians. Nevertheless these values are higher than those found in parthenogenetic Darevskia spp. Interpopulation variation in the intensity of S. saxicolae and N. tarentolae is attributable to local changes in ecological conditions. On the other hand, parasite abundance and richness increased in the warmer localities, while the effect of lizard sex and size on infection was negligible. The structure of these helminth communities in D. rudis are compared with those observed in other European lacertid lizards.

APA, Harvard, Vancouver, ISO, and other styles

26

Vitt, Laurie J., and Celso Morato de Carvalho. "Life in the trees: the ecology and life history of Kentropyx striatus (Teiidae) in the lavrado area of Roraima, Brazil, with comments on the life histories of tropical teiid lizards." Canadian Journal of Zoology 70, no. 10 (October 1, 1992): 1995–2006. http://dx.doi.org/10.1139/z92-270.

Full text

Abstract:

The ecology and life history of the tropical teiid lizard Kentropyx striatus were studied in a grassland of northern Brazil, the lavrado area. The area, located nearly at the equator, experiences a prolonged dry season with a wet season extending from May to September. Total annual rainfall averages 1750 mm. Lizards were nonrandomly distributed among habitat patches and microhabitats. Most individuals were in trees and shrubs surrounding temporary and permanent water. Most individuals were observed active during late morning, the time period during which feeding and social interactions were observed. Lizards bask to achieve active body temperatures averaging 35.7 ± 0.23 °C. Body temperature is correlated with both substrate and air temperatures; foraging lizards maintained higher temperatures than basking lizards regardless of whether they were in sun, and lizards sampled when there was cloud cover had lower body temperatures than those sampled when sun was available. Females reach sexual maturity at 74 mm snout–vent length (SVL), produce 3–9 eggs per clutch, reproduce more than once per season, and commence reproduction during the wet season. Lizards hatch from eggs at 31 mm SVL. Maturity appears to be reached in 1 year or less. Overall, female reproductive characteristics are similar to those of other tropical teiid lizards that have been studied, with body size explaining much of the variance in reproductive characteristics across species. There is pronounced sexual dimorphism, with males larger in body size as well as certain other characteristics independent of body size. Sexual dimorphism appears to be a consequence of sexual selection. The diet is varied, but is dominated volumetrically by frogs, eruciform larvae, and spiders. Lizard body size accounted for only 5.5% of the variance in prey size and there was no difference in prey size due to sex. The occurrence of frogs and lizards in K. striatus stomachs suggests that teiid lizards may influence the structure of lizard and frog assemblages. The similarity of K. striatus to other studied tropical teiids in reproductive characteristics, morphology, activity period, activity temperatures, and diet underscore the conservative nature of the ecology of teiid lizards, presumably a consequence of their mode of prey acquisition.

APA, Harvard, Vancouver, ISO, and other styles

27

Schofield, Julie A., Aaron L. Fenner, Kelly Pelgrim, and C. Michael Bull. "Male-biased movement in pygmy bluetongue lizards: implications for conservation." Wildlife Research 39, no. 8 (2012): 677. http://dx.doi.org/10.1071/wr12098.

Full text

Abstract:

Context Translocation has become an increasingly common tool in the conservation of species. Understanding the movement patterns of some species can be important to minimise loss of individuals from the translocation release site. Aims To describe seasonal and sex-biased movements within populations of an endangered Australian lizard. Methods We monitored seasonal movement in the endangered pygmy bluetongue lizard (Tiliqua adelaidensis) by using pitfall trapping, with a total of 49 440 trap-nights from three sites over 2 years. Other studies have shown that individual pygmy bluetongue lizards normally remained closely associated with their spider burrow refuges, with very little movement. Thus, we interpreted any captures detected through pitfall trapping as out of burrow movements. We investigated whether there was any seasonal, age or sex bias in moving individuals. Key results We found that male pygmy bluetongue lizards were more likely to move than were females. After adults, neonates were the second-most captured age class. Spring was the peak movement time for adults, whereas movement of neonates occurred in autumn. Key conclusions The majority of movement can be attributed to males in the breeding season, whereas females move very little. Implications The present study provides some baseline data that would allow more informed decisions about the most appropriate individuals in a population to choose for a translocation program and the times to conduct translocations to allow the maximum chance for establishment.

APA, Harvard, Vancouver, ISO, and other styles

28

Nielsen, Stuart V., Brendan J. Pinto, Irán Andira Guzmán-Méndez, and Tony Gamble. "First Report of Sex Chromosomes in Night Lizards (Scincoidea: Xantusiidae)." Journal of Heredity 111, no. 3 (February 19, 2020): 307–13. http://dx.doi.org/10.1093/jhered/esaa007.

