title: Females Have Larger Ratio of Second-to-Fourth Digits Than Males in Four Species of Salamandridae, Caudata.
abstract: Digit ratio (2D:4D) denotes the relative length of the second and fourth digits. It is considered to be a suitable biomarker of the in utero balance of fetal sex hormones, which affect early development of individuaĺs behavioral and morphological characteristics. In recent decades, digit ratio attracted a great attention in biology and psychology. However, for unmasking the biological basis of the phenomenon, extensive studies on non-human animals are necessary. Despite it was hypothesized that digit ratio is well conserved in all Tetrapoda, and there exist studies on mammals, birds, and reptiles, there are only two such study on anuran amphibians. Therefore, the aim of this study is to investigate the 2D:4D in the most basal salamanders, Caudata. We have studied digit ratio in four species of newts: Triturus cristatus, Mesotriton alpestris, Lissotriton montandoni, and Lissotriton vulgaris, using museum collection. We used computerized measuring of each limbś photos. We have found out that, in M. alpestris, females 2D:4D of all four limbs were significantly larger than in males. In L. montandoni and L. vulgaris, only 2D:4D of rear limbs significantly differed, in females being larger. In T. cristatus, digit ratios of males and females did not statistically differ. Thus, the results confirmed our hypothesis that at least in M. alpestris, L. montandoni, and L. vulgaris, females seem to have larger 2D:4D comparing to males, the pattern known from most mammals and opposite to birds, reptiles and anuran amphibians.
authors.affiliation: Department of Zoology, Institute of Zoology, Poznań University of Life Sciences, Poznań, Poland.
authors.forename: Mikołaj
authors.initials: M
authors.lastname: Kaczmarski
authors.affiliation: Department of Human Evolutionary Biology, Institute of Anthropology, Faculty of Biology, Adam Mickiewicz University in Poznań, Poznań, Poland.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Kubicka
authors.affiliation: Department of Zoology, Institute of Zoology, Poznań University of Life Sciences, Poznań, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Tryjanowski
authors.affiliation: Department of Ecology, Faculty of Humanities and Natural Sciences, Laboratory and Museum of Evolutionary Ecology, University of Prešov, Prešov, Slovakia.|Department of Nature Conservation, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra, Poland.
authors.forename: Martin
authors.initials: M
authors.lastname: Hromada
mesh_terms: D059925:Anatomic Landmarks; D000818:Animals; D005260:Female; D007091:Image Processing, Computer-Assisted; D008297:Male; D010781:Photography; D012455:Salamandridae / Q000033:anatomy & histology* / Q000145:classification; D012737:Sex Factors; D013045:Species Specificity; D014034:Toes / Q000033:anatomy & histology*
keywords: digit ratio (2D:4D); measurements; newt; sex differences; tailed amphibians