Longer Limbs Research Articles

Does habitat modification impact morphology, performance, and inflammatory responses in an amphibian with limited dispersal capacity (Lisssotriton helveticus)?

The environment of an organism exerts selective pressures that affect mobility, feeding, reproduction as well as predator-prey and conspecific interactions. Land use changes induced by human activities modify these selective pressures and may result in the adaptation of organisms. Amphibians are ectotherms that typically show a biphasic life cycle with an aquatic and terrestrial phase, which makes them particularly sensitive to environmental change. We studied the impact of habitat modifications on palmate newt populations in the Ile de France region across four types of habitats: urban, mixed, agricultural, and natural with at least two replicates for each habitat type. We measured the morphology of newts using callipers, quantified maximal running and swimming speed and acceleration using high-speed video recordings, and quantified the swelling of the hind limb linked to an inflammatory reaction. Our results show that in urban habitats, newts are larger and heavier and have a better body condition. Females, moreover, have a larger head in natural habitats, possibly due to diet specialisation of females during the breeding season. In mixed and agricultural habitats, newts have longer limbs and show a tendency to run faster, possibly associated with the selective pressures on movement in mixed habitats. Differences in inflammatory responses were observed between sexes but not habitat types. Overall, our results show differences in morphology and trends for differences in performance in newts living in different habitats suggesting that animals are adapting to human-induced changes in their environment.

The Effects of Different Degrees of Leg Length Discrepancy on Vertical Ground Reaction Force in Children and Adults: Treatment Implications.

Previous studies on the degree of leg length discrepancy that causes limb biomechanical problems did not differentiate between adults and children. We conducted this study to determine the effects of simulated leg length discrepancy on vertical ground reaction force in children and adults to enable decision-making for intervention in patients with leg length discrepancy for different age groups or heights. This cross-sectional study involved male volunteers of children 150cm and adults with 170cm in height. Vertical ground reaction force was measured using a gait analysis study. The first measurement was taken without any leg length discrepancy as a baseline. Subsequently, different amounts of leg length discrepancy were simulated on the left leg with shoe lifts of 2, 3, and 4cm. The measurements were repeated on each volunteer with similar shoe lifts on the right leg. Therefore, 14 volunteers provided simulations of 28 leg length discrepancies for each group. The first and second peaks of vertical ground reaction force were separately analysed. The vertical GRF of a simulated leg length discrepancy was compared with the baseline. Repeated measurement of analysis of variance (ANOVA) within each group was done. In both groups, the second peak of vertical ground reaction force in the longer leg reduced gradually as the shoe lift increased sequentially from 2 to 3cm and then to 4cm. A discrepancy of 3cm and above was statistically significant to cause a reduction in the vertical GRF on the longer limb in both height groups. The degree of leg length discrepancy that caused significant changes in second peak ground reaction force in children with 150 and adults with 170cm height population was similar at 3cm. Therefore, the cut-off point for intervention for both groups are similar with additional consideration of future growth in children.

Sexual shape dimorphism in Bufo verrucosissimus (Pallas, 1814) from Lake Borçka Karagöl, Türkiye

Sexual dimorphism, i.e., differences in morphology between sexes of a species caused by intersexual differences in the strength or direction of sexual or natural selection, is prevalent throughout the animal kingdom. Contrary to differences in body size, little is known about sexual shape dimorphism in anurans. Here we investigated intersexual shape differences in Bufo verrucosissimus (Pallas, 1814) by taking 27 linear measurements to characterize body morphology of 23 males and 23 females. Relative to their overall body size, males had longer limbs and larger eyes, while females displayed larger parotoid glands and had wider heads. We speculate that these intersexual differences may have arisen due to differences in natural and sexual selection regimes acting on males and females, especially during foraging, mate searching, or intrasexual competition.

