A New Statistical Method for Comparative Anatomy

Abstract

Rules, formulas and statistical tests have been widely used in studies that use continuous variables in the normal or Gaussian distribution or other tests whose data fit this type of distribution (t and z distributions) and whose parameters can be defined. However, there are cases in which the model and goal of the scientific work allow only the use of discrete or nominal variables. The absence or presence of a structure or organ (muscles, nerves, blood vessels, bones, and ligaments), characteristics associated with these organs, such as the source of nerves, vessels and muscles and the distribution of nerves and vessels are discrete and / or nominal variables that do not fit the Gaussian distribution, nor of z or t, unless the measures of these structures are taken. A simple comparative method within the non-parametric distribution has been proposed, (1) between two different samples from the same species and (2) for two different species, based on the concepts of normal and variation in anatomy and on modal class in statistics here called Comparative Anatomy Index (IAC). The main findings on the use of this method are: (1) to allow the relationship between data from discrete or nominal variables in comparative anatomy or in other areas of morphology, (2) to generate an objective method (numerical) of comparison between samples of structures from the same species and between different species and (3) to fill the lack of a specific method for the statistical work in comparative anatomy or in morphology, in general.

Comparative anatomy of the arm muscles of the Japanese monkey (Macaca fuscata) with some comments on locomotor mechanics and behavior

“…Nonparametric methods [e.g., CAI (Comparative Anatomy Index) and GCAI (Group Comparative Anatomy Index)] were used in this work to avoid and/or decrease subjective interpretation of the anatomical data and to allow analyses of the muscles group similarities/dissimilarities among structures and species . This statistic provides higher accuracy and can avoid extensive descriptions in gross anatomy.…”

“…Indeed, numerical parametric statistical assumptions of normality and variation (standard deviation, average deviation) are not appropriate to this kind of work with nominal data. Therefore, to analyze the anatomical data objectively based on the previous studies (for detailed discussion, see reference ), we introduced the nonparametric methods to describe nominal variables such as muscles’ innervation, origin, insertion, and vascularization quantitatively and to compare them numerically among different species.…”

“…The statistical analysis used here was based on the methods described previously . The similarities of the arm muscles among different species were calculated based on these methods (Table ).…”

“…The aim of this work was to study the arm muscles of Japanese macaques with emphasis on their origins and insertions, as well as their innervation and vascularization. We previously proposed a quantitative, statistical method for comparative anatomy (SMCA) . In this study, using this statistical method, we also compared the anatomical data on Japanese monkeys with those of other primates including rhesus monkeys , the New World bearded capuchins ( Sapajus sp.)…”

Statistical approaches to assess intraspecific variations of morphological continuous characters: the case study of the family Phytoseiidae (Acari: Mesostigmata)

“…Description of intraspecific variation. Intraspecific variation of the 23 characters for the 14 Phytoseiidae species (279 data sets) was first described by commonly used statistical parameters (Sokal and Rohlf, 1981; Aversi‐Ferreira, 2009): mean (μ), median ( m ), standard error ( s ) and range [(max−min)/2]. However, as mean values were very different depending on the characters and species considered, these latter parameters could not be directly compared.…”