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1.
BMC Evol Biol ; 19(1): 178, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31492110

RESUMO

BACKGROUND: Fossil evidence suggests that extant North American lizard genera (north of Mexico) evolved during the Miocene. Although fossils of the clade Phrynosomatidae (spiny lizards and sand lizards) have been reported, there have been no previously described fossils of the fringe-toed sand lizards (Uma). In the extant biota, Uma inhabit arid deserts, and members of the western clade of Uma are restricted to sand dunes or other habitats containing fine-grained sand. RESULTS: I describe the first known fossil of Uma and refer the fossil to the total clade of Uma with an apomorphy-based diagnosis. The fossil is a partial premaxilla that was found in the Miocene strata of the Dove Spring Formation of southern California, dating to 8.77 Ma. The paleoenvironment of the Dove Spring Formation was semiarid and contained ephemeral streams that facilitated deposition, and there is no evidence of sand dune deposits in the strata containing the locality from which the Uma fossil was found. Divergence time analyses of a concatenated molecular dataset with four fossil calibrations support a Neogene origin of the total clade of Uma and of the crown clade of Uma. Those analyses also estimated a Neogene divergence between Uma scoparia and the Uma notata complex. Multispecies coalescent analyses with one fossil calibration inferred a Paleogene origin for the total clade of Uma and a Pliocene or Pleistocene divergence between Uma scoparia and the Uma notata complex. The fossil and the total and crown clades of Uma precede the evolution of modern desert ecosystems in the southwestern United States and northern Mexico by millions of years. CONCLUSIONS: The total clade and the crown clade of Uma were not restricted to arid deserts throughout their evolutionary histories. I demonstrate that an apomorphy-based diagnosis can be used to identify fossils of isolated skeletal elements for at least one clade of phrynosomatid lizard, and suggest exercising caution when using environmental tolerances of extant taxa to hypothesize paleoecological reconstructions.


Assuntos
Fósseis , Lagartos/classificação , Lagartos/genética , Animais , Evolução Biológica , California , Ecologia , Ecossistema , Lagartos/anatomia & histologia , México , Filogenia
2.
Zoology (Jena) ; 135: 125690, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31383295

RESUMO

In this study, we investigated the reproductive biology of the small lizard Eurolophosaurus nanuzae based on evidence of sperm storage by females and variations of the renal sexual segment (RSS) in males. We found a remarkable occurrence of crypts containing bundles of sperm and secretions in the epithelium of E. nanuzae oviducts. The chemical composition of the secretions associated with the sperm within the crypts was similar to secretions from the oviductal epithelium, which suggests that females can produce substances involved in the maintenance of stored sperm. Female sperm storage does not occur over the span of years for long-term reproduction; the majority of females with stored sperm occurred during the peak and late periods of the reproductive season. We discuss this result in relation to post-copulatory sexual selection strategies in the context of sperm competition for restricted successful fertilisation. In males, testicular activity was continuous, while RSS activity varied seasonally, in synchrony with female reproductive activity. Throughout the reproductive season, the RSS was hypertrophied, with maximum activity during the peak of the reproductive season. The lowest RSS activity occurred when females were not reproductive (non-reproductive season). Considering that RSS secretions are essential for reproduction, an absence or reduction of these secretions during the non-reproductive season may imply the reduced functionality of sperm during this period. Since sperm production continues throughout the whole reproductive cycle in E. nanuzae males, RSS activity could be an important indicator of reproduction, beyond testicular activity.


Assuntos
Lagartos/anatomia & histologia , Lagartos/fisiologia , Animais , Feminino , Gônadas , Masculino , Oviductos/anatomia & histologia , Reprodução/fisiologia , Comportamento Sexual Animal/fisiologia , Espermatozoides
3.
PLoS One ; 14(7): e0219053, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31291313

RESUMO

Male genitalia show considerable morphological variation among animals with internal fertilization and exhibit a high level of evolvability in lizards. Studies have suggested that sexual selection may be driving hemipenial evolution against natural selection and pleiotropy. Given the direct interaction of male and female genitals, coevolution of the aforementioned is posited by several hypotheses of genital evolution. However, there are only a few studies on female genitalia morphology, resulting in a lack of coevolution description and understanding. Studies of allometric patterns have filled some gaps by answering questions about male genital evolution and could prove a powerful tool in clarifying coevolution between male and female genitals. Here, we studied the genital morphology of Tropidurus torquatus. This Tropidurus lizard species is an emerging Neotropical lizard model organism notable for having enlarged hemipenial lobes in contrast with other tropidurid species. In this study, we analyzed hemipenial development in early and late stages, describing both morphological variation and ontogenetic allometric pattern. We used quantitative traits to describe male and female genital morphology, examining their static allometric patterns and correspondence. Our study provides a quantitative discussion on the evolution of lizard genitals, suggesting that sexual selection plays an important role in genital evolution in Tropidurus lizards.


