Pelvic Spine Research Articles

Differences in spinal axial rotation angles during the lumbar-locked rotation test between hyper and normal thoracic rotation groups: A cross-sectional study.

Trunk rotation is important in many sporting activities The thoracic spine has reciprocal relationships with the lumbar and pelvic spines, such that reduced flexibility in the lumbar or thoracic spine can lead to abnormal patterns of trunk movement and pain. However, few studies have investigated the relative trunk rotation mobilities of the thorax, lumbar, and pelvis. To compare thoracic, lumbar, and pelvic rotation angles during the lumbar-locked rotation test between hyper and normal thoracic rotation groups. Thirty-two young, active participants were enrolled in this study. After the attachment of inertial measurement units at the T1, T7, T12, L3, and S2 levels, the participants were required to stand in a comfortable upright posture for 5s to allow postural measurements before performing the lumbar-locked rotation test. The participants were then divided into hyper thoracic rotation and normal thoracic rotation groups based on T1 angle measurements obtained during the lumbar-locked rotation test. The hyper thoracic rotation group had significantly higher thoracic rotation angles on both the right (p< 0.05) and left (p< 0.05) sides compared with the normal thoracic rotation group. Furthermore, we observed flat lumbar lordosis in the hyper thoracic rotation group compared with the normal thoracic rotation group, particularly in the lower lumbar region in standing posture. Our data suggest that evaluations of thoracic mobility should consider relative thoracic, lumbar, and pelvic motions, rather than the T1 angle alone. This study provides a basis for health professionals to evaluate movement dysfunctions associated with thoracic hypermobility.

Use of Fin Rays and Fin Spines in Nonlethal Age Estimation of Florida Bass

Abstract Nonlethal age-estimation methods for Florida Bass Micropterus salmoides using fin rays and spines would enhance trophy-bass research, management, and conservation. Nonlethal removal of fin structures would also expand opportunities for collecting age-related information, specifically during small-population projects as well as tournaments and citizen-science programs, for which sacrificing fish is not an option. We assessed the bias of age estimates derived from Florida Bass anal-, pelvic-, dorsal-, and pectoral-fin rays and anal-, pelvic-, and dorsal-fin spines by comparing them to age estimates derived from otoliths (i.e., sagittae), which are the standard for ageing Florida Bass. We evaluated the precision of age estimates by calculating the absolute difference between replicate reads of each ageing structure for each reader. Linear-mixed effects model selection indicated that precision was most affected by age, structure, and the age*structure interaction, in which the effect of age varied by structure. Age estimates from otoliths were the most precise whereas pelvic spines were the least precise among all structures examined. Bias was similar across all fin structures, but the effect of age on bias varied by reader. Marginal increment analysis indicated that annulus formation was completed from November to March in Florida Bass dorsal spines, 5 months earlier than in Florida Bass otoliths. Our results suggest that nonlethally removed fin structures, especially dorsal spines, have potential for use in estimating age, growth rates, mortality, and age structure of bass populations, which could be particularly beneficial where bass can reach unusual trophy sizes.

Bio-inspired unpowered ankle exoskeleton and its correlation to pelvic list

The goal of this paper is to design and test an unmotorized ankle exoskeleton inspired by chimpanzees. The desired result is pronounced pelvic list movement more akin to that of a chimpanzee, increasing hip muscle activation. We believe that the combined stiffness of the ankle and midfoot could play a major role in regulating pelvic stiffness. An adjustable system using lead screws is used in the design of the unpowered ankle exoskeleton. Analysis is performed on the videos of the individuals walking with three different stiffness variations: normal, minimal, and maximum. Pelvic list movement and box plots with an IQR of 8.43, a range of 16.25, and a standard deviation of 4.75 suggested approximately 49.4% variation from usual walking without a device. We found evidence for our hypothesis that the chimpanzee-inspired design combining stiffness of the ankle and midfoot would influence the pelvic spine.