44 Detecting conformational differences in Fragile Foal Syndrome carriers utilizing artificial intelligence

Conformation traits impact gait and performance, and as a result vary based on intended use of the horse. For example, a horse with longer legs can cover a greater distance per stride than one with shorter legs. Limb length, therefore, is advantageous for horses expected to travel long distances for extended periods of time but may not be for those who go short distances at top speeds. Fragile Foal Syndrome (FFS) in horses results from a sequence change in PLOD1, the same gene that causes Ehlers Danlos Syndrome type IV (EDS-IV) in humans, a condition that results in longer limbs. Based on the phenotype observed in EDS, we hypothesize that FFS in the carrier state may impact extremity length including the neck, forelimbs, and hindlimbs in horses. To measure conformation parameters, we first digitally labeled specific anatomical points on a video recording of a trotting horse using the software package DeepLabCut (DLC). Representative frames for each horse at the same point within the stride were extracted from the video. The X, Y coordinates of each anatomical label were used to quantify conformation geometry. Frame extraction was done with a custom designed graphical interface that ensured the user could identify the ideal frame matching an identical body position across all horses examined. X,Y coordinate output files were thenanalyzed with a custom gait parameter pipeline written in MatLab to calculate the neck, forelimb, and hindlimb length. Each measurement was scaled to account for the varying distance horses were from the camera. Pulled tail hair was utilized to extract DNA and genotype each horse using PCR-RFLP, then followed by Sanger Sequencing for confirmation. Conformational measures were compared between genotype categories (wild type vs, carrier) in JMP Pro. Preliminary results showed that FFS carriers (n = 7) had significantly longer forelimb (P = 0.0344, t-test), hindlimb (P = 0.0258, t-test), and neck (P = 0.0013, t-test) lengths compared with wild type horses (n = 7). Future work will increase the overall sample size and number of frames captured per individual to increase statistical power and allow investigation of more conformation traits including static joint angles and back lengths. Improved understanding of conformational phenotypes that may result from the FFS carrier genotype will inform future studies of equine physiology and connective tissue disorders, leading to better decision making for breeding, sales and training, and preventing injury and loss of foals to this disease.

Characterizing lift, drag, and pressure differences across wandering salamanders (Aneides vagrans) with computational fluid dynamics to investigate aerodynamics.

Wandering salamanders (Aneides vagrans), known to occupy the crowns of old growth coast redwood trees, have recently been found to decelerate and engage in controlled, nonvertical descent while falling. Closely related, nonarboreal species with seemingly minor morphological differences exhibit far less behavioral control while falling; however, the influence of salamander morphology on aerodynamics remains to be tested. Here, we examine differences in morphology and aerodynamics of two salamander species, A. vagrans and the nonarboreal ensatina salamander (Ensatina eschscholtzii), using a combination of traditional and contemporary techniques. Specifically, we compare morphometrics statistically, then use computational fluid dynamics (CFD) to characterize predicted airflow and pressure over digitally reconstructed models of the salamanders. While similar in body and tail lengths, A. vagrans are more dorsoventrally flattened with longer limbs and greater surface area of the foot relative to body size than the nonarboreal E. eschscholtzii. CFD results show dorsoventral pressure gradients differ between the two digitally reconstructed salamanders resulting in lift coefficients of approximately 0.02 and 0.00, and lift:drag ratios of approximately 0.40 and 0.00 for A. vagrans and E. eschscholtzii, respectively. We conclude that the morphology of A. vagrans is better suited for controlled descent than that of the closely related E. eschscholtzii and highlight the importance of subtle morphological features, such as dorsoventral flatness, foot size, and limb length, for aerial control. That our simulation reports align with real-world performance data underscores the benefits of CFD for studying the link between morphology and aerodynamics in other taxa.

A New Species of Small Green Treefrog (Pelodryadidae: Litoria) from the Lakekamu Basin in Southern Papua New Guinea

We describe a new species of very small (male body length 22.0–22.8 mm), green treefrog in the pelodryadid genus Litoria Tschudi from lowland rainforest on the southern margin of Papua New Guinea's central cordillera. The new species is morphologically most similar to Litoria leucova, a small green treefrog known only from the north-flowing Sepik River catchment in western Papua New Guinea. It differs from that species by having longer limbs (TL/SVL 0.56–0.60 vs. 0.53–0.55), a poorly defined (vs. prominent) tympanum, in having a distinct lemon yellow mid-lateral line, and in its unique advertisement call comprising a slowly repeated series of short clicks followed by a discrete group of pulses produced rapidly but with highly variable inter-pulse intervals. Although genetic data are not available, the new species' association with a fast-flowing rocky stream suggests that its relationships may lie with other torrent-dwelling Litoria species.