Assuntos
Genitália Feminina/anatomia & histologia , Genitália Masculina/anatomia & histologia , Lagartos/crescimento & desenvolvimento , Animais , Evolução Biológica , Feminino , Genitália Feminina/crescimento & desenvolvimento , Genitália Masculina/crescimento & desenvolvimento , Lagartos/anatomia & histologia , Masculino , Filogenia , Seleção Genética , Comportamento Sexual
4.
Zoology (Jena) ; 134: 16-26, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31146904

RESUMO

Segmentation gives rise to the anterior-posterior axis in many animals, and in vertebrates this axis comprises serially arranged vertebrae. Modifications to the vertebral column abound, and a recurring, but functionally understudied, change is the elongation of the body through the addition and/or elongation of vertebrae. Here, we compared the vertebral and axial kinematics of the robustly limbed Fire skink (Riopa fernandi) representing the ancestral form, the limbless European glass lizard (Ophisaurus apodus), and the Northern water snake (Nerodia sipedon). We induced these animals to traverse through channels and peg arrays of varied widths and densities, respectively, using high-speed X-ray and light video. We found that even though the snake had substantially more and shorter vertebrae than either lizard, intervertebral joint angles did not differ between species in most treatment levels. All three species decreased the amplitude and wavelength of their undulations as channels narrowed and the lizard species increased wave frequency in narrower channels. In peg arrays, both lizard species decreased wave amplitude, while the snake showed no differences. All three species maintained similar wavelengths and frequencies as peg density increased in most cases. Our results suggest that amplitude is decoupled from wavelength and frequency in all three focal taxa. The combination of musculoskeletal differences and the decoupling of axial kinematic traits likely facilitates the formation of different undulatory waves, thereby allowing limbless species to adopt different modes of locomotion.


Assuntos
Extremidades , Articulações/anatomia & histologia , Lagartos/anatomia & histologia , Serpentes/anatomia & histologia , Coluna Vertebral/anatomia & histologia , Animais , Fenômenos Biomecânicos , Lagartos/classificação , Locomoção , Serpentes/classificação
5.
J Parasitol ; 105(3): 432-441, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31169454

RESUMO

Exotic species can threaten biodiversity by introducing parasites to native hosts. Thus, it is critical to identify if the same parasite species infects both native and exotic hosts. However, developmental- or environmental-induced morphological variation may render species identification ambiguous. Our study reports a range expansion in the southern United States of the pentastome Raillietiella indica from the Mediterranean gecko, Hemidactylus turcicus, as well as a host expansion into the green anole, Anolis carolinensis, in the anole's native range. Species identification was based on sequence data and male spicule shape. In agreement with a study from Australia, we found that much of the morphological variation in hook measurements, the primary diagnostic traits of raillietiellid pentastomes, was due to development. Here, we explicitly link this developmental variation to instar stage by incorporating experimental infection data obtained from the literature. We also show that the various hook traits are themselves highly correlated and, thus, likely not independent. Taking instar stage and correlated hook variables into account, we directly controlled for development on a composite hook size measurement. Using a large sample size from H. turcicus, we did not find any consistent effects of potential factors (host sex, host snout-vent-length, or parasite intensity) that may result in environmental-induced variation in relative hook size (corrected for body length). However, relative male spicule size tended to be negatively correlated with parasite intensity. In contrast, both pentastome body length and relative hook size significantly varied among host species whereas relative male spicule size was not significantly different among host species. Our study independently supports the conclusions that developmental- and host-induced morphological variations need to be accounted for to accurately identify pentastome species.