Morphological features and length-weight relationships of &lt;i&gt;Sarotherodon galilaeus&lt;/i&gt; from Oyan Lake, Southwestern Nigeria

Oyan Lake is one of the major sources of fish protein supply to many parts of Southwestern Nigeria. Investigation was conducted on the biometrics, length-weight relationship and condition factor of Sarotherodon galilaeus in Oyan Lake. Fish samples were obtained from fishermen using gillnets, hook and line, cast nets and traps. One hundred and thirty samples of S. galilaeus were collected for the study, comprising eighty-three (83) males and forty-seven (47) females with sex ratio of 1:0.57 (male:female). The mean total lengths for combined sexes, males and females were 15.5±0.15, 15.7±0.19 and 15.3±0.26cm while the mean total weights were 81.0±2.78, 83.8±0.56 and 75.9±4.70g, respectively. No significant difference (p&gt;0.05) was observed between mean total lengths of males and females. However, mean weight of males was significantly higher (p&lt;0.05) than females. Mean eye diameter (EYD) and length of caudal peduncle (LCP) were significantly higher (p&lt;0.05) in females. The range of number of pectoral rays (PRA) (12-14), number of pelvic rays (PVR) (4-5), number of anal spines (ANS) (2-3) and number of pelvic spines (PEVS) (1, no range) were the same in both sexes. There was strong correlation between weight/total length (r=0.93) and total length/length of dorsal fin base (r=0.72), while there was no correlation between body depth/head length. The mean condition factor (k) were 2.07±0.02 (combined sexes), 2.08±0.03 (males) and 2.03±0.03 (females). Growth was isometric for both sexes: males, 3.24 and females, 3.06. The results suggested that Oyan Lake is suitable for S. galilaeus.

Pelvic spine reduction affects diet but not gill raker morphology in two polymorphic brook stickleback (Culaea inconstans) populations.

Pelvic spine polymorphism occurs in several species in the stickleback family (Gasterosteidae). Given the similar phenotypic polymorphisms in multiple stickleback species, we sought to determine the extent of parallelism in the ecological correlates of pelvic spine reduction. Based on a metabarcoding analysis of brook stickleback gut contents in two polymorphic populations, we found that significant diet differences were associated with pelvic spine reduction, but we found no clear or consistent trend supporting a tendency for benthic feeding in pelvic-reduced brook sticklebacks. These results contrast with those found in threespine sticklebacks where pelvic spine reduction is often associated with a benthic diet. Hence, we found non-parallel consequences of spine polymorphism across species. Furthermore, a difference in gill raker morphology has been frequently observed between ecomorphs with different diets in many fish species. However, we found no evidence of any difference in gill raker morphology associated with pelvic spine polymorphism in brook sticklebacks.

Impact of COVID-19 on Fracture Incidence in Germany: A Comparative Age and Gender Analysis of Pre- and Post-Outbreak Periods.

In March 2020, Germany imposed a nationwide lockdown to curb the spread of COVID-19, prompting questions about the impact on the incidence of common fractures. This study examined 15 fracture types in pre-outbreak (2010-2019) and post-outbreak (2020-2021) periods, using data categorized by age (18-64 years, >65 years) and sex (male, female). Linear regression assessed annual growth rates, and mean fracture numbers were compared across periods for significant differences. Results indicated a positive correlation between fracture incidence rates and time for various types, such as cervical, thoracic, lumbar, and pelvic spine fractures, rib fractures, femoral neck, pertrochanteric femur, femoral shaft, and ankle fractures. Frequencies of proximal humerus, distal radius, femoral neck, pertrochanteric femur, femoral shaft, and ankle fractures in 2020 and 2021 were within predicted ranges from previous years. However, rib fractures and spinal fractures (cervical, thoracic, lumbar, and pelvic spine) occurred less frequently during this time. Notably, this study found a consistent decline in most fracture types for individuals aged 18-64 after the pandemic's onset, while the fracture incidence of hip fractures, often referred to as fragility fractures, for those over 65 remained unchanged. Fibula fractures showed the most considerable decrease in both age groups. In conclusion, the COVID-19 pandemic substantially impacted fracture incidence, with lower rates among individuals under 65 and unchanged fragility fractures in the elderly population.

A new gyracanthid from the Mississippian of Delta, Iowa, U.S.A.

