scholarly journals Territorial Displays of the Ctenophorus decresii Complex: A Story of Local Adaptations

2021 ◽  
Vol 9 ◽  
Author(s):  
Jose A. Ramos ◽  
Richard A. Peters
Keyword(s):  
Motor Pattern ◽  
Habitat Characteristics ◽  
Model Systems ◽  
Ancestral State ◽  
Lizard Species ◽  
Motor Patterns ◽  
Local Adaptations ◽  
Behavioral Traits ◽  
Signal Contrast ◽  
Motion Speed

Closely related species make for interesting model systems to study the evolution of signaling behavior because they share evolutionary history but have also diverged to the point of reproductive isolation. This means that while they may have some behavioral traits in common, courtesy of a common ancestor, they are also likely to show local adaptations. The Ctenophorus decresii complex is such a system, and comprises six closely related agamid lizard species from Australia: C. decresii, C. fionni, C. mirrityana, C. modestus, C. tjanjalka, and C. vadnappa. In this study, we analyze the motion displays of five members of the C. decresii complex in the context of their respective habitats by comparing signal structure, habitat characteristics and signal contrast between all species. Motor pattern use and the temporal sequence of motor patterns did not differ greatly, but the motion speed distributions generated during the displays were different for all species. There was also variation in the extent to which signals contrasted with plant motion, with C. vadnappa performing better than the other species at all habitats. Overall, this study provides evidence that members of the C. decresii complex exhibit local adaptations in signaling behavior to their respective habitat, but they also maintain some morphological and behavioral traits in common, which is likely a consequence from the ancestral state.

scholarly journals Effectiveness of movement-based animal signals is a function of display structure and habitat characteristics: simulations of Australian dragons

2020 ◽  
Author(s):  
Xue Bian ◽  
Angela Pinilla ◽  
Tom Chandler ◽  
Richard Peters
Keyword(s):  
Environmental Conditions ◽  
Habitat Structure ◽  
Signal Transmission ◽  
Habitat Characteristics ◽  
Lizard Species ◽  
Local Adaptations ◽  
Signal Efficacy ◽  
Signal Divergence ◽  
Colour Signals ◽  
Optimal Signal

Abstract Habitat-specific characteristics can affect signal transmission such that different habitats dictate the optimal signal. One way to examine how the environment influences signals is by comparing changes in signal efficacy in different habitats. Examinations of signal efficacy between different habitats has helped to explain signal divergence/convergence between populations and species utilising acoustic and colour signals. Although previous research has provided evidence for local adaptations and signal divergence in many species of lizards, comparative studies in movement-based signals are rare due to technical difficulties in quantifying movements in nature and ethical restrictions in translocating animals between habitats. We demonstrate herein that these issues can be addressed using 3D animations, and compared the relative performance of the displays of four Australian lizard species in the habitats of each species under varying environmental conditions. Our simulations show that habitats differentially affect signal performance, and an interaction between display and habitat structure. Interestingly, the signal adapted to the noisier environment did not show an advantage in signal efficacy, but the noisy habitat was detrimental to the performance of all displays. Our study is one of the first studies for movement-based signals that directly compares signal performance in multiple habitats, and our approach has laid the foundation for future investigations in motion ecology that have been intractable to conventional research methods.

scholarly journals Simulations with Australian dragon lizards suggest movement-based signal effectiveness is dependent on display structure and environmental conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xue Bian ◽  
Angela Pinilla ◽  
Tom Chandler ◽  
Richard Peters
Keyword(s):  
Research Methods ◽  
Environmental Conditions ◽  
Comparative Studies ◽  
Habitat Structure ◽  
Signal Transmission ◽  
Lizard Species ◽  
Local Adaptations ◽  
Signal Divergence ◽  
Colour Signals ◽  
Optimal Signal