Living apart together: Morphological, spatial, and genetic differentiation of three sympatric rock lizard species (Lacertidae: Darevskia) of the Caucasus

Three rock lizard species (genus Darevskia) occur in the same mountain gorge of the Greater Caucasus mountains located in Northern Georgia. Whereas Darevskia caucasica and Darevskia derjugini belong to the same phylogenetic clade known as “caucasica”, Darevskia rudis is associated to the “rudis” clade. The mountain lizards differed interspecifically in their scalation and ventral colouration patterns, but the body proportions of D. caucasica and D. rudis were more similar to each other than to D. derjugini as both had flatter heads and longer limbs than D. derjugini. Females of all three species had longer trunks and shorter limbs than males. We hypothesized that hybrids occur more likely between D. derjugini and D. caucasica rather than between species belonging to different clades. However our analysis of microsatellite genotyping clearly revealed no traces of hybridisation and/or gene flow among any of the coexisting lizard species. The absence of individuals with intermediate morphological and genetic features reflects the presence of strong reproductive barriers at the prezygotic level.

Interspecific competition in ictitheres (Carnivora: Hyaenidae) from the Late Miocene of Eurasia

The present paper deals with the ecomorphological characteristics of two sympatric species of ictitheres: Ictitherium viverrinum Roth & Wagner, 1854 and Hyaenictitherium wongii (Zdansky, 1924) from the Late Miocene of the Eastern Mediterranean. These two species represent different taxonomic groups with allegedly distinct ecological roles. The values of 11 ecomorphological proxies were calculated using cranial and dental elements, in order to make an extensive comparison between them (body mass, bite force, canines’ and incisors’ bending strength, endocranial volume, relative rostral width, dental mesowear, intercuspid notches and carnassial vs grinding surfaces). The proxies show similar results for both species, pointing out that they had a similar ecological niche in the Late Miocene ecosystems. Carnivorans are usually in the top of the food chain, so the existence of two ecologically similar species in the same spatiotemporal range results in interspecific competition. This explains the geographical distinction of the two species with several localities being dominated by only one of the two (e.g. Samos for Hyaenictitherium Kretzoi, 1938 and Pikermi for Ictitherium Wagner, 1848). The reason for the prevalence of each genus can be associated with their postcranial morphology, as Hyaenictitherium has been proposed to be better adapted to chase hunting, because of its longer limbs, while Ictitherium is characterized by shorter and stouter limbs.

Predictors of geographic range size in Australian skinks

AbstractAimGeographic range size varies greatly across species. Climate, along with aspects of a species’ biology, may influence its spatial extent. We investigate intrinsic and extrinsic predictors of range size in Australian skinks. We predicted that larger body size, longer limbs, and larger clutch sizes would be associated with larger ranges, and that ranges would be larger in colder, more arid, and more seasonal climates.LocationMainland Australia.TaxonSkinks (Scincidae).MethodsWe test for climatic and geographic correlates of range size of Australian skink species (417 of 462 described species), as well as investigate the effects of body size and clutch size (259 species). We compare detailed morphological measurements of 1,324 specimens across nine pairs of widespread and narrow‐ranged congeneric species to investigate the roles of intrinsic (body size, clutch size, morphology) and extrinsic (mean temperature and precipitation) factors in determining range size.ResultsIn the broader analysis, large range sizes were associated with the presence of fully developed limbs, low precipitation seasonality, high temperatures, and high precipitation. Ranges of species traversing the Great Dividing Range are larger by an order of magnitude than those east of the range, with western ranges being intermediate. Affinity to specific biomes explained less variation than climatic variables. For the nine species pairs, wide‐ranging species share similar morphologies and clutch sizes with overlapping narrow‐ranging congeners, but generally inhabit more arid regions.Main conclusionsWe found several extrinsic, but few intrinsic, factors were correlated with range size. The narrow mesic belts in Australia compared with the extensive expanse of arid and semi‐arid regions may explain why desert species have larger ranges. This interpretation agrees with the notion that the size of the domain, here a climatic domain rather than a physical one, may exert strong influence on species’ range sizes.