Full text

Abstract:

Abstract Squamate reptiles (lizards, snakes, and amphibians) are an outstanding group for studying sex chromosome evolution—they are old, speciose, geographically widespread, and exhibit myriad sex-determining modes. Yet, the vast majority of squamate species lack heteromorphic sex chromosomes. Cataloging the sex chromosome systems of species lacking easily identifiable, heteromorphic sex chromosomes, therefore, is essential before we are to fully understand the evolution of vertebrate sex chromosomes. Here, we use restriction site-associated DNA sequencing (RADseq) to classify the sex chromosome system of the granite night lizard, Xantusia henshawi. RADseq is an effective alternative to traditional cytogenetic methods for determining a species’ sex chromosome system (i.e., XX/XY or ZZ/ZW), particularly in taxa with non-differentiated sex chromosomes. Although many xantusiid lineages have been karyotyped, none possess heteromorphic sex chromosomes. We identified a ZZ/ZW sex chromosome system in X. henshawi—the first such data for this family. Furthermore, we report that the X. henshawi sex chromosome contains fragments of genes found on Gallus gallus chromosomes 7, 12, and 18 (which are homologous to Anolis carolinensis chromosome 2), the first vertebrate sex chromosomes to utilize this linkage group.

APA, Harvard, Vancouver, ISO, and other styles

29

Massot, Manuel, Jane Lecomte, and Jean Clobert. "Sex identification in juveniles of Lacerta vivipara." Amphibia-Reptilia 13, no. 1 (1992): 21–25. http://dx.doi.org/10.1163/156853892x00193.

Full text

Abstract:

AbstractSex of juveniles was identified by counting ventral scales in the lizard Lacerta vivipara. Sex can be determined accurately in more than 95 % of cases in the studied populations. Some aspects of the sexual size dimorphism are discussed.

APA, Harvard, Vancouver, ISO, and other styles

30

Johnson Pokorná, Martina, Marie Altmanová, Michail Rovatsos, Petr Velenský, Roman Vodička, Ivan Rehák, and Lukáš Kratochvíl. "First Description of the Karyotype and Sex Chromosomes in the Komodo Dragon (Varanus komodoensis)." Cytogenetic and Genome Research 148, no. 4 (2016): 284–91. http://dx.doi.org/10.1159/000447340.

Full text

Abstract:

The Komodo dragon (Varanus komodoensis) is the largest lizard in the world. Surprisingly, it has not yet been cytogenetically examined. Here, we present the very first description of its karyotype and sex chromosomes. The karyotype consists of 2n = 40 chromosomes, 16 macrochromosomes and 24 microchromosomes. Although the chromosome number is constant for all species of monitor lizards (family Varanidae) with the currently reported karyotype, variability in the morphology of the macrochromosomes has been previously documented within the group. We uncovered highly differentiated ZZ/ZW sex microchromosomes with a heterochromatic W chromosome in the Komodo dragon. Sex chromosomes have so far only been described in a few species of varanids including V. varius, the sister species to Komodo dragon, whose W chromosome is notably larger than that of the Komodo dragon. Accumulations of several microsatellite sequences in the W chromosome have recently been detected in 3 species of monitor lizards; however, these accumulations are absent from the W chromosome of the Komodo dragon. In conclusion, although varanids are rather conservative in karyotypes, their W chromosomes exhibit substantial variability at the sequence level, adding further evidence that degenerated sex chromosomes may represent the most dynamic genome part.

APA, Harvard, Vancouver, ISO, and other styles

31

Wibbels, T., and D. Crews. "Putative aromatase inhibitor induces male sex determination in a female unisexual lizard and in a turtle with temperature-dependent sex determination." Journal of Endocrinology 141, no. 2 (May 1994): 295–99. http://dx.doi.org/10.1677/joe.0.1410295.