ABSTRACT A new gyracanthid, Gyracanthus? jasperi, is described based on partially articulated and isolated elements from the Lower Carboniferous (Mississippian) lower Waugh Member of the Ste Genevieve Formation, at the early tetrapod site near Delta, Iowa, U.S.A. Pectoral fin spines of the new gyracanthid are characterized by the insertion on the fin spine being a half to one-third the length of the spine and maximum length:depth ratio 10:1. Ornament ridges on the pectoral fin spine converge at ≥90° along a low leading edge ridge, and ridge tubercles are oriented oblique to the ridge; the distal end of one pectoral is described using micro-computed tomography. The scapulocoracoids have an anteriorly curving bulbous apex, and a base length that is 35–40% of pectoral spine length. The procoracoid is associated with an unornamented ventral plate. A possible isolated dorsal fin spine is more symmetrical and less worn than the pectoral fin spines. Pelvic spines are dorsoventrally flattened, with oblique ridges meeting at approximately 100° proximally and 80° distally, along a smooth leading edge ridge. Scales, found on the partial articulated specimen and as isolated remains, are polyodontode with a flat base. Adults of the new taxon are estimated to have been about one meter long. Deposition was in debris flows, within a sinkhole lake most likely removed from the edge of the ocean. Other Carboniferous gyracanthids from North America are reviewed. http://zoobank.org/urn:lsid:zoobank.org:pub:5C26F98A-E630-4FD6-99A5-F08B5CBB1549

Pitx1 Enhancer Variants in Spined and Spine-Reduced Subarctic European Sticklebacks

Loss of body armour, sometimes including a reduction in or loss of pelvic spines, is an adaptation observed in many isolated freshwater populations. Pelvic reduction in sticklebacks has previously been associated with recurrent, but variant, deletions within pelvic enhancer regions PelA and PelB, which regulate expression of the homeodomain transcription factor gene Pitx1. We investigated variation in nucleotide sequences of pelvic enhancers in sticklebacks collected from two small freshwater lakes in the same watercourse and a nearby marine site in subarctic Norway. Spineless, as well as asymmetrically spined and completely spined sticklebacks are present in the upper lake, while only specimens with complete spines are found at the other lake and the marine site. Observed variation at PelA between the three sites was mainly due to variable numbers of repeats at three fragile TG-repeat loci. The length of PelA, mainly at one of the TG-repeat loci, was consistently shorter among individuals in the upper lake compared with specimens from the two other sites. However, no obvious association was revealed between enhancer variants and pelvic status. No polymorphism was found at PelB. Thus, additional genetic factors and/or environmental cues need to be identified to fully explain the occurrence of pelvic reduction in sticklebacks in this lake.

Genome-phenotype-environment associations identify signatures of selection in a panmictic population of threespine stickleback.

Adaptive genetic divergence occurs when selection imposed by the environment causes the genomic component of the phenotype to differentiate. However, genomic signatures of natural selection are usually identified without information on which trait is responding to selection by which selective agent(s). Here, we integrate whole-genome sequencing with phenomics and measures of putative selective agents to assess the extent of adaptive divergence in threespine stickleback occupying the highly heterogeneous lake Mývatn, NE Iceland. We find negligible genome wide divergence, yet multiple traits (body size, gill raker structure and defence traits) were divergent along known ecological gradients (temperature, predatory bird densities and water depth). SNP based heritability of all measured traits was high (h2 =0.42-0.65), indicating adaptive potential for all traits. Environment-association analyses further identified thousands of loci putatively involved in selection, related to genes linked to, for instance, neuron development and protein phosphorylation. Finally, we found that loci linked to water depth were concurrently associated with pelvic spine length variation - supporting the conclusion that divergence in pelvic spine length occurred in the face of gene flow. Our results suggest that whilst there is substantial genetic variation in the traits measured, phenotypic divergence of Mývatn stickleback is mostly weakly associated with environmental gradients, potentially as a result of substantial gene flow. Our study illustrates the value of integrative studies that combine genomic assays of multivariate trait variation with landscape genomics.

Evaluating Dermal Bone as a Novel Source of Endocrine Information in Ninespine and Threespine Stickleback Fish.

