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Current Biology : CB Dec 2022Sugars are an important class of nutrients found in the flowers and fruits of angiosperms (flowering plants). Although T1R2-T1R3 has been identified as the mammalian...
Sugars are an important class of nutrients found in the flowers and fruits of angiosperms (flowering plants). Although T1R2-T1R3 has been identified as the mammalian sweet receptor, some birds rely on a repurposed T1R1-T1R3 savory receptor to sense sugars. Moreover, as the radiation of flowering plants occurred later than the last common ancestor of amniotes, sugar may not have been an important diet item for amniotes early in evolution, raising the question of whether T1R2-T1R3 is a universal sugar sensor or only a mammalian innovation. Here, using brief-access behavioral tests and functional characterization of taste receptors, we demonstrate that the nectar-taking Madagascar giant day gecko (Phelsuma grandis) can sense sugars through the T1R2-T1R3 receptor. These results reveal the existence of T1R2-based sweet taste in a non-avian reptile, which has important implications for our understanding of the evolutionary history of sugar detection in amniotes.
Topics: Animals; Lizards; Sugars; Madagascar; Mammals
PubMed: 36473437
DOI: 10.1016/j.cub.2022.10.061 -
PloS One 2021We examine, for the first time, biogeographic patterns in a series of tropical montane coastal systems in northern South America. We use amphibians and reptiles, which...
We examine, for the first time, biogeographic patterns in a series of tropical montane coastal systems in northern South America. We use amphibians and reptiles, which constitute the most critical communities based upon the prevalence of endemic taxa, to assess the region's biodiversity. The montane coastal system spans an east-west distance of 925 km. It includes peaks ranging from 549 m to 2765 m above sea level and encompasses the montane complexes of northern Venezuela (including Isla de Margarita), an outlier at Santa Marta (Colombia), and ranges on the islands Trinidad and Tobago. The area supports 14 family level amphibian clades and 23 family level reptile clades. Fieldwork, museum specimen surveys, and a literature review suggest that biodiversity decreases at higher elevations. Here we examine the biogeographic patterns in the region to assess the role of the montane systems as possible refugia. We also look at the possible island and sky island effects using data from altitudes >200 m. At lower elevations, we tabulated 294 species, comprising 112 amphibians and 182 reptiles. About 45% of these taxa are endemic or exclusive to different sub-regions. At mid-elevation montane cloud forests, we find a much-reduced biodiversity with a total of 125 species (66 amphibians and 59 reptiles) exclusive or restricted to the region, and few species shared between systems. We find that biogeographical patterns follow a natural topographic disposition above 200 m in elevations. At the lower elevation cut off, there are 118 species (26 amphibians and 92 reptiles) shared among two or more of the studied mountain systems, suggesting a common origin and dispersal events, despite what seem to be topographic barriers. Biogeographical relationships support a topographic disposition of the region with close associations between the islands of Trinidad and Tobago, the Paria Range and the Turimiquire Massif, and close associations between the Sierra Nevada de Santa Marta and the Sierra de San Luis. Overall, the biogeographic relationships between amphibians and reptiles are similar. Species diversity in the eastern Caribbean region is less rich than in the west. This study includes the first herpetological surveys at the two easternmost mountains (Cerro La Cerbatana and Campeare) belonging to the Paria Range biogeographic unit, and aims to contribute to a better understanding of the rich biodiversity of the region.
Topics: Altitude; Amphibians; Animals; Biodiversity; Forests; Geography; Phylogeny; Reptiles; South America
PubMed: 33661928
DOI: 10.1371/journal.pone.0246829 -
Journal of Anatomy May 2023The water-to-land transition by the first tetrapod vertebrates represents a key stage in their evolution. Selection pressures exerted by this new environment on animals...