Full text

Abstract:

Abstract Treatment of developing embryos of two diverse species of reptiles with fadrozole (a potent and specific nonsteroidal inhibitor of aromatase activity in mammals) resulted in the induction of male sex determination. In the first experiment, males were produced in an all-female parthenogenic species of lizard (Cnemidophorus uniparens). In the second experiment, male sex determination was induced in a turtle (Trachemys scripta) with temperature-dependent sex determination. The results support the hypothesis that the endogenous production of oestrogen may represent a pivotal step in the sex determination cascade of reptiles. Further, the production of male C uniparens indicates that the genes required for male sexual differentiation have not been lost in this parthenogenic lizard. Journal of Endocrinology (1994) 141, 295–299

APA, Harvard, Vancouver, ISO, and other styles

32

Salido, Carla A., and Natalin S. Vicente. "Sex and refuge distance influence escape decision in a Liolaemus lizard when it is approached by a terrestrial predator." Behaviour 156, no. 9 (2019): 909–25. http://dx.doi.org/10.1163/1568539x-00003546.

Full text

Abstract:

Abstract The decision of when and how to escape result crucial for animals because it can result in an interruption to contribute to their fitness. In the present study, we analysed whether speed attack, sex and type of refuge influenced the flight initiation distance (FID) and the closest refuge distance (CRD) in Liolaemus pacha lizards. We also compared the use of different type of refuges. Sex influence both CRD and FID, which would be discussed according to the size of their home range, the escape speed and sexual dichromatism. The interaction between speed and type of refuge used, influence CRD, suggesting that lizards perceived different predation risks. At high-speed approaches, lizards chose the closest refuge, rocks; while at low-speed approaches, lizards chose shrubs as a refuge, mainly the small ones. Lizard’s decision-making is discussed in relation to the refuge protection, their microclimatic conditions and visibility.

APA, Harvard, Vancouver, ISO, and other styles

33

Cunningham, George D., Geoffrey M. While, and Erik Wapstra. "Climate and sex ratio variation in a viviparous lizard." Biology Letters 13, no. 5 (May 2017): 20170218. http://dx.doi.org/10.1098/rsbl.2017.0218.

Full text

Abstract:

The extent to which key biological processes, such as sex determination, respond to environmental fluctuations is fundamental for assessing species' susceptibility to ongoing climate change. Few studies, however, address how climate affects offspring sex in the wild. We monitored two climatically distinct populations of the viviparous skink Niveoscincus ocellatus for 16 years, recording environmental temperatures, offspring sex and date of birth. We found strong population-specific effects of temperature on offspring sex, with female offspring more common in warm years at the lowland site but no effect at the highland site. In contrast, date of birth advanced similarly in response to temperature at both sites. These results suggest strong population-specific effects of temperature on offspring sex that are independent of climatic effects on other physiological processes. These results have significant implications for our understanding of the ecological and evolutionary consequences of variation in sex ratios under climate change.

APA, Harvard, Vancouver, ISO, and other styles

34

OSGOOD, S. M., and J. J. SCHALL. "Gametocyte sex ratio of a malaria parasite: response to experimental manipulation of parasite clonal diversity." Parasitology 128, no. 1 (January 2004): 23–29. http://dx.doi.org/10.1017/s0031182003004207.

Full text

Abstract:

Sex ratio theory posits that the adaptive proportion of male to female gametocytes of a malaria parasite within the vertebrate host depends on the degree of inbreeding within the vector. Gametocyte sex ratio could be phenotypically flexible, being altered based on the infection's clonal diversity, and thus likely inbreeding. This idea was tested by manipulating the clonal diversity of infections of Plasmodium mexicanum in its lizard host, Sceloporus occidentalis. Naive lizards were inoculated with infected blood from a single donor or 3 pooled donors. Donors varied in their gametocyte sex ratios (17–46% male), and sex ratio theory allowed estimation of the clonal diversity within donor and recipient infections. Phenotypic plasticity would produce a correlation between donor and recipient infections for infections initiated from a single donor, and a less female-biased gametocyte sex ratio in recipients that received a mixed blood inoculum (with predicted higher clonal diversity) than recipients receiving blood from a single donor. Neither pattern was observed. Gametocyte sex ratio of most infections ranged from 35 to 42% male, expected if clonal diversity was high for all infections. Alternative explanations are suggested for the observed variation of gametocyte sex ratio among P. mexicanum infections.

APA, Harvard, Vancouver, ISO, and other styles

35

Escudero, P. C., I. Minoli, M. A. González Marín, M. Morando, and L. J. Avila. "Melanism and ontogeny: a case study in lizards of the Liolaemus fitzingerii group (Squamata: Liolaemini)." Canadian Journal of Zoology 94, no. 3 (March 2016): 199–206. http://dx.doi.org/10.1139/cjz-2015-0112.