Assuntos
Cestoides/fisiologia , Infecções por Cestoides/veterinária , Lagartos/parasitologia , Animais , Tamanho Corporal , Cestoides/anatomia & histologia , Cestoides/classificação , Infecções por Cestoides/parasitologia , Feminino , Lagartos/anatomia & histologia , Lagartos/classificação , Masculino , Fatores Sexuais
6.
BMC Evol Biol ; 19(1): 114, 2019 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-31170905

RESUMO

BACKGROUND: The Qinghai-Tibetan Plateau (QTP) is the world's highest and largest plateau, but the role of its uplift in the evolution of species or biotas still remains poorly known. Toad-headed lizards of the reproductively bimodal genus Phrynocephalus are a clade of agamids, with all viviparous species restricted to the QTP and adjacent regions. The eastern part of the range of the viviparous taxa is occupied by three closely related but taxonomically controversial species, P. guinanensis, P. putjatia and P. vlangalii. Here, we combined genetic (mitochondrial ND4 gene and nine microsatellite loci), morphological (11 mensural and 11 meristic variables), and ecological (nine climatic variables) data to explore possible scenarios that may explain the discordance between genetic and morphological patterns, and to test whether morphological divergence is associated with local adaptation. RESULTS: We found weak genetic differentiation but pronounced morphological divergence, especially between P. guinanensis and P. vlangalii. Genetically, the species boundary was not so clear between any species pair. Morphologically, the species boundary was clear between P. guinanensis and P. vlangalii but not between other two species pairs. Body size and scale characters accounted best for morphological divergence between species. Morphological divergence was related to habitat types that differ climatically. CONCLUSIONS: Our study provides evidence for genetic and morphological divergence among the three closely related viviparous species of Phrynocephalus lizards, and supports the idea that natural selection in spatially heterogeneous environments can lead to population divergence even in the presence of gene flow. Our study supports the hypothesis that the evolutionary divergence between viviparous Phrynocephalus species was a consequence of environmental change after the uplift of the QTP.


Assuntos
Variação Genética , Lagartos/anatomia & histologia , Lagartos/genética , Animais , Teorema de Bayes , China , Clima , DNA Mitocondrial/genética , Feminino , Genética Populacional , Geografia , Haplótipos/genética , Masculino , Polimorfismo Genético , Análise de Componente Principal , Especificidade da Espécie
7.
J Therm Biol ; 82: 10-17, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31128637

RESUMO

Ectothermic animals contend with variable environmental temperature through behavioral thermoregulation, including selection of activity-times and microhabitat spaces with suitable operative temperatures. Thus, an important component to understanding the influence of temperature on animals is through the assessment of thermal constraints on time and space usage. Thermal ecologists have recognized that postural adjustments are an important part of behavioral thermoregulation. However, the impact of postural adjustments on available space and time has received little attention. We hypothesized that postural adjustments would significantly affect the thermal availability of space and time for surface activity. To test our hypothesis, we used data collected over a four-year study of the thermal ecology of Eastern Collared Lizards (Crotaphytus collaris) in Arkansas. We used a novel approach to model three distinct postures used by C. collaris, and to assess the impact of posture on available space and time. For our study species and habitat, posture had a significant impact on several indices of available space and time including: a) a 13% increase in length of the reproductive activity season, b) a 35% increase in the frequency distribution of habitat within active body temperature range and c) a 42% increase in average thermal quality index. We conclude that posture can significantly impact space and time available for surface activity in species that employ it for thermoregulation. Thus, a clearer understanding of the thermal constraints on time-space usage in ectotherms requires consideration of the impact of posture on the spatiotemporal distribution of thermally suitable microhabitats.


Assuntos
Regulação da Temperatura Corporal , Lagartos/fisiologia , Animais , Arkansas , Comportamento Animal , Temperatura Corporal , Ecossistema , Lagartos/anatomia & histologia , Postura , Reprodução , Estações do Ano
8.
Integr Comp Biol ; 59(1): 168-181, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31070737