AbstractHabitat-specific characteristics can affect signal transmission such that different habitats dictate the optimal signal. One way to examine how the environment influences signals is by comparing changes in signal effectiveness in different habitats. Examinations of signal effectiveness between different habitats has helped to explain signal divergence/convergence between populations and species using acoustic and colour signals. Although previous research has provided evidence for local adaptations and signal divergence in many species of lizards, comparative studies in movement-based signals are rare due to technical difficulties in quantifying movements in nature and ethical restrictions in translocating animals between habitats. We demonstrate herein that these issues can be addressed using 3D animations, and compared the relative performance of the displays of four Australian lizard species in the habitats of each species under varying environmental conditions. Our simulations show that habitats differentially affect signal performance, and an interaction between display and habitat structure. Interestingly, our results are consistent with the hypothesis that the signal adapted to the noisier environment does not show an advantage in signal effectiveness, but the noisy habitat was detrimental to the performance of all displays. Our study is one of the first studies for movement-based signals that directly compares signal performance in multiple habitats, and our approach has laid the foundation for future investigations in motion ecology that have been intractable to conventional research methods.

Slow active potentials and bursting motor patterns in pyloric network of the lobster, Panulirus interruptus

1982 ◽  
Vol 48 (4) ◽  
pp. 914-937 ◽  
Author(s):  
D. F. Russell ◽  
D. K. Hartline
Keyword(s):  
Motor Pattern ◽  
Membrane Properties ◽  
Plateau Potentials ◽  
Motor Patterns ◽  
Potential Oscillations ◽  
Panulirus Interruptus ◽  
Pyloric Network ◽  
Current Pulses ◽  
Voltage Dependent ◽  
High Level

1. Neurons in the central pattern generator for the "pyloric" motor rhythm of the lobster stomatogastric ganglion were investigated for the possible involvement of regenerative membrane properties in their membrane-potential oscillations and bursting output patterns. 2. Evidence was found that each class of pyloric-system neurons can possess a capability for generating prolonged regenerative depolarizations by a voltage-dependent membrane mechanism. Such responses have been termed plateau potentials. 3. Several tests were applied to determine whether a given cell possessed a plateau capability. First among these was the ability to trigger all-or-none bursts of nerve impulses by brief depolarizing current pulses and to terminate bursts in an all-or-none fashion with brief hyperpolarizing current pulses. Tests were made under conditions of a high level of activity in the pyloric generator, often in conjunction with the use of hyperpolarizing offsets to the cell under test to suppress ongoing bursting. 4. For each class, the network of synaptic interconnections among the pyloric-system neurons was shown to not be the cause of the regenerative responses observed. 5. Plateau potentials are viewed as a driving force for axon spiking during bursts and as interacting with the synaptic network in the formation of the pyloric motor pattern.

Principles of rhythmic motor pattern generation

1996 ◽  
Vol 76 (3) ◽  
pp. 687-717 ◽  
Author(s):  
E. Marder ◽  
R. L. Calabrese
Keyword(s):  
Motor Pattern ◽  
Pattern Generation ◽  
Rhythmic Movements ◽  
Motor Patterns ◽  
Nervous Systems ◽  
Cellular Processes ◽  
Rhythmic Motor ◽  
Computational Analyses ◽  
Motor Pattern Generation ◽  
Rhythmic Motor Pattern

Rhythmic movements are produced by central pattern-generating networks whose output is shaped by sensory and neuromodulatory inputs to allow the animal to adapt its movements to changing needs. This review discusses cellular, circuit, and computational analyses of the mechanisms underlying the generation of rhythmic movements in both invertebrate and vertebrate nervous systems. Attention is paid to exploring the mechanisms by which synaptic and cellular processes interact to play specific roles in shaping motor patterns and, consequently, movement.

Peptidergic modulation of a multioscillator system in the lobster. I. Activation of the cardiac sac motor pattern by the neuropeptides proctolin and red pigment-concentrating hormone

1989 ◽  
Vol 61 (4) ◽  
pp. 833-844 ◽  
Author(s):  
P. S. Dickinson ◽  
E. Marder
Keyword(s):  
Nervous System ◽  
Motor Neurons ◽  
Motor Pattern ◽  
Stomatogastric Ganglion ◽  
Red Pigment ◽  
Stomatogastric Nervous System ◽  
Two Phase ◽  
Motor Patterns ◽  
Neuronal Element