Full text

Abstract:

Color polymorphisms in general and melanism in particular have been the focus of many evolutionary adaptation studies. In lizards of the genus Liolaemus Wiegmann, 1834, patterns of melanism have been poorly studied, although they have been used as diagnostic characters for identifying and describing new species. We investigated the relationships between melanism, body size, sex, and time in a population of Rawson Lizard (Liolaemus xanthoviridis Cei and Scolaro, 1980) with extensive ventral melanism. The study took place in Bahía Isla Escondida, Chubut (Argentina), during three summer seasons (2012 to 2014). We tagged each individual, recorded body measurements and sex, and took ventral photographs to estimate the proportion of melanism. Our results showed that ventral melanism increased over time as each individual increased its snout–vent length (SVL). Body size explained 44% of the variation in melanism and males were more melanistic than females. Previous comparative studies of lizards in this species group showed no relationship between melanism and different taxonomic units or with thermal functionality. Here, we present evidence suggesting that melanism might be a character with an ontogenetic origin that is strongly associated with sex and body size. This pattern could be shared among species of this group of lizards, and even more importantly, it may be related to variable selection forces occurring throughout ontogeny.

APA, Harvard, Vancouver, ISO, and other styles

36

Doughty, Paul, Barry Sinervo, and Gordon M. Burghardt. "Sex-biased dispersal in a polygynous lizard, Uta stansburiana." Animal Behaviour 47, no. 1 (January 1994): 227–29. http://dx.doi.org/10.1006/anbe.1994.1029.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Radder, Rajkumar S., David A. Pike, Alexander E. Quinn, and Richard Shine. "Offspring Sex in a Lizard Depends on Egg Size." Current Biology 19, no. 13 (July 2009): 1102–5. http://dx.doi.org/10.1016/j.cub.2009.05.027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Costantini, David, and Giacomo Dell’Omo. "Sex-specific predation on two lizard species by kestrels." Russian Journal of Ecology 41, no. 1 (January 2010): 99–101. http://dx.doi.org/10.1134/s1067413610010182.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Cooper Jr., William E. "Age, sex and escape behaviour in the Striped Plateau Lizard (Sceloporus virgatus) and the Mountain Spiny Lizard (S. jarrovii), with a review of age and sex effects on escape by lizards." Behaviour 148, no. 11-13 (2011): 1215–38. http://dx.doi.org/10.1163/000579511x598334.

Full text

Abstract:

AbstractEscape behaviour often differs between sexes, reproductive states and ages. Escape theory predicts that flight initiation distance (FID = predator–prey distance when escape begins) increases as predation risk and fitness increase, and decreases as cost of escaping increases. Similar predictions hold for distance fled and refuge entry, suggesting that age and sex differences in escape behaviour may occur when risk, fitness, and opportunity costs differ. I studied such differences in two lizard species and reviewed relevant literature on escape by lizards. In Sceloporus virgatus no difference occurred between sexes or female reproductive states in FID, distance fled, distance from refuge, or probability of entering refuge. In S. jarrovii juveniles had shorter FID and distance fled than adults; juveniles were closer than females to refuge, but this did not affect FID or distance fled. Juveniles were more likely than adults to be on rocks and use them as refuges. The literature review showed that sexual dimorphism in FID occurs in about 1/5 of species (male FID usually > female FID), but distance fled differed between sexes in only 1 of 21 species. Juveniles had shorter FID than adults in all of five species; the relationship between age and distance fled was highly variable. Reasons for patterns of age/sex differences are discussed. Because age and sex differences in these factors and escape strategy can alter multiple components affecting optimality, sometimes in opposite ways, these factors and escape strategy must be known to predict effects of age, sex and reproductive state on escape.

APA, Harvard, Vancouver, ISO, and other styles

40

Filho, J. A. Araujo, S. V. Brito, V. F. Lima, A. M. A. Pereira, D. O. Mesquita, R. L. Albuquerque, and W. O. Almeida. "Influence of temporal variation and host condition on helminth abundance in the lizard Tropidurus hispidus from north-eastern Brazil." Journal of Helminthology 91, no. 3 (April 28, 2016): 312–19. http://dx.doi.org/10.1017/s0022149x16000225.