The Effect of Simulated Leg-Length Discrepancy on the Dynamic Parameters of the Feet during Gait-Cross-Sectional Research.

Background: The effect of Leg-Length Discrepancy (LLD) on dynamic gait parameters has been extensively discussed. Podobarography is the study of foot-to-ground pressure distribution. It has been used to test plantar footprint deviations that could reveal pathology. Purpose: The aim of this study is to determine the effects of simulated LLD on dynamic gait parameters measured with a pressure platform in healthy subjects. Methods: Thirty-seven healthy subjects participated in observational cross-sectional research. A procedure was performed to capture the dynamic parameters of each participant under five different simulated LLD conditions. Support time, mean pressure, and peak pressure measures were registered on three trials for each foot and LLD level per session. An analysis of variance (ANOVA) test for repeated measures was performed to check for differences between the different simulated LLD levels. Results: The stance time of the short leg had no significant changes. The stance time of the long leg increased by 3.51% (p < 0.001), mean pressure of the short leg increased by 1.23% (p = 0.005), and decreased by 5.89% in the long leg (p < 0.001). Peak pressure of the short leg decreased by 2.58% (p = 0.031) and the long leg decreased by 12.11% (p < 0.001). Conclusions: This study demonstrates that increasing LLD causes an asymmetrical foot-loading pattern, with decreased mean and peak pressure on the longer limb, and consequently an overload on the short side. Furthermore, an increasing LLD causes increased stance time on the long leg.

Reproduction, sexual dimorphism and predation in Mochlus sundevallii in southern Africa (Reptilia: Sauria, Scincidae)

The skink Mochlus sundevallii is widespread throughout the African continent, but no detailed research on its ecology, reproduction and sexual dimorphism patterns has been performed yet. Here we address phenotypic and ecological data of M. sundevallii from the southernmost part of its distribution, using multiple populations from Southern Africa (mostly from South Africa) collected throughout different seasons. We aimed to assess the degree of intersexual and seasonal differences in morphological and reproductive aspects, as well as their experienced predation pressure. Morphological analyses confirmed that the species exhibits sexual dimorphism, evidenced by a larger body size for females and larger heads and longer limbs for males. However, tail autotomy (used as an estimation of predation rate) was found to be similar for both sexes and seasonally stable. Overall, the reproductive cycles of males and females were synchronised across the seasons, for an optimal breeding period during spring and summer, but males showed certain spermatogenic activity throughout the whole year.

Limb length in bariatric surgery of Roux-en-Y gastric bypass (RYGB): An integrative review

Introduction: Roux-en-Y gastric bypass is considered the gold standard surgical technique for obesity. The variation in limb length may be related to metabolic improvement and nutritional deficiencies. However, the ideal measurement still a controversial subject in the literature. This study aims to perform an integrative literature review and associate the optimal limb length, considering the maximum weight loss with the minimum nutritional complications. Methods: Integrative literature review conducted using electronic searches (1992 - 2020) in databases MEDLINE/Pubmed and BVS (Biblioteca Virtual da Saúde)/LILACS, through the terms "(bariatric surgery) AND (limb length)". A total of 340 articles were found, 26 articles were included in this review. Results: Current evidence supports using shorter limb lengths in patients with BMI &lt; 50 kg/m2, and longer limbs in patients with severe type 2 diabetes mellitus and/or dyslipidemia or superobese patients (BMI &gt;= 50 kg/m2), considering the benefits in comorbidities resolution. A shorter common limb increases the incidence of nutritional disorders. There is a wide variation in jejunoileal length among patients. Conclusion: Measuring the intraoperative jejunoileal length and individualizing the surgery may bring benefits in weight loss, comorbidities resolution, and reduce the incidence of nutritional disorders. However, more randomized controlled trials are needed on this topic.