1. The cardiac sac motor pattern consists of slow and irregular impulse bursts in the motor neurons [cardiac sac dilator 1 and 2 (CD1 and CD2)] that innervate the dilator muscles of the cardiac sac region of the crustacean foregut. 2. The effects of the peptides, proctolin and red pigment-concentrating hormone (RPCH), on the cardiac sac motor patterns produced by in vitro preparations of the combined stomatogastric nervous system [the stomatogastric ganglion (STG), the paired commissural ganglia (CGs), and the oesophageal ganglion (OG)] were studied. 3. Bath applications of either RPCH or proctolin activated the cardiac sac motor pattern when this motor pattern was not already active and increased the frequency of the cardiac sac motor pattern in slowly active preparations. 4. The somata of CD1 and CD2 are located in the esophageal and stomatogastric ganglia, respectively. Both neurons project to all four of the ganglia of the stomatogastric nervous system. RPCH elicited cardiac sac motor patterns when applied to any region of the stomatogastric nervous system, suggesting a distributed pattern generating network with multiple sites of modulation. 5. The anterior median (AM) neuron innervates the constrictor muscles of the cardiac sac. The AM usually functions as a part of the gastric mill pattern generator. However, when the cardiac sac is activated by RPCH applied to the stomatogastric ganglion, the AM neuron becomes active in antiphase with the cardiac sac dilator bursts. This converts the cardiac sac motor pattern from a one-phase rhythm to a two-phase rhythm. 6. These data show that a neuropeptide can cause a neuronal element to switch from being solely a component of one neuronal circuit to functioning in a second one as well. This example shows that peptidergic "reconfiguration" of neuronal networks can produce substantial changes in the behavior of associated neurons.

scholarly journals Comparative anatomy of the middle ear in some lizard species with comments on the evolutionary changes within Squamata

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11722
Author(s):  
Paola María Sánchez-Martínez ◽  
Juan D. Daza ◽  
Julio Mario Hoyos
Keyword(s):  
Middle Ear ◽  
Comparative Anatomy ◽  
General Structure ◽  
Main Function ◽  
Ancestral State ◽  
Sound Waves ◽  
Ancestral Reconstruction ◽  
Lizard Species ◽  
Evolutionary Changes ◽  
Axis Length

The skeleton of the middle ear of lizards is composed of three anatomical elements: columella, extracolumella, and tympanic membrane, with some exceptions that show modifications of this anatomy. The main function of the middle ear is transforming sound waves into vibrations and transmitting these to the inner ear. Most middle ear studies mainly focus on its functional aspects, while few describe the anatomy in detail. In lizards, the morphology of the columella is highly conservative, while the extracolumella shows variation in its presence/absence, size, and the number of processes present on the structure. In this work, we used diaphanized and double-stained specimens of 38 species of lizards belonging to 24 genera to study the middle ear’s morphology in a comparative framework. Results presented here indicate more variation in the morphology of the extracolumella than previously known. This variation in the extracolumella is found mainly in the pars superior and anterior processes, while the pars inferior and the posterior process are more constant in morphology. We also provide new information about the shape of gekkotan extracolumella, including traits that are diagnostic for the iguanid and gekkonid middle ear types. The data collected in this study were combined with information from published descriptive works. The new data included here refers to the length of the columella relative to the extracolumella central axis length, the general structure of the extracolumella, and the presence of the internal process. These characters were included in ancestral reconstruction analysis using Bayesian and parsimony approaches. The results indicate high levels of homoplasy in the variation of the columella-extracolumella ratio, providing a better understanding of the ratio variation among lizards. Additionally, the presence of four processes in the extracolumella is the ancestral state for Gekkota, Pleurodonta, and Xantusiidae, and the absence of the internal processes is the ancestral state for Gekkota, Gymnophthalmidae, and Scincidae; despite the fact that these groups convergently develop these character states, they could be used in combination with other characters to diagnose these clades. The posterior extension in the pars superior and an anterior process with some small and sharp projections is also a diagnostic trait for Gekkota. A more accurate description of each process of the extracolumella and its variation needs to be evaluated in a comprehensive analysis, including a greater number of species. Although the number of taxa sampled in this study is small considering the vast diversity of lizards, the results provide an overall idea of the amount of variation of the middle ear while helping to infer the evolutionary history of the lizard middle ear.

The effects of temperature on the burial performance and axial motor pattern of the sand-swimming of the Mojave fringe-toed lizard Uma scoparia

2000 ◽  
Vol 203 (7) ◽  
pp. 1241-1252 ◽  
Author(s):  
B.C. Jayne ◽  
M.W. Daggy
Keyword(s):  
Muscle Activity ◽  
Motor Pattern ◽  
Wave Pattern ◽  
Motor Patterns ◽  
Axial Muscle ◽  
Hind Limbs ◽  
Anterior Trunk ◽  
Cycling Frequency ◽  
The Mean ◽  
Similar Motor

Although lateral axial bending is widespread for the locomotion of ectothermic vertebrates, the axial motor patterns of terrestrial taxa are known only for a limited number of species and behaviors. Furthermore, the extent to which the trunk and tail of ectothermic tetrapods have similar motor patterns is poorly documented. We therefore recorded the activity of the epaxial muscles in the trunk and tail of sand-swimming Mojave fringe-toed lizards (Uma scoparia) to determine whether this specialized behavior has features of the motor pattern that differ from those of diverse ectothermic vertebrates. Muscle activity during initial sand-swimming was a standing-wave pattern in the trunk and tail. Next, the hind limbs moved alternately and the caudofemoralis muscles and nearby axial muscle in the trunk and tail had similar long-duration electromyographic bursts, whereas the anterior trunk had shorter, more frequent electromyographic bursts. The final tail burial involved a traveling wave of posteriorly propagated axial muscle activity within localized regions of the tail. With increased temperature (from 22 to 40 degrees C), the mean frequencies of axial oscillations increased from approximately 7 to 21 Hz, and the greatest value (33 Hz) was nearly twice the maximal limb cycling frequency during running. The mean burial time at the lowest temperature (3.8 s) was nearly twice that for a 10 degrees C higher temperature. For the axial electromyograms, a decrease in temperature of 18 degrees C more than doubled the electromyographic and cycle durations, whereas the duty factors and intersegmental phase lags changed only slightly with temperature.

Motor patterns of labriform locomotion: kinematic and electromyographic analysis of pectoral fin swimming in the labrid fish Gomphosus varius

1997 ◽  
Vol 200 (13) ◽  
pp. 1881-1893 ◽  
Author(s):  
M Westneat ◽  
J Walker
Keyword(s):  
Muscle Activity ◽  
Motor Pattern ◽  
Onset Time ◽  
Total Body Length ◽  
Adductor Muscle ◽  
Pectoral Fin ◽  
Motor Patterns ◽  
Emg Patterns ◽  
Muscle Groups ◽  
Electromyographic Analysis

Labriform locomotion is a widespread swimming mechanism in fishes during which propulsive forces are generated by oscillating the pectoral fins. We examined the activity of the six major muscles that power the pectoral fin of the bird wrasse Gomphosus varius (Labridae: Perciformes). The muscles studied included the fin abductors (arrector ventralis, abductor superficialis and abductor profundus) and the fin adductors (arrector dorsalis, adductor superficialis and adductor profundus). Our goals were to determine the pattern of muscle activity that drives the fins in abduction and adduction cycles during pectoral fin locomotion, to examine changes in the timing and amplitude of electromyographic (EMG) patterns with increases in swimming speed and to correlate EMG patterns with the kinematics of pectoral fin propulsion. EMG data were recorded from three individuals over a range of swimming speeds from 15 to 70 cm s-1 (1­4.8 TL s-1, where TL is total body length). The basic motor pattern of pectoral propulsion is alternating activity of the antagonist abductor and adductor groups. The downstroke is characterized by activity of the arrector ventralis muscle before the other abductors, whereas the upstroke involves nearly synchronous activity of the three adductors. Most EMG variables (duration, onset time, amplitude and integrated area) showed significant correlations with swimming speeds. However, the timing and duration of muscle activity are relatively constant across speeds when expressed as a fraction of the stride period, which decreases with increased velocity. Synchronous recordings of kinematic data (maximal abduction and adduction) with EMG data revealed that activity in the abductors began after maximal adduction and that activity in the adductors began nearly synchronously with maximal abduction. Thus, the pectoral fin mechanism of G. varius is activated by positive work from both abductor and adductor muscle groups over most of the range of swimming speeds. The adductors produce some negative work only at the highest swimming velocities. We combine information from pectoral fin morphology, swimming kinematics and motor patterns to interpret the musculoskeletal mechanism of pectoral propulsion in labrid fishes.

scholarly journals Roles of Ascending Inhibition During Two Rhythmic Motor Patterns in Xenopus Tadpoles

1998 ◽  
Vol 79 (5) ◽  
pp. 2316-2328 ◽  
Author(s):  
C. S. Green ◽  
S. R. Soffe
Keyword(s):  
Spinal Cord ◽  
Motor Pattern ◽  
Burst Duration ◽  
Major Influence ◽  
Cycle Period ◽  
Detailed Knowledge ◽  
Motor Patterns ◽  
Rhythmic Motor ◽  
Vertebrate Model ◽  
Longitudinal Pattern

Green, C. S. and S. R. Soffe. Roles of ascending inhibition during two rhythmic motor patterns in Xenopus tadpoles. J. Neurophysiol. 79: 2316–2328, 1998. We have investigated the effects of ascending inhibitory pathways on two centrally generated rhythmic motor patterns in a simple vertebrate model, the young Xenopus tadpole. Tadpoles swim when touched, but when grasped respond with slower, stronger struggling movements during which the longitudinal pattern of motor activity is reversed. Surgical spinal cord transection to remove all ascending connections originating caudal to the transection (in tadpoles immobilized in α-bungarotoxin) did not affect “fictive” swimming generated more rostrally. In contrast, cycle period and burst duration both significantly increased during fictive struggling. Increases were progressively larger with more rostral transection. Blocking caudal activity with the anesthetic MS222 (pharmacological transection) produced equivalent but reversible effects. Reducing crossed-ascending inhibition selectively, either by midsagittal spinal cord division or rostral cord hemisection (1-sided transection) mimicked the effects of transection. Like transection, both operations increased cycle period and burst duration during struggling but did not affect swimming. The changes during struggling were larger with more rostral hemisection. Reducing crossed-ascending inhibition by spinal hemisection also increased the rostrocaudal longitudinal delay during swimming, and the caudorostral delay during struggling. Weakening inhibition globally with low concentrations of the glycine antagonist strychnine (10–100 nM) did not alter swimming cycle period, burst duration, or longitudinal delay. However, strychnine at 10–60 nM decreased cycle period during struggling. It also increased burst duration in some cases, although burst duration increased as a proportion of cycle period in all cases. Strychnine reduced longitudinal delay during struggling, making rostral and caudal activity more synchronous. At 100 nM, struggling was totally disrupted. By combining our results with a detailed knowledge of tadpole spinal cord anatomy, we conclude that inhibition mediated by the crossed-ascending axons of characterized, glycinergic, commissural interneurons has a major influence on the struggling motor pattern compared with swimming. We suggest that this difference is a consequence of the larger, reversed longitudinal delay and the extended burst duration during struggling compared with swimming.

Effects of ileal infusions of nutrients on motor patterns of canine small intestine

1990 ◽  
Vol 259 (1) ◽  
pp. G78-G85 ◽  
Author(s):  
M. L. Siegle ◽  
H. R. Schmid ◽  
H. J. Ehrlein
Keyword(s):  
Amino Acids ◽  
Small Intestine ◽  
Gastric Emptying ◽  
Motor Pattern ◽  
Inhibitory Effects ◽  
Contraction Force ◽  
Motor Patterns ◽  
Proximal Small Intestine ◽  
Dose Dependent ◽  
Different Doses

In the present study, effects of ileal infusions of nutrients on motor patterns of the proximal small intestine and on gastric emptying were investigated in dogs. An acaloric meal was administered orally, and equicaloric loads of amino acids, oleate, and glucose were infused into the ileum at different doses (0.3, 0.6, and 0.9 kJ/min). The computerized analysis of motor patterns was focused on the differentiation between stationary and propagated contractions recorded by closely spaced extraluminal strain gauges. All three nutrients exerted inhibitory effects on gastric emptying and on contraction force and frequency of the proximal small intestine. Additionally, the propulsive motor pattern induced by the acaloric meal was modulated by reducing the number of contraction waves and their length of spread. All the effects were dose dependent. Among the three nutrients, glucose significantly changed motility at lower doses compared with amino acids and oleate. We conclude that in dogs the ileal brake mechanism is induced by all three nutrients and that it influences not only contraction force and frequency but also the motor patterns of the proximal small intestine.

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