Full text

Abstract:

AbstractEcological characteristics and environmental variation influence both host species composition and parasite abundance. Abiotic factors such as rainfall and temperature can improve parasite development and increase its reproduction rate. The comparison of these assemblages between different environments may give us a more refined analysis of how environment affects the variation of helminth parasite abundance. The aim of the present study was to evaluate how temporal variation, host size, sex and reproduction affect helminth abundance in the Tropidurus hispidus lizard in Caatinga, Restinga and Atlantic Forest environments. Overall, larger-sized lizards showed higher helminth abundance. We found a monthly variation in the helminth species abundance in all studied areas. In the Caatinga area, monoxenic and heteroxenic parasites were related to the rainy season and to the reproductive period of lizards. In Restinga, monoxenic and heteroxenic helminth species were more abundant during the driest months. In the Atlantic Forest, the rainy and host reproductive season occurred continuously throughout the year, so parasite abundance was relatively constant. Nevertheless, heteroxenic species were more abundant in this area. The present results showed that the temporal variation, body size, sex, reproductive period and habitat type influence the abundance and composition of helminth species in T. hispidus.

APA, Harvard, Vancouver, ISO, and other styles

41

Vogel, P., and D. A. P. Bundy. "Helminth parasites of Jamaican anoles (Reptilia: Iguanidae): variation in prevalence and intensity with host age and sex in a population of Anolis lineatopus." Parasitology 94, no. 2 (April 1987): 399–404. http://dx.doi.org/10.1017/s0031182000054044.

Full text

Abstract:

SUMMARYThe Jamaican iguanid lizard Anolis lineatopus is the host of 4 species of helminth parasite: an acanthocephalan (Centrorhynchus spinosus), a digenean (Mesocoelium danforthi), and 2 nematodes (Cyrtosumum scelopori and Thelandros (?cubensis). Prevalance of C. spinosus was unrelated to host age but was considerably higher in males (43%) than in females (10%). The intensity increased with host age: (range: 1–23, median: 3). Prevalence of C. scelopori increased with host age in both sexes: juveniles (<3 months) were uninfected while infection occurred in almost all lizards older than 9 months. Intensity was higher in males (range: 1–403, median: 158) than in females (range: 1–297, median: 86). The infection patterns of C. spinosus and C. scelopori differed significantly from each other and were not consistent with a simplistic direct relationship between time of exposure and infection prevalence. Acanthocephalan and digenean infections occurred at low prevalence and intensity although prevalence in older, larger lizards tended to be higher than in younger, smaller ones.

APA, Harvard, Vancouver, ISO, and other styles

42

Robert, Kylie A., Michael B. Thompson, and Frank Seebacher. "Facultative sex allocation in the viviparous lizard Eulamprus tympanum, a species with temperature-dependent sex determination." Australian Journal of Zoology 51, no. 4 (2003): 367. http://dx.doi.org/10.1071/zo03016.

Full text

Abstract:

Females of the Australian scincid lizard Eulamprus tympanum can manipulate the sex of their offspring in response to gender imbalances in the population using temperature-dependent sex determination. Here we show that when adult males are scarce females produced male-biased litters and when adult males were common females produced female-biased litters. The cues used by a female to assess the adult population are not known but presumably depend upon her experience throughout the breeding season. Maternal manipulation of the sex ratio of the offspring in E. tympanum illustrates a selective advantage of temperature-dependent sex determination in a viviparous species.

APA, Harvard, Vancouver, ISO, and other styles

43

Rhen, T., A. Schroeder, J. T. Sakata, V. Huang, and D. Crews. "Segregating variation for temperature-dependent sex determination in a lizard." Heredity 106, no. 4 (August 11, 2010): 649–60. http://dx.doi.org/10.1038/hdy.2010.102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Noble, Daniel W. A., Kerry V. Fanson, and Martin J. Whiting. "Sex, androgens, and whole-organism performance in an Australian lizard." Biological Journal of the Linnean Society 111, no. 4 (March 13, 2014): 834–49. http://dx.doi.org/10.1111/bij.12252.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Wapstra, Erik, Tobias Uller, David L. Sinn, Mats Olsson, Katrina Mazurek, Jean Joss, and Richard Shine. "Climate effects on offspring sex ratio in a viviparous lizard." Journal of Animal Ecology 78, no. 1 (January 2009): 84–90. http://dx.doi.org/10.1111/j.1365-2656.2008.01470.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Angelini, Franco, Gaetano Ciarcia, Orfeo Picariello, Virgilio Botte, and Maria Pagano. "Sex steroids and postreproductive refractoriness in the lizard, Podarcis s.sicula." Bollettino di zoologia 53, no. 1 (January 1, 1986): 59–62. http://dx.doi.org/10.1080/11250008609355483.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Kratochvíl, Lukáš, Jasna Vukić, Jan Červenka, Lukáš Kubička, Martina Johnson Pokorná, Dominika Kukačková, Michail Rovatsos, and Lubomír Piálek. "Mixed‐sex offspring produced via cryptic parthenogenesis in a lizard." Molecular Ecology 29, no. 21 (September 30, 2020): 4118–27. http://dx.doi.org/10.1111/mec.15617.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Galán, Pedro. "Structure of a population of the lizard Podarcis bocagei in northwest Spain: variations in age distribution, size distribution and sex ratio." Animal Biology 54, no. 1 (2004): 57–75. http://dx.doi.org/10.1163/157075604323010051.