RESUMO

Attachment is imperative for many biological functions, such as holding position and climbing, but can be challenged by natural conditions. Adhesive toe pads and claws have evolved in multiple terrestrial lineages as important dynamic attachment mechanisms, and some clades (e.g., geckos) exhibit both features. The functional relationship of these features that comprise a complex attachment system is not well-understood, particularly within lizards (i.e., if pads and claws are redundant or multifunctional). Geckos exhibit highly adept frictional adhesive toe pads that continue to fuel biological inquiry and inspiration. However, gecko claws (the ancestral lizard clinging condition) have received little attention in terms of their functional or evolutionary significance. We assessed claw function in Thecadactylus rapicauda using assays of clinging performance and locomotor trials on different surfaces (artificial and natural) and inclines with claws intact, then partially removed. Area root mean square height (Sq), a metric of 3D surface roughness, was later quantified for all test surfaces, including acrylic, sandpaper, and two types of leaves (smooth and hairy). Maximum clinging force significantly declined on all non-acrylic surfaces after claw removal, indicating a substantial contribution to static clinging on rough and soft surfaces. With and without claws, clinging force exhibited a negative relationship with Sq. However, claw removal had relatively little impact on locomotor function on surfaces of different roughness at low inclines (≤30°). High static and dynamic safety factor estimates support these observations and demonstrate the species' robust frictional adhesive system. However, maximum station-holding capacity significantly declined on the rough test surface after partial claw removal, showing that geckos rely on their claws to maintain purchase on rough, steeply inclined surfaces. Our results point to a context-dependent complex attachment system within geckos, in which pads dominate on relatively smooth surfaces and claws on relatively rough surfaces, but also that these features function redundantly, possibly synergistically, on surfaces that allow attachment of both the setae and the claw (as in some insects). Our study provides important novel perspectives on gecko attachment, which we hope will spur future functional studies, new evolutionary hypotheses, and biomimetic innovation, along with collaboration and integration of perspectives across disciplines.


Assuntos
Evolução Biológica , Casco e Garras/fisiologia , Lagartos/fisiologia , Locomoção , Adesividade , Animais , Fenômenos Biomecânicos , Casco e Garras/anatomia & histologia , Lagartos/anatomia & histologia
9.
Integr Comp Biol ; 59(1): 182-192, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31004492

RESUMO

In this study we developed an analytical relationship between adhesive digit orientation and adhesive force capacity to describe the tendencies of climbing organisms that use adhesion for climbing to align their toes in the direction of loading, maximizing adhesive force capacity. We fabricated a multi-component adhesive device with multiple contact surfaces, or digits, to act as a model system mimicking the angular motion of a foot and found the synthetic experiments agree with the developed analytical relationship. In turn, we find that observations of gekkonid lizards climbing on vertical substrates correlate well with our analytical relationship; a reduction in toe spacing is seen on the forelimbs when the animals are facing up. Interestingly, the toes on the hindlimbs tend to have an increase in spacing, possibly a mechanism for stabilization rather than load-bearing.


Assuntos
Lagartos/fisiologia , Locomoção , Dedos do Pé/fisiologia , Adesividade , Animais , Fenômenos Biomecânicos , Lagartos/anatomia & histologia , Dedos do Pé/anatomia & histologia
10.
Integr Comp Biol ; 59(1): 131-147, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-30874731

RESUMO

Recently-developed, molecularly-based phylogenies of geckos have provided the basis for reassessing the number of times adhesive toe-pads have arisen within the Gekkota. At present both a single origin and multiple origin hypotheses prevail, each of which has consequences that relate to explanations about digit form and evolutionary transitions underlying the enormous variation in adhesive toe pad structure among extant, limbed geckos (pygopods lack pertinent features). These competing hypotheses result from mapping the distribution of toe pads onto a phylogenetic framework employing the simple binary expedient of whether such toe pads are present or absent. It is evident, however, that adhesive toe pads are functional complexes that consist of a suite of integrated structural components that interact to bring about adhesive contact with the substratum and release from it. We evaluated the competing hypotheses about toe pad origins using 34 features associated with digit structure (drawn from the overall form of the digits; the presence and form of adhesive scansors; the proportions and structure of the phalanges; aspects of digital muscular and tendon morphology; presence and form of paraphalangeal elements; and the presence and form of substrate compliance-enhancing structures). We mapped these onto a well-supported phylogeny to reconstruct their evolution. Nineteen of these characters proved to be informative for all extant, limbed geckos, allowing us to assess which of them exhibit co-occurrence and/or clade-specificity. We found the absence of adhesive toe pads to be the ancestral state for the extant Gekkota as a whole, and our data to be consistent with independent origins of adhesive toe pads in the Diplodactylidae, Sphaerodactylidae, Phyllodactylidae, and Gekkonidae, with a strong likelihood of multiple origins in the latter three families. These findings are consistent with recently-published evidence of the presence of adhesively-competent digits in geckos generally regarded as lacking toe pads. Based upon morphology we identify other taxa at various locations within the gekkotan tree that are promising candidates for the expression of the early phases of adhesively-assisted locomotion. Investigation of functionally transitional forms will be valuable for enhancing our understanding of what is necessary and sufficient for the transition to adhesively-assisted locomotion, and for those whose objectives are to develop simulacra of the gekkotan adhesive system for biotechnological applications.