A New Species of Blue-Tailed Skink (Scincidae: Plestiodon) from the Sierra Madre del Sur, Mexico

Recent studies on the systematics and phylogeny of the blue-tailed skinks in the Plestiodon brevirostris group identified a population from the Sierra Madre del Sur of eastern Guerrero, Mexico, that appeared to represent an undescribed species. Here, we formally describe this lineage as a new species, compare it with the other species in the P. brevirostris group, identify a specimen from western Oaxaca that belongs to the new species, and provide an updated key to the group. The new species is morphologically similar and closely related to P. ochoterenae, but molecular and morphological data support its evolutionary independence. The new species is distinguished from the other species in the P. brevirostris group, except for P. ochoterenae, by the presence of a primary temporal, a well-defined lateral pale line on the neck, and a well-defined dorsolateral pale line that extends posteriorly to the level of the hind limbs. It differs from P. ochoterenae by having longer limbs and a well-defined lateral pale line on the neck. The present study further highlights the relevance of the Sierra Madre del Sur as a hotspot of endemism and undescribed diversity.

Inertial measurement units for the detection of the effects of simulated leg length inequalities

BackgroundLeg length inequalities (LLI) are a common condition that can be associated with detrimental effects like low back pain and osteoarthritis. Inertial measurement units (IMUs) offer the chance to analyze daily activities outside a laboratory. Analyzing the kinematic effects of (simulated) LLI on the musculoskeletal apparatus using IMUs will show their potentiality to improve the comprehension of LLI.MethodsTwenty healthy participants with simulated LLI of 0-4 cm were analyzed while walking with an inertial sensor system (MyoMotion). Statistical evaluation of the peak anatomical angles of the spine and legs were performed using repeated measurement (RM) ANOVA or their non-parametric test versions (Friedman test).ResultsLumbar lateral flexion and pelvic obliquity increased during the stance phase of the elongated leg and decreased during its swing phase. The longer limb was functionally shortened by higher hip and knee flexion, higher hip adduction, dorsiflexion, and lower ankle adduction. Finally, the shorter leg was lengthened by higher hip and knee extension, hip abduction, ankle plantarflexion, and decreased hip adduction.ConclusionWe found differing compensation strategies between the different joints, movement planes, gait phases, and amounts of inequality. Overall the shorter leg is lengthened and the longer leg is shortened during walking, to retain the upright posture of the trunk. IMUs were helpful and precise in the detection of anatomical joint angles and for the analysis of the effects of LLI.

Big City Living: A Global Meta-Analysis Reveals Positive Impact of Urbanization on Body Size in Lizards

Urban environments pose different selective pressures than natural ones, leading to changes in animal behavior, physiology, and morphology. Understanding how animals respond to urbanization could inform the management of urban habitats. Non-avian reptiles have important roles in ecosystems worldwide, yet their responses to urbanization have not been as comprehensively studied as those of mammals and birds. However, unlike mammals and birds, most reptiles cannot easily move away from disturbances, making the selective pressure to adapt to urban environments especially strong. In recent years, there has been a surge in research on the responses of lizards to urbanization, yet no formal synthesis has determined what makes an urban lizard, in other words, which phenotypic traits are most likely to change with urbanization and in which direction? Here, we present a qualitative synthesis of the literature and a quantitative phylogenetic meta-analysis comparing phenotypic traits between urban and non-urban lizard populations. The most robust finding from our analysis is that urban lizards are larger than their non-urban counterparts. This result remained consistent between sexes and taxonomic groups. Hence, lizards that pass through the urban filter have access to better resources, more time for foraging, and/or there is selection on attaining a larger body size. Other results included an increase in the diameters of perches used and longer limb and digit lengths, although this may be a result of increased body size. Urban lizards were not bolder, more active or exploratory, and did not differ in immune responses than non-urban populations. Overall, studies are biased to a few geographic regions and taxa. More than 70% of all data came from three species of anoles in the family Dactyloidae, making it difficult to generalize patterns to other clades. Thus, more studies are needed across multiple taxa and habitats to produce meaningful predictions that could help inform conservation and management of urban ecological communities.