Monitoring the physiology of small aquatic and marine teleost fish presents challenges. Blood samples, often the first choice for endocrinologists, can be difficult or even impossible to obtain and alternative matrices currently used for hormone analyses do not occur in fishes (e.g., hair, feathers etc.) or are not easily collected from small aquatic organisms (e.g., urine and feces). Some teleosts, however, have enlarged bony dermal elements that possibly accumulate and store steroid hormones in physiological relevant concentrations. Both threespine stickleback (Gasterosteus aculeatus) and ninespine stickleback (Pungitius pungitius) have a series of external, lateral bony plates, dorsal spines, and a pair of pelvic spines attached to the pelvic girdle. We investigated if cortisol, the primary circulating glucocorticoid in teleosts, could be extracted from stickleback dermal bone and quantified using a commercially available enzyme immunoassay (EIA). We successfully validated a cortisol EIA for dermal bone extracts, determined that cortisol was detectable in both species, and found that dermal bone cortisol levels significantly correlated with cortisol levels in whole body homogenate. Ninespine stickleback had significantly higher dermal bone cortisol concentrations than threespine stickleback and female threespine stickleback tended to have over twice the mean dermal bone cortisol concentration than males. Because both stickleback species are widely used for ecotoxicological studies, using dermal bone as a source of endocrine information, while leaving the body for contaminant, genomic, histological, and stable isotope analyses, could be a powerful and parsimonious tool. Further investigation and physiological validations are necessary to fully understand the utility of this new sample matrix.

Mature teratoma presenting as presacrococcygeal cystic mass in a neonate: a rare case report

Presacrococcygeal mass in a neonate always creates diagnostic confusion due to various etiologies. Large masses interfere with labour management and development of pelvic spine and organs. Awareness about prenatal radiological diagnosis of sacral lesion in fetus is needed for earlier and better management of mass in postnatal period. Here, we report a case of neonate with a large sacrococcygeal mass noticed in antenatal period and diagnosed as cystic sacrococcygeal teratoma by histopathology.

Phenotypic Correlates of Pelvic Spine Coloration in the Threespine Stickleback (Gasterosteus aculeatus): Implications for Function and Evolution.

Animal color patches may be static or plastic in expression and concealable or continuously visible, yet the evolution and function of these aspects of coloration have seldom been studied together. We investigated such color pattern elements using the threespine stickleback (Gasterosteus aculeatus). Despite a rich history of study of stickleback nuptial color pattern evolution, disagreement persists regarding selection pressures and function and only limited research has addressed the role of pelvic spine coloration, a potentially important, and substantially concealable, color pattern element. We investigated (i) whether male pelvic spine (along with throat and body) coloration is relatively static or plastic across the reproductive cycle, (ii) when pelvic spines are raised versus concealed across behavioral contexts, and (iii) associations between color patches and behavior in males. We found no significant variation in spine color across reproductive stages whereas body color was more plastic and intensely red during courtship and egg/fry care. Conspicuousness of pelvic spine coloration instead varied behaviorally, through increased erection frequency during social interactions and in response to a model predator. Spine erection frequency was positively associated with behaviors that enhance spine color visibility, i.e. flees and leads to nest. These findings suggest that stickleback use pelvic spines to display an intensely red color patch facultatively, either as a complement to similar body coloration or possibly as a substitute.

Patients with combined pelvic and spinal injuries have worse clinical and operative outcomes than patients with isolated pelvic injuries analysis of the German Pelvic Registry