Assuntos
Evolução Biológica , Lagartos/fisiologia , Dedos do Pé/fisiologia , Adesividade , Animais , Lagartos/anatomia & histologia , Locomoção , Filogenia , Dedos do Pé/anatomia & histologia
11.
PLoS One ; 14(3): e0211686, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30875384

RESUMO

Widespread species often show extensive phenotypic variation due to the contrasting abiotic and biotic factors that shape selective pressures in different environments. In this context, the gradual and predictable patterns of variation in climatic and environmental conditions found in mountain areas offer a great opportunity to explore intraspecific phenotypic variation. For instance, temperature is negatively correlated with altitude and virtually all aspects of the behavior and physiology of ectotherms are sensitive to body temperature. In this work, we tested the hypothesis that morphology, dorsal and ventral coloration and the chemical profile of femoral secretions show interpopulational and seasonal variation in the lacertid lizard (Podarcis liolepis). We compared lizards from three populations inhabiting lowland and highland habitats in the French Pyrenees that were closely related genetically. We found that highland lizards were larger, stockier, had longer heads and more femoral pores and had a darker dorsal coloration than lowland ones. In addition, we detected interpopulational differences in both the abundance and the richness of chemical compounds in the glandular secretions, and we also found seasonal variation in the overall chemical composition. Dorsal and ventral coloration differed seasonally and between populations. Ventral and dorsal brightness were higher in lowland than in highland lizards in the reproductive season whereas the reversed trend was found in the non-reproductive season but only for dorsal brightness. In addition, all lizards had browner dorsal coloration in the non-reproductive season, and lowland lizards were greener in the reproductive season. By integrating information from both visual and chemical systems, our works offers a comprehensive view of how these lizards communicate in a multimodal context.


Assuntos
Variação Biológica da População , Lagartos/anatomia & histologia , Lagartos/fisiologia , Fenômenos Reprodutivos Fisiológicos , Estações do Ano , Altitude , Animais , Colesterol/metabolismo , DNA Mitocondrial , Feminino , Cabeça/anatomia & histologia , Lagartos/genética , Masculino , Tamanho do Órgão , Filogenia , Pigmentação , Esqualeno/metabolismo
12.
Integr Comp Biol ; 59(1): 148-167, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-30912814

RESUMO

The study of gecko adhesion is necessarily interdisciplinary due to the hierarchical nature of the adhesive system and the complexity of interactions between the animals and their habitats. In nature, geckos move on a wide range of surfaces including soft sand dunes, trees, and rocks, but much of the research over the past two decades has focused on their adhesive performance on artificial surfaces. Exploring the complex interactions between geckos and their natural habitats will reveal aspects of the adhesive system that can be applied to biomimetic research, such as the factors that facilitate movement on dirty and rough surfaces with varying microtopography. Additionally, contrasting suites of constraints and topographies are found on rocks and plants, likely driving differences in locomotion and morphology. Our overarching goals are to bring to light several aspects of ecology that are important for gecko-habitat interactions, and to propose a framework for how they can inspire material scientists and functional ecologists. We also present new data on surface roughness and topography of a variety of surfaces, and adhesive performance of Phelsuma geckos on surfaces of varying roughness. We address the following key questions: (1) why and how should ecology be incorporated into the study of gecko adhesion? (2) What topographical features of rocks and plants likely drive adhesive performance? (3) How can ecological studies inform material science research? Recent advances in surface replication techniques that eliminate confounding factors among surface types facilitate the ability to address some of these questions. We pinpoint gaps in our understanding and identify key initiatives that should be adopted as we move forward. Most importantly, fine details of locomotor microhabitat use of both diurnal and nocturnal geckos are needed.


Assuntos
Evolução Biológica , Materiais Biomiméticos/análise , Lagartos/fisiologia , Locomoção , Adesividade , Animais , Fenômenos Biomecânicos , Lagartos/anatomia & histologia , Propriedades de Superfície
13.
BMC Evol Biol ; 19(1): 7, 2019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30621580

RESUMO

BACKGROUND: Morphological diversity among closely related animals can be the result of differing growth patterns. The Australian radiation of agamid lizards (Amphibolurinae) exhibits great ecological and morphological diversity, which they have achieved on a continent-wide scale, in a relatively short period of time (30 million years). Amphibolurines therefore make an ideal study group for examining ontogenetic allometry. We used two-dimensional landmark-based geometric morphometric methods to characterise the postnatal growth patterns in cranial shape of 18 species of amphibolurine lizards and investigate the associations between cranial morphology, and life habit and phylogeny. RESULTS: For most amphibolurine species, juveniles share a similar cranial phenotype, but by adulthood crania are more disparate in shape and occupy different sub-spaces of the total shape space. To achieve this disparity, crania do not follow a common post-natal growth pattern; there are differences among species in both the direction and magnitude of change in morphospace. We found that these growth patterns among the amphibolurines are significantly associated with ecological life habits. The clade Ctenophorus includes species that undergo small magnitudes of shape change during growth. They have dorsoventrally deep, blunt-snouted skulls (associated with terrestrial lifestyles), and also dorsoventrally shallow skulls (associated with saxicolous lifestyles). The sister clade to Ctenophorus, which includes the bearded dragon (Pogona), frill-neck lizard (Chlamydosaurus), and long-nosed dragon (Gowidon), exhibit broad and robust post-orbital regions and differing snout lengths (mainly associated with scansorial lifestyles). CONCLUSIONS: Australian agamids show great variability in the timing of development and divergence of growth trajectories which results in a diversity of adult cranial shapes. Phylogenetic signal in cranial morphology appears to be largely overwritten by signals that reflect life habit. This knowledge about growth patterns and skull shape diversity in agamid lizards will be valuable for placing phylogenetic, functional and ecological studies in a morphological context.


Assuntos
Biodiversidade , Lagartos/anatomia & histologia , Crânio/anatomia & histologia , Animais , Austrália , Lagartos/genética , Fenótipo , Filogenia , Análise de Componente Principal , Especificidade da Espécie
14.
BMC Evol Biol ; 19(1): 16, 2019 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-30630409

RESUMO

BACKGROUND: The evolution of elongated body forms in tetrapods has a strong influence on the musculoskeletal system, including the reduction of pelvic and pectoral girdles, as well as the limbs. However, despite extensive research in this area it still remains unknown how muscles within and around bony girdles are affected by these reductions. Here we investigate this issue using fossorial amphisbaenian reptiles, or worm lizards, as a model system, which show substantial variation in the degree of reductions of girdles and limbs. Using iodine-based contrast-enhanced computed tomography (diceCT), we analyze the composition of the shoulder muscles of the main clades of Amphisbaenia and their outgroups relative to the pectoral skeleton. RESULTS: All investigated amphisbaenian taxa retain the full set of 17 shoulder muscles, independent of the degree of limb and girdle reductions, whereas in some cases muscles are fused to complexes or changed in morphology relative to the ancestral condition. Bipes is the only taxon that retains forelimbs and an almost complete pectoral girdle. All other amphisbaenian families show more variation concerning the completeness of the pectoral girdle having reduced or absent girdle elements. Rhineura, which undergoes the most severe bone reductions, differs from all other taxa in possessing elongated muscle strands instead of discrete shoulder muscles. In all investigated amphisbaenians, the shoulder muscle agglomerate is shortened and shifted anteriorly relative to the ancestral position as seen in the outgroups. CONCLUSIONS: Our results show that pectoral muscle anatomy does not necessarily correspond to the loss or reduction of bones, indicating a decoupling of the musculoskeletal system. Muscle attachment sites change from bones to non-skeletal areas, such as surrounding muscles, skin or connective tissue, whereas muscle origins themselves remain in the same region where the pectoral bones were ancestrally located. Our findings indicate a high degree of developmental autonomy within the musculoskeletal system, we predict that the observed evolutionary rearrangements of amphisbaenian shoulder muscles were driven by functional demands rather than by developmental constraints. Nevertheless, worm lizards display a spatial offset of both pectoral bones and muscles relative to the ancestral position, indicating severe developmental modifications of the amphisbaenian body axis.


Assuntos
Evolução Biológica , Extremidades/anatomia & histologia , Lagartos/anatomia & histologia , Músculos/anatomia & histologia , Sistema Musculoesquelético/anatomia & histologia , Animais , Osso e Ossos/anatomia & histologia , Membro Anterior/anatomia & histologia , Filogenia , Crânio/anatomia & histologia
15.
Folia Morphol (Warsz) ; 78(1): 101-106, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30009360

RESUMO

BACKGROUND: Despite the fact that numerous reptile species are widely studied by the researchers, information describing the detailed structure of particular organs in many reptiles is missing. MATERIALS AND METHODS: The tongue of the sand lizard (Lacerta agilis) was examined under the light and scanning electron microscope. It is divided into bifurcated apex, corpus and bifurcated radix. The tip of the lingual apex is devoid of lingual papillae. RESULTS: The remaining dorsal surface of the tongue bears either fused papillae in the form of caudally directed ridges or individual papillae represented by mu- shroom-like or semilunar prominences (lingual apex) or fish scale-like papillae (lingual corpus) and horizontally laid ridges extending in the form of lobulated prominences (lingual corpus, lingual radix). Regardless of the shape, lingual papillae contain numerous muscle fibres and they are all considered to be mechanical. The lingual epithelium changes from the simple squamous into stratified squamous in the caudal direction. No salivary glands or sensory structures were recognised. CONCLUSIONS: This description is to be used mainly for comparative studies. It could also help to understand how different lizards capture the pray.


Assuntos
Lagartos/anatomia & histologia , Língua/ultraestrutura , Animais , Microscopia Eletrônica de Varredura
16.
Glob Chang Biol ; 25(2): 620-628, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30488524

RESUMO

Understanding the processes driving formation and maintenance of latitudinal clines has become increasingly important in light of accelerating global change. Many studies have focused on the role of abiotic factors, especially temperature, in generating clines, but biotic factors, including the introduction of non-native species, may also drive clinal variation. We assessed the impact of invasion by predatory fire ants on latitudinal clines in multiple fitness-relevant traits-morphology, physiological stress responsiveness, and antipredator behavior-in a native fence lizard. In areas invaded by fire ants, a latitudinal cline in morphology is opposite both the cline found in museum specimens from historical populations across the species' full latitudinal range and that found in current populations uninvaded by fire ants. Similarly, clines in stress-relevant hormone response to a stressor and in antipredator behavior differ significantly between the portions of the fence lizard range invaded and uninvaded by fire ants. Changes in these traits within fire ant-invaded areas are adaptive and together support increased and more effective antipredator behavior that allows escape from attacks by this invasive predator. However, these changes may mismatch lizards to the environments under which they historically evolved. This research shows that novel biotic pressures can alter latitudinal clines in multiple traits within a single species on ecological timescales. As global change intensifies, a greater understanding of novel abiotic and biotic pressures and how affected organisms adapt to them across space and time will be central to predicting and managing our changing environment.


Assuntos
Formigas/fisiologia , Cadeia Alimentar , Espécies Introduzidas , Traços de História de Vida , Lagartos/fisiologia , Animais , Membro Posterior/anatomia & histologia , Lagartos/anatomia & histologia , Estresse Fisiológico , Estados Unidos
17.
Sci Rep ; 8(1): 17996, 2018 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-30573764

RESUMO

Prolacerta broomi is an Early Triassic archosauromorph of particular importance to the early evolution of archosaurs. It is well known from many specimens from South Africa and a few relatively small specimens from Antarctica. Here, a new articulated specimen from the Fremouw Formation of Antarctica is described in detail. It represents the largest specimen of Prolacerta described to date with a nearly fully articulated and complete postcranium in addition to four skull elements. The study of this specimen and the re-evaluation of other Prolacerta specimens from both Antarctica and South Africa reveal several important new insights into its morphology, most notably regarding the premaxilla, manus, and pelvic girdle. Although well-preserved skull material from Antarctica is still lacking for Prolacerta, a detailed comparison of Prolacerta specimens from Antarctica and South Africa corroborates previous findings that there are no characters clearly distinguishing the specimens from these different regions and therefore the Antarctic material is assigned to Prolacerta broomi. The biogeographical implications of these new findings are discussed. Finally, some osteological characters for Prolacerta are revised and an updated diagnosis and phylogenetic analysis are provided.


Assuntos
Dinossauros/classificação , Fósseis , Animais , Regiões Antárticas , Arqueologia , Dinossauros/anatomia & histologia , Fósseis/anatomia & histologia , Lagartos/anatomia & histologia , Lagartos/classificação , Filogenia , Filogeografia/normas , Crânio/anatomia & histologia
18.
PLoS One ; 13(12): e0207719, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30517172

RESUMO

Monitor lizards (genus Varanus) inhabited Europe at least from the early Miocene to the Pleistocene. Their fossil record is limited to about 40 localities that have provided mostly isolated vertebrae. Due to the poor diagnostic value of these fossils, it was recently claimed that all the European species described prior to the 21st century are not taxonomically valid and a new species, Varanus amnhophilis, was erected on the basis of fragmentary material including cranial elements, from the late Miocene of Samos (Greece). We re-examined the type material of Varanus marathonensis Weithofer, 1888, based on material from the late Miocene of Pikermi (Greece), and concluded that it is a valid, diagnosable species. Previously unpublished Iberian material from the Aragonian (middle Miocene) of Abocador de Can Mata (Vallès-Penedès Basin, Barcelona) and the Vallesian (late Miocene) of Batallones (Madrid Basin) is clearly referable to the same species on a morphological basis, further enabling to provide an emended diagnosis for this species. Varanus amnhophilis appears to be a junior subjective synonym of V. marathonensis. On the basis of the most complete fossil Varanus skeleton ever described, it has been possible to further resolve the internal phylogeny of this genus by cladistically analyzing 80 taxa coded for 495 morphological and 5729 molecular characters. Varanus marathonensis was a large-sized species distributed at relatively low latitudes in both southwestern and southeastern Europe from at least MN7+8 to MN12. Our cladistic analysis nests V. marathonensis into an eastern clade of Varanus instead of the African clade comprising Varanus griseus, to which it had been related in the past. At least two different Varanus lineages were present in Europe during the Neogene, represented by Varanus mokrensis (early Miocene) and V. marathonensis (middle to late Miocene), respectively.


Assuntos
Lagartos/classificação , Animais , Europa (Continente) , Fósseis/anatomia & histologia , História Antiga , Lagartos/anatomia & histologia , Paleontologia , Filogenia , Filogeografia
19.
BMC Evol Biol ; 18(1): 186, 2018 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-30526474

RESUMO

BACKGROUND: Comparing sexual size dimorphism (SSD) in the light of the phylogenetic hypothesis may help to understand the phenotypic evolution associated with sexual selection (size of whole body and of reproduction-related body parts). Within a macroevolutionary framework, we evaluated the association between the evolution of SSD and the evolution of reproduction-related phenotypic traits, and whether this association has favored female fecundity, considering also variations according to reproductive modes. We focused on the lizard species that inhabit the Chaco Domain since this is a natural unit with a high diversity of species. RESULTS: The residual SSD was related positively with the residuals of the reproduction-related phenotypic traits that estimate intrasexual selection and with the residuals of inter-limb length and, according to fecundity selection, those residuals were related positively with the residuals of clutch size in oviparous species. Lizards of the Chaco Domain present a high diversity of SSD patterns, probably related to the evolution of reproductive strategies. CONCLUSIONS: Our findings highlight that the sexual selection may have acted on the whole-body size as well as on the size of body parts related to reproduction. Male and female phenotypes evolutionarily respond to variations in SSD, and an understanding of these patterns is essential for elucidating the processes shaping sexual phenotype diversity from a macroevolutionary perspective.


Assuntos
Evolução Biológica , Tamanho Corporal , Lagartos/anatomia & histologia , Caracteres Sexuais , Animais , Brasil , Tamanho da Ninhada , Feminino , Fertilidade , Masculino , Fenótipo , Filogenia , Reprodução
20.
J Morphol ; 279(11): 1665-1678, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30461040

RESUMO

Amphisabenia is a group of squamates adapted for a fossorial lifestyle. The skull is the animal's the main digging tool, and can present one of four principal shapes. The shovel-headed shape is considered to be the most specialized for digging. The South American genus Leposternon presents a shovel-headed morphotype, and is widely distributed on this continent. The general shovel-headed skull pattern may vary considerably, even within the same genus, and we hypothesized that this variation may be influenced primarily by body size and geographical factors. This study investigated the variation in skull size and shape among five Leposternon species, and examined the potential relationship between this variation and the size of the specimens and bioclimatic variables, through a geometric morphometric approach. Significant morphological variation was found among the species, and was also related systematically to body size and the geographical distribution of the specimens. As even subtle differences in the skull size or shape may represent significant modification in bite force and digging capacity and digging speed, the cranial variation found among the Leposternon species and specimens may have a direct influence on their diet and locomotor performance. Our results, together with direct observations of some of these species, suggest that shovel-headed amphisbaenians may be able to penetrate different soil types under a range of climatic conditions, especially considering the ample, but often sympatric distribution of the species studied here.


Assuntos
Lagartos/anatomia & histologia , Crânio/anatomia & histologia , Pontos de Referência Anatômicos , Animais , Tamanho Corporal , Análise dos Mínimos Quadrados , Filogeografia , Análise de Componente Principal , Análise de Regressão , América do Sul , Especificidade da Espécie
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