Inter-limb difference of mechanical work in limb length discrepancy

BackgroundLimb length discrepancy (LLD) is common and is associated with musculoskeletal disorders. Selection of adaptation strategies, the side more susceptible to complications, and the relationships between LLD magnitude and musculoskeletal complications are unclear. To elucidate these ambiguities, studies on gait parameters in LLD have been conducted. However, studies on inter-limb difference of mechanical work in LLD are rare. Research QuestionTo investigate whether inter-limb differences in mechanical work in LLD and the relationship between LLD magnitude and mechanical work performed by each lower limb are significant. MethodsThirty-seven participants with LLD and without neuromuscular disorders disturbing normal gait were included. Three-dimensional motion analysis was conducted to obtain data on mechanical work, including joint work and the individual limb method (ILM) work. Mechanical work performed by the longer and shorter limbs was compared using paired t-test. Relationships between LLD and mechanical work were investigated using correlation and multiple regression analyses in both limbs. Eighteen participants had LLD > 20 mm, large group (LG), and 19 had LLD < 20 mm, small group (SG). Data exploration was conducted for the effect of LLD severity (LG vs. SG) on mechanical work. ResultsLLD showed significant inter-limb difference of mechanical work and negative correlations with positive and negative ILM work performed by the shorter limb. The shorter limb in SG performed significantly larger positive ILM work than the longer limb, whereas the longer limb in LG performed significantly larger negative ILM work than the shorter limb. SignificanceLLD showed inter-limb difference of ILM work and different adaptation strategies between LG and SG. These differences attribute to the decrease in ILM work performed by the shorter limb with the increase in LLD. Mechanical work including ILM work should be included in future studies to prevent complications and development of treatment methods for LLD.

Shrinking into the big city: influence of genetic and environmental factors on urban dragon lizard morphology and performance capacity

Urban wildlife faces a novel set of challenges resulting in selective pressure that can lead to population-level changes. We studied Australian water dragons (Intellagama lesueurii) from urban and natural populations to test if urban populations differed in body size, shape, and performance capacity. If urban-derived morphology has arisen through selection, we predicted distinct morphological differences between wild dragons from urban and natural areas in both adult and hatchling life-stages. Urban hatchlings were morphologically distinct (shorter body lengths and longer limbs) from natural populations, while urban adult males continued this trend but only for body size (shorter body lengths). We then experimentally reared hatchlings originating from urban and natural populations within urban- and natural-style enclosures (2 × 2 factorial design) for a year to determine if differences in morphology and performance capacity (sprint speed, endurance, and clinging ability) were related to either the individual’s origin population or developmental environment. Yearlings reared in urban-style enclosures, irrespective of population origin, had smaller body sizes compared to those from natural-style enclosures, suggesting developmental environment was affecting their morphology. Despite this difference in body size, yearling dragon performance capacity was not significantly different between treatments. Overall, this study provides evidence of a complex relationship driving urban-divergent morphology – whereby urban dragons emerge as smaller hatchlings with longer limbs (innate traits) and are then further influenced by the urban environments that they develop in (phenotypic plasticity); however, and potentially owing to behavioral, ecological, and demographical differences, these changes appear to be sex-specific.

Comparison of Anatomical and Blood Biochemical Parameters of Iranian Racing and Dual-Purpose Camels (Camelus dromedarius)