BackgroundPelvic fractures are often associated with spine injury in polytrauma patients. This study aimed to determine whether concomitant spine injury influence the surgical outcome of pelvic fracture.MethodsWe performed a retrospective analysis of data of patients registered in the German Pelvic Registry between January 2003 and December 2017. Clinical characteristics, surgical parameters, and outcomes were compared between patients with isolated pelvic fracture (group A) and patients with pelvic fracture plus spine injury (group B). We also compared apart patients with isolated acetabular fracture (group C) versus patients with acetabular fracture plus spine injury (group D).ResultsSurgery for pelvic fracture was significantly more common in group B than in group A (38.3% vs. 36.6%; p = 0.0002), as also emergency pelvic stabilizations (9.5% vs. 6.7%; p < 0.0001). The mean time to emergency stabilization was longer in group B (137 ± 106 min vs. 113 ± 97 min; p < 0.0001), as well as the mean time until definitive stabilization of the pelvic fracture (7.3 ± 4 days vs. 5.4 ± 8.0 days; p = 0.147). The mean duration of treatment and the morbidity and mortality rates were all significantly higher in group B (p < 0.0001). Operation time was significantly shorter in group C than in group D (176 ± 81 min vs. 203 ± 119 min, p < 0.0001). Intraoperative blood loss was not significantly different between the two groups with acetabular injuries. Although preoperative acetabular fracture dislocation was slightly less common in group D, postoperative fracture dislocation was slightly more common. The distribution of Matta grades was significantly different between the two groups. Patients with isolated acetabular injuries were significantly less likely to have neurological deficit at discharge (94.5%; p < 0.0001). In-hospital complications were more common in patients with combined spine plus pelvic injuries (groups B and D) than in patients with isolated pelvic and acetabular injury (groups A and C).ConclusionsDelaying definitive surgical treatment of pelvic fractures due to spinal cord injury appears to have a negative impact on the outcome of pelvic fractures, especially on the quality of reduction of acetabular fractures.

Функціональний стан нижніх кінцівок у хворих з ортопедичними проявами спінальних дизрафій

Спінальні дизрафії є важливою причиною статико-локомоторних порушень у дітей. Залежно від рівня ураження спинного мозку виникає різний ступінь паралічу чи парезу нижніх кінцівок, порушення функції тазових органів, деформації кінцівок і хребта, що значною мірою впливає на якість життя дитини та її можливість до пересування та обслуговування. Мета: залежно від рівня функціональної недостатності нижніх кінцівок оцінити здатність до пересування хворих із наслідками відкритих форм спінальних дизрафій. Матеріали та методи. Матеріал дослідження становили 81 пацієнт віком від 5 до 21 року (середній вік 8 років 10 місяців): у 69 пацієнтів спостерігався парапарез нижніх кінцівок, у 12 — монопарез. Визначення рівня нейросегментарного ураження спинного мозку проводилося згідно з класифікацією Sharrard`s (1964) у модифікації Bartonek et al. (1999). Здатність до пересування оцінювали за класифікацією Hoffer et al. (1973). Результати та обговорення. Всіх хворих, включених у дослідження, розподілено відповідно до рівня функціональної м’язової сили на 5 клінічних груп із визначеним рівнем функціональної м’язової сили за класифікацією Sharrard’s (1964) у модифікації Bartonek et al. (1999), проведено оцінку фактичного ступеня пересування хворих за Hoffer (1973). Порівняння отриманого фактичного ступеня пересування до теоретично очікуваного ступеня пересування пацієнтів показало, що діти з однаковим рівнем функціональної недостатності нижніх кінцівок не завжди досягають очікуваного ступеня пересування, а залежно від впливу супутніх факторів, таких як інтелектуальний (розумовий) рівень дитини, прогресування гідроцефалії, ожиріння, тяжкість ортопедичної патології, наявність спастичності та інші, можуть досягати як вищого, так і гіршого ступеня пересування. Висновки. Рівень нейросегментарного ураження спинного мозку, що визначає рівень м’язової функції нижніх кінцівок, є важливим фактором у здатності до пересування хворих із наслідками спінальних дизрафій. Пацієнти з однаковим рівнем втрати м’язової функції не завжди досягають очікуваного рівня пересування.

Pelvic pain in Maigne\u2019s syndrome\u2014a multi-segmental approach

BackgroundMaigne’s syndrome is a poorly understood condition that affects the thoracolumbar junction. The symptoms can range from pain in the low back, pelvis, hip, lower abdomen, and groin. These symptoms can have bio-mechanical and neurophysiological attributions due to the complexity of spinal mechanics. Thoraco-lumbar junction (T12-L1) is a transitional zone with a higher degree of mean angular motion and a mean translation motion than T10-T11 and T11-T12. This higher degree of translational and rotation mobility predisposes these segments to a higher degree of stress, making them more prone to biomechanical faults such as dysfunctions and positional faults. These altered static and dynamic mechanics can create a cascade of problems along the biomechanical chain. The co-existence of thoracolumbar junction problems with pelvic pain and dysfunctions strengthens the idea of regional interdependence.Case presentationThe patient is a 44-year-old Caucasian male who reported pain in the low back with symptoms radiating to the right hip, iliac region, lower abdomen, and gluteal region. The patient tested positive for Sacroiliac joint dysfunction with both Laslett’s cluster testing and palpatory sacroiliac examination. In addition, the segmental examination showed restriction in thoracolumbar junction with positive skin rolling test and hypomobility in manual segmental testing. Thus, the manual therapy treatment targeted the thoracolumbar junction and sacroiliac joint to address the underlying biomechanical dysfunctions.ConclusionsThe manual therapy targeting both sacroiliac and thoracolumbar spine can improve pelvic and thoracic spine mobility. In addition, therapeutic exercises can focus on enhancing anterior and posterior chain force generation capacity. This combined approach helped improve functional outcomes with a significant decrease in the Modified Oswestry Disability index and significant improvement on Visual analog scale.

Sexual dimorphism patterns of the White Sea threespine stickleback (&lt;em&gt;Gasterosteus aculeatus&lt;/em&gt;)

Sexual dimorphism (SD) in the threespine stickleback Gasterosteus aculeatus reflects the different roles of the sexes in reproduction and their adaptations to different ecological niches. We quantified SD in one population of marine stickleback from the White Sea, collected during the spawning period from three spawning grounds, each at a distance of 5 km or less from the others. We used a landmark-based approach to quantify variation in 44 morphometric linear traits. In total, 749 females and 693 males were analyzed. In males, anterior body parts are larger — the base of the caudal fin and armor structures such as the first and second dorsal spines and the pelvic spine. Females have larger posterior bodies — the abdomen, pelvic girdle and the third dorsal spine. The SD of caudal body parts exhibits complex patterns. In White Sea threespine stickleback, SD patterns are generally similar to other populations of the species, but more often show male-biased patterns. Female-biased size SD may be associated with the female biased sex ratio of White Sea stickleback.

Spine, Pelvis and Hip Kinematics—Characterizing the Axial Plane in Healthy and Osteoarthritic Hips

Abnormal spinopelvic movements are associated with inferior outcomes following total hip arthroplasty (THA). This study aims to (1) characterize the agreement between dynamic motion and radiographic sagittal assessments of the spine, pelvis, and hip; (2) determine the effect of hip osteoarthritis (OA) on kinematics by comparing healthy individuals with pre-THA patients suffering from uni- or bilateral hip OA. Twenty-four OA patients pre-THA and eight healthy controls underwent lateral spinopelvic radiographs in standing and seated bend-and-reach (SBR) positions. Lumbar-lordosis (LL), sacral-slope (SS), and pelvic–femoral (PFA) angles were measured in both positions, and the differences (Δ) between SBR and standing were computed to assess spine flexion (SF), pelvic tilt (PT), and hip flexion (HF), respectively. Dynamic SBR and seated maximal trunk rotation (STR) tasks were performed at the biomechanics laboratory. Peak sagittal and axial kinematics for spine, pelvis, and hip, and range of motion (ROM), were calculated for SBR and STR. Radiograph readings correlated with sagittal kinematics during SBR for ΔLL and SFmax (r = 0.66, p &lt; 0.001), ΔPT and PTmax (r = 0.44, p = 0.014), and ΔPFA and HFmax (r = 0.70, p &lt; 0.001), with a satisfactory agreement in Bland–Altman analyses. Sagittal SBR spinal (r = 0.33, p = 0.022) and pelvic (r =0.35, p = 0.018) flexions correlated with the axial STR rotations. All axial spinopelvic parameters were different between the OA patients and controls, with the latter exhibiting significantly greater mobility and less variability. Bilaterally affected patients exhibited lower peak and ROM compared to controls. The biomechanics laboratory performed reliable assessments of spinopelvic and hip characteristics, in which the axial plane can be included. The sagittal and axial pelvic kinematics correlate, illustrating that pelvic rotation abnormalities are likely also contributing to the inferior outcomes seen in patients with abnormal spinopelvic flexion characteristics. Axial rotations of the pelvis and spine were least in patients with bilateral hip disease, further emphasizing the importance of the hip–pelvic–spine interaction.

Parallel and non-parallel divergence within polymorphic populations of brook stickleback,Culaea inconstans(Actinopterygii: Gasterosteidae)

AbstractStudying parallel evolution allows us to draw conclusions about the repeatability of adaptive evolution. Whereas populations likely experience similar selective pressures in similar environments, it is not clear if this will always result in parallel divergence of ecologically relevant traits. Our study investigates the extent of parallelism associated with the evolution of pelvic spine reduction in brook stickleback populations. We find that populations with parallel divergence in pelvic spine morphology do not exhibit parallel divergence in head and body morphology but do exhibit parallel divergence in diet. In addition, we compare these patterns associated with pelvic reduction in brook stickleback to well-studied patterns of divergence between spined and unspined threespine stickleback. Whereas spine reduction is associated with littoral habitats and a benthic diet in threespine stickleback, spine reduction in brook stickleback is associated with a planktonic diet. Hence, we find that pelvic spine divergence is associated with largely non-parallel ecological consequences across species.

Longer or shorter spines: Reciprocal trait evolution in stickleback via triallelic regulatory changes in Stanniocalcin2a

Vertebrates have repeatedly modified skeletal structures to adapt to their environments. The threespine stickleback is an excellent system for studying skeletal modifications, as different wild populations have either increased or decreased the lengths of their prominent dorsal and pelvic spines in different freshwater environments. Here we identify a regulatory locus that has a major morphological effect on the length of stickleback dorsal and pelvic spines, which we term Maser (major spine enhancer). Maser maps in a closely linked supergene complex that controls multiple armor, feeding, and behavioral traits on chromosome IV. Natural alleles in Maser are differentiated between marine and freshwater sticklebacks; however, alleles found among freshwater populations are also differentiated, with distinct alleles found in short- and long-spined freshwater populations. The distinct freshwater alleles either increase or decrease expression of the bone growth inhibitor gene Stanniocalcin2a in developing spines, providing a simple genetic mechanism for either increasing or decreasing spine lengths in natural populations. Genomic surveys suggest many recurrently differentiated loci in sticklebacks are similarly specialized into three or more distinct alleles, providing multiple ancient standing variants in particular genes that may contribute to a range of phenotypes in different environments.

Carotenoids-based reddish pelvic spines in nonreproducing female and male sticklebacks (Gasterosteus aculeatus) - Signalling social dominance?

Conspicuous ornaments are often considered a result of evolution by sexual selection. According to the social selection hypothesis, such conspicuous traits may also evolve as badges of status associated with increased boldness or aggression toward conspecifics in conflicts about ecological resources. This study tested predictions from the social selection hypothesis to explain evolution of conspicuous red color of the pelvic spines of the three‐spine stickleback (Gasterosteus aculeatus). Wild nonreproducing sticklebacks were presented to pairs of dummies which differed at their pelvic spines, having either (i) normal‐sized gray or red pelvic spines or (ii) normal‐sized gray or large red pelvic spines. The experimental tank was illuminated by white or green light, since green light impedes the sticklebacks’ ability to detect red color. The dummies moved slowly around in circles at each end of the experimental tank. We quantified the parameters (i) which of the two dummies was visited first, (ii) time taken before the first visit to a dummy, (iii) distribution of the focal sticklebacks in the two zones close to each of the two dummies and in the neutral zone of the tank, (iv) close to which of the two dummies did the focal fish eat its first food‐piece, and (v) time spent until the first piece of food was eaten. This was carried out for 22 females and 29 males sticklebacks. The results suggested no effect of the color or size of the dummies’ pelvic spines, on none of the five behavioral parameters. Moreover, neither the color of the pelvic spines of the focal sticklebacks themselves (as opposed to redness of the dummies’ spines) nor their body length was associated with behavior toward the dummies. Thus, this study did not support predictions from the social selection hypothesis to explain evolution of red pelvic spines in sticklebacks.