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Genes Mar 2024Karyotype diversification represents an important, yet poorly understood, driver of evolution. Squamate reptiles are characterized by a high taxonomic diversity which is... (Review)
Review
Karyotype diversification represents an important, yet poorly understood, driver of evolution. Squamate reptiles are characterized by a high taxonomic diversity which is reflected at the karyotype level in terms of general structure, chromosome number and morphology, and insurgence of differentiated simple or multiple-sex-chromosome systems with either male or female heterogamety. The potential of squamate reptiles as unique model organisms in evolutionary cytogenetics has been recognised in recent years in several studies, which have provided novel insights into the chromosome evolutionary dynamics of different taxonomic groups. Here, we review and summarize the resulting complex, but promising, general picture from a systematic perspective, mapping some of the main squamate karyological characteristics onto their phylogenetic relationships. We highlight how all the major categories of balanced chromosome rearrangements contributed to the karyotype evolution in different taxonomic groups. We show that distinct karyotype evolutionary trends may occur, and coexist, with different frequencies in different clades. Finally, in light of the known squamate chromosome diversity and recent research advances, we discuss traditional and novel hypotheses on karyotype evolution and propose a scenario of circular karyotype evolution.
Topics: Animals; Female; Male; Phylogeny; Reptiles; Karyotype; Karyotyping; Sex Chromosomes
PubMed: 38540430
DOI: 10.3390/genes15030371 -
Developmental Dynamics : An Official... Sep 2022Squamate reptiles (lizards, snakes, and amphisbaenians) exhibit incredible diversity in their locomotion, behavior, morphology, and ecological breadth. Although they...
BACKGROUND
Squamate reptiles (lizards, snakes, and amphisbaenians) exhibit incredible diversity in their locomotion, behavior, morphology, and ecological breadth. Although they often are used as models of locomotor diversity, surprisingly little attention has been given to muscle development in squamate reptiles. In fact, the most detailed examination was conducted almost 80 years ago and solely focused on the proximal limb regions. Herein, we present forelimb and hindlimb muscle morphogenesis data for three lizard species with different locomotion and feeding strategies: the desert grassland whiptail lizard, the central bearded dragon, and the veiled chameleon. This study fills critical gaps in our understanding of muscle morphogenesis in squamate reptiles and presents a comparative and temporospatial analysis of muscle development.
RESULTS
Our results reveal a conserved pattern of early muscle development among lizards with different adult morphologies and ecologies. The variations that exist are concentrated in distal regions, particularly the specialized autopodia of chameleons, where differentiation of muscles associated with the digits is delayed.
CONCLUSIONS
The chameleon autopod provides an example of major evolutionary modifications to the skeleton with only minor disruption of the conserved order and pattern of limb muscle development. This robustness of muscle patterning facilitates the evolution of extreme yet functional phenotypes.
Topics: Animals; Biological Evolution; Extremities; Forelimb; Lizards; Phylogeny; Snakes
PubMed: 34927301
DOI: 10.1002/dvdy.447 -
Communications Biology Feb 2023A voice box (larynx) is unique for tetrapods and plays functional roles in respiration, airway protection, and vocalization. However, in birds and other reptiles, the...
A voice box (larynx) is unique for tetrapods and plays functional roles in respiration, airway protection, and vocalization. However, in birds and other reptiles, the larynx fossil is extremely rare, and the evolution of this structure remains largely unknown. Here we report the fossil larynx found in non-avian dinosaurs from ankylosaur Pinacosaurus grangeri. The larynx of Pinacosaurus is composed of the cricoid and arytenoid like non-avian reptiles, but specialized with the firm and kinetic cricoid-arytenoid joint, prominent arytenoid process, long arytenoid, and enlarged cricoid, as a possible vocal modifier like birds rather than vocal source like non-avian reptiles. Although bird-unique vocal source (syrinx) have never been reported in non-avian dinosaurs, Pinacosaurus could have employed bird-like vocalization with the bird-like large, kinetic larynx. This oldest laryngeal fossil from the Cretaceous dinosaur provides the first step for understanding the vocal evolution in non-avian dinosaurs toward birds.
Topics: Animals; Dinosaurs; Biological Evolution; Larynx; Birds; Reptiles; Trachea
PubMed: 36792659
DOI: 10.1038/s42003-023-04513-x -
Nature Communications Dec 2023Free-ranging cats (Felis catus) are globally distributed invasive carnivores that markedly impact biodiversity. Here, to evaluate the potential threat of cats, we...
Free-ranging cats (Felis catus) are globally distributed invasive carnivores that markedly impact biodiversity. Here, to evaluate the potential threat of cats, we develop a comprehensive global assessment of species consumed by cats. We identify 2,084 species eaten by cats, of which 347 (16.65%) are of conservation concern. Islands contain threefold more species of conservation concern eaten by cats than continents do. Birds, reptiles, and mammals constitute ~90% of species consumed, with insects and amphibians being less frequent. Approximately 9% of known birds, 6% of known mammals, and 4% of known reptile species are identified in cat diets. 97% of species consumed are <5 kg in adult body mass, though much larger species are also eaten. The species accumulation curves are not asymptotic, indicating that our estimates are conservative. Our results demonstrate that cats are extreme generalist predators, which is critical for understanding their impact on ecological systems and developing management solutions.
Topics: Animals; Cats; Mammals; Biodiversity; Ecosystem; Diet; Reptiles; Birds
PubMed: 38086838
DOI: 10.1038/s41467-023-42766-6 -
Developmental Biology Mar 2023In the echidna, after development in utero, the egg is laid in the pouch and incubated for 10 days. During this time, the fetuses develop an egg tooth and caruncle to...
In the echidna, after development in utero, the egg is laid in the pouch and incubated for 10 days. During this time, the fetuses develop an egg tooth and caruncle to help them hatch. Using rare and unprecedented access to limited echidna pre- and post-hatching tissues, development of the egg tooth and caruncle were assessed by micro-CT, histology and immunofluorescence. Unlike therian tooth germs that develop by placode invagination, the echidna egg tooth developed by evagination, similar to the first teeth in some reptiles and fish. The egg tooth ankylosed to the premaxilla, rather than forming a tooth root with ligamentous attachment found in other mammals, with loss of the egg tooth associated with high levels of activity odontoclasts and apoptosis. The caruncle formed as a separate mineralisation from the adjacent nasal capsule, and as observed in birds and turtles, the nasal region epithelium on top of the nose expressed markers of cornification. Together, this highlights that the monotreme egg tooth shares many similarities with typical reptilian teeth, suggesting that this tooth has been conserved from a common ancestor of mammals and reptiles.
Topics: Animals; Tachyglossidae; Tooth; Mammals; Reptiles; Tooth Germ
PubMed: 36565838
DOI: 10.1016/j.ydbio.2022.12.005 -
Proceedings of the National Academy of... Apr 2023The dinosaur-bird transition involved several anatomical, biomechanical, and physiological modifications of the theropod bauplan. Non-avian maniraptoran theropods, such...
The dinosaur-bird transition involved several anatomical, biomechanical, and physiological modifications of the theropod bauplan. Non-avian maniraptoran theropods, such as , are key to better understand changes in thermophysiology and reproduction occurring during this transition. Here, we applied dual clumped isotope (Δ and Δ) thermometry, a technique that resolves mineralization temperature and other nonthermal information recorded in carbonates, to eggshells from , modern reptiles, and modern birds. eggshells show variable temperatures, namely 42 and 29 ± 2 °C, supporting the hypothesis of an endothermic thermophysiology with a heterothermic strategy for this extinct taxon. Dual clumped isotope data also reveal physiological differences in the reproductive systems between , reptiles, and birds. and modern reptiles mineralize their eggshells indistinguishable from dual clumped isotope equilibrium, while birds precipitate eggshells characterized by a positive disequilibrium offset in Δ. Analyses of inorganic calcites suggest that the observed disequilibrium pattern in birds is linked to an amorphous calcium carbonate (ACC) precursor, a carbonate phase known to accelerate eggshell formation in birds. Lack of disequilibrium patterns in reptile and eggshells implies these vertebrates had not acquired the fast, ACC-based eggshell calcification process characteristic of birds. Observation that retained a slow reptile-like calcification suggests that it possessed two functional ovaries and was limited in the number of eggs it could produce; thus its large clutches would have been laid by several females. Dual clumped isotope analysis of eggshells of extinct vertebrates sheds light on physiological information otherwise inaccessible in the fossil record.
Topics: Animals; Female; Calcium Carbonate; Egg Shell; Isotopes; Reptiles
PubMed: 37011196
DOI: 10.1073/pnas.2213987120 -
Scientific Reports Oct 2020Throughout their evolution, tetrapods have repeatedly colonised a series of ecological niches in marine ecosystems, producing textbook examples of convergent evolution....
Throughout their evolution, tetrapods have repeatedly colonised a series of ecological niches in marine ecosystems, producing textbook examples of convergent evolution. However, this evolutionary phenomenon has typically been assessed qualitatively and in broad-brush frameworks that imply simplistic macroevolutionary landscapes. We establish a protocol to visualize the density of trait space occupancy and thoroughly test for the existence of macroevolutionary landscapes. We apply this protocol to a new phenotypic dataset describing the morphology of short-necked plesiosaurians, a major component of the Mesozoic marine food webs (ca. 201 to 66 Mya). Plesiosaurians evolved this body plan multiple times during their 135-million-year history, making them an ideal test case for the existence of macroevolutionary landscapes. We find ample evidence for a bimodal craniodental macroevolutionary landscape separating latirostrines from longirostrine taxa, providing the first phylogenetically-explicit quantitative assessment of trophic diversity in extinct marine reptiles. This bimodal pattern was established as early as the Middle Jurassic and was maintained in evolutionary patterns of short-necked plesiosaurians until a Late Cretaceous (Turonian) collapse to a unimodal landscape comprising longirostrine forms with novel morphologies. This study highlights the potential of severe environmental perturbations to profoundly alter the macroevolutionary dynamics of animals occupying the top of food chains.
Topics: Animals; Biological Evolution; Ecosystem; Extinction, Biological; Food Chain; Fossils; Phylogeny; Reptiles
PubMed: 33009498
DOI: 10.1038/s41598-020-73413-5 -
Current Biology : CB May 2021The evolution of mammals from their extinct forerunners, the non-mammalian synapsids, is one of the most iconic locomotor transitions in the vertebrate fossil record. In...
The evolution of mammals from their extinct forerunners, the non-mammalian synapsids, is one of the most iconic locomotor transitions in the vertebrate fossil record. In the limb skeleton, the synapsid-mammal transition is traditionally characterized by a shift from a sprawling limb posture, resembling that of extant reptiles and amphibians, to more adducted limbs, as seen in modern-day mammals. Based on proposed postural similarities between early synapsids and extant reptiles, this change is thought to be accompanied by a shift from ancestral reptile-like lateral bending to mammal-like sagittal bending of the vertebral column. To test this "lateral-to-sagittal" evolutionary paradigm, we used combinatorial optimization to produce functionally informed adaptive landscapes and determined the functional trade-offs associated with evolutionary changes in vertebral morphology. We show that the synapsid adaptive landscape is different from both extant reptiles and mammals, casting doubt on the reptilian model for early synapsid axial function, or indeed for the ancestral condition of amniotes more broadly. Further, the synapsid-mammal transition is characterized by not only increasing sagittal bending in the posterior column but also high stiffness and increasing axial twisting in the anterior column. Therefore, we refute the simplistic lateral-to-sagittal hypothesis and instead suggest the synapsid-mammal locomotor transition involved a more complex suite of functional changes linked to increasing regionalization of the backbone. These results highlight the importance of fossil taxa for understanding major evolutionary transitions.
Topics: Animals; Biological Evolution; Fossils; Mammals; Reptiles; Spine
PubMed: 33657406
DOI: 10.1016/j.cub.2021.02.009 -
PeerJ 2022Mesosaurs are the first secondarily aquatic amniotes and one of the most enigmatic clades of reptiles from the early Permian. They have long puzzled paleontologists with...
Mesosaurs are the first secondarily aquatic amniotes and one of the most enigmatic clades of reptiles from the early Permian. They have long puzzled paleontologists with their unique morphologies: possessing an elongated skull with thin needle-like teeth, a long neck, large webbed hindlimbs, banana-shaped pachyosteosclerotic ribs, and a long tail. Here, we look at a large dataset of morphometric measurements from 270 mesosaur specimens in collections around the world. These measurements characterize skull, tooth, and limb proportions and their variation with size. This data presents evidence of surprising ontogenetic changes in these animals as well as new insights into their taxonomy. Our results support the recent hypothesis that is the only valid species within Mesosauridae and suggest that "" and "" represent immature stages or incomplete specimens of by showing that all three species occupy an incomplete portion of the overall size range of mesosaurs. Under the single-species hypothesis, we highlight a number of ontogenetic trends: (1) a reduction in skull length accompanied by an elongation of the snout within the skull, (2) an elongation of teeth, (3) a reduction in hind limb length, and (4) a reduction in manus length. Concurrent with these changes, we hypothesize that mesosaurs went through a progressive ecological shift during their growth, with juveniles being more common in shallow water deposits, whereas large adults are more frequent in pelagic sediments. These parallel changes suggest that mesosaurs underwent a diet and lifestyle transition during ontogeny, from an active predatory lifestyle as juveniles to a more filter-feeding diet as adults. We propose that this change in lifestyle and environments may have been driven by the pursuit of different food sources, but a better understanding of the Irati Sea fauna will be necessary to obtain a more definitive answer to the question of young mesosaur diet.
Topics: Animals; Skull; Reptiles; Tooth; Head; Diet
PubMed: 36132215
DOI: 10.7717/peerj.13866 -
ELife Jul 2021Ornithischian dinosaurs were ecologically prominent herbivores of the Mesozoic Era that achieved a global distribution by the onset of the Cretaceous. The ornithischian...
Ornithischian dinosaurs were ecologically prominent herbivores of the Mesozoic Era that achieved a global distribution by the onset of the Cretaceous. The ornithischian body plan is aberrant relative to other ornithodiran clades, and crucial details of their early evolution remain obscure. We present a new, fully articulated skeleton of the early branching ornithischian . Phase-contrast enhanced synchrotron data of this new specimen reveal a suite of novel postcranial features unknown in any other ornithischian, with implications for the early evolution of the group. These features include a large, anteriorly projecting sternum; bizarre, paddle-shaped sternal ribs; and a full gastral basket - the first recovered in Ornithischia. These unusual anatomical traits provide key information on the evolution of the ornithischian body plan and suggest functional shifts in the ventilatory apparatus occurred close to the base of the clade. We complement these anatomical data with a quantitative analysis of ornithischian pelvic architecture, which allows us to make a specific, stepwise hypothesis for their ventilatory evolution.
Topics: Animals; Biological Evolution; Dinosaurs; Fossils; Pulmonary Ventilation
PubMed: 34225841
DOI: 10.7554/eLife.66036