BACKGROUND: Animal breeds are often recognized through their specific characteristics, nevertheless, the breeds' anatomical and biochemical characteristics have not considered yet in many of the researches done on one-humped camels. There are some particular differences in camel breeds due to different climate conditions and rearing necessity. OBJECTIVES: The aim of the current study was to compare differences in anatomical and plasma biochem- ical parameters of two Iranian one-humped camels, the Jammaz (racing) and Balouchi (dual-purpose) breeds. METHODS: Anatomical parameters were body length (BL), neck length (NL), chest girth (CG), barrel girth (BG), hump circumference (HC), fore limb length (FLL), hind limb length (HLL), height at hump (HH), fore limbs interval (FLI), hind limbs interval (HLI), fore hoof circumference (FHC), hind hoof circumference (HHC), abdominal circumference (AC), shank circumference (SC) and leg circumference (LC). Moreover, concentra- tions of Glucose, blood urea nitrogen (BUN), creatinine, cholesterol, total bilirubin (Bili-T), direct bilirubin (Bi- li-D), calcium (Ca), phosphorus (P), magnesium (Mg), aspartate aminotransferase (AST), creatine kinase (CK), lactate dehydrogenase (LDH), total protein (TP), albumin (Alb), triiodothyronine (T3) and thyroxine (T4) were measured as plasma biochemical parameters. Data analysis was conducted through t-test statistics. RESULTS: Results revealed significant differences between body type traits of breeds, especially in organs related to running ability, while the Jammaz breed has more height and longer limbs than the Balouchi breed. Some blood parameters (glucose, LDH, BUN, cortisol and T4) are considerably higher in Jammaz breed, too. CONCLUSIONS: Results of the current study suggest some anatomical (especially fore and hind limb lengths, neck length and body height at hump) and physiological characteristics (lactate dehydrogenase, blood urea nitrogen, cortisol, glucose and T4) of Iranian racing and dual purpose camels as breed markers.

The youngest known Dictyodora from the Late Permian(Lopingian) deep sea in West Qinling, central China

Dictyodora has been generally considered an ichnogenus with a restricted temporal range from the Cambrian to the Mississippian. Until now, there have been no reports of Dictyodora after the Mississippian. Here we report on well-preserved and abundant Dictyodora from deep-sea sediments of the Lopingian Maomaolong Formation in West Qinling, central China, which is hitherto the youngest occurrence of Dictyodora and extends the stratigraphic range of Dictyodora to the Late Permian. Two ichnospecies of Dictyodora are distinguished: D. zimmermanni and D. cf. scotica. Unlike the small-sized Dictyodora in the pre-Pennsylvanian, the three-dimensional morphology of Dictyodora studied here shows larger amplitudes and longer limbs with clearly inclined walls and basal burrows, which are interpreted to have been made by a soft-bodied worm-like organism with a snorkel-like organ as similarly documented in previous studies. Detailed systematic ichnological features and SEM and EDS results indicate that Dictyodora here is not simply a respiration structure made during the locomotion of the trace maker, but resulted from active filling by the trace maker. Dictyodora is probably not a good indicator of the deep-marine environment in the Paleozoic. From our dataset, Dictyodora originated from the shallow-marine environment in the early Cambrian, then migrated into the deep sea in the Ordovician and the marginal-marine setting in the Wenlock, and was finally restricted to the deep-marine environment in the Carboniferous and Permian. Both Psammichnites and Dictyodora are structures made by organisms with snorkel-like organs, and both were eliminated during the end-Permian mass extinction.

Acoustic and morphological variation on two populations of Dryophytes arenicolor in central México

ABSTRACT Contrasting conditions of different habitats lead to geographic variation among populations of the same species. In widespread species, trait divergence represents a response to spatial variation in local habitat conditions and biotic interactions. Morphology and call characteristics are crucial for anuran fitness because of their direct impacts on survival and reproduction. Our aim was to analyse and compare morphological and call characteristics of two populations of Dryophytes arenicolor in central Mexico where waterbody types and presence of other species (D. eximius) differed. We measured morphological characteristics, estimated the sex ratio, and characterised the advertisement calls for each population. We found that the sex ratio differed among populations: in one population, the sex ratio was male-biased. No morphological variation was detected between populations; however, females had longer limbs and higher mass. We found differences in call characteristics among populations and even among individuals of the same population. There was an effect of calling context (solitary or chorus) on call characteristics, we found that calls from conspecifics led to an increase in values of spectral characteristics and reduction of temporal ones, whereas calls from D. eximius resulted in a decrease in values of spectral characteristics and increase in temporal ones.