Full text

Abstract:

AbstractMark-recapture techniques were used to investigate population size, age distribution, size distribution and sex ratio in a population of the lacertid lizard Podarcis bocagei in an abandoned gravel pit in northwest Spain. The study was carried out over a 2-year period. Despite relatively high maximum longevity, the population age distribution was characteristic of small, short-lived lizard species (i.e., there was a relatively high proportion of immature individuals). Population size declined over the study period, largely because of a drop in the number of immature animals: this may be partially attributable to density-dependent factors, but was probably due largely to a decline in habitat favourability as a result of colonisation of the study site by vegetation. The sex ratio was significantly female-biased in all cohorts studied, not only among adults but also among juveniles and sub-adults. However, sex ratio at hatching (as investigated by laboratory hatching of clutches laid by captured pregnant females) did not differ significantly from one-to-one. There was no difference found in survival probabilities between males and females. The observed bias in sex ratio must therefore be attributed to between-sex differences in net emigration.

APA, Harvard, Vancouver, ISO, and other styles

49

Hnízdo, Jan, Veronika Cikánová, Olga Šimková, Daniel Frynta, Petr Velenský, Ivan Rehák, and Petra Frýdlová. "Is body shape of mangrove-dwelling monitor lizards (Varanus indicus; Varanidae) sexually dimorphic?" Amphibia-Reptilia 32, no. 1 (2011): 27–37. http://dx.doi.org/10.1163/017353710x532184.

Full text

Abstract:

AbstractIn monitor lizards, males are typically larger than conspecific females, but body shape is usually quite similar in both sexes. This not only represents a puzzle worthy of evolutionary explanation, but also makes field sex determination of monitor lizards difficult. We asked whether subtle differences in body shape follow the same pattern as in other sexually dimorphic lizard taxa and thus can be explained by the same selective forces. We tested the hypotheses that (1) females have a longer abdomen due to fecundity selection and (2) males possess bigger heads due to intrasexual selection. We also hypothesised that (3) male monitors show a wider chests and longer upper fore-limbs to win male-male wrestling matches. We monitored ontogeny in 35 mangrove-dwelling monitors (Varanus indicus). Seventeen body measurements were taken every three months up to the age of 24-34 months. Sex was determined by an ultrasonographic imaging. We employed multiple approaches to remove the effect of size and used both confirmation and exploratory statistics. The results revealed that sexual differences in body shape were small and emerged after maturity. Females have a relatively longer abdomen while males wider chest and longer upper fore-limbs. Thus, the differences in body shape between male and female varanid lizards may be attributed to both fecundity and sexual selection.

APA, Harvard, Vancouver, ISO, and other styles

50

NEAL, A. T., and J. J. SCHALL. "Gametocyte sex ratio in single-clone infections of the malaria parasite Plasmodium mexicanum." Parasitology 137, no. 13 (July 12, 2010): 1851–59. http://dx.doi.org/10.1017/s0031182010000909.

Full text

Abstract:

SUMMARYSex ratio theory predicts that malaria parasites should bias gametocyte production toward female cells in single-clone infections because they will experience complete inbreeding of parasite gametes within the vector. A higher proportion of male gametocytes is favoured under conditions that reduce success of male gametes at reaching females such as low gametocyte density or attack of the immune system later in the infection. Recent experimental studies reveal genetic variation for gametocyte sex ratio in single-clone infections. We examined these issues with a study of experimental single-clone infections for the lizard malaria parasite Plasmodium mexicanum in its natural host. Gametocyte sex ratios of replicate single-clone infections were determined over a period of 3–4 months. Sex ratios were generally female biased, but not as strongly as expected under simple sex ratio theory. Gametocyte density was not related to sex ratio, and male gametocytes did not become more common later in infections. The apparent surplus of male gametocytes could be explained if male fecundity is low in this parasite, or if rapid clotting of the lizard blood reduces male gamete mobility. There was also a significant clone effect on sex ratio, suggesting genetic variation for some life-history trait, possibly male fecundity.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Lizard Sex'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles