Type 2 Diabetes Phenotype in a Small Isolated Zapotec-Speaking Community in the Valley of Oaxaca, Southern Mexico

Objective: To test the hypothesis that the type 2 diabetes mellitus (T2DM) phenotype in an indigenous population is characterized by proportionally short legs and obesity. Methods: Anthropometric characteristics were compared in females and males with T2DM (n = 20, n = 8, respectively) and without T2DM (n = 117, n = 93, respectively). Factor analysis derived dimensions were regressed on T2DM in logistic regression. Results: Weight, sitting height ratio and hip circumference were significantly lower (p < 0.0001) in females, while waist: hip ratio was significantly higher among women and men with T2DM (p < 0.0001 and p < 0.008, respectively). Arm circumference, triceps skinfold, arm muscle circumference, and right and left grip strength were significantly lower among T2DM women (p < 0.0001 for each). Five rotated principal components accounted for 86.7% of the variance: muscular (grip) strength (29.6%), body mass (27.9%), central adiposity (10.7%), body height (9.3%), and trunk length (9.2%). Regression of factors on T2DM status among females indicated muscle strength (OR = 0.16, 95% CI: 0.04 - 0.71) and central adiposity (OR = 13.76, 95% CI: 3.80 - 49.83) were predictors of T2DM. In males, muscle strength (OR = 0.28, 95% CI: 0.07 - 1.08, p < 0.06) and central adiposity significantly predicted T2DM (OR = 3.17, 95% CI: 95% 1.11 - 9.04, p < 0.008). Conclusion: Reduced muscle strength/mass and increased central adiposity characterize the T2DM phenotype.

Parallel patterns and trends in functional structures in extinct island mammals

Endemic mammalian species on islands are generally known to have followed a different evolutionary pathway than their mainland relatives. General patterns, such as body size trends, have been described regularly. How-ever, most island mammal species are unique and each of them is adapted to a specific local niche as part of an equally specific ecological assemblage. Therefore, comparing island species across taxa, islands and time is in-herently dangerous without understanding the adaptational value of the studied feature in the compared taxa and without taking the ecological setting of the taxa into account. In this contribution, general and recurring patterns are described per taxon. Some features, like body mass change and sturdy limbs, are relatively general, where-as most features, like bone fusions and change of orbital axis, occur only in a very few taxa. Some features are even contradictory, such as brain size and degree of hypsodonty, with each taxon having its own particular de-sign. In conclusion, general patterns are more often than not just trends and need to be applied with caution.