scholarly journals Ontogeny of a sexually selected structure in an extant archosaur Gavialis gangeticus (Pseudosuchia: Crocodylia) with implications for sexual dimorphism in dinosaurs

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9134 ◽  
Author(s):  
David Hone ◽  
Jordan C. Mallon ◽  
Patrick Hennessey ◽  
Lawrence M. Witmer
Keyword(s):  
Sexual Dimorphism ◽  
A Priori ◽  
Small Sample ◽  
Egg Laying ◽  
Sexually Dimorphic ◽  
Large Dataset ◽  
Unique Model ◽  
Small Sample Sizes ◽  
Gavialis Gangeticus ◽  
Slow Growing

Despite strong evidence for sexual selection in various display traits and other exaggerated structures in large extinct reptiles, such as dinosaurs, detecting sexual dimorphism in them remains difficult. Their relatively small sample sizes, long growth periods, and difficulties distinguishing the sexes of fossil specimens mean that there are little compelling data on dimorphism in these animals. The extant gharial (Gavialis gangeticus) is a large and endangered crocodylian that is sexually dimorphic in size, but males also possesses a sexually selected structure, the ghara, which has an osteological correlate in the presence of a fossa associated with the nares. This makes the species a unique model for potentially assessing dimorphism in fossil lineages, such as dinosaurs and pterosaurs, because it is a large, slow-growing, egg-laying archosaur. Here we assess the dimorphism of G. gangeticus across 106 specimens and show that the presence of a narial fossa diagnoses adult male gharials. Males are larger than females, but the level of size dimorphism, and that of other cranial features, is low and difficult to detect without a priori knowledge of the sexes, even with this large dataset. By extension, dimorphism in extinct reptiles is very difficult to detect in the absence of sex specific characters, such as the narial fossa.

A comparative geochemical study of Mars and Earth basalt petrogenesis

2013 ◽  
Vol 50 (1) ◽  
pp. 78-93 ◽  
Author(s):  
John D. Greenough ◽  
Avee Ya’acoby
Keyword(s):  
Incompatible Element ◽  
A Priori ◽  
Correlation Coefficients ◽  
Small Sample ◽  
Geochemical Data ◽  
Data Set ◽  
Element Ratios ◽  
Highly Correlated ◽  
Small Sample Sizes ◽  
Priori Information

Geochemical data, from the Mars Meteorite Compendium web site, for 13 basaltic meteorites, possibly from only four localities on Mars, are used to study Martian petrogenetic processes. To achieve this goal, an exploratory data analysis technique, multidimensional scaling (MDS), is used to quantitatively assess the relative behavior (measured with correlation coefficients) of 160 incompatible element ratios involving 25 “trace” elements. The ratios behave as in Earth basalts, suggesting that relative element incompatibility is similar in both planets. Because mineralogy controls incompatibility, the mineralogy of Earth and Mars mantles appears similar. In addition, results suggest that ratios involving elements with highly different incompatibility (e.g., La/Yb) are dominantly controlled by % melting. Plots of SiO2 (pressure proxy; decreases with increasing pressure) versus La/Yb and Nb/Y (decrease as melting increases) imply that Mars basalts, like Earth tholeiites, reflect high percentages of melting, but opposite to Earth, % melting appears to increase with increasing pressure. The moderately correlated, positive, SiO2–La/Yb Mars relationship parallels highly correlated Lunar KREEP data and contrasts with Earth’s negative correlation. The positive relationships may reflect restricted mantle convection in some (Mars and the Moon are smaller) planetary bodies. Using similarly incompatible element ratios that are sensitive to source composition, to compare Mars and Earth with MDS, Mars sources most resemble depleted Earth mantle. Additionally, these ratios group Mars sources into enriched, depleted, and intermediate types. The groupings are the same as those suggested by isotopes, and we conclude that trace element data support the hypothesis that chemical variation in Mars may reflect crystallization of a Mars magma ocean. The natural patterns in ratios and samples revealed using MDS, which has no a priori information about relationships, support integrity of the geochemical data set, despite potential shortcomings such as small sample sizes, alteration, and weathering. However, whether the meteorites are representative of Mars as a whole is unknown.

scholarly journals Serum biochemistry profile determination for wild loggerhead sea turtles nesting in Campos dos Goytacazes, Rio de Janeiro, Brazil

2011 ◽  
Vol 41 (1) ◽  
pp. 143-148 ◽  
Author(s):  
Daphne Wrobel Goldberg ◽  
Juçara Wanderlinde ◽  
Isabel Maria Alexandre Freire ◽  
Luiz Cesar Pereira da Silva ◽  
Nadia Regina Pereira Almosny
Keyword(s):  
Sea Turtles ◽  
Serum Biochemistry ◽  
Average Concentration ◽  
Reproductive Period ◽  
Small Sample ◽  
Egg Laying ◽  
Loggerhead Sea Turtles ◽  
Hepatic Volume ◽  
Calcium Phosphorus ◽  
Small Sample Sizes

Sea turtles are threatened to the point of extinction. The major goal of rehabilitating sick individuals is to eventually reintroduce them back into their habitat. In this way, they contribute to species preservation, as well as maintaining equilibrium of the ecosystems. Biochemical analysis is a commonly used test to detect illness and evaluate the general health of the animals. However, the data in the literature on sea turtles are scarce and the majority of studies used small sample sizes, being the majority of animals in captivity. The aim of the present study is to establish baseline biochemical profile values for free-ranging, nesting, female loggerhead turtles (Caretta caretta). The baseline values can then be used for comparison in the overall evaluation, physiologic status and disease diagnostics of diverse populations of sea turtles. Twenty-eight females in their reproductive period were used from Farol de São Thomé (21°45'15"S - 41°19'28"W), city of Campos dos Goytacazes, north-fluminense region. The samples were collected without anticoagulant through venapuncture of the dorsal, cervical sinus. The average values determined were calcium, phosphorus, cholesterol and triglycerides, demonstrating a correlation with vitellogenesis and egg formation. The fact that females reduce feeding in the period preceding egg laying, influenced the average concentration of urea (35.25mg dL-1), sodium (147mEq L-1), potassium (28mEq L-1), uric acid (0.6mg dL-1) and lipids. Carapace length and width, and the weight of the turtles showed a positive correlation with liver enzymes ALT and AST, suggesting that animals with larger hepatic volume have greater enzymatic activity.

Recognizing sexual dimorphism in the fossil record: lessons from nonavian dinosaurs

Paleobiology ◽  
2017 ◽  
Vol 43 (3) ◽  
pp. 495-507 ◽  
Author(s):  
Jordan C. Mallon
Keyword(s):  
Sexual Dimorphism ◽  
Fossil Record ◽  
Statistical Tests ◽  
A Priori ◽  
Mixture Modeling ◽  
Statistical Investigation ◽  
Morphological Data ◽  
Sexually Dimorphic ◽  
Quantitative Evidence ◽  
Evolution Of Life

AbstractThe demonstration of sexual dimorphism in the fossil record can provide vital information about the role that sexual selection has played in the evolution of life. However, statistically robust inferences of sexual dimorphism in fossil organisms are exceedingly difficult to establish, owing to issues of sample size, experimental control, and methodology. This is particularly so in the case of dinosaurs, for which sexual dimorphism has been posited in many species, yet quantifiable data are often lacking. This study presents the first statistical investigation of sexual dimorphism across Dinosauria. It revisits prior analyses that purport to find quantitative evidence for sexual dimorphism in nine dinosaur species. After the available morphological data were subjected to a suite of statistical tests (normality and unimodality tests and mixture modeling), no evidence for sexual dimorphism was found in any of the examined taxa, contrary to conventional wisdom. This is not to say that dinosaurs were not sexually dimorphic (phylogenetic inference suggests they may well have been), only that the available evidence precludes its detection. A priori knowledge of the sexes would greatly facilitate the assessment of sexual dimorphism in the fossil record, and it is suggested that unambiguous indicators of sex (e.g., presence of eggs, embryos, medullary bone) be used to this end.

scholarly journals Malleefowl Leipoa ocellata breeding behaviour: Insights from citizen science camera surveillance

2021 ◽  
Vol 38 ◽  
pp. 87-98
Author(s):  
Heather Neilly ◽  
◽  
David Wells ◽  
Tim Pascoe ◽  
Peter Cale ◽  
...  
Keyword(s):  
Citizen Science ◽  
Direct Observation ◽  
Small Sample ◽  
Egg Laying ◽  
Camera Traps ◽  
Male And Female ◽  
Breeding Behaviour ◽  
Small Sample Sizes ◽  
Breeding Seasons ◽  
Camera Surveillance

Observations on natural history are a useful but often overlooked branch of ecology. With the use of camera-traps, collection of data e.g. on breeding behaviour and success has never been easier, particularly when studying cryptic species. Additionally, camera-traps are well suited to citizen science because of their ease of operation and the ability to store and verify data. Malleefowl Leipoa ocellata breeding behaviour has previously been studied through direct observation or timelapse photography, resulting in small sample sizes and potentially biased observations. Using camera-trap data collected by citizen scientists, we examined the breeding behaviour of this species. We quantified the timing and duration of mound-tending activities at 20 mounds using camera surveillance for >30,000 hours (1250 days) over six breeding seasons. Time spent at the mound during five mound stages and visit frequencies by the male and female during each stage are reported. Femaleinvolvement at the mound was consistent, although males spent three times as long at the mound compared with females during egg-laying. On egg-laying days, females spent longer uncovering the mound, compared with covering the mound post egg-laying. Our findings confirm that both male and female Malleefowl spend a substantial amount of time constructing and maintaining their mound throughout the year and, most notably, that the female consistently participates in mound-tending.These insights are particularly valuable as our surveillance was over markedly longer time spans than previous studies that relied upon direct observation.

scholarly journals Preregistration in infant research - a primer

2019 ◽  
Author(s):  
Naomi Havron ◽  
Christina Bergmann ◽  
Sho Tsuji
Keyword(s):  
Best Practices ◽  
Statistical Power ◽  
A Priori ◽  
Small Sample ◽  
Infant Research ◽  
Study Planning ◽  
Power Increase ◽  
Research Plan ◽  
Small Sample Sizes ◽  
As Effects

Preregistration, the act of specifying a research plan in advance, is becoming a central step in the way science is conducted. Preregistration for infant researchers might be different than in other fields, due to the specific challenges having to do with testing infants. Infants are a hard-to-reach population, usually yielding small sample sizes, they have a low attention span which usually can limit the number of trials, and they can be excluded based on hard to predict complications (e.g., parental interference, fussiness). In addition, as effects themselves potentially change with age and population, it is hard to calculate an a priori effect size. At the same time, these very factors make preregistration in infant studies a valuable tool. A priori examination of the planned study, including the hypotheses, sample size, and resulting statistical power, increase the credibility of single studies and thus add value to the field. It might arguably also improve explicit decision-making to create better studies. We present an in-depth discussion of the issues uniquely relevant to infant researchers, and ways to contend with them in preregistration and study planning. We provide recommendations to researchers interested in following current best practices.

Underpowered and Overworked: Problems With Data Analysis in Motor Learning Studies

2016 ◽  
Vol 4 (1) ◽  
pp. 37-58 ◽  
Author(s):  
Keith Lohse ◽  
Taylor Buchanan ◽  
Matthew Miller
Keyword(s):  
Motor Learning ◽  
Statistical Tests ◽  
A Priori ◽  
Small Sample ◽  
Effect Sizes ◽  
Null Results ◽  
Editorial Boards ◽  
The Past ◽  
Dependent Variables ◽  
Small Sample Sizes

Appropriate statistical analysis is essential for accurate and reliable research. Statistical practices have an immediate impact on the perceived results of a single study but also remote effects on the dissemination of information among scientists and the cumulative nature of research. To accurately quantify potential problems facing the field of motor learning, we systematically reviewed publications from seven journals over the past 2 years to find experiments that tested the effects of different training conditions on delayed retention and transfer tests (i.e., classic motor learning paradigms). Eighteen studies were included. These studies had small sample sizes (Mdn n/group = 11.00, interquartile range [IQR]= 9.6–15.5), multiple dependent variables (Mdn = 2, IQR = 2–4), and many statistical tests per article (Mdn = 83.5, IQR = 55.8–112.5). The observed effect sizes were large (d = 0.71, IQR = 0.49, 1.11). However, the distribution of effect sizes was biased, t(16) = 3.48, p < .01. These metadata indicate problems with the way motor learning research is conducted (or at least published). We recommend several potential solutions to address these issues: a priori power calculations, prespecified analyses, data sharing, and dissemination of null results. Furthermore, we hope these data will spark serious action from all stakeholders (researchers, editorial boards, and publishers) in the field.

scholarly journals Effect of Exercise Interventions on Anxiety in People with Multiple Sclerosis

2019 ◽  
Vol 22 (3) ◽  
pp. 103-109
Author(s):  
Claudia Gascoyne ◽  
Amalia Karahalios ◽  
Thibaut Demaneuf ◽  
Claudia Marck
Keyword(s):  
Multiple Sclerosis ◽  
Primary Outcome ◽  
Meta Analysis ◽  
A Priori ◽  
Primary Outcome Measure ◽  
Small Sample ◽  
Risk Of Bias ◽  
Exercise Interventions ◽  
Mean Differences ◽  
Small Sample Sizes

Abstract Background: Evidence suggests that exercise can alleviate symptoms associated with multiple sclerosis (MS). However, it is unclear whether exercise alleviates symptoms of anxiety, present in one-third of people with MS. This systematic review and meta-analysis investigates whether exercise interventions are effective in reducing anxiety in people with MS. Methods: CINAHL, Embase, MEDLINE, PsycINFO, and the Cochrane Controlled Clinical Trials Register were searched to identify relevant randomized controlled trials (RCTs) published up to March 30, 2018. The primary outcome was postintervention difference in anxiety scores between intervention and control groups. Using a restricted maximum likelihood random-effects model, standardized mean differences were pooled and heterogeneity was estimated. Risk of bias was assessed using an a priori modified Cochrane Risk of Bias 2.0 tool. Results: Four RCTs with 133 participants were included. Exercise type included walking, aerobic activities, and cycling. Intervention duration ranged from 8 to 26 weeks. The pooled standardized mean difference in anxiety score was −0.16 (95% CI, −0.50 to 0.19), without heterogeneity. Two studies had high risk of bias, and two had some risk of bias. Conclusions: Based on available RCT data, exercise does not seem to have an effect on anxiety in people with MS. These results should be interpreted with caution because studies had concerns of bias and small sample sizes, and anxiety was not the primary outcome measure. Future studies should exhibit sufficient reporting standards, alongside publishing protocols. There is opportunity to investigate the effect of exercise in people with MS experiencing clinically relevant levels of anxiety rather than in the general MS population.

Integrating Visual and Bayesian Statistical Analyses in Single Case Experimental Research to Evaluate the Effectiveness and Magnitude of a Comprehensive Behavioral Intervention

2018 ◽  
Author(s):  
Prathiba Natesan ◽  
Smita Mehta
Keyword(s):  
Behavioral Intervention ◽  
Effect Size ◽  
Rate Ratio ◽  
Visual Analysis ◽  
Single Case ◽  
Small Sample ◽  
Statistical Analyses ◽  
Data Types ◽  
Ratio Effect ◽  
Small Sample Sizes

Single case experimental designs (SCEDs) have become an indispensable methodology where randomized control trials may be impossible or even inappropriate. However, the nature of SCED data presents challenges for both visual and statistical analyses. Small sample sizes, autocorrelations, data types, and design types render many parametric statistical analyses and maximum likelihood approaches ineffective. The presence of autocorrelation decreases interrater reliability in visual analysis. The purpose of the present study is to demonstrate a newly developed model called the Bayesian unknown change-point (BUCP) model which overcomes all the above-mentioned data analytic challenges. This is the first study to formulate and demonstrate rate ratio effect size for autocorrelated data, which has remained an open question in SCED research until now. This expository study also compares and contrasts the results from BUCP model with visual analysis, and rate ratio effect size with nonoverlap of all pairs (NAP) effect size. Data from a comprehensive behavioral intervention are used for the demonstration.

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