The water-to-land transition by the first tetrapod vertebrates represents a key stage in their evolution. Selection pressures exerted by this new environment on animals led to the emergence of new locomotor and postural strategies that favoured access to different ecological niches and contributed to their evolutionary success. Today, amniotes show great locomotor and postural diversity, particularly among Reptilia, whose extant representatives include parasagittally locomoting erect and crouched bipeds (birds), sub-parasagittal 'semi-erect' quadrupeds (crocodylians) and sprawling quadrupeds (squamates and turtles). But the different steps leading to such diversity remain enigmatic and the type of locomotion adopted by many extinct species raises questions. This is notably the case of certain Triassic taxa such as Euparkeria and Marasuchus. The exploration of the bone microanatomy in reptiles could help to overcome these uncertainties. Indeed, this locomotor and postural diversity is accompanied by great microanatomical disparity. On land, the bones of the appendicular skeleton support the weight of the body and are subject to multiple constraints that partly shape their external and internal morphology. Here we show how microanatomical parameters measured in cross-section, such as bone compactness or the position of the medullocortical transition, can be related to locomotion. We hypothesised that this could be due to variations in cortical thickness. Using statistical methods that take phylogeny into account (phylogenetic flexible discriminant analyses), we develop different models of locomotion from a sample of femur cross-sections from 51 reptile species. We use these models to infer locomotion and posture in 7 extinct reptile taxa for which they remain debated or not fully clear. Our models produced reliable inferences for taxa that preceded and followed the quadruped/biped and sprawling/erect transitions, notably within the Captorhinidae and Dinosauria. For taxa contemporary with these transitions, such as Terrestrisuchus and Marasuchus, the inferences are more questionable. We use linear models to investigate the effect of body mass and functional ecology on our inference models. We show that body mass seems to significantly impact our model predictions in most cases, unlike the functional ecology. Finally, we illustrate how taphonomic processes can impact certain microanatomical parameters, especially the eccentricity of the section, while addressing some other potential limitations of our methods. Our study provides insight into the evolution of enigmatic locomotion in various early reptiles. Our models and methods could be used by palaeontologists to infer the locomotion and posture in other extinct reptile taxa, especially when considered in combination with other lines of evidence.
Topics: Animals; Phylogeny; Reptiles; Femur; Locomotion; Dinosaurs; Biological Evolution; Fossils
PubMed: 36807199
DOI: 10.1111/joa.13833 -
Proceedings. Biological Sciences Nov 2019Natural nests of egg-laying birds and reptiles exhibit substantial thermal variation, at a range of spatial and temporal scales. Rates and trajectories of embryonic... (Review)
Review
Natural nests of egg-laying birds and reptiles exhibit substantial thermal variation, at a range of spatial and temporal scales. Rates and trajectories of embryonic development are highly sensitive to temperature, favouring an ability of embryos to respond adaptively (i.e. match their developmental biology to local thermal regimes). Spatially, thermal variation can be significant within a single nest (top to bottom), among adjacent nests (as a function of shading, nest depth etc.), across populations that inhabit areas with different weather conditions, and across species that differ in climates occupied and/or nest characteristics. Thermal regimes also vary temporally, in ways that generate differences among nests within a single population (e.g. due to seasonal timing of laying), among populations and across species. Anthropogenic activities (e.g. habitat clearing, climate change) add to this spatial and temporal diversity in thermal regimes. We review published literature on embryonic adaptations to spatio-temporal heterogeneity in nest temperatures. Although relatively few taxa have been studied in detail, and proximate mechanisms remain unclear, our review identifies many cases in which natural selection appears to have fine-tuned embryogenesis to match local thermal regimes. Developmental rates have been reported to differ between uppermost versus lower eggs within a single nest, between eggs laid early versus late in the season, and between populations from cooler versus warmer climates. We identify gaps in our understanding of thermal adaptations of early (embryonic) phases of the life history, and suggest fruitful opportunities for future research.
Topics: Adaptation, Biological; Animals; Birds; Embryo, Nonmammalian; Embryonic Development; Nesting Behavior; Reptiles; Spatio-Temporal Analysis; Temperature
PubMed: 31744441
DOI: 10.1098/rspb.2019.2078 -
Archives of Insect Biochemistry and... Nov 2019Ticks are obligate blood-sucking ectoparasites, which not only directly damage through bites but also transmit many pathogens. China has a high diversity of tick... (Review)
Review
Ticks are obligate blood-sucking ectoparasites, which not only directly damage through bites but also transmit many pathogens. China has a high diversity of tick species, 125 species have been reported, including 111 hard tick and 14 soft tick species. Many of the ticks are important vectors of pathogens, resulting in zoonoses. The dynamics of ticks are affected by both the host and habitat environment. However, systematic studies on the geographical distribution, host diversity, and specificity of ticks are limited in China. To achieve this goal, the relevant available data were summarized and analyzed in this study. Ticks are distributed in all parts of China and Xinjiang has the most records of ticks. The distribution of ticks in adjacent areas is similar, indicating that the habitat environment affects their distribution. Most ticks are widely distributed, whereas some species are endemic to their distributed regions. Ticks are parasitic on mammals, birds, and reptiles, of which mammals are the main host species. Overall, most ticks parasitize different hosts, only a few ticks have strict host specificity, such as ticks that are specifically parasitic on reptiles and bats. In addition, environmental changes and control efforts also influence the dynamics of ticks. These results can better reveal tick biological traits and are valuable for tick control.
Topics: Animals; Birds; China; Ecosystem; Geography; Host-Parasite Interactions; Mammals; Reptiles; Ticks
PubMed: 30859631
DOI: 10.1002/arch.21544 -
PeerJ 2023Pesticide use on tropical crops has increased substantially in recent decades, posing a threat to biodiversity and ecosystem services. Amphibians and reptiles are common...
Pesticide use on tropical crops has increased substantially in recent decades, posing a threat to biodiversity and ecosystem services. Amphibians and reptiles are common in tropical agricultural landscapes, but few field studies measure pesticide impacts on these taxa. Here we combine 1-year of correlative data with an experimental field approach from Indonesia. We show that while pesticide application cannot predict amphibian or reptile diversity patterns in cocoa plantations, our experimental exposure to herbicides and insecticides in vegetable gardens eliminated amphibians, whereas reptiles were less impacted by insecticide and not affected by herbicide exposure. The pesticide-driven loss of a common amphibian species known to be a pest-control agent (mainly invertebrate predation) suggests a strong indirect negative effect of pesticides on this service. We recommend landscape-based Integrated Pest Management and additional ecotoxicological studies on amphibians and reptiles to underpin a regulatory framework and to assure recognition and protection of their ecosystem services.
Topics: Animals; Pesticides; Ecosystem; Indonesia; Amphibians; Reptiles; Herbicides; Insecticides
PubMed: 36967985
DOI: 10.7717/peerj.15046 -
International Journal of Molecular... Aug 2021The lizards of the species-rich clade Scincoidea including cordylids, gerrhosaurids, skinks, and xantusiids, show an almost cosmopolitan geographical distribution and a...
The lizards of the species-rich clade Scincoidea including cordylids, gerrhosaurids, skinks, and xantusiids, show an almost cosmopolitan geographical distribution and a remarkable ecological and morphological divergence. However, previous studies revealed limited variability in cytogenetic traits. The sex determination mode was revealed only in a handful of gerrhosaurid, skink, and xantusiid species, which demonstrated either ZZ/ZW or XX/XY sex chromosomes. In this study, we explored the karyotypes of six species of skinks, two species of cordylids, and one gerrhosaurid. We applied conventional and molecular cytogenetic methods, including C-banding, fluorescence in situ hybridization with probes specific for telomeric motifs and rDNA loci, and comparative genomic hybridization. The diploid chromosome numbers are rather conserved among these species, but the chromosome morphology, the presence of interstitial telomeric sequences, and the topology of rDNA loci vary significantly. Notably, XX/XY sex chromosomes were identified only in , where, in contrast to the X chromosome, the Y chromosome lacks accumulations of rDNA loci. We confirm that within the lizards of the scincoidean clade, sex chromosomes remained in a generally poor stage of differentiation.
Topics: Animals; Comparative Genomic Hybridization; Cytogenetic Analysis; DNA, Ribosomal; Diploidy; Evolution, Molecular; Female; In Situ Hybridization, Fluorescence; Karyotyping; Lizards; Male; Sex Chromosomes; Sex Determination Processes
PubMed: 34445371
DOI: 10.3390/ijms22168670 -
Oecologia Oct 2022Increases in temperature related to global warming have important implications for organismal fitness. For ectotherms inhabiting temperate regions, 'winter warming' is... (Meta-Analysis)
Meta-Analysis Review
Increases in temperature related to global warming have important implications for organismal fitness. For ectotherms inhabiting temperate regions, 'winter warming' is likely to be a key source of the thermal variation experienced in future years. Studies focusing on the active season predict largely positive responses to warming in the reptiles; however, overlooking potentially deleterious consequences of warming during the inactive season could lead to biased assessments of climate change vulnerability. Here, we review the overwinter ecology of reptiles, and test specific predictions about the effects of warming winters, by performing a meta-analysis of all studies testing winter warming effects on reptile traits to date. We collated information from observational studies measuring responses to natural variation in temperature in more than one winter season, and experimental studies which manipulated ambient temperature during the winter season. Available evidence supports that most reptiles will advance phenologies with rising winter temperatures, which could positively affect fitness by prolonging the active season although effects of these shifts are poorly understood. Conversely, evidence for shifts in survivorship and body condition in response to warming winters was equivocal, with disruptions to biological rhythms potentially leading to unforeseen fitness ramifications. Our results suggest that the effects of warming winters on reptile species are likely to be important but highlight the need for more data and greater integration of experimental and observational approaches. To improve future understanding, we recap major knowledge gaps in the published literature of winter warming effects in reptiles and outline a framework for future research.
Topics: Animals; Climate Change; Global Warming; Reptiles; Seasons; Temperature
PubMed: 36100724
DOI: 10.1007/s00442-022-05251-3 -
Cells Jul 2021The distinctive biology and unique evolutionary features of snakes make them fascinating model systems to elucidate how genomes evolve and how variation at the genomic... (Review)
Review
The distinctive biology and unique evolutionary features of snakes make them fascinating model systems to elucidate how genomes evolve and how variation at the genomic level is interlinked with phenotypic-level evolution. Similar to other eukaryotic genomes, large proportions of snake genomes contain repetitive DNA, including transposable elements (TEs) and satellite repeats. The importance of repetitive DNA and its structural and functional role in the snake genome, remain unclear. This review highlights the major types of repeats and their proportions in snake genomes, reflecting the high diversity and composition of snake repeats. We present snakes as an emerging and important model system for the study of repetitive DNA under the impact of sex and microchromosome evolution. We assemble evidence to show that certain repetitive elements in snakes are transcriptionally active and demonstrate highly dynamic lineage-specific patterns as repeat sequences. We hypothesize that particular TEs can trigger different genomic mechanisms that might contribute to driving adaptive evolution in snakes. Finally, we review emerging approaches that may be used to study the expression of repetitive elements in complex genomes, such as snakes. The specific aspects presented here will stimulate further discussion on the role of genomic repeats in shaping snake evolution.
Topics: Animals; Biological Evolution; Chromosome Mapping; DNA Transposable Elements; Female; Gene Expression Regulation; Genome Size; Genomics; Male; Microsatellite Repeats; Phylogeny; Snakes; Species Specificity; Transcription, Genetic
PubMed: 34359877
DOI: 10.3390/cells10071707 -
BMC Biology Jun 2022In egg-laying amniotes, the developing embryo is tethered to a number of the extraembryonic membranes including the yolk sac and allantois that deliver oxygen and...
BACKGROUND
In egg-laying amniotes, the developing embryo is tethered to a number of the extraembryonic membranes including the yolk sac and allantois that deliver oxygen and nutrients and remove metabolic waste products throughout embryonic development. Prior to, or soon after hatching, these membranes detach from the animal leaving a temporary or permanent umbilical scar (umbilicus) equivalent to the navel or 'belly button' in some placental mammals, including humans. Although ubiquitous in modern mammals and reptiles (including birds), at least early in their ontogeny, the umbilicus has not been identified in any pre-Cenozoic amniote.
RESULTS
We report the oldest preserved umbilicus in a fossil amniote from a ~130-million-year-old early-branching ceratopsian dinosaur, Psittacosaurus. Under laser-stimulated fluorescence (LSF), the umbilicus is revealed as an elongate midline structure delimited by a row of paired scales on the abdomen. The relatively late ontogenetic stage (close to sexual maturity) estimated for the individual indicates that the umbilicus was probably retained throughout life.
CONCLUSIONS
Unlike most extant reptiles and birds that lose this scar within days to weeks after hatching, the umbilicus of Psittacosaurus persisted at least until sexual maturity, similar to some lizards and crocodylians with which it shares the closest morphological resemblance. This discovery is the oldest record of an amniote umbilicus and the first in a non-avian dinosaur. However, given the variability of this structure in extant reptilian analogues, a persistent umbilical scar may not have been present in all non-avian dinosaurs.
Topics: Animals; Biological Evolution; Birds; Cicatrix; Dinosaurs; Female; Fossils; Lizards; Mammals; Placenta; Pregnancy; Umbilicus
PubMed: 35672741
DOI: 10.1186/s12915-022-01329-9